Showing papers by "Benjamin Fuchs published in 2018"

Stratified spherical model for microwave imaging of the brain: Analysis and experimental validation of transmitted power

Abstract: This work presents the analysis of power transmission of a radiating field inside the human head for microwave imaging applications. For this purpose, a spherical layered model composed of dispersive biological tissues is investigated in the range of (0.5–4) GHz and is confronted to experimental verification.

A Reconfigurable Chaotic Cavity with Fluorescent Lamps for Microwave Computational Imaging.

Abstract: Several computational imaging systems have recently been proposed at microwave and millimeter-wave frequencies enabling a fast and low cost reconstruction of the scattering strength of a scene. The quality of the reconstructed images is directly linked to the degrees of freedom of the system which are the number of uncorrelated radiated patterns that sequentially sample the scene. Frequency diverse antennas such as leaky chaotic cavities and metamaterial apertures take advantage of the spectral decorrelation of transmitted speckle patterns that stems from the reverberation within a medium. We present a reconfigurable chaotic cavity for which the boundary conditions can be tuned by exciting plasma elements, here commercial fluorescent lamps. The interaction of electromagnetic waves with a cold plasma is strongly modified as it is ionized. Instead of being transparent to incident waves, it behaves theoretically as a metallic material. The independent states of the cavity obtained using a differential approach further enhance the degrees of freedom. This relaxes the need of a cavity with a large bandwidth and/or high quality factor. Experimental results validate the use of fluorescent lamps and its limitations are discussed. Images of various metallic objects are provided to illustrate the potentialities of this promising solution.

Comparison of Regularization Techniques for Microwave Imaging of Brain Stroke

Abstract: This paper studies the performance of three wellknown regularization techniques to solve the inverse problem encountered in differential microwave imaging for brain stroke applications. Reconstructions from a multi-illumination configuration based on measurement and simulation data of a multilayered spherical head phantom with an inserted anomaly are compared.