A Compact Self-Decoupling Circularly Polarized Microstrip MIMO Antenna

This paper presents a compact self-decoupling circularly polarized (CP) multi-input multi-output (MIMO) antenna. The antenna unit consists of a square patch etched with a rectangular slit in the center and a rotated L-shaped feeding line (LSFL). It is found that polarization isolation of the coupled and excited CP microstrip antenna can be realizing by adjusting the size of the rectangular slit, resulting in a self-decoupling effect. The designed CP MIMO antenna with self-decoupling features exhibits a remarkably low mutual coupling of -42.7 dB and a 3-dB AR bandwidth that encompasses the L1 band of the GPS system. In addition, the antenna has the advantages of simple structure and low profile, without additional circuits and structures.