After completing my radiometer book I started a new project constructing low power Ground Penetrating Radars (GPR's) at 4 and 12 GHz. The transmitters are simple Dielectric Resonant Oscillators (DRO's) that generate only about 5 milliwatt's of CW power. The DRO is pulsed every microsecond using a pin diode switch, whose output goes to a circulator to detect the reflected signal at different received times. Since the circulator only provides 25 dB of isolation, I am using another pin diode switch at the circulator output that is synchronized to first pin diode switch to increase the isolation to about 70 dB. The output of this switch is then connected to a 60 dB gain LNB. I hope this isolation is sufficient to not saturate the LNB so I can detect the small reflected signal at different received times (< 1 microsecond) following the DRO pulses. My question is whether this simple configuration makes any sense or do I need more isolation or greater transmitting power. .