Lmst

#OutdoorOps

A Year End Compendium of Outside the Box Antenna Ideas

We have reached the end of another year of crazy ideas here at Ham Radio Outside the Box and a repeat of last year’s severe winter has gotten underway in southern Ontario. The daily temperature high remains well below freezing and the ground is buried under a thick blanket of snow already. I have tried to “Keep Warm and Carry On” with more off-the-wall outdoor antenna experiments but succumbed to the biting wind and had to retreat to the warmth of the shack.

Here in the nice toasty warmth of my basement “Comms Room” I am surrounded by radio equipment, electronic gizmos, tools and almost enough wire to lay a new transatlantic cable. I also have computers. One of the computers runs the incredible HamClock program giving me instant access to updated solar propagation conditions, the current location of the International Space Station and real time data on the International HF beacon project.

Another computer is the one on which I am typing this post now. I recently realized that I have written so many posts related to field portable antennas I have built and tried that it would be a useful exercise to re-read them all. Heck, I surprised myself with some of the ideas that were posted and forgotten, but will now be resurrected. So, to end the year, I have composed a compendium of 35 of those posts – old and not-so-old – as a reference for readers to explore. I hope you may find some useful information for your own deployments.

I should stress that these are not all tried and tested designs. Some have worked so well I intend to keep them in my hambag for field portable radio operations. Others … well they were useful learning opportunities. Even if you only pick up a couple of tips such as the simplest, quick release method of attaching an antenna wire to the top of a pole the read will be worth your time.

NB: If you find any of these posts particularly interesting you can use the “Print” function on your computer and select “Save to PDF” or “Print to file” to keep a local copy.

ZZZZZ … ZZZZ … ZZZ

Ham Radio Outside the Box will now go into hibernation until the new year. Until then my best wishes go out to all in the hope that you will enjoy whatever religious or secular festival you celebrate at this time of year. Stay out of the cold!

https://hamradiooutsidethebox.ca/2025/11/04/a-simple-fix-for-my-broken-telescopic-whip/

https://hamradiooutsidethebox.ca/2025/08/29/two-resonant-simple-wire-antennas-for-pota/

https://hamradiooutsidethebox.ca/2025/09/23/a-simple-low-profile-multiband-antenna-for-pota/

https://hamradiooutsidethebox.ca/2025/08/05/rapid-deployment-field-expedient-random-wire-antenna-ideas/

https://hamradiooutsidethebox.ca/2025/07/23/does-an-antenna-top-hat-really-work/

https://hamradiooutsidethebox.ca/2025/07/11/an-outside-the-box-version-of-the-delta-loop-antenna/

https://hamradiooutsidethebox.ca/2025/05/21/reviving-a-webster-band-spanner-a-1950s-manual-screwdriver-antenna/

https://hamradiooutsidethebox.ca/2022/08/15/vertical-antenna-redesigned/

https://hamradiooutsidethebox.ca/2022/07/30/no-antenna-no-problem/

https://hamradiooutsidethebox.ca/2022/06/21/80m-band-antenna-fits-into-just-1-square-foot/

https://hamradiooutsidethebox.ca/2021/12/17/an-easy-t2lt-portable-antenna/

https://hamradiooutsidethebox.ca/2021/11/08/a-portable-vertical-antenna/

https://hamradiooutsidethebox.ca/2021/09/13/a-most-unusual-antenna/

https://hamradiooutsidethebox.ca/2025/05/14/matching-an-efhw-antenna-a-third-way/

https://hamradiooutsidethebox.ca/2025/04/23/ssefhw-another-shortened-end-fed-half-wave-antenna-for-20m/

https://hamradiooutsidethebox.ca/2025/03/19/a-simple-antenna-that-is-omnidirectional-directional-and-nvis/

https://hamradiooutsidethebox.ca/2025/03/05/a-quick-and-easy-qrp-emergency-field-antenna/

https://hamradiooutsidethebox.ca/2025/01/16/a-top-loaded-end-fed-half-wave-antenna-for-20m/

https://hamradiooutsidethebox.ca/2024/12/12/a-clefhw-antenna/

https://hamradiooutsidethebox.ca/2024/11/13/antenna-height-matters-true-or-false/

https://hamradiooutsidethebox.ca/2024/10/09/the-titanic-40m-field-expedient-backpack-portable-antenna/

https://hamradiooutsidethebox.ca/2024/08/16/how-does-the-speaker-wire-no-counterpoise-antenna-work/

https://hamradiooutsidethebox.ca/2024/07/18/a-neat-trick-with-a-20m-efhw-wire-antenna/

https://hamradiooutsidethebox.ca/2024/03/13/an-improved-self-supporting-low-footprint-field-expedient-antenna-for-20m/

https://hamradiooutsidethebox.ca/2024/03/06/antennas-a-riddle-wrapped-in-a-mystery-inside-an-enigma/

https://hamradiooutsidethebox.ca/2024/02/14/a-most-unusual-vertical-antenna-for-20m/

https://hamradiooutsidethebox.ca/2023/12/06/a-simpler-field-expedient-rybakov-antenna-for-winter/

https://hamradiooutsidethebox.ca/2023/11/05/an-upside-down-antenna/

https://hamradiooutsidethebox.ca/2023/10/19/using-a-municipal-flagpole-for-an-antenna-fine-business/

https://hamradiooutsidethebox.ca/2023/02/15/the-vp2e-a-strange-but-proven-antenna/

https://hamradiooutsidethebox.ca/2023/02/09/what-in-heavens-name-is-a-rybakov-antenna/

https://hamradiooutsidethebox.ca/2023/01/14/a-magic-ground-mobile-antenna/

https://hamradiooutsidethebox.ca/2025/01/23/an-off-center-fed-sleeve-dipole/

https://hamradiooutsidethebox.ca/2024/07/12/cutting-my-losses/

https://hamradiooutsidethebox.ca/2023/10/24/an-itsy-bitsy-teeny-weeny-upside-down-hf-whip/

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#amateurRadio2 #antennas #counterpoise #cw #outdoorOps #portable #pota

What really determines the efficiency of an antenna?

Is it Standing Wave Ratio (SWR)?

It is common knowledge that when an antenna has high SWR some of our transmitted power is wasted instead of being transmitted. But is this really true? The trouble with “common knowledge” is that it spreads without further scrutiny. “It must be true because that’s what everybody thinks”. But let’s consider another perspective.

What happens to our signal when it meets an antenna with high SWR? Some of the signal is radiated while the rest is reflected back down the transmission line to its source – the transceiver. What happens to the reflected signal when it reaches the transceiver? It is re-reflected back towards the antenna and the cycle repeats.

So does all the signal eventually get radiated? No. Energy is lost (RED ALERT from the physics department: Energy can neither be created nor destroyed, only converted from one form to another). Ok, my apologies to the physics department, some of the energy is converted to heat as our signal passes along the transmission line and through any ununs, baluns, impedance transformers or other devices en route. Further energy is converted to heat due to the resistance of the wires and the impedance of the transmission line itself.

Thus, on every trip between the transceiver and the antenna, some of our transmitted RF is converted to heat. If the antenna has a high SWR some of our signal travels back and forth between the transceiver and the antenna multiple times and becomes further attenuated on each trip. Therefore, if we can reduce the loss of RF (due to conversion to heat) as it passes through any devices along the journey between the source (transceiver) and load (antenna) we will improve the efficiency of our antenna system.

How can we do that?

One simple way to achieve that is to correct for the high SWR right at the antenna. A remote tuner can do that. A loading coil will compensate for the high capacitive reactance of a short antenna, but loading coils can be inefficient because of wire resistance. This is especially true in the case of base-loading coils on a quarter-wave vertical antenna. The current is highest at the base of the antenna so more RF energy will be lost to heat (P=I^2*R) than with a center-loading or top-loading coil.

So the real culprit is not SWR, but the insertion loss of ununs, baluns, impedance transformers, loading coils, transmatches and any other “energy conversion” devices, including the transmission line itself, through which our signal has to pass.

Insertion loss of Ham Radio Outside the Box’s 4:1 ununs

In the previous post I reported on my build of field test versions of a 4:1 unun and a 4:1 balun to compare how each would handle the task assigned to them. Now the job I set myself was to transform what might be called the “Ugly Sisters” builds into something with the good looks of Cinderella. And Cinderella had to be an unun tough enough to withstand rough treatment out in the Big Blue Sky Shack through all four Canadian seasons (Late Winter, Brief Summer, Early Winter, Deep Winter).

QRP 4:1 unun

I built two versions of a 4:1 unun; one for QRP and another for what I like to call QROp. “QROp” is an unofficial label I have adopted to mean about 20 watts or so. Twenty watts will give a 1 S-unit advantage over 5 watts – maybe just enough for our signal to poke its nose above the noise floor when propagation conditions are not so good.

QROp unun

There are 2 main differences between the QRP and the QROp versions: The QRP unun uses a BNC connector and a 4:1 transformer wound on a tiny FT82-43 toroid. The QROp version uses an SO-239 connector and a 4:1 transformer wound on an FT140-43 toroid.

If we look at the tables below, we can see that the QRP version may have a little too much insertion loss. When we are trying to do as much as we can with as little as possible every milliwatt is wanted. As the wonderful friendly folks on the big Canadian island of Newfoundland like to say: “A little’s a lot if it’s all you’ve got”.

Insertion Loss effects of the Ham Radio Outside the Box QRP unun

BandQRP (5 watts) UNUN Insertion Loss (dB)RF Power Lost (watts)% RF Power Lost10m0.390.438.612m0.370.418.215m0.350.397.817m0.340.387.614m0.330.377.430m0.320.367.240m0.350.397.880m0.730.7715.4

Insertion Loss effects of the Ham Radio Outside the Box QROp unun

BandQROp (20 watts) UNUN Insertion Loss (dB)RF Power Lost (watts)% RF Power Lost10m0.241.085.4012m0.231.035.1515m0.220.994.9517m0.210.944.7014m0.200.904.5030m0.200.904.5040m0.200.904.5080m0.220.994.95

A little extra heat in winter

You would think Canadians wouldn’t mind a little extra heat in winter. It’s true, but not when the source of that heat is our precious transmitted RF. In case you were wondering, the amount of RF converted to heat by inefficient devices is mostly undetectable. If it can be easily detected the “magic smoke” can’t be far behind. When it’s 253 Kelvins outside you just ain’t gonna notice when the temperature rises to 254 Kelvins (note: the physics department advised me to use Kelvins to avoid confusion between degrees Fahrenheit and degrees Celsius).

Oh no! There’s more?

Yes indeed. An unun does not attenuate Common Mode Current (CMC). For that we need a Common Mode Current Choke (CMCC). CMC is the current on the outer surface of a coax braid. Differential mode current is carried on the core and inner surface of the coax braid. Does a CMCC also have insertion loss? Yes, but how much? Let’s take a look.

Insertion Loss of a QRP (5 watts) Common Mode Current Choke (CMCC)

BandQRP (5 watts) CMCC Insertion Loss (dB)RF Power Lost (watts)% RF Power Lost10m0.250.285.612m0.220.255.015m0.210.244.817m0.190.214.214m0.170.193.830m0.150.173.440m0.140.163.280m0.130.153.0 QRP CMCC

Insertion Loss of a QROp (20 watts) Common Mode Current Choke (CMCC)

BandQRP (5 watts) CMCC Insertion Loss (dB)RF Power Lost (watts)% RF Power Lost10m0.180.814.0512m0.160.723.6015m0.150.683.4017m0.130.592.9514m0.110.502.5030m0.100.462.3040m0.090.412.0580m0.080.371.85 QROp CMCC

The (not so) grand total of RF going up the chimney

BandTotal QRP (5W) % RF power lost to heatTotal QROp (20W) % RF power lost to heat10m14.29.0912m13.28.7515m12.68.3517m11.87.6514m11.27.0030m10.66.8040m10.06.5580m18.46.80

The white bearded man in the red suit and his flying reindeer might be grateful for a few watts of heat going up the chimney at this time of year, but those of us in the frozen barren tundra of the northern states and provinces, as well as licensed ham dwellers in other cold lands, may not see things the same way.

What can we conclude?

If we only consider the insertion loss – in this example – of the 4:1 voltage unun and the Common Mode Current Choke and ignore resistive losses in the transmission line, and possibly insertion loss in a transmatch (“tuner”), we can determine the potential efficiency of our antenna system.

For our QRP devices the efficiency varies between 81.6% and 90% across the bands
For our QRO devices the efficiency varies between 90.9% and 93.5% across the bands

This conclusion is based on the assumption that there is no loss in the antenna itself. We are treating the antenna, the transmission line, unun and CMCC as the “antenna system”. I have made no allowance for SWR losses for the reasons stated in the introduction to this post.

What a load of old codswallop!

I am an expert in the sense that “X” is an unknown quantity and “spurt” is a drip under pressure. I may be completely wrong; I may have fallen off my horse and bumped my head on a rock. I may have come to a fork in the road and taken it as Yogi Berra once famously said. If you would like to correct me on any wrong assumptions please do so. I receive a lot of direct emails from readers and, while they are most welcome, if you write a comment to this post instead it may trigger an interesting technical discussion here.

A big thank you to all the new and many existing subscribers to Ham Radio Outside the Box. It is people like you who make writing these posts so worthwhile. I appreciate every one of you.

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#amateurRadio2 #antennas #cw #outdoorOps #unun

POTA PERformer radials – can we make a compromise?

There has only been one light snowfall in southern Ontario so far this season – just a few centimeters that melted away within a couple of days. In anticipation of upcoming heavier snowfalls and a semi-permanent white blanket that will last until spring, I bravely shrugged off the chilly outside air and set up my Ham Radio Outside the Box version of the POTA PERformer antenna out in the backyard to experiment with radial lengths.

The cunningly repaired broken shortened whip with a capacitive top hat, to compensate for its inductive reactance on the 20m band, sat atop my custom spike mount that, despite falling temperatures, could still be pushed into the ground about 25cm (10 inches). Two radials were attached each of which sloped down to a fiberglass stake about a foot (30cm) above ground. The radials are approximately 5m (17ft) long for the 20m band with links to shorten the wires for the 17m and 15m bands.

Now, to find a shortcut

The objective for the day’s tests was to investigate whether compromises could be made in the radial lengths. Why? Later in the winter, when the snow lies deep and crisp and even, it can become a real chore to wade through accumulations of the infernal white stuff to adjust the radial lengths for band changes. I have adopted 2mm banana plugs for the links – a great idea in the summer, but maybe I neglected to consider what will happen when even a few snow flakes freeze on those tiny connectors in the winter!

So, how to minimize pedestrian excursions through the challenges of winter operating conditions to accommodate band changes? The POTA PERformer is an efficient antenna but it was designed in California where the climate is just a little milder than in Ontario. Should I go back to using a random wire antenna – like the Rybakov – until spring comes around again?

I could perhaps use “fan radials” i.e. separate radials for each band. That would probably work but setting them up might still involve wading through deep snow. In the past I have used ground radials laid on the snow – a multiband arrangement that requires no adjustment for band changes, but is less efficient.

Back to the backyard tests; what did I find out?

First, my approximately 16.5ft (~5m) raised radial wires provided an acceptable SWR (less than 2:1) on 20m and 17m (with the whip length shortened for 17m).
Second, the same wires – with the links adjusted for 15m and the whip shortened again – gave an acceptable SWR on 15m, 12m and 10m.

So, is this a result? Maybe not. There is a potential for lost efficiency when the radiating element is shorter than the counterpoise. Let me explain.

Let’s assume we are using a field portable version of the POTA PERformer in which the feedpoint remains quite close to the ground – maybe 1 to 1.5 meters. The two radial wires slope away from the feedpoint to an end point even lower to the ground. Now, if we examine the current distribution on a halfwave dipole, we can see that the maximum current, and therefore the point at which maximum RF is radiated, is located in the center of the dipole.

