Broadband Suppression of Mutual Coupling in Compact Base Station Antenna Array by Adjusting Hybrid Coupling in Spatial Filtering Baffles

This letter presents a broadband resonator-based in-band decoupling concept for base station (BS) applications, addressing the deteriorated radiation performance resulting from the strong in-band mutual coupling. The baffles, featuring asymmetric periodic split-ring resonators (SRRs) and a metal strip, are developed to block mutual coupling between antenna array elements. To better provide guidelines for designers, the decoupling mechanism is analyzed by simulation. Simulated and measured results demonstrate its effectiveness of low mutual coupling (< -20 dB) over a wide band (3.4-5.1 GHz, 40%) and well-repaired radiation patterns in both the vertical plane (V-plane) and horizontal plane (H-plane) without any extra profile or auxiliary configuration. The proposed scheme not only enhances port isolation with stable radiation performance over the broadband but also extends the capacity of the resonator-based baffle scheme by creating coupling interactions among resonators, indicating that it has great potential application prospects in 5G base station arrays.