Design Of The VHF/UHF Broadband And Miniaturized Antenna

VHF/UHF frequency band vehicle-mounted antennas are widely used in modern military and civil communications,but the traditional narrow-band antennas are no longer adapt to the increasingly complex electromagnetic environment and communication needs.Therefore,the main research directions of vehicle-mounted are broadband and miniaturization.In this paper,a single-port VHF/UHF band broadband miniaturized antenna is designed by using multiplexers according to the actual engineering needs.The main research contents are as follows:1.Research on VHF broadband antenna.In order to satisfy the vehicle-mounted environment,the antenna structure adopts the whip antenna.The antenna uses the sharing structure of single and dipole radiators to realize the miniaturization of the antenna and solve the mismatch problem caused by the over-wide frequency band index of the antenna.The sharing structure of single and dipole radiators can be understood as using one radiator to realize two antenna modes,splitting the working frequency band into two parts,so that the antenna has different working modes in different frequency bands.Adding new feed point to the disconnection in the middle of the radiator,can realize the dipole operation mode.The negative effect of the dipole feeder on the performance of the antenna can be solved by using ferrite magnetic ring.These two antenna modes adopt the lossless broadband matching network to meet the requirements of standing wave ratio.Through simulation and measurement,the VHF broadband antenna basically achieves the target requirements.2.Research on UHF band antenna and multiplexer.According to the requirement of high gain of UHF antenna,an equivalent structure of binary array antenna is proposed,which uses slot coupling feed to avoid the unbalanced feed issue of traditional binary array.In addition,by analyzing the distributed current of the radiator,the antenna size is further shortened compared to the original antenna,which realizes the antenna miniaturization.In order to reduce the horizontal space occupied,this paper places the UHF antenna coaxially on the VHF antenna,and designs a triplexer composed of two duplexers cascaded to realize the single-port feed of the antenna system.After the actual test,the VHF/UHF broadband antenna basically meets the design requirements.