Research On Miniaturized Gap Waveguide Slot Array Antenna For Millimeter Wave Train-Ground Communication

Maglev rail transit has become a hotspot of competition in the rail transit field due to it’s advantages in wide speed range,strong climbing,low noise,good stability,environmental protection and energy saving,etc.Advanced technologies such as cloud computing,Internet of Things,big data,Beidou positioning,next-generation mobile communications,and artificial intelligence are gradually integrated and integrated with high-speed railway technology,which proposes a higher level of technology for the realization of magnetic levitation intelligent construction,intelligent equipment and intelligent operation.Therefore,it is of great significance and value to develop high-speed maglev railways and study high-speed maglev communication systems and key technologies.The main goal of this subject is to study the miniaturized vehicle-mounted antenna in the millimeter-wave vehicle-to-ground communication system of the high-speed maglev train.By adopting the form and technical approach of gap waveguide slot array antennas,the vehicle-mounted antenna that meets the high-speed maglev millimeter wave vehicle-to-ground communication system is developed.By rationally designing the number and layout of the array antenna elements,it can meet the requirements of vehicle antennas.On the basis of satisfying the relevant electrical performance,the miniaturization of the on-board antenna communication system is realized.In addition,this topic aims at the shortcomings of parallel-fed gap waveguide slot antennas: the feed network is complex and redundant and it is difficult to achieve two or more array arrays,so research and improvement are carried out.The main work can be summarized as the following aspects:1.Design of single-layer gap waveguide slot array antenna.Based on the ridge-gap waveguide,a 2×16-element planar circularly polarized slot array antenna that works in the37～39 GHz frequency band is designed and proposed.The annular slot unit was used to radiate right-handed circularly polarized waves.And the same feed amplitude and phase was realized through a ridge gap waveguide with one-32-way power divider.By reasonably designing the unit spacing and array spacing,the antenna can meet the fan beam required for millimeter-wave vehicle-to-ground communication.The measured results show that in the frequency band of 37–39 GHz,the voltage standing wave ratio of the antenna is less than1.45,the gain is greater than 21 d Bi,the axial ratio is less than 3.5 d B,the half power beam width in elevation plane is about5°,and the half power beam width in azimuth plane is 35°.The antenna is an all-metal structure,with stable working performance,stronger mechanical performance,and good engineering capabilities,realizing the miniaturization of the millimeter wave vehicle-to-ground communication antenna system.When a wireless communication system composed of a single-layer gap waveguide slot array antenna is installed in the communication system A,it successfully realizes the low-speed traction of the train by the base station.2.Design of double-layer gap waveguide slot array antenna.In order to improve the large size of the single-layer gap waveguide slot array antenna feed network,a double-layer gap waveguide slot array antenna was designed.Through the two gap waveguide turning structures,the upper layer ridge gap waveguide feed network is turned to the lower layer,and the size of the single-layer gap waveguide slot array antenna in the width direction is reduced.The designed antenna could meet the designed requirements of the millimeter wave vehicle-to-ground communication system.The size of the vehicle-mounted antenna communication system is obviously reduced in the width direction,and the miniaturization of the vehicle-mounted communication array antenna is further realized.3.Design of 3×3 gap waveguide slot array antenna.In order to realize a parallel-fed gap waveguide slot array antenna with more than two arrays,a new type of ridge gap waveguide circularly polarized slot antenna unit is proposed and simulated.The unit is small in size and can be used in arrays with more than two rows;In order to simplify the ridge gap waveguide feeding network,three new power divider are designed and simulated.The new power divider uses the bow-shaped path for phase compensation,and the structure is simpler.Finally,a 3×3 gap waveguide slot array antenna are designed and simulated.The simplification of the feed network of the parallel-fed ridge gap waveguide slot array antenna and the array of more than two rows are realized.