Investigations On The Planar Reconfigurable Antenna

With the rapid development of modern mobile communications, higher necessary of ultra-wideband, high-capacity, multi-function is greatly needed in the entire communication system. As one of the key wireless communication components, the antenna becomes more and more important in further research and development. With the growing new functions of wireless communication system, it often needs to set up many kinds of functions in transmitting and receiving at the same system. So light weight, low cost, easy integration and multi-function have become important research directions in the antenna technology. According to the different environmental needs, reconfigurable antenna can adjust its working mode, so it works more efficiently in complex environment, and provides more possibilities for reliable communication.In this thesis, a preliminary exploration has been made for the reconfigurable antenna. The main work and innovations are organized as follows:First of all, based on the traditional multimode substrate integrated cavity, we proposed a novle polarization changeable antenna element. By adopting multiple feeding ports in the design, the radiation polarization can be changed when the antenna element is fed by using differnent feeding port.Secondly, based on the above research, a novel reconfigurable planar array antenna with reconfigurable polarizations is proposed. It consists of switching circuit, power circuit and the antenna unit with variable feed ports. The principle and design methods of the compact power circuit and switch circuit are introduced at first, and then they are integrated with four antenna units, forming a 2*2 antenna array. By properly choosing the feeding ports of the antenna units through switching circuits, the different circular polarization waves are generated by the designed array antenna.Finally, a novel planar reconfigurable monopulse antenna with compact size is proposed and designed. The antenna can transform the pattern of the antenna array by controlling the state of the switching circuit, and then sum beams, difference beams in azimuth and elevation planes, and bi-difference beams are generated. Without using complex beam forming network, the design complexity of the antenna is significantly simplified. The capability of reconfigurable monopulse beams ensures the proposed antenna is a good candidate for smart wireless access point applications.