xpyttl napisa³(a):
If you're going to be doing the math anyway, analog or digital, and
providing some sort of calibration mechanism, you don't need to get too
weird about the directional coupler.

DC (coupler) isn't a problem for me. I've made few reflectometers (both
HF and VHF) based on homebrew couplers. I've tested toroids, pcb's and
copper tubes.

I am rather afraid (terribly afraid) about mistakes in my op-amp
mathematics ;-)

Now I'm thinking about ad 8302, 8307 and also (used in my FSM - ad8313)

MAc
sp9mrn