3/5) A quick test with my #nanovna_v2 gives hope 🙂

I decided to measure the impedances in a typical #hamradio #antenna setup with an unmatched antenna, here simulated by a 270R resistor.

At 3.5MHz, the feeder (25m H155) transforms this to 30+j51 ohms. Using the #nanovna_v2, I adjusted the tuner to a 50 ohm match at the tuner input.
Terminating the tuner input with 50 ohm, I removed the feeder and measured into the tuner output. I got (almost) the exact conjugate: 33-j53 ohm 👍🏼🙂
So the tuner presents a capacitive conjugate to match the inductive part of the impedance presented by the feeder.

That’s all there is to it: the antenna tuner doesn’t ’tune the antenna’, it creates a decent match to the transceiver while presenting a complex-conjugate to whichever impedance is presented by the end of the feeder, thereby securing maximum power transfer 🙂

#testandmeasurement #antennatuner #antennabuilding #hamr #mfjenterprises #rohdeschwarz

Log periodic antennas are wide-band directional devices, suitable for signal hunting or simply wide-band communication. Their gain isn’t impressive, this one is rated to about 6dBi, that’s the price you pay for bandwidth.

The commercially made are really expensive, literally an order of magnitude above this eBay unit which was about 60$. But I suspect they have a similar PCB inside anyway 😂🤷🏼‍♂️

So how well does this unit perform? My #nanovna_v2 cuts off at 4GHz but starting at about 700MHz, it surely delivers a reasonable match below SWR 1:2 (620MHz for SWR 1:3)

I’ll have to bring it to the lab at work to test the upper frequency limit 🙂 For now, let’s go signal hunting! 😎

#rfengineering #rfengineer #antennaengineering #testandmeasurement #hamradio #hamr #osinttools #osint #sigint #esm #elint #comint

I never tried TDR (Time Domain Reflectometry) on the #nanovna_v2 before, but it turns out to be quite accurate! 😃

Once calibrated and configured with the right velocity factor (66% for RG-58), the length of the cable is seen as a major reflection from the non-terminated far end.

TDR analysis has always been a bit of magical, it’s like you’re able to look inside the cable and observe what’s going on in there.

At work we have really high bandwidth instruments, providing fantastic TDR resolution - but this little unit does quite well too 👍🏼🙂

I might be going on a field trip in a week where this could come in handy - stay tuned 👌🏻

#hamradio #timedomainreflectometer #nanovna #testandmeasurement #rfengineering #rfengineer #electronics #electronicsengineering