Wideband Quasi-Monostatic Simultaneous Transmit and Receive Reflector Antenna

A dual polarized quasi-monostatic simultaneous transmit and receive (STAR) antenna system operating over 2:1 bandwidth with high isolation, co-polarized transmitting (TX)/receiving (RX) radiation, and high TX gain is proposed. The TX antenna is apex matched parabolic reflector illuminated by a coaxial cavity feed. The RX antenna is also coaxial cavity and mounted back-to-back with the TX feed. Thus, the configuration is termed quasi-monostatic. High front-to-back (F/B) ratio of the RX and TX feed antennas and the separation between them ensures high isolation. The fabricated system achieves 61 dB (average) isolation for CP and >38.5 dB for linearly copolarized TX and RX antennas. Moreover, the amplitude and phase imbalances in beam forming network (BFN) have lesser impact than the BFN-based STAR antenna systems. The antenna system operates from 4 to 8 GHz with VSWR <1.8, gain >7 dBic, and >20 dBic for the RX and TX, respectively. Additional techniques to further improve isolation are outlined.