Compact Multi-Mode MIMO Patch Antennas With a Simple Inductive Loop for Pattern Diversity

This study presents a compact multi-mode MIMO patch antenna system with enhanced isolation and pattern diversity. It is revealed that strong mutual coupling arises from an inherent coupling mode in tightly arranged patches. A decoupling mode is introduced via a simple inductive loop to cancel the coupled energy. The proposed technique is particularly suitable for multi-mode patch antenna scenarios, enabling highly isolated configurations. Experimental validation demonstrates −10 dB impedance bandwidths of 9.2% and 15.2% for the two ports, alongside isolation levels better than 17 dB, confirming its potential for pattern-diverse MIMO applications.