Beam-switchable textile antenna for wireless body area networks (WBAN)

Abstract

The research work in this dissertation focuses on beam-switchable textile antenna for wireless body area network (WBAN) application. The idea of beam-switchable textile antenna helps to reduce the antenna size and more flexible. Beam-switchable antenna is useful in the rapid growth of the wireless communication system. The advantage of beam-switchable antenna is to avoid the associated signal equalization problems that are incurred as the wearer moves or turns. This dissertation proposed a novel beam-switchable textile antenna (BSTA) with reconfigurable ability which uses Radio Frequency (RF) PIN diodes biasing circuit as the switching mechanism. BSTA is the first effort in realizing a combination of such beam-switching feature onto a wearable radiator by exploiting silver loaded epoxy adhesive to provide a solderless connection between conductive textiles and the RF circuits. Four PIN diode switches are integrated into shieldit super of symmetrical BSTA designed. The BSTA is capable to achieve beam steering ±16° with peak simulated and measured directivities of 6.8 dBi and 6.69 dBi, respectively. The antenna maintains input impedance approximately 50 Ω at 2.45 GHz without the use of additional quarter wavelength transformers. With dimension of 88 x 88 mm2, it is compact enough to be integrated in clothing for WBAN applications. Based on preliminary assessment of specific absorption rate (SAR) results, this research confirms that BSTA is safe to the human being where the simulation SAR result is less than 1.6 W/kg and 2 W/kg for 1g and 10g mass of tissues correspondingly at particular body parts based on ICNIRP regulation. With all capabilities demonstrated and discussed, the BSTA antenna has big potential in realizing a new smart garment antenna.