Design and analysis of a 4-port mm-wave MIMO antenna with mutual coupling reduction via integrated decoupling structure

A compact four-port millimeter-wave MIMO antenna with an integrated hybrid decoupling structure is proposed for 5G applications. The antenna is fabricated on RT Duroid 5880 (ϵr=2.2, thickness = 0.8 mm) with an overall size of 12.5 × 12.5 mm2. The orthogonally arranged radiators, together with the decoupling structure, suppress surface-wave and near-field coupling without increasing the antenna footprint. The antenna operates from 38–42 GHz, covering the 38–40 GHz portion of the 5G NR n260 band, and provides inter-port isolation better than 30 dB. The design achieves a peak gain of 6.5 dB, radiation efficiency above 98%, ECC below 0.008, DG above 9.99 dB, CCL below 0.4 bits/s/Hz, and TARC below −10 dB. The fabricated prototype shows good agreement between simulated and measured results, confirming its suitability for compact high-data-rate mm-wave MIMO systems.