Research On High Gain Low Sidelobe Waveguide Slot Array Antenna

With the development of radio technology,radar systems are widely used in various fields such as meteorological forecasting,environmental monitoring,and astronomical research,and the requirements for radar functions have become more stringent.The antenna is one of the key parts of the radar system,and its performance requirements have also improved with the development of wireless communication technology.Among them,the slot distribution of the waveguide slot array antenna is easier to control than other antennas,so it is easy to achieve low sidelobe performance,which makes it stand out in various radar antennas.The waveguide slot array also retains many excellent characteristics such as high transmission efficiency,large power capacity,and regular spatial structure of the waveguide structure.Therefore,it has an irreplaceable position in the design of radar antennas.In addition,in the monopulse radar technology,in addition to obtaining the distance signal of the tracked target from the echo signal,the azimuth and elevation angle signals of the target are also obtained to accurately locate the target.This requires the matching sum-difference receiver to be designed at the end of the antenna to form the sum-difference feed network.For the needs of high-gain,low side-lobe and sum-difference functional antennas in radar systems,the following research work was conducted in this paper:(1)Based on the sum-difference performance,a sum-difference network for feeding the waveguide slot array is designed.The sum-difference network is composed of four 3 d B directional coupler connected at the end and an external phase shifter.At the center frequency point.The transmission amplitude of each port of the sumdifference network is distributed between-6.4 d B and-5.7 d B,close to the theoretical value of-6 d B.(2)A high-gain low side-lobe waveguide slot array antenna was designed.The antenna has a VSWR<2.0 in the frequency range from 9.3 GHz to 9.5 GHz and a maximum gain of 27.1 d Bi at the center frequency.The maximum side-lobe level of the H plane pattern is-30.4 d B,E-plane pattern maximum side-lobe level is-17.4 d B.(3)The sum-difference performance of the antenna was verified.The pitch difference beam gain at the center frequency is 23.4 d Bi,the zero depth is-31.0 d B,the azimuth difference beam gain is 24.5 d Bi,and the zero depth is-18.0 d B.The above microwave devices are modeled,simulated and optimized by ANSYS HFSS electromagnetic field simulation software,and their theoretical analysis is performed.The working principle and design process of the antenna are described in detail.In addition,the antenna has been processed and tested in reallife.The test results show that the waveguide slot array antenna designed in this paper satisfies the design requirements and has high gain,low side-lobe characteristics.And the ability to combine and receive the sum-difference beams is good.Can be applied to monopulse radar systems.