Design and Optimization of a Compact Inset Feed Microstrip Antenna for 5G Applications with Enhanced MIMO Performance

This study presents the design, simulation, and optimization of a compact inset feed microstrip antenna for fifth-generation (5G) applications. With dimensions of 6.2 × 8.4 × 1.57 mm³, the proposed antenna utilizes a Rogers RT5880 substrate (εr = 2.2, loss tangent = 0.0013) and operates at resonant frequencies of 28 GHz and 26 GHz. The design, performed using CST Microwave Suite 2018, achieves an operational bandwidth of 5.368 GHz (25.144–30.512 GHz), with a relative bandwidth of 19.3%. At 28 GHz, the antenna exhibits a return loss of -25.166 dB and a gain of 7.33 dB, while at 26 GHz, it achieves a return loss of -13.2 dB and a gain of 7.88 dB. Enhancements using a 2-by-1 MIMO configuration, including inverted, mirrored, and nearby arrangements, were investigated. The inverted configuration demonstrated the highest gains of 8.15 dB and 7.96 dB at 26 and 28 GHz, respectively. The proposed antenna demonstrates applicability in compact mobile devices, Internet of Things (IoT) systems, and smart city infrastructure, underlining its practical relevance.