Patent ID: 7855617

Claim:
A circulator capable of simultaneous transmit and receive operations, high frequency, enhanced high isolation, broadband performance and noise figure suppression comprising: an antenna port; a transmission port; a receiving port; three quadrature hybrids, one for each said port; two directional couplers; wherein each port is connected to a quadrature hybrid for splitting an input signal into two output components, the said output components have a ninety degrees relative phase difference to each other; each of said quadrature hybrid in addition to the connection to the above mentioned ports has at least two output connections each of which are connected to a separate directional couplers and if a fourth connection, said fourth connection is attached to a matching load circuit; said directional couplers have four ports: an INPUT port, a COUPLED port, a THROUGH port and an ISOLATED port; the INPUT ports of said directional couplers are connected to the inner ports of the quadrature hybrid at said transmit port; the COUPLED ports of said directional coupler are connected to the inner ports of the quadrature hybrid at said antenna port; the ISOLATED ports of said direction coupler are connected to the inner ports of the quadrature hybrid at said receive port; the THROUGH ports of said directional coupler are individually terminated by a to matching load; the inner ports of the quadrature hybrid at the transmit (Tx) port are the ports other than the ports that are connected to the Tx port and the matched load; the inner ports of the quadrature hybrid at the antenna (Ant) port are the ports other than the ports that are connected to the antenna port and the matched load; the inner ports of the quadrature hybrids at the receive (Rx) port are the ports other than the ports that are connected to the receive port and the matched load; this arrangement of circuits allows the portion of the coupled quadrature signals from the transmit port to be mainly directed towards the antenna quadrature hybrid and be recombined in phase at the antenna port, the residual coupled quadrature signals that are passed through said directional couplers enter the receive quadrature hybrid and are phase cancelled; said arrangement simultaneously allows the receive signal entering the antenna port and proceeding to the antenna quadrature hybrid to enter the receive quadrature hybrid and to be combined in phase at the receive port.