We would like the high current point to lie within the radiating element, not the counterpoise. For the purposes of this discussion we are going to refer to the two radial wires as “the counterpoise”.

Going back to my backyard tests, I found that:

a 20m counterpoise “worked” on the 17m band.

a 15m counterpoise also “worked” on the 12m and 10m bands.

In each of these cases the radiating element was shorter than the counterpoise.

Referring to the accompanying diagrams we can see that the high current point, in each case, lies within the counterpoise.

Does this finding matter?

Changing the radiating element versus counterpoise balance creates an antenna that looks very much like an Off Center Fed Dipole (OCFD).

If an OCFD is mounted high enough above ground it doesn’t matter at all although two things need to be considered here:

Changing the radiating element versus counterpoise lengths changes the impedance at the feedpoint.
The overall length of the dipole might change unexpectedly. This can be seen with Greg KJ6ER’s Challenger antenna which is a vertical OCFD halfwave dipole that is shortened by laying part of the counterpoise wire on the ground.

A relatively small change in the ratio between the radiating element versus counterpoise lengths changes the feedpoint impedance, but this can be compensated by adjusting the whip length to still obtain a usable SWR.

However, we cannot compensate for the proximity to ground of the counterpoise in the POTA PERformer. If the current maximum occurs at the feedpoint (1 to 1.5 meters above ground) very little power is lost. But, if the current maximum occurs below the feedpoint we are going to keep the earthworms warm in winter.

Not the best plan

So we can conclude that using a 20m counterpoise on 17m risks losing some of our RF energy to the ground. The same applies for using a 15m counterpoise on 12m and 10m. The following diagram summarizes this.

The way forward

“Fan radials” may still be a solution but they require some careful experimentation. There is interaction between the wires for each band due to mutual capacitance. This is compounded when multiple bands are involved. To make matters worse, when used out in the Big Blue Sky Shack where the wind doth blow through the wires and changes the interaction, who knows what wild swings in SWR may occur? The radio I have dubbed my “very clever poodle” (QMX: see last post) will not take kindly to that.

A final thought

I have watched several videos in which a very short whip is mounted on a picnic table and used with a single long counterpoise wire draped down to and across the ground. Sometimes the “Magic (Tune) Button” assists in finding an SWR that keeps the radio smiling. Contacts get made, so what’s the problem? I hope the above discussion answers that question.

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The following copyright notice applies to all content on this blog.

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#amateurRadio2 #antennas #counterpoise #ground #outdoorOps #pota #qmx

A simple outside the box fix for a broken telescopic whip

“If it ain’t broke, don’t fix it”

Or conversely, if it is “broke” you have two choices. Order a replacement from the other side of the planet, and wait for the slow boat from China to navigate thousand of nautical miles across the stormy waters of international seas. Or, alternatively, and my preferred solution, is to see if it can be fixed. So when I managed to break the 18.5ft telescopic whip I had ordered from China a year or so ago, I was faced with that choice.

Hair of the dog

There is an old supposed remedy for the after effects of over indulgence in adult beverages. It is called the “hair of the dog that bit you”, often simplified to “hair of the dog”. The idea is that, in the morning, if you drink some more of the beverage that caused the problem you will recover. I rate that high on the skepticism index.

The dog that bit my antenna was another product from the same oriental source as the whip. It was a “top hat” designed for the PAC-12 antenna. This set of electric antlers proved too heavy for the whip that was never designed to carry them. The tip of the whip swayed rather wildly in the wind, before collapsing on the ground and decapitating itself in the process. The top hat survived but the top two sections of the whip parted company from the rest, never to be reconnected again.

What remained was 15 feet and 9 inches of whip that sat in a dark corner of the shack until, one day, a random firing of neurons in my brain came up with an idea. I call the idea “hair of the dog”; i.e. I wondered if I re-attached the top hat, the same one that caused the problem in the first place, to the shortened whip would it at least get me back on 20-meters?

The shortened wounded whip was a little too short to be resonant on the 20m band. Could the addition of a top (capacitance) hat lower the resonant frequency sufficiently to fix the problem? I embarked on an impromptu mission to find out.

Unextended top hat and whip

Top loading a vertical whip is a very efficient way of convincing an electrically short antenna to resonate on a lower frequency. In effect, it increases the electrical length of the antenna. I have been chided by sagacious readers for using the term “electrical length”. The term may be technically incorrect but it makes it easier to understand what happens when an antenna is loaded. Is my top-loaded shortened whip as efficient as a full-length unloaded whip? I’ll leave that for the experts to comment upon.

There are advantages to a top-loaded vertical whip for field portable operators like myself. For a start, a shorter whip is less conspicuous. While activating a park back in the spring of this year, a uniformed Ontario Parks warden pulled up in her official pickup truck to see what I was up to. Ontario Parks wardens have the same authority as police officers when it comes to park rules and regulations. They can impose on-the-spot fines for infractions of a sometimes vague set of rules like “disturbing trees”. She told me that my long whip antenna had caught her eye. When I told her I was using Morse Code to contact other amateur radio operators and read out the list of all the states I had contacted, she was genuinely interested. We struck up a good rapport, especially when discussing which trail the resident park bear preferred. Although that encounter with officialdom went well I prefer to operate under the radar – nothing to see hear, move right along please.

Custom, ham-made (by me) support pole.

As I write this we are well into fall. The winter months still lie ahead of us – 7 months of dreary, snowy, icy weather. So I took advantage of cool temperatures and still unfrozen ground to test my top-loaded shortened whip. I mounted the whip on my recently constructed support that uses PVC plumbing bits and part of a fiberglass driveway marker driven into the ground. For lucky readers in the southern states and other milder climates, a driveway marker is a thin pole used to identify the edges of a driveway when the snow comes. I use 5ft markers, and during last winter’s unusually heavy snowfall, they disappeared deep beneath the snow banks left by the snow plows on their daily runs. I gotta move to sunny Florida, snakes and gators be damned!

It might be considered folly to adopt a hair of the dog approach to fixing the whip but, of course, the lower sections of a telescopic whip are thicker than those at the top. Thicker sections are less likely to experience the wild, wind-induced, oscillatory motion that caused the initial problem. In fact, I had to shorten the whip by another two sections to bring resonance within the 20-meter band, thereby enhancing the physical rigidity even further.

For this initial backyard test I used a set of four 13ft radials that lie mostly on the ground. I know this isn’t the most efficient way of providing the “other half” of an antenna. I have now improved on that by extending the support pole to 43 inches (109cm) and replaced the ground radials with two sloping, above ground radials with links for 15m, 17m and 20m.

Very soon our ground will be frozen hard – like concrete – and then other support options will be required. However, this top-loaded short whip is going to be traveling with me on my winter POTA activations. It works fine business on 20m but, even with the whip extended to its full 15 feet 9 inches, the top hat can’t get it to work on 30-meters. Shortening the whip further (and collapsing the top hat’s “antlers”) allows the higher bands to be used, which is useful while band conditions create openings there.

When I broke the whip I started to look into finding a replacement. The Chameleon 25ft whip sounded interesting but then I watched a video in which one of these whips waved at the heavens during windy conditions. I could foresee another catastrophic collapse in my future if I went that route. I wondered whether a park warden might consider a very tall waving whip a hazard to other park users and wave an infraction notice at me in response. No, there had to be a safer solution and I think this top-loaded formerly broken whip fits the bill quite nicely.

Meanwhile, back in the shack …

Work continues on renovating my rigs to return to QRP operations when band conditions permit. I have been using my Yaesu FT-891 throughout the summer. I like to think of the FT-891 as a QRP rig with optional QRO capability. The trouble is, it is too easy to tweak the power just a little to give my signal a little more muscle. My QRP Labs QMX is a great little radio but it isn’t built for hostile environments – like Ontario winters. Unfortunately I chose the low band QMX when ordering so I am limited to 80m, 60m, 40m, 30m and 20m – no access to the higher bands which have been quite active lately. I do have another option – a rugged, pugnacious but rather old little rig that covers all bands. It was built back in the era when there were fewer options for QRPers and lacks some of the features we now take for granted. There is a way to add on the missing features; I’ll publish the details in an upcoming post.

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#Antennas #CW #MorseCode #OutdoorOps #Portable #POTA #QMX

Which is best – An EFFICIENT antenna or an EFFECTIVE antenna?

What’s the difference? An EFFICIENT antenna is one that converts as much transmitted energy as possible into radiated RF energy. “Efficient” is not clearly defined but is often understood to mean more than 90%. An EFFECTIVE antenna is undefined. The term is subjective and could refer to a favorite antenna that “gets the job done”. If an antenna brings in the QSOs it could be described as “effective”.

This antenna in Toronto which stands at 553.3 meters (1,815.3 feet) seems to be quite effective.

Even an efficient antenna won’t guarantee we will make QSOs. It is quite possible that an inefficient but effective antenna will bring in more QSOs than an efficient antenna. How can this be so?

To answer that question we have to examine the factors that affect the effectiveness of an antenna. These factors are unrelated to whether an antenna is actually efficient (although efficiency certainly helps).

Propagation Conditions: When our friendly neighborhood star gets hyperactive and hurls, for example, CMEs (Coronal Mass Ejections) in our direction things can get quite difficult for radio communications. We have witnessed this frequently during the recent maximum of the 11-year solar cycle.

As an aside, many ancient civilizations worshiped the Sun as a god. In the absence of our advanced technologies perhaps they could be forgiven for doing so. In terms of volume, the Sun is a million times larger than the Earth (source: Encyclopedia Britannica). It sustains all life on Earth and at some point in the distant future it will destroy the Earth when it runs out of the fuel that keeps its immense internal fusion reactor working. At that point it will swell into a red giant encompassing the orbits of all the inner planets.

But back to the Sun’s effect on radio communication, it controls which bands are active at any given time. It controls whether the ionosphere has the ability to refract RF back to the Earth’s surface, and to what degree. It doesn’t matter what kind of antenna we are using when a solar storm creates an HF blackout. For that reason it makes sense for amateur radio operators to pay attention to propagation conditions when planning to operate. Ham Radio Outside the Box discussed what all the propagation parameters mean in an earlier post. Personally, I pay particular attention to the Solar Flux Index, Sunspot Number, K-index, Bz (Interplanetary Magnetic Field) and the Solar Wind Speed.

How many stations are on the air?

There are times when the “band is dead”, meaning if we scan the band we don’t hear any activity. Sometimes, all it takes is for one station to call CQ and the band joins the “undead”. At other times there just ain’t nobody listenin’; for example, Superbowl Sunday may not be the absolutely best time to get on the air. On the other hand, during ARRL Field Day in June the bands are usually a tad busy. I once made the mistake of waiting until Field Day was over before starting a POTA activation. Of course most Field Day stations had gone off-air by then so I ended up with a busted activation. Field Day contacts are valid POTA QSOs too so I probably could have completed the activation in short order if I had jumped on the air a few minutes earlier.

During the week many hams are at work and the bands are quieter. Those of us who, being of a certain age, are unencumbered by employment may still be disturbing the peace and quiet of the ionosphere.

So if we want to test whether our new antenna is a good’un it probably makes sense to get on the air when there are plenty of other hams pounding brass by the light of brightly glowing tubes (or “valves” as they are called in the land of the Pilgrim Fathers).

Location, location, location

As Bobby Darin might have sung if he had been a ham:

“Somewhere, beyond the sea; Somewhere waiting for me; Another ham on golden sands; Is watching the bands for me”

If you are a ham on golden sands – for example on the Atlantic or Pacific coast you can take advantage of the “Salt Water Effect” which makes even a wet noodle look like a great antenna. From my location in Southern Ontario Canada I would have to travel 1000km north to find salt water inside my own province, but that would be on the frozen shore of James Bay. Alternatively, at about half that distance, and across the US border, is New York City. I have tried operating on the beach beside the world’s largest underwater salt mine on Lake Huron but it didn’t do it for me.

If we can’t go down to the sea to CQ another alternative is to get high – as in up a mountain. Once again, I struck out. The highest peak in Ontario soars to a mind numbing, breathtaking … well actually it doesn’t even make it to 3000 feet (about 900 meters). Height helps!

What kind of antenna is the other guy using?

I remember having a great QSO with a ham in France from my backyard in Ontario. I was testing a wire antenna for NVIS that was only about 12 feet above ground. I was blown away by how clearly he could hear me. When I told him about my antenna he had the good grace to compliment me on how well it was working. A low antenna, designed for NVIS can sometimes still put out a -6dB signal (down 1 S-unit) at a low radiation angle and snag some DX. After the QSO I checked him out on QRZ.com and saw what kind of antenna he was using – it was a multi-element Yagi up about 70 feet on a tower. Now that was what I would call an “effective antenna”! It was doing the heavy lifting during the QSO, not my puny wire.

So the lesson here is, if you are operating QRP with one of those trendy 4ft base-loaded whips, and you are getting great DX contacts, it may not be your modest compromised miracle antenna that is getting the job done, it could instead be the DX operating from a powerful super station.

So could an inefficient, but effective, antenna beat out an efficient antenna? Perhaps; it is possible if the inefficient, but effective, antenna is up a mountain – or a saltwater beach for example.

What’s to be done?

Let’s get back to what makes an antenna “effective”. The millions of us who live within the interior of the great north American continent don’t have to imagine what it is like to operate far away from salt water and mountain peaks; we live it every day. Some among us have further limitations such as living in an HOA where the guardians of the establishment will descend like a swarm of screaming demons upon any ham who erects an antenna higher than a blade of grass. The custodians of many public spaces bring fire and brimstone upon anyone who dares disturb their trees, so throwing a weighted object up into the green canopy and pulling a nice long, efficient wire antenna up and over a branch is out of the question. But there is a solution.

Imagine you have to live with all these limitations and maybe even more. The best antenna you can get on the air is only 30 percent efficient. The bands are in turmoil due to a minor solar storm. If you are a QRP diehard your signal will at best be limited to a couple of watts. If you get lucky you may still make some contacts; if you don’t – well that’s the fun of QRP. A day in the park flattening your battery calling CQ with no responses is better than a day at home doing chores, or so they say.

Here at Ham Radio Outside the Box our motto is: “QRP when possible, QRO when required”. Or, to put it another way, a day in the park flattening your battery calling CQ at a blistering 30 watts and making QSOs is better than a day at the park flattening your battery calling CQ at 2 watts with no responses. That’s the fun of what I like to call QROp.

What are your experiences? Do you have a favorite antenna that gets the job done?

Coming up in a future post … A return to QRP and why I am reluctant to take my QRP-Labs QMX to the field.

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A Road Trip with the POTA Tripod Antenna – with surprises!

A spell of warm, sunny weather and a chance to get out to see the fall colors in early October prompted my wife and I to go on a road trip up to Ontario’s Muskoka region and on to the fabulous Algonquin Park. The park is Canada’s largest and oldest and is the home to thousands of black bears, as well as moose, deer and wolves. Sadly, all the wildlife hid from us on this trip.

Propagation conditions remained uncertain at best, so the third passenger on the truck journey north was my Yaesu FT-891 QROp rig set to an unusually high 35 watts. And the antenna of choice was the 13ft tall vertical based on a tripod that has been the subject of recent posts. Once again, this antenna got the job done, and even revealed some surprises.

Inside Algonquin Park, at Mew Lake campground, I set up to check band conditions. As usual, I started by hunting other activators to see what kind of signal reports I would receive. Bad propagation numbers do not always result in difficulty making contacts. I had considered just leaving the radio in the truck and enjoying the sunshine on the quiet beach by the lake, but after settling into my camp chair I grew restless and within a few minutes I was calling activators and making QSOs.

