Design and Fabrication of Antenna Structures for Wireless Body Area Network and Testing on A Phantom

Abstract

Wireless Body Area Network (WBAN) is an ongoing research field that enables the transmission of biological signals from human body to an off-body device for further processing and action. Compact antennas with stable on-body behaviour are achieving interest for signal transmission for WBAN applications. Advancements of flexible electronic devices and sensor nodes has demanded conformal antenna structures for the wearable devices. Moreover, human body is a non-planar structure and endures various postures and movements. Use of stiff material for making on-body antenna may cause uneasiness to the user. In addition to this, antenna performance is unavoidably exposed by the user s movement. Thus, antenna must have stable resonance and impedance while structural deformations. Beside this, body tissue is also affected by the exposure of near field radiations which needs to follow safety regulations. The existing on-body antenna structures still grieves from number of challenges like complex and comparatively bigger structures, highly immune to body tissue, low efficiency and gain, narrow bandwidth and unstable performance. The work presented in this thesis has concentrated on the two main aspects of antenna technology: design of new structures for on-body data transfer applications and presenting the applications of antenna in medical sector. Design, realization and performance evaluations of five antenna topologies for on body and off body communication is presented. In the first design a conformal, wide band, MIMO antenna is proposed for on body and off body data transfer application. Inverted U-shaped slot is deployed at the ground plane for reducing mutual coupling between the two radiators. This antenna has the excellent diversity performance, possess wide bandwidth and it can easily withstand frequency detuning effect due to structural deformation. Antenna has compact planar dimensions of 14 mm × 25 mm and less than -30 dB mutual coupling.