Reconfigurable Wearable Antennas for Body-Centric Communications

Abstract

In the last two decades, wireless body area networks (WBANs) have seen a rapid development to support a wide range of applications in our daily life. Fostered by this development, wearable textile antennas, as potential components of such networks, have attracted more and more research interests. Furthermore, several practical realizations of reconfigurable wearable antennas have been proposed aiming to maintain the required antenna performance of flexible devices under disadvantageous conformal conditions and changing operating environments. In this context, a number of reconfigurable wearable antennas, as well as several passive wearable antennas with additional functionalities, are proposed in this thesis. These designs will be presented in three main parts. The first main part of the dissertation will discuss the techniques and components used to realize reconfigurable wearable antennas. Starting with Chapter 3, the pros and cons of four different shorting strategies realized using standard components in wearable antenna designs are investigated. The comparison between these four shorting methods is conducted comprehensively aiming at guiding designers in selection of the most appropriate shorting method for their specific application. Chapter 4 proposes a novel reconfiguration module to provide a stable and repeatable electrical connection between rigid electronics and flexible textile conductors in a coplanar arrangement. Chapter 5 through Chapter 7 form the second main part of the thesis, which focuses on reconfigurable wearable antenna designs utilizing the proposed techniques and components. A wide range of reconfigurable wearable antennas is proposed in this part including frequency-, radiation pattern- and polarization-reconfigurable antennas. The chapter also includes reconfigurable wearable antennas designed with the combination of these tunability. The proposed antennas have significant improvement in their versatility compared to passive wearable antennas reported in the literature. More importantly, the practicability of the proposed antennas is successfully demonstrated. The last main part of the thesis presents wearable antennas integrated with radio frequency identification (RFID) sensor modules. Chapter 8 proposes a wearable textile antenna with a computational battery-less RFID module fully integrated in the antenna cavity. The antenna and the RFID module form a complete device which is demonstrated to work well in practical situations. In Chapter 9, a dual-band reconfigurable ultra high frequency (UHF) wearable antenna and a dual-band dual-port reconfigurable textile antenna for wearable UHF applications are presented. In summary, this dissertation provides new concepts, techniques and components to design reconfigurable wearable antennas. Based on the proposed techniques and components, a wide range of novel reconfigurable wearable antennas with promising practicability are presented.