Research Of Multi-frequency And Differential Filtering Antenna

With the development of wireless communication technology and approximation of 5G era,the modern wireless communication system has raised higher requirements on the miniaturization,integration and multi-functional of RF front end.As two important components of RF front end,it is great significance to study the integrated design of antenna and filter.Filtering antenna is a single component that integrating function and antenna radiation characteristic.In traditional design of wireless system,the antenna and the filter are designed individually and then connected by coaxial line,which will affect the matching performance of RF front end,cause the system loss and make the system size increase.Through the research and design of the filtering antenna,the system size and the cost of the system design can be reduced effectively and the work efficiency can be improved.This article introduces the research status of filtering antenna at home and abroad,studies the development trend and some existing problems of the filtering antenna,and a few filtering antennas which has good performance are designed,specific work is as follows:1.A dual-band filtering antenna for WLAN application is designed.To realize the dual-band characteristics,a pair of SIR(Step Impedance Resonator)are introduced into the filtering antenna as the filter structure,through the aperture on the common floor,the signal is coupled to the patch on the top layer and make it radiate.By adjusting the parameters of SIR reasonably,the frequency ratio can be controlled effectively,so that the structure will work in the expected working frequency.A high band-edge gain selectivity and high gain can be obtained by adjusting the size and position of aperture.2.Two tri-band filtering antenna with high frequency selectivity are designed.Both of filtering antenna adopt a new type of multimode resonator as filter structure,which has realized tri-band characteristics,two transmission zeros are produced at 2 GHz and 3.3 GHz so that the filter structure has good frequency selectivity in the 2.4 GHz frequency band.The first filtering antenna is consist of thefilter structure and a monopole antenna,an open strip is added in the middle of the monopole antenna,it is connected with the resonator by a short microstrip line.This filtering antenna has the advantages of simple structure,convenient processing,and has steady radiation patterns for three passbands.The secondfiltering antenna uses a coupling probe to integrate the filter structure and the radiation patch into the same device.The integrated filtering antenna has the characteristics of high frequency selectivity in 2.4 GHz and broad bandwidth in5.2 GHz.3.Two four-cell differential filteingr antenna arrays are designed.Both of the two filtering antenna array adopt differential feed technology,which couples the single to the aperture on the floor and radiates the patch on the top layer of the substrate.Both of the filtering antenna array work in the band of 5.2 GHz,which has good frequency selectivity,it has stable radiation pattern in the passband.