There are two ways to perform an activation

Calling CQ is the best way; it makes an activator the target for eager hunters and often results in pile-ups. If you know how to handle a pile-up you can complete an activation in short order. But, when conditions are not so good, calling CQ repeatedly and getting no responses can be disheartening. Once I have spotted myself on the POTA website I like to complete at least a basic 10 QSO activation even if it takes a while. Trouble is, when time is limited, other priorities may take precedence and that can result in a busted activation and disappointment. Of course, it is still fun to get on the air out in the Big Blue Sky Shack, but there is another way to have fun and do an activation.

On several occasions I have taken a more relaxed approach and simply hunted other activators until I have completed 10 or more QSOs. This method is a little more difficult because it is necessary to compete with other hunters for each QSO. The advantage, as I see it, is there is no compulsion to complete the minimum 10 QSOs if conditions are bad. I can stop at any point and just consider it a fun day in the park. If I make my 10 contacts I file my logs with POTA and every QSO is automatically a “P2P” (Park-to-Park).

“Hunted activations” are my backup method when time is limited and conditions are bad. On that day in Algonquin Park I chose this method and ended up short of the required minimum of 10 contacts for a valid activation. We had two more days in this mini fall vacation and better conditions were ahead of us, but that day the park had other attractions we wanted to see.

Our overnight accommodation was a “bricks and mortar tent” with breakfast included. Many years ago I canoed into the backcountry inside Algonquin Park every summer and slept in a tent at the edge of several of the park’s many lakes. It was refreshing to get away from the crowds and enjoy the solitude of nature out in the wilderness. In almost complete darkness, at 2:00 AM one night, that solitude was interrupted by a very close encounter with a very large black bear. Fortunately the bear didn’t have me on his supper menu that night. After ransacking the campsite and attempting to claw the food bag down from a tree, it moved on in search of easier meals.

“CB or Ham?” inquired the lady with the Whippet

Activating Arrowhead Provincial Park in the October sunshine surrounded by beautiful fall colors.

Leaving the safe, solid, bear-proof accommodation in a nearby town the next morning we entered one of our favorites among Ontario’s parks where we would spend the entire day, with plenty of time for radio. The QTH for the day was Arrowhead Lake Provincial Park (CA-0140), a park I have activated before so I already knew the best location for setting up the radio.

The operating site was at the far end of the lake beside the dog beach. The accompanying picture shows my relaxed operating position. We spent several hours at the dog beach and that included meeting and greeting several dogs (we love dogs).

A couple of ladies came by and one of them asked me: “CB or Ham?”. It is nice when I don’t have to explain ham radio to a visitor. She seemed genuinely surprised though when I explained that I was using Morse Code to contact other hams all over North America. And her pet Whippet was very excited to meet a CW operator in person.

Band conditions had improved since the previous day and the contacts were much easier to obtain. I started out hunting other activators as usual and the contacts just kept adding to my log despite the K-index sitting at an uncomfortable high of 4. The activation wasn’t as fast as if I had called CQ, but time was not pressing so I earned a complete activation, with QSOs to spare, over a period of an hour and a half. Eventually, as the area grew busier, I decided to pack up and head back to the “tent”.

POTA activation at CA-0140 Arrowhead Provincial Park – October 2025

Smoke on the Wahta

The next day we had to head back home, but the route took us via another of my favorite parks – Torrance Barrens Nature Reserve (CA-1669). The “Barrens” is a couple of hours relaxed drive south of Algonquin and the trip took us through the Wahta Mohawk First Nation reserve where tax-free bargains can be found on gasoline and smoking products. My wife and I are not smokers but we are always amused by a sign along the road advertising “Smoke on the Wahta”. Readers who grew up in the same era that we did may recognize the reference to a popular song from the 1970s.

Activating The Barrens

The Barrens is located at the south end of Muskoka and is a popular haunt for astronomers. The topography is characterized by the exposed ancient rock at the southern end of the Canadian Shield.

Exposed 2 Billion years old rock covers much of Torrance Barrens Serene natural beauty elsewhere at Torrance Barrens. Antenna worked fine – despite my failure to deploy the tripod’s top section!

I set up my station on the bare rock near a small lake and once again started hunting other activators to test band conditions. After only four QSOs I switched to CQ mode. Things were going well and in just 27 minutes I completed 15 QSOs. Then suddenly, as I was finishing a QSO with KC5F in North Carolina, my radio shut down. I powered the radio back up again and managed to finish the contact before the radio shut down once again. I checked the voltage of my Bioenno Lithium Iron Phosphate battery and saw the reason why – the voltage was 11.5 volts. I hadn’t recharged it during the trip and it had given up on me. Lithium batteries maintain a fairly constant voltage until they are almost fully discharged. Neglecting to keep them well charged comes with surprises – like a forced QRT.

But that wasn’t the only surprise of the day. As I was packing up my station I noticed that I hadn’t fully erected the antenna. The top tube section of the tripod, which forms part of the radiating element, was not extended. Despite this error the antenna performed very well. I was pleasantly surprised and pleased with the results for the day.

POTA activation at CA-1669 Torrance Barrens Conservation Reserve – October 2025.
Good results despite improperly erected whip and a battery that ran out of charge!

A final word about the radials

I had originally intended to use the linked, tuned radials from my wire version of the POTA PERformer antenna, but there was a problem. Those two raised radials contain links for 17m and 15m. The link for 17m is at 13ft along the 17ft radial wires and the link for the 15m band is at 11ft. Now here’s the rub (as Shakespeare would have said), the radiating element is also 13ft long. Since there is a 4:1 impedance transformer in the feedline the impedance on 17m was out of the tuning range of my LDG Z-11 Pro antenna matching unit.

The solution was to use a set of four 13ft radials laid partly on the ground. Now the LDG Z-11 can easily find a match on all the bands from 20m to 10m. Is 4 radials enough? The feedpoint of the antenna is raised about 3ft/1m above ground so maybe less ground plane is required. Setting antenna physics aside, the prime rule for temporary field expedient antennas is to use the antenna you have and just get on the air.

Winter is fast approaching

Up here in the Great White North life contains 3 absolute certainties: death, taxes and snow! The time for relaxed operating in the sunshine beside a lake is nearly over; now it’s time to get back to planning antennas for operating while shivering in my truck!

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Construction of the Simple Low Profile Multiband POTA Antenna

Following on from the previous post, there seems to be some interest in how the Simple, Low Profile, Multiband POTA antenna was actually built. Although the antenna is described as “simple”, that term relates more to how it is deployed and its appearance than its actual construction.

The construction does not involve any special tools or techniques, but it does involve some care to transform a photographer’s lighting tripod into a ham radio antenna. This is especially true since only the top two of the three vertical tube sections of the tripod are used as part of the antenna radiating element. The base tube section, to which the legs are attached, is only used as a support structure for the rest of the antenna. Thus the problem emerges of how to electrically isolate the top two tube sections from the bottom tube.

Where can you purchase such a tripod?

I was able to buy one from my local Habitat for Humanity charity store but a very similar product is available from Amazon. Simply search your local Amazon online store for “Amazon Basics Aluminum Light Photography Tripod Stand with Case”. It is a very inexpensive product – even here in Canada!

Where can you purchase the whip?

The whip can be purchased at hfportable.com (“Home of the Buddipole”). Search for the “Long Telescopic Whip”. I already owned one of these that I acquired several years ago and mine measures 9 feet 4 inches fully extended. The product on the Buddipole website describes it as being “nearly 10 feet long”. As an alternative you could use any 17ft telescoping whip extended to 9 feet. The tripod tubes form the other 4ft of the radiating element. Peter G3OJV advises against using a longer radiating element. Apparently 13 feet is the magic length for this antenna.

Adhesive copper tape

After completing the basic build I realized adding copper tape to the contact areas would be a good idea. There is a choice of copper tapes available from your friendly mom-and-pop Amazon store. I purchased 15mm tape which came on a 20m roll (20 meters, that’s interesting; I wonder what else I could use it for?)

Conductive grease

The tripod tubes nest inside one another allowing the tripod to be collapsed for transport and storage. This means contact will be made and broken at every deployment. Therefore I recommend conductive grease to lubricate, prevent oxidation and assist high conductivity where the tubes connect to each other.

Challenge #1: Joining the lower radiating tube to the bottom support tube

There are three tubes in the tripod. The top two tubes, along with the whip, form the radiating element. They must be electrically isolated from the bottom tube. Although the tubes are coated with a thin layer of black paint, continuous use may create scratches leading to unwanted conductivity. A short length of shrink tubing over the bottom of the second tube fixed that issue. Note in the picture the copper adhesive tape applied over a bare section of the tube (after paint was removed with a Dremel tool). This is where the feedpoint is connected.

Coax is attached by means of 3/8×24 CB mirror mount fixed onto the copper tape feedpoint area. This was described in the previous post. The mirror mount is fastened with two bolts with wing nuts so that it can be moved when the antenna is taken down.

Bottom end of center tube showing the insulating section of shrink wrap and the copper tape connection area for the feedpoint.

There is a possibility that a very small capacitive coupling between the overlapping sections of tube will occur although no adverse effects of any such coupling have been observed.

The lower tube section is electrically isolated from the legs by means of plastic fixtures, so there is no ground connection. The lower tube section is therefore just electrically floating.

If any RF is getting across the junction of the two lower tubes due to capacitive coupling it is likely to be so small as to be inconsequential.

Challenge #2: A good electrical connection between the upper tubes

Isolating the top two sections of tube from the base section was relatively straightforward. Now the problem of how to ensure a very good electrical connection between the top two sections had to be dealt with.

The tubes are concentric, but are a loose fit to enable the intended light fixtures on top of the tripod to be raised and lowered easily. But the loose fit became a problem when the need arose to electrically connect two sections. Not just connect, but ensure a very low resistance connection was made. It would be highly undesirable if the connection were intermittent or had a high resistance. “High resistance” in this context could be as little as an ohm or two since the RF current this close to the feedpoint is quite high.

So here is how the problem was tackled. As can be seen in the accompanying image, two broad slits were sawn in the top end of the center tube section. The plastic clamps that secure tube sections together compress these slits.

Center tube (left) with slits. Top tube (right) with copper tape bulge

Now it was only necessary to use layers of copper tape to create a slight bulge at the bottom end of the top section of tube, where it mates with the center section. When the antenna is erected the copper tape bulge in the top tube engages with the compressed slits in the center tube and form a secure electrical connection.

Challenge 3: Connecting the whip

The whip is attached to the top end of the top tube of the tripod. It would have been very simple to use a CB mirror mount, but I wanted the entire assembly to appear as one continuous length of tube.

To achieve this it was necessary to fix a 3/8×24 coupling nut inside the top end of the top tripod tube. I guess I got lucky here because one of the coupling nuts in my junque drawer turned out to be a nice snug fit inside the tube. But a snug fit isn’t good enough for an electrical connection so a tiny hole was drilled through the tube and coupling nut. A small nut and bolt was then added to ensure a tight fitting. For good measure, the outside surface of the coupling nut was coated with conductive grease to reduce the electrical resistance and prevent corrosion during use outdoors in the Big Blue Sky Shack.

I hope this post will encourage others to build their own version. As was shown in the last post, the antenna does a creditable job and is so easy to transport to a park (or mountaintop) and super fast to set up. I am happy to respond to any further inquiries; just leave a comment below or send me an email (qrz.com has my correct email address).

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A Simple, Low Profile, Multiband Antenna for POTA

Sometimes it is necessary to set up for a POTA activation in an area where other park users like to go. In this situation we can either entertain distracting inquiries from people passing by who may just be curious about our activity, or blend into the environment and not be noticed. I prefer the latter. So when I learned of a field antenna that could be mistaken for an innocent fishing pole I was immediately interested. But, of course, this is Ham Radio Outside the Box so I just had to re-invent the idea to create my own variant. I was influenced by three ideas I had read, or seen, online.

Influencer #1

The spark that ignited the creation of this new antenna came from Peter Waters G3OJV who recently published a YouTube video with the title: “Invisible HF Vertical Ham Radio Antenna”. Peter used a 13ft vertical wire worked against a set of ground radials to cover the 20m, 17m, 15m, 12m and 10m bands. A 13ft vertical antenna is, perhaps coincidentally, comparable to a half-size Rybakov. A full-size Rybakov comprises a vertical wire 24-29ft long that can be tuned to all the bands from 40m and up. Just like the Rybakov, Peter’s antenna employs a 4:1 impedance transformer and requires a tuner.

Influencer #2

I liked Peter’s idea very much, but I immediately considered that a ground-mounted vertical antenna requires an extensive system of radials to be efficient. Laying out lots of radials is not very convenient for temporary, portable antennas. I still recall the “dancing lady” who stopped by one of my activations. When she was advised to be careful of the wires on the ground, she performed an entertaining little dance routine to avoid stepping on them. Greg, KJ6ER popularized the idea of using a raised vertical to reduce the number of radials to just two. Greg’s now famous POTA PERformer antenna uses this technique and it works very well.

Influencer #3

My third influencer was actually two hams. Jim Heath W6LG posted a video about using a photographer’s lighting tripod to build a portable antenna. Jim’s idea was expanded upon by Frank K4FMH with his “Eiffeltenna”. Frank and Jim both proposed using a telescoping whip mounted on the steel tubing of the tripod to create the radiating vertical element of the antenna. But both had the same idea of working the radiating element against a ground plane of radial wires or Faraday cloth.

Could I combine these three ideas to create a shortened portable antenna with a raised feedpoint and just two raised radial wires that could be used on multiple bands? Of course, the answer is most definitely yes. I built the antenna, took it out to the field to test it and was pleasantly surprised by how well it worked.

Antenna feedpoint at top of bottom tripod tube section. NB: the insulating washer had to be inserted so that the coax braid is isolated from the mirror mount – the opposite of its usual orientation. Whip mount on top tripod tube section

The key component was a lighting tripod purchased at a charity store for less than the cost of a Happy Meal at the Golden Arches. The whip is from Buddipole and extends to 112 inches (2.85 meters). The tripod has two extending steel tubes mounted in a lower fixed section. The challenge was to create a feedpoint at the top of the fixed section, about 3ft (1m) above ground, while ensuring isolation from the bottom tripod tube section and reliable connectivity between the top two sections when fully extended. The total length of the top two tube sections plus the whip totaled 13ft – perfect!

In order to mount the whip to the top tripod tube section, a coupling nut was slipped into the top tube and secured by drilling a hole through the tube and coupling nut so that a small nut and bolt could be inserted. The coupling nut is a very snug fit already so there is a good electrical connection. The Buddipole whip and top tripod tube are just about the same diameter and color making the appearance of a continuous length to enhance the “fishing pole” illusion.

The whole antenna (less radials) packed and ready to go

There was also a key design requirement that the tripod had to be collapsible for carrying to an operating site. This complicated the design, but for every problem there is a solution. I used a Dremel tool to remove the paint where an electrical connection was required. That created a bare steel-to-steel connection which may corrode over time. I may further improve the connectivity by applying copper tape to the points where the tubes meet.

Antenna base showing the radial connections and Guanella 4:1 unun

I took the antenna out to the field to see whether it could perform well enough to complete a POTA activation. I chose nearby CA-0281 – MacGregor Point Provincial Park for the trial. MacGregor Point lies on the Ontario shore of Lake Huron about a hundred miles (160km) across the lake from the State of Michigan. The Great Lakes are freshwater bodies that do not enhance propagation in the way that saltwater does, but at least there were no topographical features to impede my signal to the west and southwest.

Propagation conditions were not so good with a lot of QSB so I didn’t expect a great result. My radio was my trail-hardened Yaesu FT-891 at 30 watts CW.

Before calling CQ I decided to try hunting some stations to see where my signal could reach. This was so successful that I was able to secure a “basic 10” QSO’s by hunting alone. The results were impressive enough to give the antenna a strong thumbs up.

