Closely Arranged Self-Decoupled Antenna Pair With Dual-Ports Filtering Properties

A closely arranged self-decoupled antenna pair with dual-ports filtering properties for fifth-generation (5G) mobile terminal is proposed in this paper. The antenna pair can achieve coupling suppression in multi-frequency bands. To address coupling at the operating band, a high-isolation antenna pair is designed by exciting two orthogonal modes of the loop antenna. To reduce coupling in adjacent frequency band, the two ports of the antenna pair are designed with filtering properties. Firstly, based on the cross-coupling mechanism, electromagnetic coupling branches are introduced to generate out-of-phase radiation paths in adjacent frequency bands, resulting in radiation nulls for port 1. Next, the nonradiative mode and lumped elements are designed to obtain the radiation nulls of port 2. Due to the shared-radiator and partial structure reutilization, the dual-ports filtering antenna pair exhibits a compact configuration. Based on the proposed filtering antenna pair, an 8 × 8 multiple-input multiple-output (MIMO) array is developed, which operates in the 3.3–3.8 GHz, with isolation better than 16.9 dB and an envelope correlation coefficient lower than 0.05. In addition, the MIMO array features the advantages of zero ground clearance and full-port filtering properties.