So I just fired off an article on a fun #electronics #hamradio #physics research side project I'm quite excited about, and to shorten the time waiting for the reviewer feedback, I thought I'd tell y'all broadly what it's about.

It's about reflections in radio systems.

The question I'm addressing is what happens when a transmitter is for example connected to an antenna via a transmission line like a coax cable, but the antenna is somewhat mismatched and some of the energy is reflected at the antenna and coming back towards the transmitter.

The cliché answer would be that a properly power matched transmitter has 50 Ohms of output impedance and thus it will reabsorb all the returned waves. You see, the reflection coefficient formula for a 50 Ohm cable is Gamma=(Z-50)/(Z+50), and for Z=50 this just gives zero.

It turns out (and has been known by those who care about these kinds of details) that this is generally not the case for radio frequency power amplifiers.

The point I am making in my article is that it is even more not the case 😊
In general, whether and how waves are reflected or absorbed by the signal source can not only depend on how much drive the transmitter receives, but also on the relative timing of the wave coming back. 1/n