| With the rapid development of microwave technology and electronic science,electromagnetic modeling and numerical calculation on computer platform based on the numerical method of electromagnetic fields have become the main method for analyzing the electromagnetic scattering characteristics of objects in practical engineering applications.However,the fast-growing engineering demands have prompted the increasing complexity and electrical size of the simulation objects,which put higher demands on the performance of numerical algorithms.The research on more efficient and accurate numerical algorithms to improve the efficiency of electromagnetic simulation is of great importance in practical engineering applications.Based on this background,the improved algorithm based on the characteristic mode basis function and its application in the electromagnetic scattering characteristics analysis are proposed and in-depth studied in this dissertation for the monostatic,wideband and bistatic electromagnetic scattering problems of electrical large objects,respectively.Firstly,the application of characteristic mode basis functions in the monostatic electromagnetic scattering problem of the electrically large objects is studied.A blocking-based characteristic mode basis function method is proposed to solve the single-site scattering problem with low efficiency and large number of basis functions in the traditional characteristic basis function method.The blocking technique is used to divide the electrical large object into several smaller blocks,and the characteristic mode basis functions are constructed using the effective characteristic modes on each block for linear expressing the induced current.Then,a downscaled reduced matrix equation is constructed to quickly solve the current coefficients.Compared with the traditional characteristic basis function method,the studied method improves the efficiency of basis function construction and reduces the number of basis functions and the dimension of the reduced matrix as well.Further,the application of characteristic mode basis function in the wideband electromagnetic scattering problem of the electrically large objects is studied,and a universal characteristic mode basis function method is proposed.The method constructs the characteristic mode basis function at the highest frequency point of the frequency band to be solved and reuses it as universal basis function for lower sampling frequency points,avoiding the repeated construction of basis functions at different sampling frequency points.Compared with the traditional ultra-wideband characteristic basis function method,the universal characteristic mode basis function method significantly improves the efficiency of solving the wideband electromagnetic scattering problem.Finally,the application of characteristic mode basis functions in the bistatic electromagnetic scattering problem of electrically large objects is studied.To address the difficulty of constructing a sparse basis for three-dimensional objects in the method of moments based on compressive sensing and the instability of the results caused by the measurement matrix constructed by the method of randomly extracted impedance matrix,a calculation model of the compressive sensing-based method of moments based on the characteristic mode basis function is proposed.On the one hand,the sparse basis is constructed by using the characteristic mode basis function to achieve the sparse transformation of the induced current on the surface of the three-dimensional object.Since the elements of the impedance matrix do not need to be completely filled,the efficiency of impedance filling is greatly improved.On the other hand,a deterministic measurement matrix is constructed by uniformly extracting the impedance matrix to obtain stable calculation results,which overcomes the problem of unstable calculation results of the traditional method of moments based on compressive sensing.Figure [44] Table [6] Reference [131]... |
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