
271Microwave Components
may completely damage the receiver in case it leaks into it. Barring Doppler
radars where leakage of a small fraction of transmitted power is used as a
reference signal, the isolation between transmitters and receivers has to be as
perfect as possible. This isolation can be achieved by using either some pas-
sive devices or active devices. The passive devices include hybrid junctions
(viz. magic tee, rat race tee and short slot couplers), circulators and turn-
stile junctions. Hybrid junctions provide isolation to the tune of 20–30 dB in
normal course and up to 60 dB with extreme precision but have 6 dB inher-
ent loss