Radials oriented southwest. 20m band, 30W CW signal reached Utah and New Mexico
despite poor propagation conditions.

Finally, did the “fishing pole” disguise work? The park was quiet, but two park wardens stopped nearby to empty a bear-proof trash bin (MacGregor Point has just one resident black bear that I have only seen once). The wardens did not show any interest in my activity, neither did several other passers-by. My cunning cloaking device apparently worked fine business.

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What happens when you press the magic TUNE button?

What happens when you press the magic TUNE button on your radio, or external automatic tuner? You will likely hear the rapid clicking sound of relays trying different combinations of capacitors and inductors as it looks for the lowest SWR to present to the radio.

But, a “tuner” does NOT actually tune your antenna. It simply provides an impedance match between your antenna system and your transceiver. It used to be more accurately called a “transmatch” but that term is seldom used these days.

The transceiver may “see” a perfect match coming from the “tuner”, but that low SWR exists only between the “tuner” and the radio. The SWR between the antenna system and the “tuner” might, in fact, be as high as 10:1! Like many other tuners, my LDG Z-11 Pro can resolve impedance mismatches up to 10:1.

Is that bad? And what happens to the signal after it passes through the “tuner”?

Greater minds than mine have discussed those questions at great length. Here is my understanding of what happens. Let’s say the antenna is an electrically short, non-resonant whip. It has a high capacitive reactance and will present a high SWR if it were to be directly connected to a transceiver. Instead, the antenna is connected to a “tuner” which transforms the impedance and provides a match close to the 50+j0 ohms preferred by the transceiver.

** But the SWR at the ANTENNA remains unchanged! **

Will the antenna still radiate a signal?

As is often said in antenna related forums, “RF gotta go somewhere”. However, because the antenna has a high SWR, only part of the signal is radiated and the rest is reflected back down the coax toward the shack. It is often thought that the reflected signal is converted into heat in the tuner (or transceiver). While that might be expected according to the Laws of Thermodynamics, it is only partially true. Actually most of the signal is re-reflected back toward the antenna where more signal is radiated with the remainder reflected, once again, back to its source. These back and forth reflections continue until there is no signal left to be radiated.

So all the signal eventually gets radiated then?

Once again, the Laws of Thermodynamics apply. Let’s assume the antenna is connected to the shack via a length of coax, and the tuner is in the shack. It could be an internal antenna tuner built into the transceiver, or an external tuner. As the signal passes along the coax toward the antenna it is attenuated due to the ohmic losses in the cable. At each reflection a little more of the signal is converted into heat in the coax. So, no, all the signal is not eventually radiated.

The transceiver reports a low SWR, but that only extends as far as the “tuner”. Between the tuner and the antenna signal losses are incurred due to the impedance mismatch. The amount of loss depends on the degree of impedance mismatch in the antenna system.

So now what? Non-resonant antennas are bad?

No, non-resonant antennas are not bad at all. If the big issue is lossy coax, but we use a very short coax – or no coax at all – the loss may be insignificant. In a field portable situation it is often possible to directly connect an antenna to the “tuner” or transceiver, eliminating the coax completely. If the antenna is non-resonant and a long transmission line is required, the coax may be replaced with ladder line, window line or open-wire line which has very low loss.

Another alternative is to use a remote antenna tuner. The signal will still be attenuated as it travels along the coax from the transceiver out toward the antenna, but the remote tuner will reduce the number of reflections necessary to radiate as much signal as possible.

Coax affects SWR

It is important to note that long lengths of coax affect the SWR seen by the radio. Some signal is lost in the coax, and that is also true for common mode current reflected back from the antenna. This means the SWR seen by the radio may appear to be better than it really is at the antenna.

A non-resonant high SWR antenna used with a tuner incurs insertion loss in the tuner and resistive loss from multiple reflections back and forth along the coax. These losses are not necessarily a concern and should be weighed against the convenience of being able to use the tuner to match multiple bands. A resonant antenna may incur less loss due to no tuner being required and low SWR at the antenna but it is a single band antenna.

There are situations in which only an inefficient, non-resonant antenna is available. In that case the inefficiency may be combatted by increasing the power transmitted. Paraphrasing the FCC’s Part 97.313 rules: An amateur station should use as much transmitter power as is necessary to carry out the desired communications. Clearly, if you are a die-hard QRPer and you only have an inefficient, non-resonant antenna to work with … well that’s the fun of QRP isn’t it?

This is a very complex topic and I can’t pretend to be an expert, so this post is intended to present the way I understand it. You may disagree, or have other explanations or opinions. If so, please share what you know in the comments.

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Two Resonant Simple Wire Antennas for POTA

One antenna that has garnered a significant following among POTA operators is the POTA PERformer designed by Greg Mihran KJ6ER. In essence it is a raised quarter wavelength vertical with 2 above ground radials. A simple idea that Greg has engineered into a rapid deployment, highly efficient, multiband, portable antenna. Greg has backed up his design with a detailed analysis supporting the claimed high performance characteristics. Many operators, including myself, have built and used the POTA PERformer and can verify that it is indeed a very good antenna.

NB: I have already covered the POTA PERformer in a recent post and concluded that just a single raised radial was sufficient. However, after reading Greg KJ6ER’s analysis in more detail I am now convinced that using 2 radials raises the antenna’s efficiency.

There are three innovative antenna designs in KJ6ER’s kit bag. The other two are both half-wave designs. The POTA Challenger is an off-center fed half-wave that supports 20m and up; the Dominator is an end-fed half-wave that supports 17m and up. I have not tried to build a Dominator (yet) since most of my own POTA operations are on 20m, but the Challenger caught my attention so much that I had to build my own version.

When I first looked at the design I was completely bewildered. It comprises a 25ft telescopic vertical whip with a wire counterpoise, part of which lies directly on the ground. Does that look like a typical half-wave antenna, I thought to myself? I had never seen anything like it before so my skepticism was aroused. After exchanging a couple of emails with Greg I was encouraged to go right ahead and build one in the hope that actually using it to fire RF up to the edge of space and back would bring about a better understanding of this strange new electromagnetic beast.

Well, I did build my own version of the Challenger, massaged the design a few times and came up an antenna that got me some very encouraging signal reports from the land of far, far away. Of course, this blog is called “Ham Radio Outside the Box” so, just like Frank Sinatra, I “did it my way”. To learn more please read on.

The Ham Radio Outside the Box version of KJ6ER’s Challenger

First, I would like to wholeheartedly endorse the work of Greg Mihran, KJ6ER. One might have expected him to be selling commercial versions of his antennas, but instead, he has published detailed build instructions and readily responds to emails from fellow hams. That is the true spirit of our hobby; hams helping hams.

Ham Radio Outside the Box interpretation
of KJ6ER’s Challenger antenna

It wouldn’t be fair to even refer to my own version as a “Challenger”. Instead I will just say that it is inspired by KJ6ER’s Challenger. It follows the same ideas but implemented in a different way. I don’t own a 25ft telescoping whip and didn’t really want to have to buy one, so I decided to incorporate a wire radiating element, supported by my 7-meter Spiderbeam telescoping fiberglass pole.

Then, whereas the Challenger is a multiband (one band at a time) antenna supporting every HF band from 20m and up, I looked at my own POTA activations and realized that I rarely stray from the 20m band. Maybe a monoband antenna is all I need. That keeps the design sweet and simple. I like sweet and simple when I am out in the Big Blue Sky Shack. I did wake up one morning with an urgent need to rush down to my basement shack and sketch out an idea for a multiband version that still uses wire elements. More information on that idea later in this post.

Spiderbeam with wire radiator loosely coiled around it.

I took the dimensions of the radiating element and counterpoise wires directly from KJ6ER’s document. Of course, a wire – in this case teflon covered 20awg multi strand wire from BNTECHGO almost certainly has a slightly different velocity factor from a tapered stainless steel telescoping whip as I discovered when the antenna was erected. It was necessary to shorten both wires a little to bring the antenna into resonance in the CW portion of the band.

Another gotcha is the height of the feedpoint. It has a quite dramatic effect on the tuning. The first iteration of the Ham Radio Outside the Box version used a taller pole. The wires were trimmed to obtain a 1.07 SWR, but when I substituted the shorter pole and re-erected the antenna with the feedpoint only 12 inches above the ground, the SWR shot up into the stratosphere.

NB: KJ6ER built a “backpack” version of his Challenger in which the feedpoint is lowered to 12-inches above ground. I found this height allows me to use my 7m Spiderbeam pole and also makes it easier to orient the counterpoise so that it makes good contact with the ground.

After further adjustments of the wire length a low SWR was restored. I ended up with 22ft/6.7m for the radiating element length and 5.5ft/1.7m for the counterpoise. If you were to reproduce this design your own dimensions might be different; an antenna analyzer is a very useful tool to have.

A multiband version?

The original Challenger uses a telescopic whip so switching bands is quick and easy by simply adjusting the length of the whip. The counterpoise length must also be adjusted, but this is accomplished by means of a linked wire.

I have not built a multiband version of the Ham Radio Outside the Box interpretation of the Challenger but I have entertained two ideas for how to accomplish this goal. First, simply using links in the radiating element wire might be the simplest and easiest way to do it. There is a second possible way and that is to employ parallel radiating element wires in the manner employed by the DX Commander vertical antenna. If you are not familiar with the DX Commander, do a web search on the name and you will see what I mean.

I am so impressed with the portability, efficiency and small footprint of this antenna that it is going to replace some of the other SWAs (Simple Wire Antennas) in my field operations kit bag.

Same Pole, Different Wire

Ham Radio Outside the Box POTA PERformer wire variant supported on a Spiderbeam pole

The title of this post is “Two Resonant Simple Wire Antennas for POTA” so what is the second one? I had built my first version of the POTA PERformer using an MFJ-1979 telescoping 17ft/5m whip mounted on a tripod. If I wanted to do a field outing carrying both this and my own Challenger variant I would have to carry my Spiderbeam pole and the tripod. Since I often stray far from my truck when operating out in the Big Blue Sky Shack I need to economize on the amount of gear I have to carry. Maybe I could build a wire version of the POTA PERformer that could be supported by the 7m Spiderbeam pole.

I realized I already had such a beast – a super light QRP version I built many years ago. Now I needed to copy that idea and build it for QRP or QROp (20-30 watts). So, the new SWA Ham Radio Outside the Box version of the POTA PERformer was born, and again it is a monoband 20m antenna.

As we can see from these images, the simple wire version of the POTA PERformer adapts very well to being supported by the compact, lightweight Spiderbeam pole.

The vertical radiating wire is attached to a standard 3/8x24tpi to SO-239 adapter. The two radial wires connect to the adapter via a 2mm banana connector so they can be separated for storage. The female 2mm connector is crimped and soldered to a 3/8 inch ring connector.

The image also shows the ham-brewed-by-me common mode current choke made from an FT240-43 ferrite toroid core wound with several turns of RG-58 and tested with a nanoVNA to ensure it is doing its job.

Now I only have to carry the Spiderbeam pole and two small freezer bags containing the wire elements for both the PERformer and Challenger variants and I have choices when I get to my operating site. Which to choose? I highly recommend reading KJ6ER’s documents, linked below, especially Greg’s “Antenna Primer”. Greg explains everything you need to know so much better than I ever could.

Cloud Drive File Links (KJ6ER):

YouTube™ Interview with Michael Martens, KB9VBR –
youtube.com/watch?v=cClmWBYzNaE
ARRL™ QST 2024 Antenna Design Competition –
bit.ly/AntennaDesignCompetition
ARRL™ QST September 2025 PERformer Article (First Page) –
bit.ly/QSTSeptember2025FirstPage
KJ6ER Antennas Primer –
bit.ly/KJ6ERAntennasPrimer
PERformer 40M-6M Quarterwave Vertical –
bit.ly/KJ6ERPERformer
PERformer 40M-6M Quarterwave (Assembled, Etsy) –
bit.ly/KJ6ERPERformerKit
Challenger 20M-6M OCF Halfwave Vertical –
bit.ly/KJ6ERChallenger
Dominator 17M-10M EF Halfwave Vertical –
bit.ly/KJ6ERDominator
Dominator 17M-10M EF Halfwave 2-Element Vertical Beam –
bit.ly/KJ6ERDominatorBeam

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How many truly field expedient ham radios are available? Maybe only 2!

Only two? If you were to ask the military you might get a different answer. Indeed many hams actually use ex-military portable radios, such as the PRC series. Those radios are in a class of their own, but they are often heavy, designed to be carried into the field by fit, strong, young soldiers. But what are the choices for those of us who still like to backpack our ham gear into the back country, despite being well past our “best before” date?

I anticipate many readers might think differently, but this post is about my own criteria for assessing the field worthiness of a portable amateur radio transceiver. I am sure you are proud of your favorite radio. It has probably served you well over many xOTA activations. If, after reading this post, you feel your rig is up to the challenge then please nominate it for inclusion in the exclusive list of truly field expedient amateur radio transceivers by leaving a comment.

What makes a radio field expedient?

There are lots of radios – especially QRP rigs – that are lightweight and easy to carry in a small pouch. Does that make them field expedient? Perhaps, but are they hardened against environmental factors that may be encountered in the field? Lightweight and easy to carry in a small pouch are useful features but not always enough to guarantee success in the field. In this post I will outline my personal experiences which may be very different to your own. I don’t treat my field radio equipment with kid gloves. It gets bounced along rocky trails, subjected to extremes of temperature, moisture, bugs, sand and dust. A really good field radio will resist adverse environmental conditions. If it can’t handle that task out-of-the-box it must be covered in layers of protection to compensate.

Humps excluding Marilyns?

The Parks on the Air (POTA) program has brought about a huge increase in the number of hams taking their equipment out into the field to operate. POTA joins a broad array of similar activities like Summits on the Air (SOTA), World Wide Flora and Fauna (WWFF) and – mostly in Europe – Beaches on the Air (BOTA), Bunkers on the Air (also BOTA) and the very strangely named HuMPs Excluding Marilyns Awards (HEMA) program. Although this list is not exhaustive – there are other outdoor programs not listed – it illustrates the breadth and expanse of programs enticing hams to step outside their comfy shacks to assault the ionosphere.

Hit the road Jack

Just as there are many outdoor ham radio programs available to challenge us, there are also many different ways to tackle those challenges. My greatest admiration is reserved for those who climb mountains carrying their radio gear in a backpack, climbing steeply for many kilometers, ascending lofty snow-capped peaks before reaching the activation zone. In contrast, there are many who prefer to operate from inside a vehicle in a parking lot. There are certain advantages to operating this way. Your car or truck is your own private space where your park activation is less likely to be interrupted by other curious park users. It also provides shelter during inclement weather. I operate this way myself – but only during the winter when snow blizzards, ice-storms and temperatures cold enough to freeze your breath make the surface of the planet inhospitable.

During the warmer months my own preference is to enjoy the great outdoors in what I like to call the “Big Blue Sky Shack”. It is in this environment that I have encountered the conditions that truly sort out the rugged radios from the rest. My home turf is the small city of Owen Sound at the foot of the Bruce Peninsula in southern Ontario, Canada. The Bruce Peninsula extends 100km from my home up into Lake Huron along the Niagara Escarpment. Along the western side of the peninsula Lake Huron is bounded by sandy low lying land with many islands. The eastern side of the peninsula is dramatically different with tall cliffs plunging down into Georgian Bay – a 15,000 square kilometer extension of Lake Huron. The terrain on the peninsula varies between soft sand and hard ancient bedrock.

Lake Huron shore Ontario Canada

Winds crossing Lake Huron from the state of Michigan on the other side, 160km (100 miles) away, pick up a lot of moisture from the lake which is deposited onto the narrow peninsula in the form of rain or snow. Waves hitting the shoreline can be quite high – maybe not high enough for surfing, but enough to create spray along beaches.

