Frequency Selective Surface Textile Antenna for Wearable Applications

The design of an efficient frequency selective surface (FSS) array structure for a wearable antenna as a reflector is introduced in this paper. An ultra-wideband antenna capable of increasing the gain over Industrial, Scientific, and Medical (ISM) bands at 2.4 GHz and 5.8 GHz and reducing the Specific Absorption Rate (SAR) in the human body to be used for Wearable Body Area Network (WBAN) application is presented. Due to heavy data transmission for applications like wireless LAN, WiMAX, Bluetooth, and Zigbee, traffic at 2.4 GHz is getting congested. This has opened a new frequency in the ISM band at 5.8 GHz. The proposed antenna structure includes a circular patch with semi-circular and diamond-shaped slots which is fabricated on textile material. Flannel fabric is chosen as a substrate. The slots introduced in the circular patch antenna aim in obtaining impedance bandwidth of 4.5 GHz from 1.5–6 GHz covering ISM bands with optimal results at 2.4 GHz and 5.8 GHz. FSS structure is used as a reflector to enhance and stabilize the gain throughout the wideband. Thus, the proposed antenna has a wideband and Omni-directional pattern making it useful for WBAN. The designed FSS structure reduces the SAR value to 0.56 W/kg and 0.511 W/kg at 2.4 GHz and 5.8 GHz respectively. The gain is 3.4 dBi at 2.4 GHz and 3.35 dBi at 5.8 GHz when the FSS reflector is placed at 1 mm below the antenna. The overall dimension of the antenna with reflector setup is 42 × 43 × 3 mm3 which is 0.7λ wavelengths making it feasible to be worn on the human body.