Design Of The Waveguide Inclined Narrow Wall Slots Array Antennas With Large Dimension

Waveguide slots array antenna is widely used in the field of communications and radar,with a compact,light weight,easy to control the aperture distribution and easy to achieve low sidelobes or even low sidelobes and other characteristics.This paper designs a waveguide inclined narrow wall slots array antennas with large dimension which is one of the important components of the vessel traffic service(VTS)radar system.As the design of the antenna is large,the antenna length of 5.8m,the antenna simulation design,processing and testing have brought no small challenge.In this paper,the design method of the waveguide inclined narrow wall slots array antennas is studied by using the three design equations of Elliott waveguide slot array antenna and the integrated method of array antenna for the needs of a VTS radar system.A large-sized waveguide narrow-edge slot array antenna is designed to meet the requirements of the system.The main research work of this paper is to design the antenna which meets the requirements of the index according to the design method of waveguide narrow-edge slot array antenna,and verify the feasibility of the method.According to the requirements of the index,the number of units,the unit spacing and the theoretical calculation of the gap admittance are initially identified.Then the gap admittance function is fitted and the gap and slot depth are obtained by interpolation.And the model is established in HFSS.In the narrow edge of BJ-100 standard waveguide,a total of 226 slot units are obtained and the simulation results are obtained.The near field data of the initial model are extracted and compared with the theoretical values.The model is further optimized by changing the gap angle or gap spacing according to the difference between the near field data and the theoretical data.The final simulation results in terms of gain,sidelobe level and half power beam width all meet the system requirements.The structure of the antenna is determined,and three waveguide slot array antennas in VTS radar systems are processed.The waveguide array antennas in VTS radar systems are tested by plane near-field measurement in the anechoic chamber of Xi’an University.The results are in good agreement with the simulation results and verify the correctness of the design method.Another work in this paper is to improve the design of a rotary joint in the system.The center frequency of the rotary joint is 9.41 GHza and the bandwidth is 60 MHz.The voltage standing wave ratio is less than 1.2 in the working frequency band,and the insertion loss is less than 0.5d B.By analyzing the influence of the structural parameters of the rotating joint on the performance of the rotary joint,the parameters of the model are adjusted,and the simulation model of the voltage standing wave ratio and the insertion loss satisfy the index requirement in the working frequency band.The results show that the measured results of the voltage standing wave ratio and the insertion loss in the working frequency range are in good agreement with the simulation results.