Design and Performance Analysis of a Compact Two-Port Circularly Polarized MIMO Antenna for Sub-6 GHz 5G Applications

This research presents the design of a compact, dual-port, circularly polarized (CP) multiple-input-multiple-output (MIMO) antenna operating within the sub-6 GHz band designated for 5G cellular networks. This design emphasizes achieving smaller dimensions while preserving the functionalities of circularly polarized (CP) radiation and multiple-input-multiple-output (MIMO) technology. Utilizing a single radiating slot fed by an elliptical ring slot, the single antenna achieves circular polarization between 3.67 GHz and 3.81 GHz. The proposed MIMO antenna provides an impedance bandwidth of 340 MHz (reflection coefficient ≤,-10 dB) spanning from 3.57 GHz to 3.91 GHz and a 3 dB axial ratio bandwidth ranging from 3.65 GHz to 3.76 GHz. This configuration effectively covers the prospective 5G band with right-handed circular polarization. The performance of the MIMO antenna was validated through the evaluation of key metrics like the envelope correlation coefficient (ECC) and diversity gain (DG). The results demonstrate a low ECC value (ECC < 0.001), indicating minimal signal correlation between antenna ports. Additionally, the measured antenna isolation exceeds −20 dB, signifying sufficient decoupling between the ports. These findings confirm the antenna's suitability for MIMO applications by satisfying the established requirements for low correlation and adequate isolation in a MIMO environment.