How to slap that pesky impedance into compliance...
#SmithChart
My first #HB9CV #antenna, believe it or not, made from 5mm brake lines and a foot of 15mm copper pipe 🙂
I need it for a 70cm radio #foxhunt event in a couple days - looked different places for design guidelines, some of them came up with quite different results 🤷🏼♂️🤨
Decided to just have go at it, based on a combination of what I could find in the legendary #Rothammel antenna book and some online sources and it turned out quite well 😃
Resonance is a bit low, 431MHz, but it’ll do fine as a direction finding device: what I really want is the characteristic kidney shaped radiation pattern, allowing me to turn the antenna backwards, looking for a minimum in the received signal.
Funny to see how the #smithchart impedance plot has a distinct turn at the resonance frequency 🤓
#rfengineer #hamr #antennadesign #testandmeasurement #electronicsengineering
#hamradio #rfdesign #smithchart
#nerd #amateurradio #impedancematching
They're doing huge road works here...
While under a High Wind Warning >50 MPH & up to 4" of rain from remnants of Helene, reacquainting myself with #Smithchart measurements and building #KM4CFT Jonathan's #qrp #EFHW in a linked configuration for 40,30,20,17 & 15 meters. #AmateurRadio #HamRadio
#ZachStar says the scariest thing in #EE is the #SmithChart. I am of a different view. Many E&M topics, including resonant cavities, waveguides, antennae, etc., are far more daunting than impedance matching transmission lines.
Sure, a paper Smith Chart is not so hot, but a Smith Chart slide rule is quite fun to use. And an HP network analyser with a built-in Smith Chart makes it all definitely non-scary.
In an other life I did a lot of #RF Radio Frequency work. Transmission line principles were bread and butter.
This #article explains a lot in a small space. Recommended.
It makes use of a #SmithChart, one of the cleverest bits of maths I know. There is a link on the page I gave that jumps to an equally good explantation of smith charts.
#Electronics #Mathematics #Impedance #Radio #RadioTheory #Calculation
An amp is unconditionally stable if the magnitudes of the reflection coefficients at the source, load and the amplifier's i/o ports are simultaneously < 1
requirement : amp be a linear network with no poles in the right half plane
#Antenna is a one port network #smithchart
So, I just discovered this website on #antennas: http://www.antenna-theory.com/
It not only has sections on different types of antennas but also introduces one to the preliminaries required to understand the subject (such as impedance matching on transmission lines with the help of Smith chart).
#electromagnetism #RFengineering #MicrowaveEngineering #TransmissionLines #SmithChart
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