The Research On Microstrip Reconfigurable Antennas

The research on reconfigurable antennas is a hot point in the antenna field. Researches on reconfigurable antennas based on microstrip patch antenna have been done, and several schemes of pattern reconfigurable and frequency-pattern reconfigurable antennas are presented in this dissertation. This work provides good basis for the future research work.In Chapter 1, the advances in the study of the reconfigurable antenna presented in the end of the 1990s are introduced systemically. In order to increase wireless integrated information systems' capabilities, expand their functionality and widen their bandwidths, the concept of reconfigurable antenna is presented. The technology background of the research on the reconfigurable antenna is micro-electro-mechanical system (MEMS) technology. At present, this work is still at the beginning. There is much unknown domain in this field needed to be explored, so it is a challenge to do researches on the reconfigurable antenna.In Chapter 2, the basic theory of the antenna radiation is introduced at first. Then, the theories about the microstrip antenna are introduced, such as the mechanism of the microstrip antenna radiation, the advantages and disadvantages of the microstrip antenna, and two methods based on transmission line model and cavity model, which are used to analyze the microstrip antenna.In Chapter 3, the frequency and pattern characteristics of three two-element microstrip Yagi antennas are analyzed. A slot unit is introduced to the two-element microstrip Yagi antenna and changed the characteristics of the antenna. At first, the mechanism of the Yagi-Uda antenna and the Yagi microstrip antenna is introduced. Then, the mutual between the driven and the parasitic element is analyzed in detail, and the even-odd-mode method is presented to explain the pattern characteristics of the two-element Yagi microstrip antenna. At last, a slot unit is etched on the parasitic element. By changing the size and location of the slot, the frequency and pattern characteristics of the two-element Yagi patch antenna are changed. The influence of the dimensions and locations of the slot on the Yagi antenna is analyzed in detail.In Chapter 4, several schemes of pattern reconfigurable Yagi patch antenna are presented by introducing slot units. The frequency and pattern characteristics are analyzed in detail with the slot units are etched on the parasitic elements of the five-element Yagi patch antenna, and methods to reduce the side-lobe level, increase the beam tilt angle and widen the frequency bandwidth are presented. Based on the analysis, three single-port 1-dimension 5-element pattern reconfigurable Yagi patch antennas are designed. By switching the states of the parasitic elements, the radiation beams can scan in the E-plane in the upper space. Based on the single-port pattern reconfigurable Yagi...