Colpoys Lookout POTA: CA-6007 looking out over Georgian Bay
at the entrance to Colpoys Bay

In winter we usually experience continuous snow coverage between December and April, and in summer temperatures can often reach into the 30s Celsius – as much as 50 degrees higher than in the depths of winter.

February 2025 Owen Sound Ontario Canada

Honestly, just what gets me out of my nice air-conditioned in summer, heated in winter home-based shack? A love of the great outdoors! To enjoy the fresh air, to smell the scent of Canada’s 300 billion trees; maple, birch, spruce and pines. Unfortunately my radios have an inconveniently different point of view. They like a nice stable temperature, dry atmosphere and are highly averse to the ingress of sand and small flying, biting critters like mosquitoes and the dreaded no-see-ums. I once disabled my CW paddles by liberally spraying a cloud of bug repellent in response to an all out attack by these dreaded winged pestilences. If only radio equipment manufacturers would take these things into consideration then both I and my radios could get equal enjoyment out in the Big Blue Sky Shack. Really, why on Earth would CW key manufacturers not routinely protect their products from being sprayed with oily bug repellent? I jest of course.

Yaesu FT-817 non-ND. A classic radio from 2001.

Operating outdoors was an early passion of mine, before many of the programs we now enjoy even existed. I had purchased Yaesu’s FT-817 as soon as it was released. This was the early FT-817 before the revised FT-817ND was released. I still own that radio and have often thought about selling it, but whenever I lift it off the shelf and look into that tiny pug-like face I realize how much I would miss it. The FT-817 was built for the outdoors. It’s case just exudes ruggedness even though it still has shortcomings that limit its usefulness as a portable, field expedient radio. For example, it has provision for internal batteries – a set of AA NiCads, but its current draw is so high that the battery life is way too short for serious portable operations.

Yaesu FT-897 circa 2004 and still in service at my home QTH

I then graduated to another Yaesu rig that also exudes ruggedness. I worked for a while in a ham radio store and every day I was exposed to many different radios that I could operate whenever I wished. But one radio caught my eye and each and every day the desire to own it grew stronger. It was the Yaesu FT-897, a 100 watt radio with all the band coverage of the FT-817 plus Digital Signal Processing (DSP). The case has that same bullet proof aura as the FT-817. It can support two internal battery packs so that when one is fully discharged a flick of a switch changes to the other pack. Both of these Yaesu radios have a rubber shrouded microphone plug that seals out unwanted stuff like sand, moisture, bugs – and bug spray! The FT-897 also sports a rugged 1/4 inch headphone jack which I really like.

What’s at the back Jack?

But … and it’s a big but … turn both of these radios around to see the rear panel and you will find 3.5mm (1/8 inch) jacks and mini-DIN connectors. What’s so wrong with that? Maybe nothing if your operating style involves working from your vehicle. But take that radio onto a beach (as I often do) and witness the magnetic attraction these miniature connectors have for sand particles. I have a strong dislike for 3.5mm plugs and jacks – especially the jacks. They are usually enclosed within a tiny sealed plastic box. If even a couple of grains of sand get inside contact integrity can be compromised. And besides, are these things designed for hundreds or thousands of insertions? I think not; they are designed to be cheap to produce. Cheap, fragile connectors may be appropriate on a mobile phone that is likely to be replaced every couple of years, but not for a field expedient portable radio. I have owned a couple of handheld radios from a certain manufacturer based in Japan (not Yaesu) that had particularly fragile 3.5mm jacks that failed very quickly. It was those radios that prompted my crusade against these pernicious connectors.

Ok, so we have radios with fragile connectors; what can we do about it?

I came up with one easy solution that doesn’t cost a penny. Simply leave these reliability-challenged connectors connected. Don’t unplug those headphones, microphones, CW keys and whatever other peripheral paraphernalia uses them. To achieve that you have to create an enclosure that secures all your external devices so that you don’t need to disconnect and pack them away separately each time you operate.

I built two of my field radios into steel ammo cases so that everything can be left connected between operating sessions. My little QRP Labs QMX radio is just bristling with connectors that are vulnerable to hostile environments. Inside its cozy 30 caliber ammo case it can remain totally oblivious to the hazards surrounding it out in the field. I pop off the heavy-duty steel lid that protects it in transit, connect an antenna, switch on the battery, lift out the connected earbuds and I am QRV.

My other main field radio is a QRP/QRO-optional Yaesu FT-891 built into a 50-cal ammo case. The FT-891 has several vulnerabilities and protecting it has become an ongoing project. The radio is a little too big to fit entirely within its (literally) bullet-proof steel box with the ammo case lid attached. The detachable head is mounted to an aluminum front panel and protected by thick steel U-bolts. All the vulnerable connectors remain safely connected inside the steel case. The only external connections required are for the battery, headphone and CW key.

5-pin DIN connector and tough, thick coily cord for connecting CW paddles. The colored buttons are for CW memory recall (homebrew FH-2 remote keypad).

The battery is connected by Powerpole connectors; the headphone is a Heil Traveler with a beefy inline connector and the key connects via a jack on the front panel. The original 3.5mm jack on the aluminum front panel has been replaced; first with a cheap 1/4 inch jack which proved equally unreliable, then with a 5-pin DIN connector. I had considered buying a very rugged 3-pin XLR plug and jack but I already had the DIN jack as well as an old CB mic cord with a 5-pin DIN plug. We shall see whether they can withstand the rigors of the environment on the beaches and cliffs of the Bruce Peninsula.

Now, going back to the title of this post: “How many truly field expedient ham radios are available? Maybe only 2!”. Well, which two radios did I have in mind when I wrote that? Imagine designing and building a commercial radio with a strong, rugged, water resistant case and military grade connectors. You could take such a radio out into almost any environment and be confident that it will remain reliable and get the job done. Does such a radio exist? You have to look beyond the islands of Japan; beyond China. I have highlighted the dangers of sand getting into vulnerable connectors, so would it surprise you if a company in a very sandy country came up with such a radio? I am not sure which country actually manufactures these radios but one of its biggest distributors is in Dubai. If you would like to know more visit Lab599.com. They produce two radios that are truly field expedient and environmentally protected. Only one of the radios is currently featured on the website but a newer handheld HF transceiver has also been released.

Why I am taking up gardening

I want to grow roses; lots and lots of red roses. I can’t afford to go out and buy enough red roses to convince senior management (she prefers to be called “She-Who-Must-Be-Obeyed”) to let me buy a Lab599 TX-500 🙂

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Rapid Deployment Field Expedient Random Wire Antenna Ideas

The image shows amateur radio station VA3KOT/P inside its stealth enclosure – an old airline pilot briefcase made from stout, strong leather.

This is an almost complete station:

Yaesu FT-891 QRP/QRO-optional in its field hardened steel 50-cal ammo box enclosure
Bioenno 12Ah LiFePO4 battery
9.5ft tactical collapsible whip
Adjustable loading coil for the whip
PAC-12 capacitance hat for the whip
LDG Z-11 Pro auto tuner (I like to think of it as a super fast L-match with a good memory)
CWMorse aluminum paddles
Heil Traveler headset (the microphone is feeling neglected due to not having been used for a very long time)
Ham-made (by me) Guanella 4:1 balun
Selection of coax cables
Set of ground radials
Random wire antennas (we’ll talk about those shortly)
Operating table (yes, operating table too; see image below)

What’s missing? Just a chair. I have a selection of lightweight folding and collapsible camping chairs to support my delicate derriere.

Oh yes, the table; these pilot cases (NB: I am not a pilot) are so strong that, if stood on end, they make an excellent support for the radio.

When everything is packed inside the pilot’s case then it is a little on the heavy side (not to be confused with the Heaviside which is a layer of the ionosphere). The weight is manageable if it is only being carried a short distance, but I have a small folding cart for transporting it further away from my vehicle.

So what about a rapid deployment, field expedient antenna?

Rule 1: It has to fit inside the briefcase. Rule 2: If an antenna doesn’t fit inside the briefcase refer to rule 1.

I have 2 choices that meet Rule 1; a “tactical” (meaning it is painted green and looks like it might not be out of place on a Humvee) collapsible whip. It can be mounted directly on a 3/8x24tpi bracket fixed to the rear of the ammo box. It is usually deployed with a loading coil and capacitance “top” hat.

Rear connections. Note the bracket for mounting the tactical whip on the left. The antenna wire and radials are plugged into the magnetically attached 4:1 balun. The CW paddles are secured to a steel bracket which is also magnetically attached to the ammo box – a steel box is very handy for attaching accessories with small rare earth magnets.

Second choice is a simple wire antenna. I am currently in favor of random wires due to their inherent multi-band flexibility. Although I have never been a fan of auto tuners, for several reasons, their speed in finding and memorizing a match for multiple bands is very valuable for the kind of hit-and-run style activations that I enjoy. The LDG Z-11 Pro is an L-match which means it is perhaps more efficient than a typical C-L-C type of manual tuner.

Don’t risk disappointment

I have read a lot of blogs and watched a lot of videos in which an operator buys a commercial wire antenna and deploys it in the field without investigating whether the antenna is actually going to work in the manner they expect. We don’t all have the time or inclination to model an antenna to find out how best to use it, but it can lead to disappointment if we don’t do the homework first.

‘Tis a gift to be simple, ’tis a gift to be free

It is very simple to make a “Simple Wire Antenna” (SWA) and it can even be free if you can scrounge some leftover wire. Climb an old telephone pole and pull down disused POTS (Plain Old Telephone Service) wire if your neighborhood has switched to fiber lines. Okay, I’m kidding, don’t do that; some poles also carry high voltage electric cables.

I have had great success recently with a sloper wire 27 feet (8.23m) long supported from a tree, or my Spiderbeam 23ft (7m) pole, and worked against four 13ft (4m) ground radials. The LDG tuner easily finds a good match of 1.5:1 or less on my main bands of interest: 20m, 30m and 40m. Out in the field there is no lossy coax transmission line involved – apart from very short sections to plumb in the Guanella 4:1 balun and tuner. This wire is a little short for 40m but presents no problem for the tuner. I have received some very good signal reports using this wire.

Then I wondered, if the wire was longer, could the antenna work even better? EZNEC helped me decide. I modeled three random wires: 27ft (8.23m), 41ft (12.5m) and 84 ft (25.6m). To make it a fair comparison, the same band (20m) was compared and the three wires were modeled in exactly the same sloper configuration. The results were very revealing.

Model 1: 27ft random wire sloper

The elevation plot shows a good directional signal with a small amount of gain at an elevation of 35 degrees.

The azimuth plot shows a wide angle of radiation with ~5dB of Front-to-Back signal strength.

The 27ft sloper has been a solid, reliable performer with strong signal reports being typical.

Model 2: 41ft random wire sloper

It would be tempting to throw a 41ft wire up into a tree and run it as a sloper down to the ground, but the results might be very disappointing.

Although the gain is increased, the elevation angle of maximum radiation has also increased to 75 degrees and the directionality has all but disappeared.

This would make the antenna a cloud warmer and much of the signal would disappear into space. Your CQs might perhaps be answered by extra-galactic radio operators a few thousand years in the future. How patient are you?

Model 3: 84 ft random wire sloper

If you have a much better throwing technique than mine, you might be able to get your throw weight up 62 feet in a tree to pull up an 84ft random wire sloper. But, if you look at these charts you may not want to do it.

Your signal now goes straight up into outer space. In most parts of the world 20m is not an NVIS band so almost your entire signal is wasted. As an aside, I recently experimented with a “V” wire antenna with 29ft arms supported at the ends by trees. I QSOd on it but I received a very disappointing 449 RST report for my 30 watts of signal. When I modeled the antenna afterwards I realized why – the radiation pattern was very similar to this 84ft sloper!

Why does this happen?

What causes the increase in radiation elevation? A big clue emerges when we examine the current distribution on the antenna wire. Remember, high current points along the wire are responsible for the majority of the RF energy radiated.

Current distribution in a 27ft wire Current distribution in a 41ft wire Current distribution in an 84ft wire

As we can see from the three charts, a 27ft wire has just a single high current point.

Along a 41ft wire a second high current point begins to emerge and the interactions raise the radiation angle.

When we look at the 84ft wire we can see that there are two full current maxima and the emergence of a third. Once again, these interact to raise the radiation angle.

Was this a fair comparison?

I think it was fair. None of the three wires is overly difficult to erect as a sloper. Some hams get a lot satisfaction from shooting wires high into trees on the assumption that higher and longer is better. In fact, on the lower bands an 84ft sloper might perform quite well. With the popularity of POTA, and the solar cycle at its peak, a lot of activity is to be found on 20m which is why I chose this band for the comparison.

What if …

Maybe, if we orient an 84ft wire differently, we can get it to be the outstanding performer we would expect on the higher bands. I have QSOd on several occasions with an end-fed 84ft wire hung about 5ft above ground supported by a long hedge, or low branches of small trees. Even at QRP power levels I got good results despite the antenna having no gain.

So let’s follow the old adage of getting as much wire as possible, up as high as possible, but with the proviso that it must abide by the limitations of being rapidly deployable and field expedient. How about an Inverted-L?

In fact, to make it RDFE (Rapidly Deployable, Field Expedient) I am going to call it a Lazy Inverted-L. The feed end of the wire connects to the rig (sitting on the pilot’s briefcase) at a height of 2 feet. The wire then goes to the top of my Spiderbeam 23ft (7m) pole about 3 feet (1m) away with the remainder sloping down to the far end supported 3ft (1m) high on a trekking pole. It might not be the best setup but remember it must be “RDFE”.

Model 4: 84ft Inverted-L antenna

The results are quite encouraging. First, the antenna has a decent amount of gain for a SWA. Second, the elevation angle has two useful components: a forward lobe at 35 degrees elevation with a -3dB point down to 15 degrees for a chance of getting some DX action.

There are two more lobes behind with a higher radiation angle that could yield short range contacts.

Where’s the gotcha?

The azimuth for maximum radiation changes from band to band. That would mean re-orienting the wire for band changes. Fortunately the RDFE, Lazy Inverted-L orientation makes that a fairly easy task.

Imperial or Metric?

I have tried to use both Imperial and Metric dimensions in this post. I was brought up using Imperial measurements, earned my Physics degree which was taught entirely in metric units and now tend to mix them up. Canada is officially metric but supermarkets still mark the prices of meat and produce in dollars per pound. Why? Because it sounds cheaper I guess! Okay fellow hams, what’s your favorite HF band? Mine is 65.6168ft. Yes, that’s 20m.

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Does an antenna top hat really work?

Antenna “Top Hat” aka Capacitance Hat

There are several ways to shorten a vertical whip antenna, for example, a loading coil, linear loading (folding back all or part of the radiating element) and one that has intrigued me for quite a while – a capacitance hat, also known as a top hat.

A top hat (shown in this image) is a series of conductors erected horizontally, and connected to, the radiating element of a vertical whip antenna.

Top hats provide capacitance with respect to ground and are used for two main reasons:

To shorten the required physical length of a vertical antenna
To raise the maximum current point higher up the antenna

One significant disadvantage of using a top hat is that it adds weight to the top of the antenna. That may not be a problem for a fixed installation where a thick, rigid vertical element can be used. But for field expedient portable operations using, for example, a telescoping whip it can be a very bad idea indeed. Let me explain why.

I recently purchased a top hat designed for a PAC-12 antenna from AliExpress. I attached it to the top of my 18.5ft whip obtained from the same source. The top of the whip waved around in the air and clearly was not going to be a practical arrangement. These Chinese whips are made much lighter than similar products from other sources (e.g. MFJ-1979 which I also own) and consequently are not as strong. To be fair, the manufacturer would probably advise against abusing their lightweight whips in the manner of my little experiment. I guess I overstressed the thin top sections of the whip which subsequently parted company from the lower sections. I attempted a repair which wasn’t successful, so I am now the owner of a shorter whip which may see service in a future antenna experiment.

