Research On The Frequency Reconfigurable Antenna

With the rapid development of wireless communication technologies, frequency reconfigurable antennas that can operate with different modes have attracted much attention. A variety of studies have come up with different techniques to achieve frequency reconfigurable antennas. Such as, using tunable materials, which are materials the inherent electrical properties(permittivity, permeability, or conductivity) of which can be controlled by the application of an external bias(electric, magnetic, or optical). In this paper, several kinds of frequency reconfigurable antennas are another solution to achieve the reconfigurability by switching ON and OFF to change the physical size of antennas. The main work and results of this dissertation are as follows:Firstly, the background and the domestic and international status of the frequency reconfigurable antennas are briefly analyzed and summarized; then briefly introduce the basic parameters evaluating antenna performance.Secondly, a band-notched UWB frequency reconfigurable antenna is presented. It could reconfigure its working frequency in three modes. One of them is one band-notched ultra-wideband antenna with a stopband covering 3.3-4 GHz; the other one band-notched ultra-wideband antenna with a stopband covering 5-5.9 GHz; the dual band-notched ultra-wideband antenna with a stopband cover from 3.3-4 GHz and 5-5.9 GHz。.Besides, the affection of some main parameters and the simulated surface current distributions for each resonant frequency are described. There is a good agreement between the measured and simulated results.Finally,On the base of comprehensive simulation and optimization, a frequency reconfigurable antenna with a compact size of 16mm×22mm×1 mm, is demonstrated. By changing the state of the switch,the operating frequency bands of the antenna are altered. The measured VSWR and radiation patterns are in agreement well with the simulated results. Above all, the radiation patterns at each resonant frequency are similar and the patterns at H-plane are almost omnidirectional. This kind of antenna would be suitable to use in the field of wireless communication.