High-speed M Odeling And Low Sidelobe Design Of Waveguide Slot Array Antenna

Waveguide slot array antenna consists of many half-wave slots on the rectangular waveguide wall.In this structure,the feeding path is united with the radiation units.The physical sizes and relative positions of radiation units can be adjusted easily.And the integrated metal boxbeam construction could withstand strong impacts.Therefore,waveguide slot array antenna has the advantages of compact structure,light weight,high reliability,easy to be conformal,high aperture utilization ratio and convenient control of aperture distribution.So it is widely used in radar,communication and many other fields.This paper focuses on the waveguide slot array antenna of low sidelobe level,and works on exploring an automatic design and optimization method.The main content is as follows.1.Based on the basic theory of slot antenna,the design principle of rectangular waveguide slot antenna is described.And according to Elliott's design equations of waveguide slot array antenna,the design procedure of standing-wave-feed slot array antenna and travelling-wavefeed slot array antenna is briefly described,with the help of a widely used electromagnetic simulation software Ansoft HFSS.Furthermore,the basic principle of Taylor pattern synthesis is introduced.It provides a theoretical foundation for the software development and antenna design in the following chapters.2.An automatic design software for waveguide slot array antenna is developed independently to realize the automatic design of standing-wave-feed slot array antenna and travelling-wave-feed slot array antenna.The software is developed in MATALB environment.It can control HFSS through Script interface to accomplish automatic modeling and simulation.And it is linked with Microsoft Word for recording simulation reports automatically.It is proved that the software can greatly improve the efficiency of antenna design.3.In order to improve the antenna performance and reduce the sidelobe level,two different optimization methods are explored,including direct optimization based on Genetic Algorithm(GA)and indirect optimization based on Equivalent Admittance Method.The advantages and disadvantages of these two methods applied in the design procedure are compared through simulation.And the Equivalent Admittance Method is embedded in the automatic design software.4.With the help of the self-developed automatic design software for waveguide slot array antenna,a low sidelobe level standing-wave-feed slot array antenna is accomplished,which meets the requirements well.And it is used to form a planar slot array antenna.Relying on the design principle of waveguide coupling slot,the planer slot array antenna is fed by coupling slots.The designed planar slot array antenna operates at 24 GHz with a bandwidth of 100 MHz.Its VSWR is less than 1.5 and pattern gain more than 35 d B.The sidelobe level and beam width of azimuth and elevation plane could meet the requirements well.Eventually,the antenna is fabricated and measured.The simulation and measurement results are in good agreement.