Research And Design Of Dual-band Filtering Antenna For Wireless Communication

Nowadays,with the development of wireless communication technology,from 1G to the emergence of 5G,the communication frequency bands are becoming more and more refined and higher requirements are also placed on wireless terminals.Terminals will develop in the direction of multifunction,high performance,and miniaturization.However,the higher the performance requirements,the more complicated the circuit is due to the equipment structure.How to keep the volume unchanged or even further miniaturize is a problem.The passive microwave device design of the RF front-end cannot meet the current needs.The integrated design of the filter and the antenna enables the resulting filtering antenna to have the functions of radiation,filtering,and balance conversion,and can also meet the requirements of system integration and miniaturization.In the case of the subdivision of the communication frequency band and the expansion of the business,the design of the multi-band filtering antenna is significant.Therefore,this paper explores filter theory and multi-frequency antennas,and studies the design methods of filtering antennas,and makes corresponding design of multi-band filtering antennas which can be used in wireless communications.The main research contents include the following parts:First,a dual-band filtering antenna based on a double-layer structure is proposed.Through coaxial feeding,the excitation antenna works in the n77/n78 and n79 frequency bands.The antenna consists of two rectangular radiation patches on the upper substrate,step impedance resonator(SIR)and L-shaped stubs on the lower substrate.The high frequency resonance is used to form the 4.55-4.64 GHz(n79)frequency band,and the low frequency resonance is used to form the 3.37-3.53 GHz(n77/n78)frequency band.The measured gain in the low frequency band is 6.38 d Bi,and the second single-stage frequency band has reached 1.02 d Bi.The antenna produces a radiation null between the two frequency bands,has high out-of-band gain roll-off and strong edge selectivity.It can be used for 5G wireless communication applications below 6GHz.Secondly,based on the slot-coupled feeding method,a dual-band antenna is proposed.The antenna can have two upper and lower dielectric plates,each with a thickness of only 0.8mm.Based on this dual-frequency antenna,a dual-frequency filter antenna is designed without adding a filter structure to the circuit.This antenna has two upper and lower dielectric plates.The air medium in the middle is to reduce the equivalent dielectric constant of the dielectric plate to increase the radiation efficiency of the antenna,which can make the antenna impedance matching effect better.The upper dielectric substrate is a monopole antenna,the upper dielectric substrate of the lower layer contains a ground plate with etched slits,and the lower layer is a designed microstrip line structure.The radiation null is generated between the two frequency bands and outside the band,the in-band operation is not interfered,and it has a better filtering response.This filter antenna has a compact structure.The structure works in the 3.5-3.6GHz(Mimax)frequency band with a gain of 5.31 d Bi and 4.46-4.56GHz(C-band)with a gain of 7.3d Bi.The design of miniaturized and integrated filtering antenna in wireless communication provides a new idea.