Bandwidth and Gain Enhancement of Microstrip Antenna Using an Integrated Quarter Wave Transformer Feed Network

This paper presents the design, analysis, and optimization of a high-efficiency rectangular microstrip patch antenna (RMPA) operating at a center frequency of 3.5 GHz for sub-6 GHz 5G wireless applications. The design is implemented on a Rogers RT/duroid 5880 dielectric substrate (ε_r = 2.2, tan δ = 0.0009) with a thickness of 1.575 mm. To ensure efficient power transfer and reduce reflection losses, an impedance-matching quarter-wave transformer feed network is designed to seamlessly match the high edge impedance of the radiating patch to a standard 50 Ω transmission line. Detailed mathematical analysis based on the transmission-line model yields an optimized patch width of 33.86 mm and length of 28.32 mm. Theoretical analysis and simulated performance indicators, including the reflection coefficient (S11), Voltage Standing Wave Ratio (VSWR), radiation patterns, and total efficiency, are comprehensively presented.