Computational aspects of a spatial-spectral domain integral equation for scattering by objects of large longitudinal extent

With a 3D spatial spectral integral-equation method for EM scattering from finite objects, a significant part of the computation time is spent on a middle region around the origin of the spectral domain. Especially when the scatterer extends to more than a wavelength in the stratification direction, a fine discretization on this region is required, consuming much computation time in the transformation to the spatial domain. Numerical evidence is shown that the information in the middle region of the spectral domain is largely linearly dependent. Therefore, a truncated singular-value decomposition is proposed to make the computation time largely independent of the discretization on this middle region. For a practical example the increased computational efficiency and the approximation error of the singular-value decomposition are shown

A spectral volume integral method using geometrically conforming normal-vector fields

Scattering characteristics of periodic dielectric gratings can be accurately and efficiently computed via a spectral volume integral equation combined with normal-vector fields defined on the grating geometry. We study the impact of the geometrical discretization on the convergence rate of the scattering characteristics for two-dimensional gratings in both TE and TM polarization and compare these with an independent semi-analytical reference for circular cylinders. We demonstrate that geometrically conforming normal vector fields lead to substantially faster convergence and shorter computation times, as opposed to the commonly applied staircasing or slicing

Accurate full-wave analysis of micromachined coplanar waveguides

We propose a full-wave mode-analysis method suited for micromachined coplanar waveguides (MCPWs). This method is based on the mixed-potential integral equation, in combination with a zero-search algorithm. Results are presented for a semicircular step-index fibre as well as for a MCPW

Numerical kernel construction for bodies of revolution with high-order Fourier modes

Boundary integral equations for bodies of revolution have a Green’s function kernel that can be written as the azimuthal integral over the free-space Green’s function. We show that existing approximation methods for computing this integral suffer from efficiency or stability problems. Improvement of one of these methods leads to controllable accuracy while retaining efficiency

Iterative solution of field problems with a varying physical parameter

In this paper, linear field problems with a varying physical parameter are solved with the conjugate gradient method and a dedicated extrapolation procedure for generating the initial estimate. The scheme is formulated in detail, and its application to three-dimensional scattering problems for a rectangular conducting plate and an inhomogeneous, dispersive dielectric body are discussed

Analysis of stochastic resonances in electromagnetic couplings to transmission lines

Resonances present in coupling phenomena between a randomly varying thin-wire transmission-line, and an electro-magnetic field are stochastically characterized. This is achieved by using the first 4 statistical moments in order to appreciate the intensity of the resonance phenomena. The stochastic method proposed is applied to a thin-wire transmission line connected to a variable impedance, and, undergoing random geometrically localized perturbations

Enhancing the computational speed of the modal Green function for the electric-field integral equation for a body of revolution

We propose an interpolation technique to reduce the computation time of the integrals involved in the electric field integral equation modal Green function for a perfectly conducting body of revolution in free space. The proposed technique is based on applying an appropriate interpolation to the singular part of the modal Green function, which is computationally expensive. By analyzing the electromagnetic scattering of various objects, it is shown that the proposed interpolation scheme can reduce the corresponding computational time by more than a factor of 100