Low SAR-UWB Rectangular Microstrip Magnetic Monopole Antenna for S-Band and Biomedical Applications

The development of low specific absorption rate (SAR) antennas is crucial for safety and efficiency in wireless communication and biomedical applications. This study introduces a low SAR ultra-wideband (UWB) rectangular microstrip monopole antenna with an extended ground plane. The design operates effectively in free space and on a human body phantom. It achieves a reflection coefficient of -42.59 dB at 2.48 GHz and covers the S-band from 2.31 GHz to 4.12 GHz with a peak gain of 5.09 dBi in free space. The antenna maintains consistent performances when placed on a human phantom. With reverse and front patch faces, its gain improves to 5.53 dBi and 5.80 dBi, respectively. Experimental validation of the fabricated prototype shows excellent agreement with simulations conducted using high-frequency structure simulators (HFSS) and advanced design systems (ADS). Additionally, lumped-element equivalent circuits are used to analyze impedance behavior in both environments, confirming the antenna’s robustdesign.