High isolation lange-ferrite circulators with NF suppression for simultaneous transmit and receive

This paper presents a new type of circulator that consists of three Lange couplers and two ferrite circulators for broadband, high isolation, transmit noise suppression and simultaneous transmit and receive (STAR). The operation principal of the circulator is based on quadrature phase cancellation and combination techniques. Preliminary results show that the isolation between the transmit and receive port is 24 dB in frequency range of 5–12 GHz without optimization and 60 dB isolation with 800 MHz bandwidth with optimization. The NF data at the receive port show significant suppression of transmit noise for Gain-NF product that exceeds 21 dB.