AliExpress top hat for a PAC-12 antenna. NB: I drilled a through hole in the hub to fit it on my tactical whip.

I own another whip – a “tactical”, military style whip that is 9.5ft long. It is made from several sections of fairly rigid tube held together by shock cord. Although the sections taper toward the top, the uppermost section is still quite strong. When the top hat was attached to this whip, the whip bowed very slightly but appeared to be quite able to support the weight.

“Tactical” 9.5ft military style whip

The AliExpress top hat arrived in a surprisingly small package. It comprises a central hub secured to the whip by a small hex screw and four tiny telescoping whips that expand to 12 inches long. When fully assembled the top hat has a diameter of about 24 inches.

How did it perform?

I was a little skeptical about this arrangement. Could a small capacitance hat compensate for the short (9.5 feet) length of my whip on the 20m band? It was a shot in the dark and the short answer is no it could not. But that isn’t to say the top hat totally failed in its mission. In fact, it did make a difference as will be explained in a minute.

A small top hat alone cannot easily compensate for a very short antenna. There are ways to improve the top hat – such as adding a perimeter wire linking the tips of all the horizontal conductors, or even making the horizontal conductors longer. For rapid deployment in the field the perimeter wire is tricky to implement. The stock AliExpress top hat can be assembled and installed in about a minute; adding a perimeter wire makes the assembly more complicated – especially when backpacking the whole station into the bush.

Making the top hat’s horizontal conductors longer introduces another complication. These conductors carry a very small current; if they are made much longer the current will increase (e.g. as in a Marconi T-Antenna) and they will radiate.

A much simpler, but less efficient, idea is to combine the top hat with a loading coil, and that is the route I took. I revived an old ham-made adjustable loading coil I had built for another project a few years ago. The loading coil had to be placed at the bottom of the whip for mechanical stability. Since this is also the maximum current point the coil will introduce i^2R loss, but compromises have to be made.

VA3KOT’s trail-hardened FT-891 rig with ham-made adjustable loading coil and 9.5ft top-hat loaded whip

The end result was a base loaded 9.5ft whip with a 24-inch capacitance hat at the top of the whip. The adjustable coil enabled the antenna to work on 20m, 30m and 40m by simply adjusting the coil slider. Four 13ft radials were laid orthogonally on the ground at the base of the whip as a counterpoise.

Step One

First, the top hat was left to one side and the coil slider was adjusted to find a match on each of the three bands of interest. I used my RigExpert antenna analyzer to measure the results, then when a match on each band was found, my trail-hardened Yaesu FT-891 was deployed and verified the results.

Step Two

The top hat was then installed and the tests repeated. Now the coil setting for each band was quite significantly different. The required inductance was reduced which means the i^2R loss was also reduced – that was encouraging. So the shortening effect of the top hat was verified, but what about the point of maximum current; was that raised too?

I attempted to model the antenna using EZNEC. I have to admit that I have only a very limited knowledge of antenna modeling, so I cheated a little. I modeled a full-size quarter-wave whip for 20m and looked at the antenna currents. Then I added the top hat to the model and looked at the antenna currents again. Would the top hat raise the maximum current sufficiently to get it above the loading coil and thereby reduce losses in the coil? The following chart shows the results.

Bingo! (but no big prize)

As we can see by looking at the chart, the top hat does indeed raise the maximum current point. The model divided the whip into 50 segments and the current maximum is raised from segment 1 with no top hat, to segment 10 with a top hat. That means the point of maximum radiated energy is raised to a point 20% up from the bottom of the whip. Hallelujah.

But just a cotton-pickin’ minute, the actual maximum current changes very little between the first and tenth segment so did we actually achieve anything useful? Well yes we did actually. If we look at segment 50 on the chart we can see that without the top hat the current drops to zero at the top of the whip. On the other hand, with the top hat installed, there is still significant RF current all the way up the whip – so the entire whip is contributing to radiation!

Did the maximum current point clear the loading coil?

I won’t win a Nobel prize for this bit of non-science, but here is my analysis. If the whip is 9.5ft long, the loading coil is compensating for most of the other 7.5ft of a nominal 17ft whip. 20% of 17ft is 3.4ft so that falls well within the loading coil. Hence no, the current maximum will still be in the loading coil. If any reader can convert the above into real science I would welcome your input.

This was interesting experiment and convinced me that top hats really do improve a vertical whip antenna. Will this arrangement actually be used in my field portable operations? Yes, for sure; the top hat has the effect of “decompromising” (to some extent) a compromise antenna. When the prime mission is to carry a rapid deployment, field expedient portable antenna into the bush, remote from roads and parking lots, this antenna has earned in its place in my backpack.

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An Outside the Box version of the Delta Loop antenna

I have written about delta loop antennas before – notably in April 2023 in a post entitled “Delta Loopy Ideas“. A few weeks ago I received an email from Alan WA3EKL who suggested I should take another look at delta loops and offered a lot of helpful advice, tips and suggestions for making this type of antenna a success. Alan’s suggestions have been a tremendous help in designing this latest iteration of my rapid deployment, field expedient, portable delta loop antenna for the 20m band.

Before we go on to describe what is definitely an “outside the box” variant of the delta loop I should comment that I remain welded to the idea that delta loops can be tricky to set up. There are so many variables to consider:

orientation (apex up, down or sideways)
feedpoint (at the apex, at a corner, a quarter wave from the apex or somewhere in between) giving horizontal or vertical polarization
loop length (1005/wavelength or some other length, bare or insulated wire)
equilateral triangle (or not)
height of wire above ground
Matching device (quarter-wavelength 75 ohm coax / impedance transformer / L-network / tuner)

On the positive side you can simplify all the variables and just throw up an “inside the box” version. You will make contacts – but will the standard, don’t-bend-the-rules version of a delta loop be as efficient as possible?

My personal quest has been to find an antenna that is efficient enough to let me carry on working QRP during the Sun’s current spate of hissy fits. With that in mind I wanted to experiment with the variables to see if every last picowatt of RF energy could be transferred from my humble, so-small-its-hard-to-see-without-a-lens QRP-Labs QMX transceiver to the ionosphere via whatever variant of the delta loop became necessary. I have a muscle radio that could get the job done, but there is an engineering and physics challenge built into this quest. Part of the challenge of QRP is to use brains over brawn.

So let’s examine those design variables and see what emerges from the mist. First up:

1. Orientation (apex up, down or sideways)

There are arguments to be made for and against each way of orienting the loop – and let’s emphasize that we are discussing only vertical orientations here. This is not meant to be a treatise on the basic theory of delta loops, so let me just state that only one orientation fills my needs. The use case we will discuss here is a rapid deployment, field expedient, portable antenna. The antenna must be lightweight, pack into a very small space and will remain erected for perhaps only an hour – just long enough to complete a POTA activation.

The orientation that fills this need is an apex up triangle supported by a telescoping fiberglass pole (a 7m Spiderbeam) at the center. Each end of the bottom section of the loop is supported by a modified trekking pole stuck in the ground.

The Spiderbeam pole could be omitted if a tree limb is available for the center support. A fence or bush could replace the trekking poles. I prefer to be self-sufficient out in the Big Blue Sky Shack and not depend on whatever might be available at the end of the trail. Trekking poles can also be used for their intended purpose en route to the operating site.

2. Feedpoint

2:1 impedance transformer at feedpoint

A delta loop can be fed at the apex, at a corner, a quarter wave from the apex or somewhere in between. I chose to feed my loop at a corner for convenience. The choice of feedpoint affects whether the radiated signal is vertically or horizontally polarized. Frankly, I don’t care; the radiated signal is going to be fired up to the periphery of the “Final Frontier” where it will be kicked around by the ionosphere’s D-layer, then refracted back down to Earth with who-knows-what polarization. We might be more concerned at, say, a Field Day site where it might be desirable to chose vertical or horizontal polarization to avoid interference in the near field with other stations.

3. Loop length

Far end of antenna supported on a trekking pole

Those who don’t wish to rock the boat of antenna orthodoxy will just cut their wire using the formula 1005/wavelength. Should the wire be bare or insulated? Does it matter? Some sources say absolutely not. Other sources suggest the effect of insulation is finite, but insignificant.

I decided to consult the stone tablets to get an official view of the effect of wire insulation. First I consulted the EZNEC manual in which EZNEC creator Roy Lewallen W7EL suggests the difference between bare and insulated wire is very small – perhaps 2-3%. EZNEC allows users to specify wire insulation in its calculations. If we consider that a 20m delta loop has a nominal wire length of 71.5ft, even a 2% impact could change the wire length by almost 18 inches. Significant? Perhaps not, but when I explain how I derived the wire length of my Outside the Box delta loop you may understand how my thinking was swayed on this issue.

Bottom wire section center secured to pole with a Canadian Jam Knot

One source may not be enough to establish a rule, so I also consulted the excellent website portable-antennas.com from Rob DM1CM. Modeling a delta loop on that site was a simple exercise of selecting various drop-down selection boxes – fast and easy. Portable Antennas.com also allows wire insulation to be calculated into the loop design. After plugging in the numbers for my loop the model gave a correction factor of 0.9754 when insulated wire is used. Based on a 71.5ft loop length that would suggest a shortening of 1.76 feet even using just a 2% shortening factor.

How did I determine my loop length? I made the decision to choose the loop length by trimming the wire until I obtained resonance in the CW QRP portion of the 20m band. I set my RigExpert AA55 Zoom antenna analyzer to plot an R,X (Resistance and Reactance) chart. The wire was then trimmed until the RigExpert showed an X value of zero. The wire length? I laid the wire out on the lawn I had neatly cut the day before and measured the length – it turned out to be just 68 feet. If the shortening factor of the wire insulation is taken into account the corrected length would be between 69.36 and 70.1 feet. Is that significant? Perhaps; if the resonant frequency were changed by 2% it might no longer lie in the desired part of the band.

4. Equilateral triangle? Height above ground

Ideally a loop antenna should enclose as much area as possible (source: well, I read it somewhere). My design was influenced by two factors – the height of the Spiderbeam pole (7m, 23ft) and the recommended height of the bottom section of wire above ground (source: Alan WA3EKL recommended between 4 and 6 feet; I chose 4 feet). So the Outside the Box variant of a delta loop is not an equilateral triangle. The bottom section of the wire (the hypotenuse) is longer than the other two sides. Less efficient than an equilateral triangle? Piff!

5. The matching device

Alan WA3EKL suggested a quarter-wavelength section of 75 ohm coax to match the impedance of the loop to 50 ohms, but cautioned against the use of foam dielectric coax whose velocity factor can change over time which affects its electrical length. The only 75 ohm coax I had available is RG-6 which has foam dielectric so I ruled that out.

I recently watched an interesting YouTube video by Michael KB9VBR, who was discussing his way of matching a delta loop antenna. Michael used an impedance transformer with an impedance ratio of 2.5:1 (8:5 turns ratio). That seemed like a convenient and field expedient way of matching the delta loop impedance of 100-120 ohms to 50 ohms so I built one. Out in the antenna test range (my backyard) it was discovered that a 2:1 ratio worked best (turns ratio 7:5).

The final result

My Outside the Box delta loop antenna is resonant at 14168 KHz (slightly higher than planned, but not a problem). The minimum SWR is 1.03:1 at 14175 KHz. At the lower band edge at 14000 KHz, the SWR is 1.15:1 and at the upper band edge of 14350 KHz, the SWR is 1.11:1. And, yes, I have made contacts with it. I bent the rules but the end result is worthy of making the trip to the field this summer.

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An improved tank circuit EFHW coupler

About a month ago Ham Radio Outside the Box posted about “a third way” to match the high impedance at the feedpoint of an End-Fed Half-Wave antenna. A link to the original article is at the bottom of this post. A “30-minute special” was built to prove the concept actually works. It did work fine business (as we say on-air), but that initial implementation had a serious limitation – it was limited to a single band due to the use of a fixed capacitance (a trimmed short length of coax). How could we adapt the basic design to cover multiple bands? Read on to hear about a new improved EFHW coupler that does indeed cover multiple bands.

A QRO(p) coupler

Searching through the vaults containing a vast reserve of assorted electronic components at Ham Radio Outside the Box laboratories (my basement) I unearthed an air-spaced variable capacitor. These now rare items were common in the days of TRF (Tuned Radio Frequency) receivers. For a long time now Superheterodyne circuits have seen the gradual demise of air-spaced variable capacitors.

What’s behind the big knob?

When you look a radio in the face you will usually see that one of the knobs is larger than the rest. That would be what we used to call the “Tuning” knob; nowadays it is more likely to be labeled “VFO”. That would be our first clue as to whether the component behind the front panel is an air-spaced variable capacitor or one of those new-fangled devices called a “Rotary Encoder”. If you turn the knob until you hit an end stop it is a variable capacitor; if it turns freely it is a rotary encoder. For somebody like myself who first gained an interest in radio when capacitors were called “condensers” that is important and useful when deciding whether to purchase an old radio at a yard sale with a view to scavenging its parts.

The component I found in the underground vaults is an even rarer device – it has a slow-motion gear drive. That is a valuable feature when tuning a high-Q tank circuit. I re-used the T200-2 powdered iron core and coil windings from the original single-band coupler. Consumer grade AM radio sets often used a thin cord stretched around an elaborate system of pulleys to achieve the same fine adjustment in tuning, but a mechanical gear system is more robust and reliable.

The capacitance range of the “tuning condenser” was measured using my “Almost All Digital Electronics L/C Meter IIB” and those values, along with the fixed value of the toroidal inductor, were plugged into a LibreOffice spreadsheet to find the range of resonant frequencies available with this coupler. My target was 20m, 30m and 40m – the bands I use most frequently. Good luck struck again, my junque box variable capacitor was able to cover those three bands so I got to work building the new coupler.

Construction

There are only two main components – an inductor and a variable capacitor so putting the coupler together didn’t take very long. For expedience I re-used an old Hammond aluminum enclosure from a long forgotten project. I would have preferred a plastic enclosure but I didn’t have a suitable plastic box available. Now that the device has been proven to work I plan to purchase a domestic electrical box from the hardware store. Hammond aluminum project boxes are sturdy and well made, but they have what I perceive to be a design flaw – sloping walls – which makes them unsuitable for projects like this one. Another consideration is that the kind of variable capacitor employed in this project should be electrically isolated from its enclosure because the body of the capacitor is connected to its static plates. We want to prevent stray capacitance or unwanted conductive paths.

This project was built for my “QROp” rig which is a Yaesu FT-891 capable of 100 watts but which I rarely use above 20 watts. I have even used it as a QRP rig by dialing the HF Power setting down to 5 watts. The disadvantage of operating the FT-891 as a QRP rig is the high current consumption. There is very little practical difference in signal strength between 5 watts and 20 watts, but 20 watts might just edge my signal above the noise during poor band conditions. So I am now working on a QRP version.

Working QRP usually involves lightweight station equipment although that isn’t always the case – refer to my post: “My radio is tiny. So why is my POTA backpack so heavy?“. No matter how small your transceiver is, all the ancillary equipment (like a chair, drinking water etc) adds weight to your pack. Lightweight radio gear doesn’t really allow use of heavy variable capacitors. A QRP version of this coupler will replace the heavy, bulky, air-spaced variable capacitor with polyvaricons which are very small and very lightweight.

Incidentally, why are these miniature variable capacitors called “polyvaricons”? Is the name a contraction of “polymer variable condenser“? Condenser? Surely that should be “polyvaricaps”. Now this old codger feels at home!

Polyvaricons scavenged from secondhand AM/FM radios

Tip: Polyvaricons are available from various QRP parts suppliers but there is another source that is very convenient and cheaper. I went to a local charity shop recently and bought a couple of budget AM/FM radios for pocket change. The checkout clerk told me I had 7 days to check that the radios actually work and I could return them if they didn’t.

