TCM-Based Self-Decoupling in Circularly Polarized MIMO Microstrip Patch Array

This paper provides a self-decoupling method for circularly polarized (CP) multi-input multi output (MIMO) microstrip patch array based on the theory of characteristic mode (TCM). To realize self-decoupling CP radiation, mode currents and mode electric fields are synthesized by using the theory of characteristic mode (TCM) to determine the feeding position with the following requirements: it should be located in the minimum region of current difference J1-J2 of excitation unit A to satisfy circular polarization performance, and it should also be located in the minimum region of electric field E1+E2 of coupling unit B to satisfy self-decoupling performance. Due to the advantages of theoretical guidance, simple, less optimization, and fast determination of feed point position, the proposed method provides a novel insight of the design of self-decoupling MPA array.