Design And Optimization On Asymmetric Slot Array Of Dielectric Loaded Asymmetric Inverted Trapezoidal Single Ridge Waveguide

Compared with the symmetrical single ridge waveguide slot array,the asymmetric single ridge waveguide slot array has the advantages of small size,no parasitic sidelobe,wide angle scanning and low sidelobe level.Therefore,asymmetric single ridge waveguide slot arrays are widely used in airborne and shipborne phased array radar system.However,the rectangular single rideg waveguide has large cross section size and narrow bandwidth,and its attenuation coefficient is large.It can not meet the requirements of modern communication system of antennas.In addition,the design and optimization methods of asymmetric single ridge waveguide slot array are mostly based on the three design equations of Elliott.These methods are only applicable to traditional rectangular asymmetric single ridge waveguide slot arrays,when the cross section of the waveguide is complicated,it is no longer applicable.For above problems,the study of transmission characteristics of asymmetric single ridge waveguides with complex cross section and a design optimization method suitable for asymmetric single ridge waveguide slot array for complex cross section can effectively improve the communication quality.Based on dielectric-loaded Asymmetric Inverted Trapezoidal Single Ridge Waveguide(AITSRW),the influence of the position of the medium and the width of the medium on normalized cutoff wavelength,single-mode bandwidth,normalized attenuation constant,power-handling capability and characteristic impedance of dielectric-loaded AITSRW are studied by using the Finite Element Method(FEM)combined with MATLAB programming.In the basis,a structure with the best transmission characteristics is selected as feed waveguide.General structure of slot array is determined according to design index.Amplitude distribution of excitation is calculated,and then the conductance distribution is determined.According to transmission line theory,the slots conductance and physical parameters are calculated by establishing 10-element model of parameter extraction in three-dimensional finite element software HFSS.On the basis of above analysis,a 16-element slot array antenna fed by the dielectric-loaded AITSRW is simulated.The results show that this array has good radiation characteristics of high gain,low sidelobe and narrow beam.Compared with related reference,using the dielectric-loaded AITSRW as the feed waveguide can further realize the miniaturization of the antenna.For the reasons of the deviation in actual processing,side-lobe levels and gain should reserve certain margin.There is a cterain diffetence between the aperture distribution of some slot in the array of initial design and the ideal situation.On the basis of the analysis of the cause of the deviation,“Approaching ideal aperture distribution of near field” is set as the target function to optimize the antenna's resonance parameters by using Genetic Algorithms(GA).Main program of GA and a series of script functions which can call HFSS for modeling simulation are written in MATLAB.Data is delivered between the two software via VBSCRIPT interface.The optimized slot array is modeled and simulated in HFSS.The optimization results show that the performance of the array has been greatly improved after the optimization.