The Performance of a CPW-fed printed UWB Antenna for Wireless Body- Worn Applications Xiaoning Qiu (1) , and Ananda. Sanagavarapu. Mohan (1) * Microwave and Wireless Technology Research Laboratory, I&C Group, Faculty of Engineering, University of Technology, Sydney (UTS) PO Box 123, Broadway, N.S.W. 2007, Australia E-mail: {xnqiu, ananda}@eng.uts.edu.au Introduction Ultra-wideband (UWB) technology appears to be a promising solution for future short-range high-speed indoor wireless personal area networks (WPAN) and wireless body area networks (WBAN) as well as for microwave imaging of abnormal tissues etc. The UWB wireless systems cover a very wide spectrum of frequencies that ranges from 3.1 to 10.6 GHz. As antennas are the key components of any UWB wireless system, it is essential that they have ultra-wideband performance particularly with respect to impedance bandwidth (< -10 dB), omni radiational characteristics and linear phase response. Usually for UWB wireless body-worn applications, antennas with omni-directional radiation characteristics are preferred [1]. Recently, the use of directional antennas for WBAN applications is proposed [2]. For WBAN applications, the antennas are placed closed to the human body and thus Specific Absorption Rate (SAR) has become an important design criterion for wireless devices. It is well known that the portable wireless devices must meet various SAR regulatory standards [4]. Thus, the ultra-wideband antenna performance in the presence of human body is of practical importance for the design of WBAN/WPAN UWB wireless networks. In this paper, we aim to theoretically investigate the interaction between a printed CPW-fed UWB antenna and a lossy cylinder to study the reflection coefficient, radiation characteristics and SAR over the band. The antenna characteristics for different cases were calculated using the commercially available High-Frequency Structure Simulator (HFSS ® ). The printed CPW-fed UWB antenna was first fabricated and tested in free space environment [3]. Here, we theoretically investigate the influence of our printed UWB antenna when located close to a lossy body with an aim for body-worn. Antenna Configuration and Simulation modeling The configuration of the printed CPW-fed antenna is shown in Fig. 1 (a). The printed antenna was constructed by printing it on Rogers ® RO4003C substrate with dielectric constant of 3.38 and thickness of 1.524mm. A 50Ω CPW transmission line with a fixed single-strip width of 5.5mm and with a 0.3 mm gap between the strip and the ground is used for feeding the antenna. Other dimensions of the antenna element and the ground plane are shown in Fig. 1 (a) (units are in mm). ©2006 IEEE 2109