On-body flexible printed antennas for body-centric wireless communications

摘要

This thesis considers wearable antennas that are useful for body-centric communication systems. Novel wearable printed monopoles with flexible neoprene substrates and drapable conductive elements have been designed, synthesized and measured with respect to their on-body performance. Starting with a comprehensive literature review of wearable antennas this work contains an introduction to wearable antenna designs, flexible materials for wearable antenna fabrication, human body models and the impacts of the human body on the efficiency of small wearable antennas. Definitions of material effective and total conductivity, the calculations of antenna Q and mutual couplings between antennas and the human body using the Method of Moment (MoM) are presented. Four types of flexible printed monopoles have been designed and measured. They are two single band monopoles for ISM (433.05 434.79 MHz) service, one multiband monopole for GSM 900 (890 960 MHz), DCS (1710 1880 MHz), PCS (1850 1990 MHz), UMTS (1920 2170 MHz), and WLAN2.4GHz (2400-2484MHz) frequency bands and a UWB band antenna (3.1-10.6GHz) respectively. Effects of the ground plane dimensions on printed monopoles are illustrated first by changing the dimensions thereof and subsequently by adding wing structures. The new designs yield improved impedance match for printed monopoles. It also shows how meander lines can used to miniaturize antennas and add additional resonances. Models of the human body were created in Microstripes, a 3D electromagnetic (EM) simulator, to analysis the impacts of the human body on the performance of the wearable antennas mentioned above.