3.5 GHz Microstrip Antenna Design with Specific Absorption Rate Analysis

Abstract

This paper presents a fifth-generation (5G) 3.5 GHz microstrip antenna along with a specific absorption rate (SAR) analysis. The antenna is designed using basic microstrip antenna equations to determine its dimensions. The design employs a coaxial feeding method, with the optimal feeding location at P3 (10 mm, -6 mm) to achieve 50 Ω impedance matching. The antenna demonstrates good performance at 3.5 GHz, with a reflection coefficient, S11 of –27 dB and a gain of 2 dB. SAR is then assessed by placing the antenna at 10 mm from the head phantom. The presence of the head phantom affects antenna performance, resulting in a slight decrease in the resonant frequency due to head tissue conductivity. Furthermore, the presence of the head phantom modifies the radiation pattern and decreases radiated power as electromagnetic energy is dissipated within the phantom tissue. The SAR analysis indicates that the location of the coaxial feeding influences the SAR value, with the best location (P3) yielding the lowest SAR of 5.6 W/kg for 1 g and 2.33 W/kg for 10 g of tissue, with input power fixed at 0.25 W (23.98 dBm). The maximum permissible power for the proposed microstrip antenna is 0.07 W (18.45 dBm), resulting in SARs of 1.56 W/kg for 1g and 0.65 W/kg for 10g of tissue, respectively. Both values are within the standard SAR limit and are deemed safe for use.