A Reconfigurable Chaotic Cavity with Fluorescent Lamps for Microwave Computational Imaging

TL;DR

This paper introduces a reconfigurable microwave cavity using fluorescent lamps as plasma elements to enhance imaging capabilities by increasing system degrees of freedom, enabling faster and lower-cost scene reconstruction.

Contribution

It presents a novel reconfigurable chaotic cavity with plasma-tuned boundary conditions, improving degrees of freedom without requiring large bandwidth or high quality factor.

Findings

Experimental validation of fluorescent lamps as plasma elements

Enhanced imaging of metallic objects demonstrated

Discussion of limitations and potential improvements

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.