Browsing by Author "Chew, W. C."
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Item Open Access Fast algorithm for scattering from planar arrays of conducting patches(Institute of Electrical and Electronics Engineers, 1998-04) Gürel, Levent; Chew, W. C.A direct (noniterative) algorithm for the solution of the electromagnetic scattering from three-dimensional planar arrays of conducting patches is developed. For an N-unknown problem, the computational complexity of this new solution technique is shown to be O(N2 log2N), which is considerably lower than the O(N3) computational complexity of the conventional direct solution techniques. The advantages of the reduction in the computational complexity is pronounced in the solution of large electromagnetics problems, such as scattering from large and finite arrays of patches, synthesis and analysis of finite-sized frequency selective surfaces (FSS's), and radiation and scattering from large phased-array antennas, to name a few.Item Open Access Fast direct (noniterative) solvers for integral-equation formulations of scattering problems(IEEE, 1998) Gürel, Levent; Chew, W. C.A family of direct (noniterative) solvers with reduced computational complexity is proposed for solving problems involving resonant or near-resonant structures. Based on the recursive interaction matrix algorithm, the solvers exploit the aggregation concept of the recursive aggregate T-matrix algorithm to accelerate the solution. Direct algorithms are developed to compute the scattered field and the current coefficient, and invert the impedance matrix. Computational complexities of these algorithms are expressed in terms of the number of harmonics P required to express the scattered field of a larger scatterer made up of N scatterers. The exact P-N relation is determined by the geometry.Item Open Access Fast direct solution algorithm for electromagnetic scattering from 3D planar and quasi-planar geometries(IEEE, 1997) Gürel, Levent; Chew, W. C.A non-iterative method and its application to planar geometries in homogeneous media is presented. The method is extendable to the cases of quasi-planar structures and/or layered-media problems. The fast direct algorithm (FDA)/steepest descent path (SDP) takes advantage of the fact that the induced currents on planar and quasi-planar geometries interact with each other within a very limited solid angle. Thus, all the degrees of freedom required to solve a `truly 3D' geometry are not required for a planar or quasi-planar geometry, and this situation can be exploited to develop efficient solution algorithms.Item Open Access Fast noniterative steepest descent path algorithm for planar and quasi-planar patch geometries(IEEE, 1998) Gürel, Levent; Chew, W. C.The fast noniterative steepest descent path (SDP) algorithm for planar and quasi-planar patch geometries are discussed. The comparison of scattered fields as computed by the method of moments (MOM) and fast direct algorithm (FDA)/SDP are described. The solution times of FDA/SDP, MOM, and recursive aggregate-T-matrix algorithm (RATMA) are obtained by solving the scattering problems of increasingly larger planar arrays of patches without taking advantage of the periodicities and the symmetries of these arrays.