Resarch On The Pattern Reconfigurable Antenna

The Reconfigurable antenna, which is to m eet the high-capacity, multi-functional, ultra-wideband requirement in the modern communication systems, has been proposed. It also gets a rapid developm ent by th e high-performance, low-power switching technology, such as PIN switches and MEMS switches. Reconfigurable antennas can be divided into the following catego ries according to th eir performance, i.e., frequen cy reconfigurable antennas, pattern reconfi gurable antennas, frequency and pattern reconfigurable antennas and pol arization reconfigurable antennas. Since the design of the frequency reconfigurable antenna is rela tively simple, many past studies have been done on it. The Pattern reconfigurab le antenna has become a research hotspot recently, because it can greatly increas e the capacity and safety of the system, and it also can achieve the wider scanning angle of the patte rn. Researches on pattern reconfigurable antenna elements are performed, and a frequency and pattern reconfigurable antenna is also investigated. The thesis includes the following six chapters.The first chapter introduces the backgr ound and the state of the reconfigurable antennas at home and abroad. At the same time, the latest research results of the pattern reconfigurable antenna has been disp layed. The structures, functions and reconfiguration methods of the pattern reconf igurable antennas are given in detail as well.Chapter II introduces th e theories o f microstrip antenna, Yagi-Uda antenna and inverted-F antenna. Besides, the design princi ples and design m ethods of the DC bi as network have been given, which has a great im pact on the perform ance to the reconfigurable antenna. We also give the topology of the DC bias network.Chapter III presents the design of a dua l-band azimuth pattern reconfigurable antenna. Firstly, according to the principles of Yagi-Uda antenna and microstrip antenna, the pattern reconfigurability mechanism of the proposed antenna is explained in detail. Next, the antenna could operate in both lo wer and upper bands of the WLAN, the main beam in azimuth plane of proposed antenna ca n be easily adjusted in dif ferent four directions in both frequency bands, especial ly in the lower frequency range, the f our states of the reconfigurable pattern could nearly cover the whole azimuth plane. Finally, simulation results and test results are in good agreement.In Chapter IV, a new radiation pattern a nd frequency reconfi gurable antenna is demonstrated, according to the p rinciples of Yagi-Uda antenna and printed inverted-F antenna, the reconfigurable antenna can achie ve the four directions of the horizontal plane at one frequency, at the same time, it can operate both frequency bands(5.24 GHz and 5.77GHz) in the sam e radiation pattern. T he design of the DC bias circuit is very representative. simulation results and test re sults of the radiation pattern and frequency reconfigurable antenna are in good agreement.Chapter V present a reconfigurable antenna, which is capable of switching between the monopole-like pattern and the boresight pattern. The reconfigurable antenna which is composed of double loops is presented. The operation frequency of the antenna is 11.8GHz. By controlling the switch loaded the inner loop and outer loop, the reconfigurable antenna could been achieved.The last chapter gives the summ ary of the whole thes is and the prospect for the future work.