Isolation improvement in MIMO antenna with a simple hybrid technique of orthogonal and inverse currents

This paper presents a compact high-isolation multiple-input multiple-output (MIMO) antenna developed using a hybrid approach. The proposed technique combines induced orthogonal currents and self-inverse currents to enhance the antenna’s performance. Orthogonal currents are generated by strategically etching open slots on the antenna patches, while self-inverse currents are introduced by integration of annular vias. By carefully adjusting the radius and position of the annular vias and optimizing the patch geometry, the design achieves optimal resonance frequency alignment and significantly improved isolation. The fabricated prototype exhibits an exceptional isolation of 55 dB at 5.75 GHz, accompanied by a realized gain of 6.7 dB. Measured radiation patterns in the $\varphi =0^{\circ }$ and $\varphi =90^{\circ }$ planes show excellent agreement with simulated results. The proposed low-profile antenna design has a substantial potential for enhancing MIMO applications in contemporary wireless communication systems.