I replied that I guarantee they won’t work in about an hour from now as I am going to tear them apart to use their components!

Polyvaricons usually have several sets of plates some of which are high capacitance and some are low capacitance. To make fine adjustments of the capacitance in a QRP version of this project I plan to exploit this feature. Combined with replacing a bulky SO-239 with BNC connectors, all in a small lightweight plastic project box should reduce the size and weight and make a QRP version suitable for backpacking.

Why not use an L-match?

I believe an L-match, discussed in previous posts, is a more efficient coupler for End-Fed Half-Wave antennas. Unlike the tuned tank circuit design, an L-match does not involve the use of a transformer which introduces potential losses. So why have I gone ahead with a tuned tank circuit coupler instead?

I have corresponded with readers who use L-matches as couplers for EFHW antennas. One thing stands out about L-match couplers – each band requires a separate coupler with a fixed capacitance and fixed inductance. This is not conducive to rapid band changes in the field. An alternative is an L-match tuner employing a variable capacitor and variable inductor. I have built one of these but I am of the opinion that this introduces potential losses due to the switched inductance. Even a variable capacitance introduces the potential for losses because of the way contact is made with the moving vanes.

There is a way to configure variable capacitors to overcome this problem. Builders of small magnetic loops often employ it because even a tiny ohmic resistance can impact loop efficiency. In regard to inductance changes, perhaps plug-in inductors could be used just like in the old days when capacitors were condensers.

This whole series of posts here on Ham Radio Outside the Box documents the pursuit of a highly efficient replacement for the broadband impedance transformer commonly used with EFHW antennas. What is your opinion? I invite your comments on this topic.

Re-read the original post:

https://hamradiooutsidethebox.ca/2025/05/14/matching-an-efhw-antenna-a-third-way/

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My radio is tiny. So why is my POTA backpack so heavy?

We have mountains in Ontario. We call them mountains, but they are really just small hills. So I have never had to actually hike for miles up steep slopes carrying a backpack with all my radio gear, plus anything else I might need for a mountaintop activation. To all those who operate in this fashion, you have my sincere admiration.

VA3KOT’s POTA kit packed and ready to go.

Get your kicks on fourteen zero six

At the other end of the scale we have what has been called PLOTA (Parking Lots On The Air) activators. These operators perform their activations while sitting in their vehicles. It is tempting to think they probably grab their morning coffee at the a drive-thru en route to the activation. I confess that I have done this too, but only when the temperature drops down to double digits with a minus sign in front. I imagine that, in southern states, when it gets hot enough to cook eggs on the sidewalk, operating in air-conditioned comfort is almost a necessity. If this style of operating works for you, or is necessary in your environment, then you are doing your part to keep outdoor radio operations alive and thriving.

Mr Blue Sky

In between hiking up an inhospitable mountain, exposed to the elements, and being welded to a car seat is another option. Maybe this is the true expression of operating outdoors – leaving your vehicle and carrying your station into the back country, or even a local park. This is my personal choice. It combines a love of the great outdoors with a love of radio – what I have dubbed operating in the Big Blue Sky Shack.

There are options even within that. Do you carry your gear from your vehicle to the nearest picnic table, or do you backpack everything you need (seat and table included) down a trail, blatting the bugs that are intent on drinking your blood, admiring the wildlife while avoiding large mammals intent on eating you, to find a clearing in the trees where you can set up.

Oh Yuck!

Let me tell you a story about picnic tables that may discourage you from regarding them as a comfortable, convenient place to operate. I used to be an RV camper; it was fun but for several reasons I eventually sold my trailer. During one camping trip a neighboring camper was packing up his giant fifth wheel. I watched as he laid his sewage hose out to dry on a picnic table. For those who have never owned an RV (or caravan as it is known in many parts of the world), a sewage hose is used for emptying the contents of the “black tank” at the “dump station” on the way out of the campground. But I am sure you always use a plastic table cloth, don’t you? Well consider this, your table cloth is going to pick up millions of bacteria from the picnic table surface and transfer them to your food. Yuck!

Little boxes

Going back to the supremely fit, energetic types who climb real mountains to operate. They tend to carry extremely lightweight radios; often the whole station packs away into a tough, rugged plastic case that slips into the pocket of a backpack. I have often thought of emulating this idea. But instead, not being quite as fit as I could be, and with age-related physical limitations, I have chosen a different approach. My backpack station is a little on the heavy side (not to be confused with the Heaviside which is a layer of the ionosphere that makes our hobby possible).

Say, friend, I got a heavy load

At the heart of it all is a QRP-Labs QMX transceiver. This tiny device is so light it almost defies gravity – but it is not a complete portable radio station. So I built a backpack frame that can carry everything I need – and it is surprising what that includes when you can’t pop back to your vehicle to grab something else. Here is a list of what I carry:

Transceiver – QRP-Labs QMX (low band version)
Talentcell 6500 mAh LiFePo4 battery
Drok buck converter to regulate the voltage fed to the transceiver
Putikeeg CW paddle key
Earbuds
Ham made line isolator (common mode current choke)
Selection of RG-316 coax cables
Rite in the Rain log book, pencils
UTC wristwatch
Reading glasses
Selection of wire antennas and radials
18.5ft telescoping stainless steel whip
Lightweight tripod for supporting the whip on rocky ground
Spiderbeam 7m telescoping fiberglass pole
Telescoping plastic seat
Multitool
Small tarp
Selection of cordage

Modified lighting tripod – a bargain purchase at a charity store. Shoulder strap was added later.

Of course there are even more things that must be carried such as water, bug spray, snacks etc. Those little hardened plastic boxes with a tiny radio, key and wire antenna are impressive to behold, but they are not a complete and independent station incorporating everything needed for personal comfort and survival far from shelter and the means of egress.

Experience has taught me not to rely on commercial backpacks to carry all my gear. Most are intended to carry the typical range of items needed by a hiker. I bought a rugged, military style, cotton canvas backpack from a local supplier and was disappointed when I tried to use it to carry my radio equipment. There was no padding, no frame; it was very uncomfortable to carry. Clearly it was made for lighter, softer loads than mine.

Another alternative is real backpacks made for the military. They are built tough but are also very tough on the budget. I just couldn’t justify spending many times more on a backpack than the radio equipment inside it.

Custom antenna bracket secured with a quarter inch nut and bolt – and Gorilla tape! Note the radial attachment point.

Just in case

The solution involved a little bit of work in my garage workshop using many items I had already hoarded ready for future project ideas. I had to purchase two 30-cal steel ammo cases, but they were very inexpensive. One was sold for storing hunting ammunition, but the other was a bona-fide military surplus case with markings indicating it was intended for storing 200 cartridges of 7.62mm rounds and other items. I plan to repaint it sometime before it gets me into trouble. Why steel ammo cases? They are built tough for protecting delicate equipment, they are cheap, and they provide sufficient heft to create a firm operating platform.

Vertically stacked cases are the right height for field operations while the operator is seated on a camping stool.

Both steel cases are stacked vertically on a modified aluminum backpack frame. The bottom case holds antennas, cables etc. The top case holds radio, battery, key etc. Everything is pre-assembled inside the radio case – just pop the lid, insert the earbuds, turn on, tune in and go.

Telescoping plastic stool from Amazon

My Putikeeg CW key has very strong magnets on its base and holds very securely to the steel case. I use it in vertical fashion, with the paddles peeking up above the rim of the steel case. The assembly sits at a very comfortable height for operating the radio without the need for a table. My seat is a lightweight, plastic, telescoping thing with a padded cushion on top. It is an ingenious design with many latches holding it up. I was very cautious about trusting my posterior atop this perch at first, but it supports my weight just fine. The pictures tell a lot more than many more words can convey.

Whatever style of outdoor operating you prefer you are helping keep amateur radio alive. This post describes the way I operate and is not meant to be judgemental about any other style. There is room enough in our hobby for whatever way you like to operate. In fact, I invite you to comment or send me a description of your outdoor radio equipment – even if it is mounted on a set of four wheels 😉

All tuned up on fourteen zero six. The antenna connects to the BNC on the right. The Putikeeg paddles are secured by strong magnets. Earbuds are on the right. Beneath the radio are the 6500 mAh LFP battery, Drok buck voltage regulator and a line isolator.

My POTA gear is constantly evolving so what you see and read here may not be what you see if we meet on a trail sometime. I like to experiment and try out different ideas. Some call me nuts; maybe they are right but I’m having fun.

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Shark’s Teeth and Canadian Jam – a tall story

I recently purchased a Spiderbeam mast from a vendor in the United States. The list price was US$78 – a great price for a high quality product. But the story didn’t end there – not by a long shot. The cost for shipping via courier was an additional US$44. I expected there would be more to pay once the product crossed the border into Canada and that expectation couldn’t be more true. There was plenty more to pay! I received an email from the courier telling me I owed them a further CDN$90 and that to expedite delivery would I like to send them the loot in advance. I paid the ransom and received another email saying thanks for the cash, now your delivery is going to be delayed by three days!

I began to feel that I was being treated like a sucker; I was charged brokerage fees, handling fees, processing fees and, of course, taxes owed to the Canadian government. Then along came the credit card bill from the bank advising me of their extortionate exchange rate to convert US dollars into Canadian dollars. In the end my US$78 mast cost well over CDN$250! I am going to take very good care of this most precious piece of ham radio gear.

What did I buy with that small fortune?

I chose the Spiderbeam 7m (23ft) mast, primarily because it collapses down to a very manageable 28 inches and, although heavier than most, is still light enough to backpack into a field operating location. Is 7m tall enough? Well I thought about that for a while and decided it would be quite sufficient for my needs. Spiderbeam masts are built from heavier gauge fiberglass tubing than other similar products. Many telescoping fiberglass poles – especially those intended for fishing – are very flexible. When deployed for ham radio purposes they tend to bend which reduces their effective height. Spiderbeam masts remain fairly straight – a 7m mast supports a wire at 7m; it doesn’t bow down under the weight of the wire.

Crash prevention

Many years ago I invested in an MFJ 31ft telescoping fiberglass pole. One day, while testing an antenna in my yard, a gust of wind blew the mast over. It crashed against the wall of my house destroying several sections near the top of the mast. Fortunately I was able to restore it to a shortened length of 29ft by replacing the broken sections with those scavenged from a Crappie fishing pole. It has served me well since but it is heavy and collapses to a length of around four feet.

Everything packs into a camping chair bag

My new Spiderbeam mast is going to be very well protected – it cost far too much to replace if it became damaged. So here is a short account of what I have done to protect it during transit and while in use out in the Big Blue Sky Shack.

First, in transit, I pack it inside a length of 2-inch (50mm) PVC plumbing pipe. That all goes inside an expanding document tube which, in turn, goes inside a carry bag previously used for a camping chair. The bag is also used for packing tent pegs and guy lines.

What is the plumbing pipe for?

Well I guess I could just set the Spiderbeam mast down on the ground and guy it in place. However, by slipping it inside the plumbing pipe it can be easily removed for adjusting the antenna wire when needed.

Shark’s teeth?

“Shark’s teeth” cut into support tube to prevent the base from slipping

Experience has taught that tall masts have a tendency to slip at the bottom. It is simple physics; 23 feet of mast supported 2 feet from the base provides enough leverage to topple the mast in windy conditions, or when a long wire under tension is attached at the top.

In the past I have dug a small divot to hold the base in place – effective but with a tendency to generate disapproval from park wardens. Now, to protect my precious Spiderbeam from catastrophic collapse I cut a set of “shark’s teeth” at the base of the support tube. It works and, if I ever encounter a growling bear on the trail, I can show it my shark’s teeth to intimidate it into retreat.

Guy lines secured to support tube using Canadian Jam Knots

The top of the support tube has a small section of enhanced diameter created by slipping several strong rubber bands covered in electrical tape. It’s purpose is to prevent the guy lines from slipping – simple and effective. The guy lines made from 550 paracord are secured using Canadian Jam knots. I have no idea why Canada is credited with this particular style of knot, but it is a very secure way of tightening a guy line around the support tube. Canadian Jam knots are also very easy to release when it is time to pack up the station.

Modified Taut Line Hitch – sliding knot to tighten guy lines Super light aluminum pegs hold the guy lines to the ground

At the other end of the guy line I use modified taut line hitches to create an adjustable loop around lightweight “aircraft grade” aluminum tent pegs. The modified taut line hitch involves a couple of extra wraps of cord to make it more secure. I have found standard taut line hitches tend to loosen a little when tied on paracord.

Finally, at the top of the pole, I attached a small loop of very thin, but strong, cord. I took a few inches of cord, formed a loop and tied a simple knot at the end. The knot was fat enough to fit tightly in the top, hollow section of the Spiderbeam mast. It was secured with hot melt glue and is very secure. I don’t think it could be dislodged even if I wanted to remove it.

The loop can be wrapped around an antenna wire, then slipped over the top of the mast as seen in the picture. To remove the wire I simply lift the wire above the top section of mast to release it quickly and easily.

Cord loop at top of Spiderbeam pole for holding antenna wire

So far, all is well. The small fortune I have invested from my meager retirement savings into this excellent Spiderbeam mast is going to be very well protected!

Releasing the antenna wire is easy – simply lift the wire to the top of the pole and the cord loop releases

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Testing and modifying the “POTA PERformer” antenna

What is the POTA PERformer? Greg Mihran KJ6ER has introduced us to an antenna that he calls the “POTA PERformer”. The capitalized PER in its name is an abbreviation for “Portable, Elevated, Resonant”. But what is it really? The POTA PERformer is an adjustable elevated vertical radiating whip with two adjustable elevated radials. In concept there is nothing really new about it, but the unique implementation devised by KJ6ER is quite interesting.

Get up off the ground

Tripod mounted whip at Ham Radio Outside the Box

Most hams will be aware that a quarter wave vertical antenna, mounted on the ground, requires an extensive system of radials to be efficient. I have successfully used such an arrangement with as little as four radials during a POTA activation out in the Big Blue Sky Shack. But, as they say, even a poor antenna will get you contacts when conditions are right. Some recommend as many as 120 radials although anything over 16 provides very little further improvement. In a portable situation laying out a lot of radials for a short-term temporary station doesn’t make a lot of sense. So what is the alternative?

Less is more

If the base of the antenna is raised above the ground, fewer radials are needed to form an effective counterpoise and make the antenna efficient. How many? KJ6ER has settled on two radials for the POTA PERformer. If the radials are arranged at 90 degrees to each other the antenna has a directional radiating pattern. But using two radials increases the footprint on the ground and that could be an important consideration if, for example, we are operating on a narrow trail. Could we get away with just one radial? I modeled a POTA PERformer using EZNEC and came up with a comparison, shown in the following table.

TABLE: 1 radial versus 2 radials

Now I’ll admit that I am no expert in computer modeling, but the results I obtained seem to differ from what KJ6ER found. In either case, whether two radials or just a single radial are used, we have a directional antenna that can be rapidly deployed in the field.

One radial or two? Now here’s a surprise!

The original POTA PERformer is a multiband antenna. It covers all the bands from 20m up to 6m with a 17ft telescopic stainless steel whip and adjustable length radials. KJ6ER suggests extending the band coverage to 30m and 40m by means of a loading coil at the base of the whip and then … surprise … combining the two radials to create one long radial wire. I suspect the 30m/40m version may lack some of the gain and efficiency of the higher band version due to the losses involved in base loading a vertical radiator. Perhaps a full length vertical wire supported by a pole, or a tree, might be better.

I have always felt there is something incongruous about using a counterpoise that is longer than the radiator. Perhaps that concern is unfounded if we consider that a raised radial wire also radiates.

