Research And Design Of Roadside Unit Array Antenna In ETC System

At present,the electronic toll collection system has been used in most of the highway toll stations in China.By using the electronic toll collection system,the speed of traffic can be greatly improved.And in the actual use process,there are still some problems in the electronic toll collection system,such as car following interference,adjacent channel interference and so on.These problems seriously affect the traffic speed of high-speed intersections,so it is very important to improve the performance of roadside unit antenna.Based on the above purpose,this thesis studied and designed the roadside unit array antenna.The main contents are as follows:1.The roadside unit array antenna with different amplitudes is designed.1)Firstly,the same amplitude roadside unit array antenna is designed.The basic unit of the antenna adopts the method of square patch cutting angle.And four basic antenna unit are fed in sequence to form the radiation unit of the antenna.The feed network of the antenna adopts a 1:4 equal amplitude power divider.The simulation results show that the bandwidth of antenna is 5.6-6.04GHz,the axial specific bandwidth is 5.65-5.85GHz,and the width of half power beam on E plane is 9.59°.And some parameters of the antenna are achieved.2)Based on the equal amplitude array antenna,the roadside unit array antenna with different amplitude is further designed.Due to the high sidelobe problem of the array antenna with equal amplitude,this antenna adopts the method of Dolph Chebyshev inequality to design the feed network to reduce the side lobe of the antenna.The antenna is made and measured.Finally,the measured results show that the antenna bandwidth is 5.67-5.88GHz,the axial ratio is less than 3d B in 5.7-5.9GHz,the gain is above 15d Bi in the 5.7-5.9GHz,the E-plane half power beamwidth is 9°,the side lobes are-16.5d B and-18d B.And the measured results meet the expected design index.3)Due to the wide beam width of the H-plane of the unequal amplitude array antenna,this paper further extends the unit to study the unequal amplitude array antenna.The simulation results show that the H-plane beam width of the antenna is 14.5°,and finally the H-plane beam width of the antenna is narrowed.2.A roadside unit array antenna based on its shape fusion algorithm is designed.This antenna integrates self shape fusion algorithm into the research and design of array antenna.The shape of the antenna unit is changed through the joint simulation of HFSS and MATLAB.The simulation results show that the initial antenna bandwidth is 5.63-6.03GHz,and the final antenna bandwidth is 5.66-6.13GHz.And the bandwidth of the array antenna is improved.3.A 4×8 element roadside unit array antenna is designed.The antenna is used to reduce the beam width of the antenna.Firstly,a 1×8 element antenna is designed to achieve narrow E-plane beam width.Then the array is expanded to form a 4×8 element array antenna.The simulation results show that the beamwidth of E-plane is 21.6°,and the beamwidth of H-plane is 13.52°.And the narrow beamwidth of E-plane and H-plane is realized.