Analysis of a MIMO Circular Patch Antenna Operating at 3.5 GHz for New TEchnology 5G and IoT NETWORK

Abstract This work introduces the design and performance analysis of a compact 2×1 MIMO circular patch antenna system intended for future 5G and IoT smartphone applications. The antenna operates in the sub-6 GHz spectrum, resonating at 3.5 GHz, and is implemented on two different substrates: conventional FR-4 and high-permittivity silicon (εr = 11.9). To enhance impedance matching and radiation characteristics, a partial ground plane incorporating a defective ground structure (DGS) is employed. The proposed circular patch element has compact dimensions of 32.36 × 32.36 mm² with a radius of 11.38 mm, providing wideband operation across 3.2000–4.2000 MHz. Simulation results demonstrate outstanding performance, achieving a reflection coefficient |S11| of –44.439 dB and a mutual coupling coefficient |S21| of –34.249 dB, ensuring isolation levels better than –20 dB between the antenna ports. This enables efficient operation across the 3–6 GHz range, which encompasses key 5G frequency allocations such as 5G WLAN and IoT bands. A comparative substrate analysis highlights the influence of dielectric properties on antenna gain, efficiency, and isolation. Additional performance metrics further validate the antenna’s effectiveness, including a very low envelope correlation coefficient (ECC), high diversity gain (DG), enhanced radiation efficiency, and improved channel capacity. The complete antenna design, simulation, and optimization were conducted using the CST Microwave Studio environment, and the obtained results confirm that the proposed system is a promising candidate for compact, high-efficiency 5G MIMO antenna designs suitable for integration into modern smartphones