Planar patch antenna system with high isolation for full‐duplex applications

Abstract

In this Letter, a differential-fed planar antenna system is presented with large isolation between transmission and reception ports for full-duplex applications. The proposed system contains two antenna pairs, each of which is composed of two identical single-ended microstrip patch antennas operating at 12 GHz. Each element in the array is fed 180° out-of-phase by utilising rat-race hybrid couplers making the whole system differential-fed. The patch antenna array and the hybrid ring couplers are designed on two separate substrate materials with the ground plane in between. Simulation results show high isolation S 21 < − 70 dB through the entire band of interest while measured results approach S 21 < − 50 dB in a reflective environment. The design also exhibits good impedance matching, reasonable gain values, and high efficiency.