Abstract: A matched pair circulator antenna isolation circuit provides isolation between an antenna and one or more receivers and transmitters and may also be applied to other RF devices. A portion of the transmit signal is extracted by a first RF circulator and divided into two phase-inverted signals. The first phase-inverted signal is coupled through a first directional coupler to cancel most of the transmit signal present in the receive signal. The second phase-inverted signal is coupled through a second directional coupler to cancel remaining transmit signal in the output of the first directional coupler. The output of the second directional coupler is coupled to the input of the receiver.

Abstract: An isolation circulator network includes three circulators and a 180 degree ybrid coupler for isolating an RF transmitter from a nearby RF receiver. The isolation circulator network comprises: a first circulator for transforming a first RF signal, RF.sub.1, into a second RF signal, RF.sub.2 and a third RF signal, RF.sub.3 ; a second circulator for throughputting the third RF signal; a third circulator for transforming the second RF signal into a fourth RF signal, RF.sub.4, and a fifth RF signal, RF.sub.5, and for throughputting a sixth RF signal, RF.sub.6 ; and a 180-degree hybrid coupler which provides a seventh RF signal, RF.sub.7 in response to receiving the third, fifth, and sixth RF signals, where RF.sub.7 =(RF.sub.5 -RF.sub.3 +RF.sub.6).