[amsat-bb] TUning the antennas on a Cubesat

Someone asked me how to tune the antennas on a cubesat without the instrumentation totally becoming part of the antenna system itself?

I said you have to put the SWR instrument inside the cubesat as we did here: http://aprs.org/PSAT2/SWR-testing-0160x.jpg

But that only works on a 1.5U cubesat where and MFJ Antenna Analyzer will fit!

The other method is to just put in a bidirectional coupler chip, and then feed the forward and reflected voltage taps to the internal cubesat telemetry system and then compute the SWR from these two Forward and Reflected power telemetry channels.

Bob, WB4APR