A Self-Decoupled MIMO Patch Array with Gain Filtering Property

A self-decoupled multiple-input-multiple-output (MIMO) patch array with bandpass gain filtering characteristics is proposed in this paper. Firstly, by leveraging weak-field coupling, the isolation between two rhombus-shaped patch antennas is improved by 7.3 dB. Then, a dual-slot structure is etched on each patch to introduce a controllable decoupling null within the passband by tuning the electromagnetic coupling ratio. Furthermore, a stacked rhombus patch with dual slots is employed to simultaneously broaden the impedance bandwidth and the decoupling bandwidth, while also achieving desirable bandpass gain filtering characteristics. Finally, a two-element self-decoupled MIMO antenna is fabricated and measured. The measured results show good agreement with simulations, demonstrating that the proposed design achieves high isolation and effective filtering performance with a simple antenna structure.