Design And Implementation Of High Performance Filtering Antenna

With the development of communication systems,one of the key technologies is proposed to solve the shortage of spectrum resources and space resources,which is to design high performance antennas.High performance antennas are designed to reduce losses and improve transmission efficiency of systems,therefore,improving the transmission quality of the entire communication systems.The high performance filtering antenna is to integrate the filter and the antenna to design,which can realize the function of frequency high selectivity,polarization reconfigurability,and single-band/multi-band reconfigurability.Compared with the traditional filter and antenna designed separately,the impedance matching circuit between the filter and antenna is removed by this design method.It is effective to reduce the loss of the matching circuit and the size of whole structure.Thence,it is easier to obtain a small size and high gain of antenna.Finally,this approach makes it easier to implement integrated systems.High performance filtering antennas are researched in this thesis.Based on the design of traditional antenna,and combined the method of high selectivity filter with reconfigurable network,high performance filtering antenna are designed.Three aspects about the main research are included in this thesis as follows:1.The design method of the novel coupled filter and wideband monopole are researched,and the principle of the filtering antenna are analyzed.Based on the theoretical analysis,a high frequency selective filtering antenna is designed with a fractional bandwidth of 41.9%,a flat gain about 4.26 dBi in the operational band.Besides,two trans:mission zeros realized at 1.75 GHz and 3.9 GHz out of the passband,which presents the excellent out-of-band rejection.2.A wideband circularly-polarized reconfigurable-filtering antenna is proposed in the paper.The function of reconfigurability and filtering are achieved after adding the reconfigurable filtering network.In order to obtain the wideband circular polarization antenna,several parasitic units and capacitive coupled feeding units are added on traditional truncated corner patch antenna.Left-hand circular polarization(LHCP)and right-hand circular polarization(RHCP)can be switched by adjusting the working states of different PIN diodes.Finally,the wideband reconfigurable filtering antenna with a fractional impedance bandwidth of 35%,a 3-dB axial ratio(AR)bandwidth of 23.5%,a flat gain about 6.3 dBic in the operational band,and the out-of-band rejection is better than 25 dB is achieved.3.According to the design principle of the novel coupled filter and the reconfigurable technology,a simple and compact wideband\dual-band reconfigurable filtering antenna is designed in this thesis.At wideband state,the fractional impedance bandwidth of the reconfigurable filtering antenna is about 92.8%,while the fractional impedance bandwidths are 40.3%and 13.3%at dual-band state,respectively.Besides,the reconfigurable filtering antenna with stable radiation in the passband is realized.