Advanced Design and Analysis of UWB U-slot Microstrip Patch Using Theory of Characteristic Modes

Abstract

Ultra wide band is rapidly advancing as a high data rate wireless communication technology. As is the case in conventional wireless communication systems, an antenna also plays a very crucial role in UWB systems. However, there are more challenges in designing a UWB antenna than a narrow band one. A suitable UWB antenna should be capable of operating over an ultra-wide bandwidth as allocated by the FCC. At the same time, satisfactory radiation properties over the entire frequency range are also necessary. This thesis focuses on UWB antenna design and analysis. Studies have been undertaken covering the areas of UWB fundamentals and antenna theory. In recent years, the U-slot patch antenna established itself as a versatile, low profile and cost effective antenna that can be fine tuned for ultra-wideband operations. The main objective of this thesis is to propose an effective practical design procedure to design U-Slot antenna and provide physical insight into the design using full wave analysis methods. This research work focuses on developing a novel scheme to design wideband U-Slot antenna. To validate the design technique antenna is fabricated and measured results are compared with the simulated to assess the performance. In this dissertation, effect of reactive loading on probe fed, single layer, U-Slot loaded microstrip antenna is investigated using Theory of Characteristic Modes (TCM). Detailed analysis of reactive loading due to feed location and arm-angle variation is presented. Optimized reactive loading has been shown to produce a modified U-Slot structure without increasing any cost and complexity. The optimized loaded antennas are wideband with a relatively stable radiation pattern. Furthermore, we propose an optimization guideline for a wide band design with stable radiation patterns.