Study On Miniaturized Ultra-Wideband Antenna And Reconfigurable Technology

People have entered the era of long-distance wireless communication since the first electromagnetic wave signal spread across the Atlantic. With the development of more than a century, people have been inseparable from the communication in the 21 st century. The communication technology makes people's life more convenient and more comfortable, and the Industry and military industry system is becoming more and more dependent on communication technology. With the continuous improvement and development of the wireless communication technology, the wireless communication system has become more and more complicated. At the same time, the progress of the science requires the wireless telecom equipment to be small, portable, intelligent, anti-interference to adapt to the complex electromagnetic environment. As the transceiver of the wireless communication system, the antenna is an indispensable part in the system. As a result, the performance of the antenna will directly affects the quality of the communication system. The series of problems requires more on the antenna. Thus, the miniaturized ultra-wideband antenna and reconfigurable technology have become the research hot spot. This thesis mainly revolves the two kinds of antennas and multiple miniaturized ultra-wideband antennas and reconfigurable antennas are designed in this thesis. The main works of this thesis are as followings.1.two compact antennas are proposed, compact Vivaldi antenna and compact Spiral antenna. By adding a strip and modified radiator to enlarge the current path. With the help of High Frequency Structure Simulator(HFSS), the current distributions on radiation patches are shown to the operation mechanism of minimization.2.two band-notched antennas for WLAN/Wi MAX Applications are proposed. By cutting slots or /and adding parasitic strips to UWB antenna, notched bands can be achieved. Main parameters of the loaded structures are investigated to control the positions of the stop-bands, and the notched bands can be controlled independently. Such an antenna can adapt itself to bad environment.3.two frequency-reconfigurable antennas achieved by using varactor diodes or lumped inductors and a left/right hand circular polarized reconfigurable antenna accomplished by loading PIN diodes are proposed, which truly achieve regulating the frequency/polarization characteristic of antenna. The reconfiguration of frequency and polarization is achieved by changing the surface current distributions of the patches, which provide a good introduction to designing reconfigurable antenna.