New Performance Studies and Design of a Circular Patch MIMO Antenna Array for Innovative 5G Smartphones

Abstract

This study presents the design and detailed performance evaluation of a miniaturized 2×1 MIMO circular patch antenna system tailored for next-generation 5G and IoT smartphone applications. The antenna operates within the 5 GHz spectrum, exhibiting a primary resonance at 3.5 GHz. Two dielectric substrates were examined FR4, widely used in practice, and high-permittivity silicon (εr = 11.9) to assess their influence on antenna performance. To improve impedance matching and radiation characteristics, the design incorporates a partial ground plane combined with a defective ground structure (DGS). The circular patch has dimensions of 32.502 × 61.049 mm² and a radius of 11.451 mm, providing a broad operating bandwidth from 3100 MHz to 4000 MHz. The proposed antenna demonstrates excellent performance, with a reflection coefficient |S11| of –72.311 dB and mutual coupling |S21| of –82.829 dB, confirming superior port isolation. Consequently, the MIMO configuration operates efficiently across the 3 GHz – 6 GHz range, maintaining isolation levels better than –20 dB, in line with 5G WLAN and IoT communication standards. The comparative substrate study highlights the impact on key metrics such as gain, efficiency, and isolation. Additional performance evaluations indicate a very low envelope correlation coefficient (ECC), high diversity gain (DG), excellent radiation efficiency, and strong channel capacity, All critical for reliable multi-antenna communication systems. The antenna array was designed and optimized using the CST simulation environment, and the results validate its effectiveness, demonstrating that the proposed design is highly suitable for compact, high-performance MIMO implementations in 5G and IoT devices.