What does 'isolation' mean in a radar antenna system spec text? How to measure it?
There may be circulators, or precision waveguide functions, that provide 85dB isolation.

[If megawatt pulses (+90 dBm), such isolation still allows +5dBm into the receiver. Thermal floor is about -100dBm.]

Or ionizable gas section in the waveguide, that become plasma when hit by high energy of the TX pulse.