Lange-ferrite circulator for simultaneous transmit and receive (star) with high isolation and noise suppression

Abstract

A three port circulator capable of simultaneous transmit and receive operations, high frequency, enhanced high isolation, noise suppression at the receive port and broadband performance comprising: an antenna port; a transmission port; a receiving port; wherein each port is connected to a 90 degree combiner/divider or 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 90 degree combiners/dividers or quadrature hybrids in addition to the connection to the above mentioned ports has at least two output connections each of which are connected to a ferrite circulator and if a fourth connection, said fourth connection is attached to a matching load circuit; this arrangement of circuits allows the phase shifted signals from the transmit port to enter the 90 degree combiner/divider or quadrature hybrid and be recombined in phase at the antenna port, any residue signal due to impedance mismatch at the antenna port and/or the isolation or imperfect suppression of mode degeneracy of the ferrite circulator at the Y-junction will get to the 90 degree combiner/divider or quadrature hybrid at the receive port and is phased cancelled; said arrangement simultaneously allows the receive signal entering the antenna port and proceeding to the 90 degree combiner/divider or quadrature hybrid at the antenna port and to be combined in phase by the 90 degree combiner/divider or quadrature hybrid at the receive port.