Research And Design Of Antenna For The Vehicle-to-Vehicle Communication System

The popularity of family car results in more and more vehicles running in the traffic network,which increased the traffic loading.Traffic accidents is occured frequently,such as traffic jams,rear-end,collision and so on.Vehicle-to-Vehicle(V2V)communication system achieves information exchange between moving vehicles by using communication equipments on the vehicle.It is conducive to ease the traffic congestion and reduce the traffic accidents.Obviously,V2 V antenna occupies an important position for V2 V communication system to transmit and receive information.In this thesis,V2 V antenna is researched and designed with the basis of low profile and omnidirectional requirements for V2 V communication.The main work is as follows:1.A horizontal polarized V2 V antenna is proposed by periodically eatching “ji” slots and designing a balun with half-wavelength between the left and right branches.Using the periodic slots change magnitude and direction of the surface current,which forms horizontal polarization and omnidirectional radiation.Balun realizes the impedance transformation between patch and feed input,and reduces the impact on the surface current distribution of patch.This antenna operates at 5.76GHz-6.04 GHz,which covers the V2 V communication band 5.85GHz-5.925 GHz.The maximal gain is 1.77 dBi,and the out of roundness of radiation pattern is less than 1.2dB in the horizontal plane.2.Vehicle communcaiton belongs to the near-ground communication.In order to reduce antenna loss,a vertical polarized V2 V antenna is proposed.The antenna obtains better broadband 4.74GHz-6.79 GHz by loading shorting pins and etching two sets V-shape slots.The relative bandwidth reaches 35.55%.It contains the V2 V communication band and the WLAN communication of 5GHz band.This antenna acquires a good omnidirectional radiation pattern in the horizontal plane,whose out of roundness is less than 0.5dB.The maximal gain is 4.2dBi.3.Considering the advantages of circular polarization antenna in vehicle communication,a circularly polarized V2 V antenna is proposed.According to polarization decomposition of circularly polarization and orthogonality between horizontal polarization and vertical polarization,six 7-like parasitic patches are added on vertical polarized antenna.The parasitic structures produce a horizontal polarization by coupling excitation,which makes antenna achieve left-hand circularly polarization and horizontal omnidirectional radiation.The effective bandwidth is 5.65GHz-6.08 GHz,andthe maximal gain is 4.47 dBi.The out of roundness of horizontal radiation pattern is less than 1dB.This antenna can be used as an on-board unit antenna for V2 V communication,Automatic Vehicle Identification(AVI)and Electronic Toll Collection(ETC)system.4.Simulation and analysis are made by combining a vehicular model and the V2 V antennas.In this paper,the vertical polarized V2 V antenna is analyzed as an example.A simplified vehicular model is established in the electromagnetic simulation software.The performance of antenna is analyzed by simulation results of radiation pattern and magnetic field distribution,while the antenna is placed in different positions on the vehicular model.Three antennas have the advantage of low profile and omnidirectional radiation.The vertical and circular polarization V2 V antennas are measured,which are coincident to the simulated results.They meet the requirements of V2 V communication,which makes them to have engineering significance.