Research On A Current-Charge System Of Integral Equations And Its MoM Model

The method of moments is one of the most important methods to analyze electromagnetic problems based on integral equations,which has been widely applied in electromagnetic scat-tering and radiating problem because of its excellent computational accuracy.With the devel-opment of science and technology and the progress of manufacturing technology,a number of engineering applications has called for electromagnetic simulation and wideband electromag-netic simulation of complex and fine structures.In this situation,the discrete scale is very small compared to wavelength,thus inducing the low-frequency problem if the traditional method of moments(MoM)with RWG functions is used.In order to overcome this problem,many methods have been put forward,such as augmenting scalar charge unknown or scalar potential unknown,and improving the discretion,which all can overcome the low-frequency problem to a certain extent.In this paper,we will investigate surface integral equation formulations for scat-tering from perfectly conducting objects and their MoM model.The specific details include the choice of basis functions and testing functions,discussing singularity treatment schemes,and introducing Adaptive Cross Approximation algorithm(ACA)to solve the corresponding moment method model.The main works of this thesis are listed as follows:1.The simultaneous system of the electric current and charge integral equation(ECCIE)and its MoM model is introduced to overcome the low-frequency problem.A novel scheme of computing the scattering far-field and the reason that it can avoid low-frequency error are discussed in detail.Some numerical examples are provided to demonstrate the correctness of the MoM model of the present ECCIE.2.Both discreting and testing schemes of using different functions(RWG function and/or BC function)are researched for improving the accuracy of the ECCIE.The accuracy of the magnetic field integral equation(MFIE)in low frequency is improved by using BC function and mixed discretization.Moreover,numerical examples are provided to demonstrate the accuracy of this scheme used to the ECCIE from low frequency to middle frequency.3.The simultaneous system of the combined-field integral equation and the charge integral equation(C-ECCIE)is proposed to avoid resonance in the transition band,and its non-resonant character is researched from low frequency to middle frequency.Numerical examples demonstrate the effectiveness of this method.4.The ACA algorithm is introduced into the MoM model of the C-ECCIE,realizing mul-tilevel compression for the system matrix and accelerating the calculation of the corre-sponding matrix-vector product.Numerical examples demonstrate both the feasibility and the acceleration effect of this scheme.