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Planar and Cylindrical Active Microwave Temperature Imaging: Numerical Simulations

Abstract:

Active microwave imaging systems for biomedical appli cations have been gaining attention in recent years. The need for internal structure information imposes the use of diffraction tomography approaches. Two different geometries, planar and cylindrical, have been used for this purpose. In this paper we present a comparative study at 2.45 GHz concerning both measurement and reconstruction parameters for the two configuration s. For the sake of comparison, a numerical model consisting of two nonconcentric cylinders is considered and reconstructed using both geometries from simulated experimental data. The scattered fields and reconstructed images allow to extract very useful information about dynamic range, sensitivity, resolution and quantitative image accuracy for the choice of the configuration in a particular application. The geometries chosen are planar and cylindrical array configurations. Both geometries can measure forward and backward scattered fields. The backscattering measurement improves the image resolution and reconstruction in lossy mediums, but, on the other hand, has several dynamic range difficulties. This tradeoff between only forward and forward-backward field measurement is analyzed using a planar array for forward scattering and a cylindrical one for forward-backward. As differential temperature imaging is a weakly scattering problem, Born approximation algorithms can be used. The simplicity of Born reconstruction algorithms and the use of FFT make them very attractive for real-time biomedical imaging systems [19]. © 1992 IEEE