Circularly Polarized MIMO Antenna System for Millimeter Wave 5G Applications Using Characteristic Mode Theory

ABSTRACT This study introduces a quad‐port multi‐input multi‐output antenna design specifically suited for fifth‐generation wireless technology. The antenna geometry is characterized by a flower‐shaped configuration, featuring five petals complemented by a circular slot, positioned in the ground plane to improve operational bandwidth. The effective realization of wide‐band characteristics has been studied utilizing the analysis of characteristic modes. The design antenna demonstrates simulated performance parameters that cover the millimeter‐wave frequency band from 25.6 to 32.4 GHz, delivering a maximum gain of 6.1 dBi and ensuring minimum port isolation of > 15 dB across all ports. In addition, a circular stub is purposefully positioned over the slot to facilitate circular polarization radiation behavior at 26.3 GHz, exhibiting an axial ratio bandwidth of 0.5 GHz (26–26.5 GHz). Further, the proposed antenna design is subjected to validation encompassing diversity metrics. The proposed antenna structure is successfully fabricated, and its performance is experimentally validated. A comprehensive comparative analysis is then conducted to evaluate its alignment with the simulated results.