Embedding approach to modeling electromagnetic fields in a complex two-dimensional environment

An approach is presented to combine the response of a two-dimensionally inhomogeneous dielectric object in a homogeneous environment with that of an empty inhomogeneous environment. This allows an efficient computation of the scattering behavior of the dielectric cylinder with the aid of the CGFFT method and a dedicated extrapolation procedure. Since a circular observation contour is adopted, an angular spectral representation can be employed for the embedding. Implementation details are discussed for the case of a closed 434 MHz microwave scanner, and the accuracy and efficiency of all steps in the numerical procedure are investigated. Guidelines are proposed for choosing computational parameters such as truncation limits and tolerances. We show that the embedding approach does not increase the CPU time with respect to the forward problem solution in a homogeneous environment, if only the fields on the observation contour are computed, and that it leads to a relatively small increase when the fields on the mesh are computed as well

Transient excitation of a layered dielectric medium by a pulsed electric dipole

In this paper, we consider the transient excitation by a pulsed vertical or horizontal dipole of a continuously layered lossy dielectric slab embedded in between two dielectric half-spaces. The focus of the paper is on finding a highly efficient numerical implementation. To this end, we choose all spatial approximations independent of frequency. In the first place, this concerns the inverse spatial Fourier transformation in the Sommerfeld representation of the fields. A suitable quadrature rule is obtained by introducing a normalized wave number, and identifying the result in terms of dual analytic signals. In the second place, this concerns the spectral fields for which a new integral equation is derived with a degenerate kernel. This integral equation is solved by a fully recursive procedure. Representative results are presented and discussed that can be understood from physical intuition

Synthesis technique for imaging small deviations in a known two-dimensional dielectric configuration

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Computing electromagnetic fields in engineering applications: a diakoptic approach

The trends and needs in the development of technologies like antennas and microwave circuits have clearly indicated a constantly increasing level of complexity of these structures, as well as the need of efficient and accurate analysis and synthesis tools. Such tools should provide an efficient yet accurate design approach, avoiding or minimizing the time consuming experimental optimization phase. In this paper, we present an overview of electromagnetic modelling techniques, responding to these trends, developed in the authors' research groups

Optimization approach to reconstructing 2D objects

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Electromagnetic excitation of a thin wire : a traveling-wave approach

An approximate representation for the current along a perfectly conducting straight thin wire is presented. The current is approximated in terms of pulsed waves that travel along the wire with the velocity of the exterior medium. At the ends of the wire, these pulses are partially reflected, with a constant reflection coefficient and delay time. Subsequently, the traveling-wave representation for the current is used to derive an approximate expression for the electric field outside the wire that is caused by this current. For voltage excitation, this expression contains only closed-form contributions. For plane-wave excitation, the expression contains a single integral over the initial pulse that must be computed numerically. Although the expression obtained is essentially a far-field approximation, it turns out to be valid from distances of the order of a single wire length. Results for a representative choice of wire dimensions and pulse lengths are presented and discussed. © 1998 IEEE