Study On Filter Antenna Applied In 5G Mobile Communication System

With the rapid development of modern mobile communication technology,more and more frequency bands are used by multi-band and multi-standard wireless systems such as 2G,3G,4G and 5G.The massive use of limited spectrum resources and frequency bands has led to the consumption and congestion of existing spectrum.Therefore,mutual interference between signals of adjacent or similar frequency bands is also greatly increased.So,in order to eliminate the interference of unwanted or harmful signals to the communication system,it is necessary to add a filter to the system.At the same time,this also increases the size and loss of the system.This is unacceptable for systems with high space requirements.Thus,a great deal of work has been carried out on integrating filters and antennas into one subsystem.This subsystem that enables miniaturization and low loss is called an integrated filtering antenna(IFA).It not only avoids the matching and cascading of the 50 ohm transmission line between the antenna and the filter,but also has radiation characteristics and filtering characteristics.Filtering antennas have gradually become a research hotspot in this field because of their excellent performance.In this paper,the filter antenna with low profile,small size,light weight and easy integration is deeply studied.Based on this,the following filter antennas with different polarization functions are designed.The research content of the thesis mainly includes the following parts:1?A new type of H-shaped slot-coupled microstrip filtering antenna with microstrip filter structure is proposed.The antenna is composed of an upper dielectric substrate and a lower dielectric substrate.It is an antenna(array)with dual patch radiating elements.In the antenna design,the microstrip line transfers energy to the top layer patch through the H-shaped slot on the metal ground plane.The microstrip filtering structure is connected to the microstrip line and simultaneously implements a filtering function and a power distribution function.The simulated and optimized antenna has a 0.74GHz bandwidth from 3.05 to 3.79GHz.In the frequency range of 3.4 to 3.6GHz,its average gain in tlie direction perpendicular to the antenna plane is close to 1 ldBi.The test results are close to the simulation results,showing good gain and wider bandwidth.2?A dual-polarized H-shaped slot-coupled microstrip filtering antenna is proposed.The antenna is mainly composed of a feed network,a metal ground plane with H-shaped slots and parasitic radiation patches.In the antenna design,the filtering structure is connected to the microstrip line to form the feed network.Among them,the filtering structure is also a power divider,which simultaneously implements the functions of filtering and power division.The feed network and the parasitic radiation patch are respectively located on different dielectric plates,and the energy transfer between the two is achieved by H-shaped slots coupling on the grounded metal plane between the two dielectric plates.The±45°tilted H-shaped slots and the corresponding microstrip feed line are orthogonal to each other to achieve dual polarization of the antenna.Thereby a dual-polarized antenna with filtering function is obtained The proposed antenna is simulated and optimized,and the antenna is fabricated and tested.The test results show that the dual-polarized filtering antenna has better filtering characteristics and better polarization isolation.3?A eircularly polarized antenna has been modified to turn it into a circularly polarized filtering antenna with bandpass filtering.A circularly polarized filtering antenna is constructed by introducing the split ring resonant structure into the feed structure and implementing a band pass filtering function.The proposed circularly polarized filter antenna has excellent filtering function and has suitable axial ratio characteristics in the pass band range,realizing circular polarization radiation characteristics.