A Microstrip Antenna with EBG Reflector Design for WBAN Communications

In this paper, a microstrip antenna is designed for wireless body area network (WBAN) on the polyimide substrate, working in ISM band of 2.45 GHz. The return loss at the resonant frequency can reach - $\mathbf{2 2} \mathrm{dB}$, and the bandwidths can reach $2 \mathrm{GHz}-$ 5 GHz. In order to improve impedance matching, the monopole antenna in Y structure is used as radiator with the trapezoidal bottom, which is feeded by coplanar waveguide (CPW) with etching rectangular slot. The EBG reflector is designed to reduce the radiation effect on the human body, which can achieve in phase reflection and reduce the back reflection. The simulation results show that the specific absorption rate (SAR) of the antenna is less than the international safety standard $1.6 \mathrm{~W} / \mathrm{kg}$, when the distance from the antenna to the body surface is 5mm.