This paper proposes an acceleration technique to fast evaluate the monostatic radar cross section (RCS) with the multilevel physical optics (MLPO) algorithm. The proposed method combines the adaptive cross approximation (ACA) algorithm with the MLPO to fast evaluate two‐dimensional monostatic RCS (two‐dimensional monostatic RCS over a range of elevation angles θ and azimuths angles φ at a fixed frequency f, or a range of frequencies f and azimuths angles φ at a fixed elevation angle θ) responses. Owing to the phase compensation in the MLPO, the matrix corresponding to the compensated back‐scattered field of each group is highly rank‐deficient, which is compressed with ACA in a multilevel fashion therefore a lot of central processing unit time will be saved. The rank‐deficiency, accuracy and computational complexity of the proposed method have been studied through a couple of numerical examples, which illustrate the effectiveness of the proposed approach.

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gain. The value of the transmitted field in dB is plotted in Figure 9 for different heights of the cavity. As expected, when the thickness of the cavity does not satisfied the condition (4) at 9.4 GHz, a shift in the maximum radiated level appears due to the formation of the propagating waves. On the contrary, when (4) is satisfied, the maximum radiated power is in the broadside direction but its level is decreasing with h. It is shown in Figure 8 that the expected 3-dB beam width could be decreased from 40 ( Fig. 3) to 10 , gain improvement is expected accordingly. CONCLUSIONSIn this article, several methods susceptible to increase the performances of an antenna were studied while preserving its characteristics. The purpose of this study is to obtain successful structures in term of compactness, gain, and bandwidth. For this purpose, an original and not intuitive combination of inductive and capacitive elements for the conception of a SPR-CMA was proposed, thanks to an automatic and not intuitive CAD tool based on the coupling between mGA and the TLM method. ABSTRACT: A modified compressed block decomposition (CBD) preconditioner combined with the multilevel fast multipole algorithm (MLFMA) is proposed for efficiently solving large dense complex linear systems that arise in electromagnetic problems. The modified preconditioner utilizes some improvements to improve the CBD preconditioner which is constructed from the available sparse near-field matrix. On the basis of the modified preconditioner, an efficient matrixvector multiplication is implemented. Accordingly, the modified preconditioner is comparable with the unpreconditioned generalized minimal residual algorithm (GMRES) in terms of the number of iterations and the total solution time. Remarkably, the modified preconditioner provides a reduction close to one order of magnitude in both the number of iterations and the total solution time. V C 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1915-1919, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26149Key words: compressed block decomposition (CBD); multilevel fast multipole algorithm (MLFMA); electromagnetic scattering INTRODUCTIONIn electromagnetic wave scattering calculations, a classical problem is to compute the equivalent surface currents induced by a given incident plane wave. Such calculations, relying on the Maxwell equations, are required in the simulation of many industrial processes ranging from antenna design, electromagnetic compatibility, computation of back-scattered fields, and so on. All these simulations require fast and efficient numerical methods to compute an approximate solution of Maxwell's equations. Using the equivalence principle, Maxwell's equations can be recast in the form of integral equations that relate the electric and magnetic fields to the equivalent electric and magnetic currents on the surface of the object. The method of moments (MoM) [1, 2] is one of the most widely used techniques for electromagnetic problems. For a large elec...

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This paper proposes a multigrid preconditioner for integral equation fast analysis of electromagnetic scattering problems. The multigrid model is constructed by recursively dividing every triangular element on the coarse level into 4 small ones. The Rao-Wilton-Glisson (RWG) basis functions defined on the coarse level are expressed with linear combinations of those on the fine level, and the expansion coefficients of which are used to construct the restriction and interpolation operator. To further accelerate the convergence of iterative solution, a set of solenoidal basis functions on the coarse level are constructed additionally, which are also expressed with linear combinations of RWG basis functions on the fine level and adopted to construct the second restriction and interpolation operator. The two sets of coarsening techniques are then combined together to remove the low-frequency components of the iterative error. Numerical results show that the proposed method can reduce both the steps of iteration and CPU time compared with the iterative solver without preconditioning.Index Terms-Electromagnetic scattering, iterative solver, multigrid preconditioner.