Research On VHF/UHF Multiban Broadband Antenna Technology

Frequency hopping spread spectrum and other technologies are more and more widely used in modern mobile communications.The performance of traditional narrowband antenna can not meet the corresponding requirements.Therefore,multi-antenna working simultaneously in a fixed narrow space has become a new research focus in this direction.In this paper,the UWB characteristics of VHF/UHF band antennas in specific physical space are studied.The related research contents are as follows:1.Research and design of VHF-UHF three-band broadband antenna.Firstly,the basic concept and application of antenna loading technology are described.Based on the principle of loading antenna,LC parallel network loading technology and ferrite magnetic ring loading technology are combined organically.The pattern characteristics and impedance characteristics of VHF monopole antenna are studied,and an ultra-wideband monopole antenna model loaded by lumped elements and ferrite materials is proposed.Based on the broadband theory of wire antenna and coaxial choke technology,a broadband dipole antenna structure is proposed to widen the bandwidth of antenna in a limited size,and choke its feeder with choke coil to ensure the feed balance of antenna.Finally,the lossless broadband matching network is optimized based on genetic algorithm and numerical approximation analysis method,and the broadband configuration of antennas is realized.The design of the whole antenna is completed by combining multi-antenna coaxial integration technology.2.Research on Optimization of unipolar loading structure and dipole choke technology.Firstly,aiming at the deterioration of antenna performance caused by feeder passing through the loaded inductance of VHF monopole antenna,a new loaded structure composed of feeder lumped inductance is proposed,which improves the antenna pattern characteristics.Secondly,the choke mechanism of dipole antenna feeder is studied,and a small broadband choke model based on band-stop filter principle is proposed.The choke is optimized and designed by CST software,which improves the performance of dipole antenna.Finally,based on the concept of coaxial integration of antenna,the equivalent structure of the coupling between the dipole antenna feeder and the inner wall of the monopole antenna is analyzed,and a decoupling structure is studied and designed to reduce the current coupling effect on the performance of the monopole antenna.