Quadrature-directed quasi circulator

A circulator capable of simultaneous transmit and receive operations, high frequency, high isolation and noise figure suppression comprising: an antenna port; a transmission port; a receiving port; three quadrature hybrids, two directional couplers; wherein transmit signal entering the transmit port are split into quadrature components and coupled separately and directionally by the two directional couplers to the antenna port where the coupled quadrature components of the transmit signal are recombined in phase, while the transmit leakage to the receive port are recombined destructively in phase; said arrangement simultaneously allows the receive signal entering the antenna port to be split into quadrature components by the antenna quadrature hybrid and transmitted through the directional couplers separately and entering the receive quadrature hybrid where the quadrature components of the receive signal are recombined in phase at the receive port; said arrangement reduces the insertion loss from the antenna port to the receive port.