Design and Verification of A TCM-based Self-decoupling Method for Linearly and Circularly Polarized MIMO Patch Antennas

This paper provides a self-decoupling method based on the theory of characteristic mode (TCM) for linearly polarized (LP) and circularly polarized (CP) MIMO patch array. The method mainly uses the electric field and current distribution of the selected characteristic mode to limit the feeding area that will produce better radiation performance, so as to realize the LP/CP radiation while ensuring the decoupling effect. Specifically, the overlapping region between the minimum value area of the characteristic current subtraction distribution on the excitation patch and the null-field area of the characteristic electric field addition on the coupled patch is the better feeding position region. The proposed method is suitable for both LP MIMO patch antenna and CP MIMO patch antenna with opposite rotation sense. Therefore, the designs of $1 \times 2$ MIMO antennas and verification are provided in this paper.