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— In this paper, we present the formulation of a finite-element/boundary-integral method for the analysis of three-dimensional doubly periodic structures based on arbitrary nonorthogonal lattice configurations. The method starts from a functional description of the field problem where only a single unit cell of the array is considered. This unit cell is(More)
A novel diagonalized multilevel fast multipole method (MLFMM) for time harmonic Maxwell's equations is proposed which realizes considerable memory savings without compromising accuracy and computational speed. The improvement is achieved by expanding the k-space integrals over the unit sphere in spherical harmonics. Since the spherical harmonics expansion(More)
This paper presents a transformation of Maxwell's equations for general nonlinear material operators into a system state equation of an equivalent nonlinear distributed parameter system. The proposed formulation has a fair amount of practical and didactic advantages, with regard to modeling hysteresis and memory effects, understanding causality, control and(More)
—Inverse Synthetic Aperture Radar (ISAR) imaging is one of the most sophisticated methods to obtain information about the scattering or radiation properties of a finite sized object. The idea is to process the scattered or radiated fields coherently over a certain frequency bandwidth and over a certain angular range in order to generate the image. In a(More)
Scattering Center Models (SCMs) are an approach to efficiently characterize electromagnetic scattering of complex shaped objects in terms of a distribution of equivalent sources. SCMs have been widely used in the area of radar target modeling, particularly for object characterization and classification. Recently, the SCM approach has been adapted to model(More)
An iterative technique for the reconstruction of longitudinally inhomogeneous lossy dielectric material loaded in a uniform metallic waveguide is addressed in this paper. The problem is first formulated as an inverse scattering one based on an integral equation in terms of the unknown complex permittivity. By using knowledge of scattering parameters, the(More)
Image formation by inverse synthetic aperture radar (ISAR) methods is one of the most advanced approaches to explore the scattering or radiation properties of a finite sized object. ISAR imaging is based on the coherent processing of radar signals, which are collected for a range of observation angles and for a certain range of frequencies. In a radar(More)