Appliction of Circulator

Normally, three prot circulators are used as duplexers. Connection a transmitter to port 1, antenna to port 2, and receiver to port 3 permits simultaneous transmission and reception of signals while
protecting the transmitter from reflections due to antenna mismatch. In high power systems, a limiter is
commonly used between port 3 and the receiver to prevent receive burnout.
Another common use of circulators is as coupling elements is reflection amplifier ,such as parametric
amplifiers.Which is illustrated in Figure3. In this application three single-juction(3-port) circulators are
connected in series with terminations(dummyload).