A Field-Reshaping Self-Decoupling Technique with Loading of Shorting Pins for MIMO Patch Antenna Array

This paper proposes a self-decoupling technique based on edge-field reshaping for MIMO patch antenna arrays. Theoretical analysis reveals that poor port isolation in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$E$</tex>-plane-coupled patch antenna pairs results from strong electric coupling. By strategically placing shorting pins along the coupling edges of each patch antenna, the concentrated electric field at the edges initially is redistributed into a local weak-field region, effectively mitigating mutual coupling between adjacent patches. To validate the proposed method, a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{TM}_{01}$</tex>-mode rectangular patch antenna pair with edge-loaded shorting pins is designed. Simulation results demonstrate that the isolation between two patch antennas, separated by a spacing of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.01 \lambda_{o}$</tex>, is improved from 3 dB to over 20 dB, with a realized gain of 9.2 dBi.