Finite Element Domain Decomposition Modeling And Application Of Complex Platform Multi-Aperture Antenna Array

Complex platform multi-aperture antenna array modeling is an important foundation for radiation performance evaluation and optimization of airborne,vehicle-mounted and ship-borne multi-antenna.The challenge lies in the multi-scale characteristics of the geometric dimensions and material parameters of the platform,antenna array and radome.The finite element domain decomposition method(FEM-DDM)can model regions with different scales,so it is an effective way to deal with multi-scale challenges.However,FEM-DDM still faces the problem of insufficient efficiency in practical applications,and the time-consuming pre-processing process(geometric modeling,domain division,etc.)is one of the bottlenecks restricting the efficiency of FEM-DDM.This thesis studies the efficiency improvement method of the FEM-DDM pre-processing process,which improving the modeling efficiency of the complex platform multi-aperture antenna array.The specific research content is as follows.Firstly,three typical regions in the complex platform multi-aperture antenna array are studied for their efficient pre-processing methods.The first type of typical region is a large smooth region that is widely present on the platform.The difficulties of pre-processing are the large-scale grid,complex manual operations,and time-consuming domain division.In this thesis,a multi-layer recursive-bisection method is used to quickly and automatically decompose this type of region.Simulations show that it can uniformly divide a million tetrahedral grid into 40 sub-domains in only 6 seconds.The second type of typical region is the region formed by the planar finite periodic structures widely used in the antenna array.This type of region has the infinite period assumption that does not hold,and the finite period assumption leads to a large number of repeated computations.According to the boundary conditions of the periodic element,this thesis simplifies the two-dimensional planar periodic structure into 9 characteristic sub-domains,thereby avoiding a mass of repeated computations when filling the finite element matrix,and improving the computation efficiency of matrix filling and saving memory storages.The simulation shows that the proposed method reduces the memory requirement of finite element matrix by 197 times for the 40×40 dimension Vivaldi antenna array with 28.21 million FEM unknowns and improve the time efficiency of matrix element computation by 59 times.The third type of typical region is the region constructed by the curved surface conformal array and the platform.This type of region is widely presented in the conformal design of the array and the platform.The difficulty of the pre-processing lies in the conformal geometric modeling of a large number of array units and the platform surface.This thesis combines HFSS and MATLAB tools to automate the programming and design of the location of a large number of array elements,so as to realize the fast,automatic and precise layout of array elements on the curved surface.Secondly,this thesis uses a large-scale planar antenna array as an example to demonstrate the engineering application capabilities of the aforementioned pre-processing methods.In order to achieve fast and accurate modeling of large-scale planar antenna arrays,this thesis uses boundary element as the finite element truncation boundary condition to improve the accuracy and efficiency of radiation calculation.The finite element modeling method of the array antenna feed is examined,and the finite element modeling of the current probe excitation and the waveguide mode excitation is realized.The cavity-backed microstrip antenna and the dielectric resonator antenna(DRA)are used as examples to verify the accuracy of radiation calculation and feed modeling.On the basis of radiation calculation and feed modeling,this thesis comprehensively applies the aforementioned pre-processing methods,and employs the domain decomposition finite element boundary element method to conduct integrated modeling of Vivaldi antenna array with 100-unit and radome.The simulation experiment indicated that the calculated results in the thesis are in good agreement with the reference results.Finally,for realizing integrated and flexible modeling of the complex platform and the multi-aperture array antenna,this thesis introduces the two-fold domain decomposition method based on the FEM-DDM.The two-fold domain decomposition method not only decomposes the finite element region,but also uses the discontinuous galerkin method to decompose the boundary element region,thereby further improving the flexibility of partition modeling.Using the two-fold domain decomposition method and the aforementioned pre-processing method,this thesis realizes the analysis of the integrated electromagnetic characteristics for the complex platform and the antenna array.In the end,the engineering application ability of the proposed method is demonstrated by the example of solving complex enginnering problems such as the integrated analysis of the UAV group with the airborne antenna,the full-scale fighter machine with the airborne antenna array.