Hi guys,

I've run into a niggling problem with my station. It goes something like this:

I've got two Windoms about 35 ft apart. One (80 meter resonant) is used for transmit and receive. The second Windom is 40 meter resonant and inverted form the first- used for noise sensing and beamforming.

System works great, can null out almost any noise which appears on both antennas.

The problem is during transmit. Too much RF is coming into my second receiver, ADC 2, and is over driving it. I can compensate at some transmit levels with a step attenuator. I've also ordered an RF limiter for the second antenna which should solve the problem.

What I'd like to know is what equation can I use to model the return RF on the second antenna if the gain of both antennas is known?

Since I've never really done antenna modelling or setup a field day station I'd like to understand the problem fully even if I've already found a fix.