A bandwidth enhanced 915 MHz antenna for IoT wrist-watch applications

Abstract

This paper presents a 915 MHz planar inverted-F antenna (PIFA) topology for a wrist-worn wireless sensor application. When compared with a conventional PIFA implementation, an impedance bandwidth enhancement of more than 100% is achieved. The bandwidth enhancement is realized with inclusion of a parasitic element that excites an additional mode close to the resonant frequency. A parametric analysis of the key parameters is performed in order to optimize the antenna for 915 MHz operation. The measured results for the on-body prototype antenna show a -10 dB bandwidth of 26.4 MHz and a Peak Realized Gain of -0.57 dBi at 915 MHz. The simulated peak radiation efficiency of 46.8% is achieved. In addition, the design exhibits a low specific absorption rate (SAR) value of 0.004 W/kg.