Low-profile miniaturized circularly polarized MIMO DRA with diagonal technique for 5G Sub-6 GHz and improved mutual coupling suppression

This research explores a circularly polarized (CP) multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) designed specifically for 5G Sub-6 GHz and WiMAX applications. The antenna system utilizes a unique H-shaped feeding strip to excite each DRA element. This specialized feeding mechanism facilitates the activation of higher-order degenerate modes, including TE δ13ˣ and TE 1 δ 3ʸ , which are essential for achieving circular polarization. The antenna exhibits a reflection coefficient of −37.52 dB at 3.49 GHz, covering the entire CP passband and operating over a broad bandwidth of 1.35 GHz (3.40–4.75 GHz) yielding a return loss of 35.52%, making it suitable for Sub-6 GHz applications. An axial ratio bandwidth of 24.6% (3.4–4.2 GHz) is observed, with inter-port isolation of greater than −25.3 dB throughout the usable frequency band with a maximum efficiency of approximately 98%, indicating near-lossless power radiation. Additionally, the estimated gain is 5.95 dBic. The proposed MIMO design presented effectively reduces the intersecting spatial field components between antenna elements, leading to a lower envelope correlation coefficient and enhanced inter-port isolation. This diversity gain of the proposed antenna is a strong candidate for use in rich multi-path environments, helping to mitigate the effects of channel fading.. Initially, the proposed antenna design was examined using the time-domain solver of CST, followed by the fabrication of a prototype for experimental validation. The antenna exhibits a stable response, making it well-suited for 5G Sub-6 GHz and WiMAX applications.There is a satisfactory alignment between the results obtained from simulations and those observed experimentally.