In this paper, a multiband wearable antenna is proposed capable of operating at ISM (2.4-2.5 GHz), S-band (2.0-4.0 GHz) and WiFi (5.1 GHz) bands. The antenna is designed on the Kapton Polymide flexible substrate having a thickness of 1 mm and overall dimension of 38 × 42 mm ² . The design of the anticipated antenna is derived from the conventional microstrip patch antenna and is simulated using electromagnetic solver CST Studio Suite 2019. The specific absorption rate (SAR) is evaluated on a three-layer cylindrical phantom. Keeping an input power of 25 mW, the maximum SAR 1g values obtained are 0.075, 0.0535 and 0.028 W/Kg at frequencies of 2.48, 3.9 and 5.1 GHz respectively. The achieved SAR 1g values are well below the FCC limit of 1.6 W/Kg averaged over 1g for human tissue. Antenna demonstrates resonance amplitude well below -10 dB and efficiency greater than 60 %.