Circularly polarized MIMO filtering dielectric resonator antenna for 5G sub-6 GHz applications

This research presents an innovative hexagonal dielectric resonator antenna (DRA) with circular polarization and multi-input multi-output (MIMO) characteristics. The DRA consists of two dielectric layers, providing a fractional bandwidth of 9% (4.05 to 4.38 GHz).The antenna ground plane features has an S-shape slot, when coupled with a 50 omega microstrip line, enables the generation of right-hand circular polarization. To enhance performance, the feed line includes a bandpass filter with a semi-elliptical form, resulting in outstanding selectivity. The proposed design demonstrates a gain of 9.2 dBi and encompasses a 3 dB axial ratio bandwidth of 9.29%. The proposed design is fabricated, and a comparison is made between the simulated and the measured results. Furthermore, the study introduces a MIMO antenna system by combining two filter arrays. The MIMO antenna demonstrates a reasonable port isolation of >25 dB across the operating band with acceptable MIMO parameters.