Uv-mlfma And Interpolation Method For Fast Analysis Of Complex Electromagnetic Characteristics

With the development of CEM and computer technology, The analysis of the electromagnetic scattering and radiation of 3D complex targets have attracted much more attention in engineering applications. At the same time remote sensing and target identification are demanded to the halfspace researching.The UV-MLFMA is proposed to solve the difficulties when the MLFMA applied to the multiscale problems. The UV-MLFMA is based on the multilevel UV method and MLFMA, the hybrid matrix is splited into three terms, the "near" terms, the "intermediate" terms and the "far" terms. The "near" terms are evaluated by the method of moments (MoM), the "intermediate" terms are evaluated via the multilevel UV method, and the "far" terms are evaluated by the MLFMA. During the process the CPU time and the memory required are decreased efficiently. The hybrid method also can analyze the characteristic of the wire antennas placed on automobile, vessel or other complex conducting objects.Next, the UV-MLFMA is used to analyze scattering by arbitrary three-dimensional (3-D) perfect electric conductor (PEC) targets above a lossy half-space. The real-image representation of the Green's function is appropriate for expansion when the source and observation points are separated by a wavelength or more. This determines the large finest group size of the MLFMA, which leads to a low efficiency. The UV-MLFMA avoids this problem efficiently.UV-MLFMA method can accelerate the computation at special frequency point,but when is used for analyzing wideband problems,the method is time wasting,because it require fill matrix and slove the linear equation at any frequency point. Therefore, Active Learning method and MBPE are introduced,both of which are model-based technique. Then Active Learning method are used to interpolate RCS simultaneously in both the spatial and frequency domains. In the analyze of microstrip circuits and Ultra-wideband antennas,The near field impedance and MSAI preconditioning matrices are interpolated by MBPE at intermediate frequencies over a relatively large frequency band with rational function interpolation technique Compared with direct computation results. Numerical results show the flexibility and efficiency of the two methods.