Design And Implementation Of Filter Antenna

With the rapid development of wireless communication systems,the integration,multifunction,and miniaturization of radio frequency devices are important development trends in the future.Filters and antennas are two key components of the RF front-end.If they are integrated into a single device,i.e,a filtering antenna with both radiation and filtering functions,the size of the RF front-end can be effectively reduced.In addition,due to its radiation filtering characteristics,the filtering antenna can be used to suppress inter-frequency mutual coupling interference between multi-frequency antenna arrays and achieve high integration of multi-system antennas.Therefore,the research on filtering antennas is an important research interest in the field of antennas.Considering the wide application of omnidirectional antenna and patch antenna in wireless communication,this paper focuses on the filtering function integration of a broadband dipole patch antenna and a short-circuit patch antenna,the main contributions are as follows:First,three wideband filtering dipole antennas are designed by integrating the filtering function in the feeding network of the dipole antenna,which have the characteristics of low profile,wide bandwidth,and high out-of-band radiation suppression.(1)A filtering dipole antenna is designed by utilizating the current distribution zeros of the microstrip open circuit transmission line.The simulation results show that the impedance bandwidth is 29.6%,and the upper/lower stopband radiation suppression is more than 12.5/23 d B.(2)A filtering dipole antenna is designed by loading microstrip or slotline stubs in the feeding network.The simulation results show that the impedance bandwidth is 29.6%,and the upper/lower stopband radiation suppression is more than 12.5/23 d B.(3)A filtering dipole antenna is designed by loading multi-slotline stubs in the feeding network.Measured results show that the impedance bandwidth is 30.4%,and the radiation suppression is more than 17/19 d B within upper/ lower stopband.Second,two filtering patch antennas are designed by integrating the filtering function on the radiator of the antenna,and compared with the traditional microstrip antenna,it has improved E-plane beamwidth.Since no additional filtering circuit is introduced,the filtering antenna has a simple structure and a compact size.(1)A filtering patch antenna with a pair of symmetrical J-shaped slots etched on the driven patch is designed.Measured results show that the impedance bandwidth is 3.7%,the upper/lower stopband radiation suppression is more than 12.6/15 d B,and the E-plane half-power beamwidth is about 100°.(2)A filtering patch antenna with a split-ring-shaped slot etched on the driven patch is designed.Measured results show that the impedance bandwidth is 3.1%,the radiation suppression is more than 8.5/13.4 d B within upper/lower stopband,and the E-plane half-power beamwidth is about 100°.