Broadband Full-Duplex Monostatic Circular-Antenna Arrays: Circular Arrays Reaching Simultaneous Transmit and Receive Operation

Broadband copolarized monostatic circular-antenna arrays based on mode orthogonality principles are presented for in-band full-duplex (FD) applications. The simultaneous excitation of circular phase modes in a circular array with four elements provides ideally infinite isolation. However, once the realistic beamformer network (BFN) is used, the isolation between the transmitter (Tx) and receiver (Rx) is reduced and becomes bound by the internal...