An EBG enhanced dual band wearable antenna for high gain and ultra low SAR in WBAN and ISM systems

Abstract

This paper presents a compact, low-cost dual-band antenna design with low specific absorption rate (SAR) for Wireless Body Area Networks (WBAN) and Industrial, Scientific, and Medical (ISM) applications. The proposed antenna operates at 2.4 GHz with linear polarization and 5.8 GHz with circular polarization, fabricated on a 1.52 mm thick RF35 dielectric substrate (28 $$\times $$ 40 mm). The design features a coplanar waveguide (CPW) feed integrated with substrate-integrated waveguide (SIW) technology to enhance bandwidth and return loss characteristics. The antenna has broad bandwidths of 0.5 GHz with a 2.4 GHz center and 1 GHz with a 5.8 GHz center. To mitigate back radiation and reduce SAR, a 4 $$\times $$ 4 electromagnetic bandgap (EBG) structure was incorporated, resulting in significant performance improvements. The EBG implementation increased the maximum gain from 3.66 to 8.56 dB at 2.4 GHz and from 3.97 to 10 dB at 5.8 GHz. Additionally, SAR values decreased from 7.34 to 1.62 W/kg for 1 g of tissue at 2.4 GHz and from 2.18 to 0.91 W/kg at 5.8 GHz. Prototype measurements confirm simulation results, demonstrating the antenna’s suitability for WBAN and wearable ISM applications, including sensor networks and Wi-Fi devices. The design offers advantages of independent band tuning, circular polarization at the higher frequencies, and compliance with safety standards for human exposure to electromagnetic fields.