Research On Key Technologies Of Composite Reconfigurable Antenna

With the rapid development of wireless communication system,continuing increasing of data transmission,increasingly tense of channel resources as well as the constant compression of cost and volume have raised a higher challenge to the performance of the wireless system.Facing the growing demand of system performance,on one side,wireless systems need to integrate more and more antennas,but on the other side,the traditional single function antenna modules have been difficult to meet the demand of current development for high cost,large volume,high power consumption,serious electromagnetic coupling and many other shortcomings.Reconfigurable antenna technology is proposed to solve the contradiction mentioned above and has received significant concern from researchers.Reconfigurable antenna can be divided into four categories: frequency reconfigurable antenna,pattern reconfigurable antenna,polarization reconfigurable antenna and multi-parameter composite reconfigurable antenna.The composite reconfigurable antenna is extremely valuable because it can reconfigure more than one single parameter,but it is the most difficult to be designed due to the theoretical study's lack.In this paper,reconfigurable technology is studied and five reconfigurable antennas are proposed.The main research contents and achievements are shown as follows:1.Designed a frequency reconfigurable antenna which are based on monopole antenna and parasitic radiation principle.By controlling the on-off state of the PIN diode to connect or disconnect the parasitic patch to the main patch the frequency reconfiguration can be achieved.The antenna has been fabricated and measured and the test results showed that the antenna can work in UWB status and dual band(UWB and 2.45GHz)status,respectively.2.Two pattern reconfigurable antennas are designed in this paper.One is a clubs-shaped wideband pattern reconfigurable antenna which is based on tapered slot antenna and monopole antenna principle.The antenna works in three radiation states by controlling the on-off states of two embedded PIN diodes: omnidirectional radiation and two end-fire radiation.The other is half-wavelength dipole antenna of symmetrical structure,which can realize the switch of radiation pattern through controlling on-off state of PIN diodes which were embedded in the two arms of T-shaped transmission line.Test results shows that the antenna radiates at two end-fire directions in WiMAX(3.3-3.6GHz)band.3.Based on the synthesization of the front design including the frequency reconfigurable antennas and pattern reconfigurable antennas,a pattern and frequency composite reconfigurable antenna is proposed.This antenna can realized any combination state of three end-fire patterns and two frequencies(2.5GHz and 3.5GHz).The antenna performance matches well with the simulation,and its peak-gain of end-fire is 4.7d Bi at 2.5GHz and 5.4dBi at 3.5GHz.4.Introduced reconfigurable antenna technology based on new materials and simulated a frequency and polarization composite reconfigurable antenna based on liquid crystal dielectric anisotropic characteristics.The simulated results show that the resonant frequency of antenna can tune from 3.04 GHz to 3.18 GHz under the effect of the external polarization bias voltage and by controlling on-off states of two PIN switches,the feed path can be changed,as a result,the reconstruction of vertical polarization and horizontal polarization can be realized.