A Dual CP Quad-Port MIMO Antenna with Reduced Mutual Coupling for X-band Application

A compact quad-port MIMO antenna with dual-polarization is proposed. Each of the four antenna elements features a modified rectangular radiator (MRR) backed by a partial ground plane and fed by a T-shaped microstrip line. The four antenna elements are interconnected by an X-shaped strip and isolated by a modified plus-shaped (MPS) structure, resulting in over -18 dB of isolation. With a small footprint of only 36 mm × 27 mm, the antenna exhibits a 10-dB impedance bandwidth with a completely overlapping 3-dB axial-ratio bandwidth (ARBW) of 19.32% (7.90-9.59 GHz). Additionally, it can provide a gain of over 3.5 dBi, an efficiency of over 70%, and an envelope correlation coefficient (ECC) of less than 0.01 in both isotropic and real propagation scenarios.