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A 2.5D BiCGS-FFT Forward Solver to Model Scattering in a mm-Wave Imaging System Host Publication: Finds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet Authors: S. Van Den Bulcke, A. Franchois, L. Zhang and J. Stiens Publication Date: Sep. 2006 Number of Pages: 4
Abstract: A free-space active mm-wave imaging system is being developed at the VUB, in order to study the performance of various imaging modes for applications in indoor security and non-destructive testing. The system presently consists of a mm-wave vector network analyzer operating in the 75 to 300 GHz range, which measures the S-parameters in amplitude and phase with a dynamic range of more than 80 dB. At the transmitting side a horn antenna emits an incident Gaussian beam, which is focused by a lens at the object location. At the receiving side the scattered field is focused by a lens for image formation at a receiving horn antenna. The total distance between transmitting and receiving sides typically is 75 cm. Two imaging modes will be investigated in our future work: a qualitative and a quantitative technique. The qualitative technique is based on an optical approach and will use a non-coherent illumination in order to reduce the effects of speckle and glint on the image formation. The quantitative technique is derived from microwave imaging principles and is largely based on the exact solution of Maxwells equations. In both cases, an exact model of the wave-field propagation and scattering is indispensable to carefully study system performance and imaging capabilities as a function of design parameters. In this contribution we present an exact forward solver for a two-dimensional (2D) inhomogeneous dielectric object embedded in a homogeneous background medium. The object is illuminated with a given three-dimensional (3D) time-harmonic incident field and the 3D scattered field is computed. This 2.5D configuration is adopted, since it reduces the computational burden while maintaining the capability of accurately studying the system performance. A volume integral equation approach is used, whereby a contrast source integral equation is discretized with the Method of Moments and solved iteratively with a stabilized biconjugate gradient Fast Fourier Transform (BiCGS-FFT) method. We will show simulation and validation results for a number of test objects.
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