An ultra-wide band low-SAR flexible metasurface-enabled antenna for WBAN applications

Abstract

In this study, an ultra-wideband low-specific absorption rate (SAR) flexible metasurface-enabled wearable antenna is proposed for wireless body area network applications. The antenna and metamaterial (MM) structure were designed and analyzed using a commercial electromagnetic simulation software program which uses a finite integration technique solver. The antenna is designed and fabricated on a jeans textile substrate in the size of 58 x 80 x 1 mm(3). Moreover, MM reflector was designed on a felt textile substrate to reduce the SAR effect of the antenna and to increase the antenna performance (such as impedance matching, radiation pattern, and realized gain) parameters. Designed and fabricated antenna parameters and the SAR value results with and without MM are investigated. The simulated peak SAR values when the antenna with MM is placed on the body model are 0.86, 0.198, and 0.103 W/kg at frequencies of 4 GHz, 7 GHz, and 10 GHz, respectively, for 10 g of tissue. The simulated peak SAR value of the antenna with MM is also reduced by a percentage of 97, compared to the simulated peak SAR value of the antenna without MM. The peak SAR values of the antenna were less than the European safety limit of 2 W/kg for 10 g of tissue when the MM was used as an isolator. Furthermore, the simulated peak realized gain value of the antenna with the MM was increased by 98% (from 4.6 to 9.1 dB) compared to the simulated peak realized gain value of the antenna without MM. Simulation and measurement results showed that performance characteristics and peak SAR values of the proposed antenna were suitable and safe for wearable technologies.