I'm using two patch antennas, tuned to 10.61GHz, to transmit a pulse and then re-transmit a reflected pulse. There is virtually no time delay between the incident and reflected pulse. The initial transmission from antenna 1 to 2 works great. However, I do not see the reflected pulse after transmission from 2 to 1. If I put a circulator between the 2nd antenna and the load, I can clearly see the reflected pulse. Will the incident and reflected pulse interfere with each other in free space (air) differently than they will in a coax cable? If I remove the antennas and replace them with an thru adapter, then the incident and reflected pulses propagate just fine - as far as I can tell they don't interfere with each other. This setup is very similar to a radar in that it uses one antenna for send and receive. However, a radar is operating at considerably longer range and because of the propagation delay, there is time to switch the antenna between a send and a receive setup. I have less than 1ns, so there's no time to implement some sort of switching. Thanks!