Jerry,

Thanks, the antenna handbook has a design for a bi-directional coupler that
looks like it will work. At this point I think the next step is to separate the
input to the A port from the reflected signal. Putting a pad in the circuit to
increase isolation affected the reflected reading. I am also sorting through
those readings.

Dan

Jerry Martes wrote:
"dansawyeror" wrote in message
. ..

Owen,

Yes, you are right. The single coupler doesn't isolate the channels.
Putting a 10 dbm attenuator between the tee and the coupler changes the 50
Ohm reading. I think a dual directional coupler is required. I will have
to put this on hold until that problem is solved.

Thanks - Dan


Dan

Are you open to trying to assemble something to measure the reflection
coefficient rather than to put the project on hold?
The HP 41952A Transmission/Reflection Test Set uses only one directional
coupler. It uses a power splitter at the input with a pad to level the
outputs from the "Fwd" and "Rev" ports. I can scan some info from the HP
41952 and E-mail them to you if you have interest in building something.
I would think it would be fairly easy to build devices for HF if you
already have a decent directional coupler.

Jerry