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3D scattering by large inhomogeneous 2D objects: Validation of a full-wave 2.5D VIE Solver with mm-wave Gaussian beam and microwave experiments Host Publication: Finds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet Authors: S. Van Den Bulcke, A. Franchois, J. Geffrin, L. Zhang and J. Stiens Publication Date: Jul. 2008 Number of Pages: 2
Abstract: For the development of active millimeter wave imaging systems, e.g. to detect concealed ob-
jects on the human body, it is important to be able to simulate some representative scattering
con¯gurations. Typically, Gaussian beams are used in active imaging systems. Since these beams
only illuminate a spatially limited region, the human body and various objects can be treated as
two-dimensional (2D) (in)homogenous cylinders. However, the incident Gaussian beam has a 3D
character. Therefore, a 2.5D full-wave Volume Integral Equation (VIE) forward solver is developed:
only the cylinder's cross-section is discretized, reducing the number of unknowns strongly, while the
incident ¯elds (e.g. oblique plane waves and 3D Gaussian beams) maintain their full 3D character.
In this paper, a vectorial Gaussian beam is constructed by using a dipole source in a complex point.
This elegant implementation is valid in the near and far ¯eld of the beam. Furthermore, simulation
results are compared to measurements to validate the 2.5D numerical scheme. In a ¯rst measure-
ment set-up, the scatterer is a long inhomogeneous dielectric cylinder, illuminated by plane waves
under di®erent elevation angles at microwave frequencies in the range 1 - 18 GHz. Simulations
agree well with the experimental results for normally incident plane waves and plane waves with
a small elevation angle, for all measured frequencies. For larger elevation angles, the ¯niteness of
the cylinder in°uences the results and decreases the agreement. The second measurement set-up
consists of a long te°on cylinder, illuminated by a normally incident Gaussian beam at 94 GHz.
The measured incident and total ¯eld amplitudes correspond well to the simulated ones. Hence, the
2.5D algorithm is proven to be a valuable simulation tool to study scattering of long inhomogeneous
dielectric objects, illuminated by 3D plane waves or 3D Gaussian beams under di®erent elevation
angles.
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