Performance evaluation of circularly polarized patch antenna on flexible EPDM substrate near human body

This paper presents the performance evaluation of a circularly polarized wearable antenna on flexible Ethylene Propylene Diene Monomer (EPDM) foam substrate. EPDM is a rubber based material with high flexibility, good shock resistance and easy attachment to any curved surface. The designed antenna operates for Industrial, Scientific and Medical (ISM) band and Wireless Body Area Network (WBAN) applications at 2.45 GHz. Copper tape is used as the conductive material for the patch and the ground plane on 3 mm thick EPDM foam substrate having dielectric constant 1.23 and loss tangent 0.02. A rectangular slot along diagonal axis at the center of the circular patch is used for achieving circular polarization at 2.45 GHz. The measured operating frequency range of the antenna spans from 2.36 GHz to 2.48 GHz with the gain of 6.03 dB at 2.45 GHz. A set of comparative results of the antenna in free space and different body parts like arm and leg are compared to validate the operability of the antenna in real environment. This study provides new understanding about rubber material as substrate for flexible wearable antennas.