EBG structure and reconfigurable technique in antenna designs: Applications to wireless communications

This dissertation focuses on the electromagnetic band-gap (EBG) structure and reconfigurable technique in antenna designs applied to wireless communications. The research covers a wide range of interesting antenna issues from theoretical analysis to measurement results and from basic concepts to various applications.; The finite difference time domain (FDTD) method is a powerful engine for analyzing electromagnetic and antenna problems. In this dissertation, the capability of the FDTD method has been expanded in both application range and computational efficiency. To broaden the application range, the FDTD method has been utilized to simulate antenna mutual coupling and human effect. To increase the computational efficiency, the Prony method and the auto-regressive moving average (ARMA) estimator are investigated and good results have been obtained.; Using the FDTD method, electromagnetic band-gap (EBG) structures are investigated. The investigation is concentrated on electromagnetic features of the EBG structures and its applications in the antenna area. Some numerical models closely associated with antenna applications are successfully developed for the study of surface wave suppression and plane wave reflection. Based on the above studies, various applications have been explored. Due to the surface wave suppression effect, the EBG structure is integrated with patch antennas and arrays for high gain, low back lobe, and reduced mutual coupling. Another EBG application is to build low profile antennas. A low profile CP curl antenna in the presence of EBGs has been successfully designed. When compared to a curl antenna over a PEC ground plane, the antenna height is greatly reduced.; Another important part of this dissertation is a novel reconfigurable antenna design. The patch antenna with switchable slots (PASS) demonstrates a desirable feature to realize multiple functionality with a simple structure. The operational mechanism of the PASS is introduced. Various PASS designs like dual frequency operation, dual band CP performance, and circular polarization diversity are discussed. The PASS applications in wireless communications are also highlighted. Some of these applications include GPS receivers and planetary robots.