Customizing the original clever idea

I have tried the POTA PERformer with both a single radial and two radials. Both versions “worked” and I made contacts. It is difficult to interpret which was better, but my own preference – for field expediency – is a single radial. The 20m, 30m and 40m bands are my preferred haunts, only for the reason that two of my QRP radios do not support the higher bands. Even though the POTA PERformer is a great idea with very positive reports from several sources on YouTube and elsewhere, it doesn’t fit well with how I like to operate. Here is why.

Please remain seated

A raised radial wire is a tuned counterpoise. Its length is important. That means band changes involve adjusting the length of the radial(s). One way of doing this is to insert a non-conducting link in the wire and move it between linked sections to set the conducting part of the counterpoise to the correct length for the band of operation. The overall length remains the same but the sections of the wire not being used are isolated from the rest of the antenna. Another way that I have tried is to use a metal measuring tape and unwind it to the correct length. Perhaps using multiple raised radials where each wire is adjusted for a different band would also work. Whatever method is used, getting out of your chair and fiddling with radials and whip lengths is a time consuming distraction. So what’s the alternative; how can you stay in your seat and change bands?

Get on the ground and spread ’em!

Sacrificing a little efficiency is required but it can be done. My own method is to spread out four radials wires in a fan pattern on the ground, facing the direction I want my signal to go. Are four ground radials enough? If the vertical element is ground-mounted then using only four radials results in efficiency loss. But, if the whip is elevated? Who knows, but it works.

Since ground radials are detuned their length is not critical. No adjustment is required whether operating on 20m, 30m or 40m. The only requirement is that there is sufficient copper on the ground to provide a good counterpoise; I use 4x13ft radials. Orienting all the radials in one particular direction does improve the signal in that direction to a small extent. How much efficiency is lost? That is very hard to quantify but the convenience factor is high.

A 17ft whip with an adjustable loading coil (bypassed for 20m) will cover all three of the bands that I need. I have also used a 9ft “tactical” whip whose fixed length sections are held together with bungee cord. This shorter whip uses a separate loading coil for each band and is usually only employed with my QROp rig (a 100 watt radio that is usually set to 20 watts or less). This radio gives the ability to transmit a little more power when needed.

“QRP when possible, QROp when needed” – Ham Radio Outside the Box

Is there any real difference between 5 watts and 20 watts? Maybe not but it does give me a nice warm feeling – especially if I get too close to the antenna while keying up.

To better understand and learn more about the POTA PERformer it is worthwhile downloading and reading Greg KJ6ER’s PDF document. It may inspire you to build one or even devise your own variant to suit your unique operating needs.

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Reviving a Webster Band Spanner – a 1950s manual screwdriver antenna

About 20 years ago I was approached by a neighbor who, knowing that I am a ham, asked if I might be interested in looking at some of the old ham junque he had accumulated over many years. He was a fine gentleman, in his golden years, who was no longer active in the hobby. Hesitating for less than a microsecond I eagerly agreed. Among the treasures I acquired was a Signal Electric straight key. I believe it was an R48 model first introduced in 1920 when it sold for $2.80. But my prized acquisition was a Webster Band Spanner antenna.

The Band Spanner was produced in the 1950s and 1960s by the Webster company in San Francisco. It is a center-loaded manual screwdriver antenna intended for mobile operation. Unlike modern screwdriver antennas, like the popular Tarheels, that use an electric motor to make band changes, the Band Spanner has to be manually adjusted for each band by sliding the whip up and down.

Two models were produced; the A-61 and the A-62. The A-61 (that I acquired) has an extended length of 93 inches and a collapsed length of 60 inches. The longer A-62 model has an extended length of 117 inches and a collapsed length of 63 inches. Both models support the 75-40-20-15 and 10 meter bands. There is a mark on the whip indicating the mid-point of each band. I suspect the WARC bands could also be tuned although it would be necessary to locate the correct whip length by trial and error. The antenna is rated for “100 watts or more”.

Whip connection contact Coil section (top), lower radiating section (bottom)

The Band Spanner is constructed from a fiberglass support column with a 24-inch long internal loading coil. At the base of the whip is a circular contactor that connects with the windings of the loading coil. As the whip is raised or lowered, the contactor connects to individual exposed turns of the loading coil inside the support column. This type of continuous adjustment permits exact resonance to be achieved anywhere within a band. It is a very high Q antenna – moving the whip just one click up or down (one turn of the loading coil) makes a significant difference to the tuning.

Would the vibration of a vehicle change the tuning?

Whip locking screw

You might expect that a bumper-mounted antenna would be subjected to a lot of stress as a vehicle crashed through pot-holes and other rough ground, but there is a very tight connection between the whip and the loading coil. The connection is so tight that it requires some force to adjust the whip length and it is quite possible to skip a turn if too much force is used. The tight connection has a another positive benefit – it makes the connection point self-cleaning. There is also a locking thumb screw at the base of the whip to help secure it in place.

Stationary mobile operation

Bumper mount

I am not a mobile HF operator; there are enough distractions already to compromise driving safety, so I prefer to use the Band Spanner as a stationary mobile antenna. For those who do intend to use it as a mobile antenna, there is the H-200 ball mount (shown in picture).

I have tried several ways of mounting the Band Spanner as a temporarily fixed position portable antenna. The manufacturer suggests using a matching section of 21 feet of RG-8/U coax and grounding the shield of the coax to the vehicle body. I did once try using such a matching section with a Band Spanner on a tripod, but it didn’t seem to improve the tuning at all. Most recently I attached my Band Spanner to my “QROp” (5-100 watts) radio set. It is a Yaesu FT-891 mounted inside a mil surplus 50-cal ammo box. The Band Spanner was connected directly to the rear of the rugged steel case. My ham-made L-match tuner was used for fine adjustment of the SWR.

Ammo can radio set with FT-891 transceiver; ham-made L-match; CWMorse extruded aluminum paddles; Bioenno 12Ah LiFePO4 battery in canvas pouch (left of picture) and Webster Band Spanner antenna attached at rear.

Tuning was fairly easy. I set the radio to 20m and 5 watts power output. I threw a 17ft wire counterpoise on the ground behind the radio. A single wire counterpoise is not really sufficient ground for this antenna so additional inductance had to be added via the L-match. I would usually lay out at least 4 radials for a portable vertical antenna, but I was on a mission. I wanted to find out if the Band Spanner could be employed as the radiating element of a “POTA PERformer” type of antenna. Ham Radio Outside the Box will be exploring the “POTA PERformer” in more detail in an upcoming post. For now we can describe it as simply a raised quarter wave whip with raised tuned radials.

Now comes the surprise

Having tuned the antenna with one ground radial to less than 1.5:1 SWR I thought I was on a roll. Next step, I raised the radial so that it would not be detuned by contact with the ground. I now had the Band Spanner set for the 20m band, finely adjusted by means of the L-match to give a good SWR. I expected some further adjustment might be necessary with a raised 17ft counterpoise, so imagine my dismay when the radio flashed its “high SWR” warning.

The Band Spanner is intended to be used while mounted to a couple of tons of steel vehicle serving as its counterpoise. It is a very short, loaded vertical antenna with very high Q performance. A lesson I learned early in my ham career, but overlooked in this exercise, was that a short-loaded, high Q vertical whip requires a carefully tuned counterpoise – or a good ground. Simply using a raised 17ft wire isn’t good enough. I would have had to precisely trim the raised radial wire to get a good SWR. To make this even more complicated, a precisely trimmed radial wire counterpoise for each band would be required. So the mission objective to examine the Band Spanner’s suitability as a portable POTA PERformer was concluded. In future, the Band Spanner will be used with the best ground system I can erect during a temporary field installation.

Another thought …

A Band Spanner (or even better – a motorized screwdriver antenna) could possibly be used in an HOA situation. If it were ground mounted, with a good system of buried radials, it could potentially be disguised to prevent detection by the HOA hounds.

And finally …

I am not sure of the actual age of my Webster Band Spanner. They were produced in the 1950s and 1960s so I estimate it to be at least 60 and maybe as much as 75 years-old. The bumper mount has entirely lost its plating and is now a dull rust color. The fiberglass support column is equally dull and has lost its identifying markings. But, the antenna still functions as the Webster company intended all those years ago, which is more than can be said for its owner who is of the same vintage!

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Matching an EFHW antenna – a third way

There is no doubt about the popularity of the End-Fed Half-Wave antenna. It is used by a very large number of hams, especially during portable operations like POTA, SOTA, WWFF etc. Why is it so popular? The principal reason seems to be ease of deployment. The EFHW requires only a single support and can even be used without any kind of transmission line – i.e. it can be directly connected to a radio without any coax, so zero transmission line losses!

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But despite those advantages the EFHW has its critics. There are two principle objections: first the commonly used 49:1 impedance transformer, or UNUN if you prefer, is claimed to be inefficient.

Secondly, the antenna wire is only a half wavelength long on its design band. Although it can be used on its even harmonics the antenna becomes multiple half-wavelengths long. Of course, we know that the impedance of the wire is theoretically replicated every half-wavelength so that shouldn’t be a problem.

It is even possible to get a 1:1 SWR match on other bands by pressing “the magic (Tune) button”. That doesn’t make the antenna any better but it does convince the transceiver that it shouldn’t roll back the power, or even worse, throw an exothermic hissy fit.

The disadvantage of using an EFHW as a broadband antenna is that the radiation pattern may change with each band. It may even break up into multiple lobes, making getting contacts a hit-and-miss affair.

If you are standing on the top of a wind swept mountain with a storm approaching and you need to get your 4 contacts to qualify a SOTA activation, you may not be entirely engrossed in the finer points of antenna physics. I have been an EFHW user for many years and have thousands of QSOs in the log. For a long time I was blissfully unaware of what a terrible antenna I was using while I battled countless pile-ups and enjoyed the thrill of operating my radio out in the Big Blue Sky Shack.

Those were the days my friend

As I read more and more about the theory of the End-Fed Half-Wave antenna I would deploy mine and agonize about efficiency and radiation patterns while reminiscing about the days when ignorance was bliss and I just enjoyed my hobby.

Keep It Sweet and Simple – Use a dipole

Critics often argue that a simple dipole is a good replacement for the EFHW. After all, both antennas are a half wavelength long; the main difference is where they are fed. A center fed dipole has a nominal impedance of 70 ohms, not 50 ohms, so still not perfect. It is usually erected as a “flat-top” which requires three supports. No problem in a quiet corner of the forest where nature benevolently provides ample leafy poles, but in a public park where zealous guardians of arboreal sanctuary patrol the greenwoods you may indeed have a problem.

A dipole can be erected in other ways, for example as a sloper. Now only one support is required but another tiny problemette arises – the feedline has to be kept at 90 degrees to the radiating wire. In either deployment fashion a long feedline is required. Let’s say we are operating a flat-top dipole on 20m. The antenna should be a half wavelength above ground so we need three 33ft/10m supports and 33ft/10m of coax feedline. The center support pole could be omitted but the weight of 33ft of coax plus a 1:1 UNUN at the feedpoint will drag the feedpoint down.

The long and winding (coaxial) road

Unless the operator is sitting right beneath the feedpoint, even more coax is needed to reach the radio. Two issues here, the coax will incur some loss although it is often too small to be significant. Secondly, the SWR will be changed by the coax loss – perhaps for the better, but it may create the illusion of a better SWR than is actually occurring up on the antenna wire.

Don’t leave home without it

You could connect the dipole feedpoint directly to the radio and operate the antenna in a “V” orientation. I did do exactly that during an emergency (I had inadvertently left my antenna at home) and successfully completed a POTA activation using a spare piece of wire. It must be realized that the feedpoint in such an arrangement is a high current point, and hence a point of maximum power radiation. Some of the radiated energy will be cooking the earthworms – and the operator!

Linked 20m, 30m, 40m EFHW arrangement

So back to the “horribly inefficient, avoid-at-all-costs, snake oil” End-Fed Half-Wave antenna. How can we overcome the problems exaggerated by its naysayers? First, make it a single band at a time antenna. What do I mean by that? Use a separate wire for each band? There is a very simple way to do that. I designed and built a 3-band EFHW for 20m, 30m and 40m. I started with a half wavelength of wire on the 20m band but added a 2mm banana connector at the end. I then attached an extension wire to make the the antenna a half wavelength on the 30m band – again with a 2mm banana connector at the end. Then another extension for the 40m band. Each section of wire is attached with a short piece of thin cord to allow the links to be adjusted for each band.

And now for something completely different

Now for the biggest objection to the EFHW – the matching device. Ham Radio Outside the Box has already discussed two different matching devices, the 49:1 impedance transformer and the L-network. Now we have a third competitor in the race to perfection – the tuned tank circuit. I have to credit two sources for the inspiration to try this method: Steve AA5TB and John M0UKD. Both these gentlemen have built what is essentially a parallel tuned circuit to match the very high impedance at the feedpoint of an End-Fed Half-Wave wire to the 50 ohms expected by a transceiver.

EFHW parallel tuned circuit matching device

Being an avid experimenter by nature I had to build one myself to see if it would work. I get the most enjoyment out of projects that go from adrenalin inspired enthusiasm to field trials in a half hour or less. As a result the finished product is often inelegant but hopefully functional. And so it was with this project. Having a collection of radio-junque accumulated over decades helps.

The picture shows a little project I threw together in a half hour to test whether AA5TB and M0UKD were promoting a good idea or snake oil. Both were using a variable capacitor to tune the tank circuit but, in my haste, I substituted a coax capacitor to make a matching device that would serve only a single band – I chose 20m.

**RED ALERT** **RED ALERT** **RED ALERT**

The parallel tuned circuit comprises, in addition to a variable capacitance (mine is variable by trimming its length with side cutters), the secondary winding of an impedance transformer. An impedance transformer? Isn’t that the weak link in the common 49:1 UNUN design employed by the unenlightened multitude?

I forged on regardless. A powdered iron toroidal core is used instead of the usual ferrite material. Why? To reduce the inductance to a level that can be resonated by the capacitor. As an experiment I tried winding 14 turns of magnet wire on a FT82-43 core but the inductance was way too high. The alternative is to use a powdered iron core and the only one I had in my junque box was a T200-2 so it would have to do. Another alternative is to wind an air core inductor. I soldered the coax capacitor in parallel with the secondary winding then wound two turns over the center of the secondary to create the primary winding.

Now, armed with my faithful side cutters I boldly went out onto my deck and hooked my new hastily built tank circuit matching unit to a piece of wire that I had previously established to be a true half wavelength on 20m. I attached a short coax between the matching device and my RigExpert AA55 Zoom antenna analyzer, fully expecting a “you gotta be kidding me” message on the display.

Surprise!

The RigExpert displayed a different message: “no snake oil here” craftily encoded by the numeric “1.8:1”. I was cheerily gobsmacked and, encouraged, I adjusted my “variable” capacitor with the side cutters a tiny bite at a time and watched as the SWR dropped inch-by-inch (2.54cm-by-2.54cm?). When the SWR dropped below 1.5:1 I laid down the side cutters and declared the match “good enough”.

Like a bridge over troubled waters

It all seemed too easy. The troubled waters of the End-Fed Half-Wave antenna have now been crossed by three different bridges: the traditional 49:1 UNUN, an L-match and now a tuned tank circuit. If the inefficiency of the traditional 49:1 UNUN arises in the flux leakage between its windings then the tuned tank circuit approach replicates that weakness. Perhaps flux leakage is even worse when using a powdered iron toroid or air core design. In one of AA5TBs projects the tank circuit inductance comprises an air core inductance with an 8-turn secondary and only a single turn primary which I found very surprising.

There are still more ways of matching the high feedpoint impedance of an EFHW antenna that may be explored later on Ham Radio Outside the Box, but for now the simple L-network seems to offer the best hope for a high efficiency matching device. What is your opinion? Let me know in the comments or, if you prefer, send me an email (good on qrz.com). I reply to all email received.

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