84 research outputs found
A Robust Approach for the Derivation of Closed-form Green's Functions
Cataloged from PDF version of article.Spatial-domain Green’s functions for multilayer,
planar geometries are cast into closed forms with two-level approximation
of the spectral-domain representation of the Green’s
functions. This approach is very robust and much faster compared
to the original one-level approximation. Moreover, il does
not require the investigation of the spectral-domain behavior of
the Green’s functions in advance to decide on the parameters
of the approximation technique, and it can be applied to any
component of the dyadic Green’s function with the same ease
Closed form Greens functions for general sources and stratified media
Cataloged from PDF version of article.The closed-form Green's functions of the vector and scalar potentials in the spatial domain are presented for the sources of horizontal electric, magnetic, and vertical electric, magnetic dipoles embedded in general, multilayer, planar media. First, the spectral domain Green's functions in an arbitrary layer are derived analytically from the Green's functions in the source layer by using a recursive algorithm. Then, the spatial domain Green's functions are obtained by adding the contributions of the direct terms, surface waves, and complex images approximated by the Generalized Pencil of Functions Method (GPOF). In the derivations, the main emphasis is to put these closed-form representations in a suitable form for the solution of the mixed potential integral equation (MPIE) by the method of moments in a general three-dimensional geometry. The contributions of this paper are: 1) providing the complete set of closed-form Green's functions in spectral and spatial domains for general stratified media; 2) using the GPOF method, which is more robust and less noise sensitive, in the derivation of the closed-form spatial domain Green's functions; and 3) casting the closed-form Green's functions in a form to provide efficient applications of the method of moments. © 1995 IEE
Spurious radiation from microstrip interconnects
Cataloged from PDF version of article.The level of spurious radiation from microstrip
interconnects, which are modeled here as either single or asymmetric
parallel microstrip lines terminated by arbitrary complex
load impedances, is investigated in this paper. The calculation
of the spurious radiation requires a knowledge of the current
distributions on the microstrip lines, and the first step is to
compute these distributions efficiently. This is carried out here
by using the method of moments in conjunction with closedform
spatial domain Green’s functions that circumvent the need
for time-consuming evaluation of Sommerfeld integrals. Once
the current distributions on the etches have been obtained, the
level of spurious radiation, which is defined as the radiated
power crossing the plane parallel to the plane of interconnects,
is calculated. The dependence of the spurious radiation on the
lengths of the lines and on the termination impedances of the
etches is also studie
Electromagnetic scattering solution of conducting strips in layered media using the fast multipole method
Cataloged from PDF version of article.The fast multipole method (FMM) is applied to the
solution of the electromagnetic scattering problems in layered
media for the first time. This is achieved by using closedform
expressions for the spatial-domain Green’s functions for
layered media. Until now, the FMM has been limited to the
homogeneous-medium problems. An integral equation based on
the two-dimensional scalar Helmholtz equation is solved to compute
the electromagnetic scattering from sample geometries of
conducting strips in layered media in order to demonstrate the
accuracy and the efficiency of the new method
An efficient method for electromagnetic characterization of 2-D geometries in stratified media
Cataloged from PDF version of article.A numerically efficient technique, based on the spectral-domain
method of moments (MoM) in conjunction with the
generalized pencil-of-functions (GPOF) method, is developed for
the characterization of two-dimensional geometries in multilayer
planar media. This approach provides an analytic expression for all
the entries of the MoM matrix, explicitly including the indexes of
the basis and testing functions provided that the Galerkin’s MoM
is employed. This feature facilitates an efficient modification of the
geometry without the necessity of recalculating the additional elements
in the MoM matrix. To assess the efficiency of the approach,
the results and the matrix fill times are compared to those obtained
with two other efficient methods, namely, the spatial-domain MoM
in conjunction with the closed-form Green’s functions, and a fast
Fourier transform algorithm to evaluate the MoM matrix entries.
Among these, the spectral-domain MoM using the GPOF algorithm
is the most efficient approach for printed multilayer geometries
A numerically efficient technique for the analysis of slots in multilayer media
Cataloged from PDF version of article.A numerically efficient technique for the analysis of slot geometries in multilayer media is presented using closed-form Green's functions in spatial domain in conjunction with the method of moments (MoM). The slot is represented by an equivalent magnetic-current distribution, which is then used to determine the total power crossing through the slot and the input impedance. In order to calculate power and current distribution, spatial domain closed form Green's functions are expanded as power series of the radial distance rho, which makes the analytical evaluation of the spatial domain integrals possible, saving a considerable amount of computation time
Numerically Efficient Analysis of Planar Microstrip Configurations Using Closed-Form Green's Functions
Cataloged from PDF version of article.An efficient technique for the analysis of a general class of microstrip structures with a substrate and a superstrate is investigated in this paper using newly-derived closed-form spatial domain Green's functions employed in conjunction with the Method of Moments (MoM). The computed current distributions on the microstrip structure are used to determine the scattering parameters of microstrip discontinuities and the input impedances of microstrip patch antennas. It is shown that the use of the closed-form Green's functions in the context of the MoM provides II computational advantage in terms of the CPU time by almost two orders of magnitude over the conventional spectral domain approach employing the transformed version of the Green's functions
Use of discontinuous expansion and testing functions in the method of moments for electromagnetic problems
The purpose of this paper is to show that there is an additional constraint to be satisfied by the current density when discontinuous expansion functions are used, and the discontinuous expansion and testing functions together can be employed in the application of the MoM in the spatial and spectral domain with the use of this additional constraint
Use of computationally efficient method of moments in the optimization of printed antennas
Cataloged from PDF version of article.Derivation of the closed-form Green’s functions
and analytical evaluation of the method of moments (MOM)
matrix entries have improved the computational efficiency of
the significantly in the analysis of printed geometries. With this
background in mind, an extension of this efficient numerical technique
is to incorporate an optimization algorithm and to assess its
potential as a computer-aided design (CAD) tool. Therefore, we
have employed the Gradient search and Genetic algorithms, in
conjunction with the electromagnetic (EM) simulation technique,
to a number of representative examples of interest
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