Microwave Imaging Using a Disordered Cavity with a Dynamically Tunable Impedance Surface

Timothy Sleasman, Mohammadreza F. Imani, Jonah N. Gollub, David R. Smith

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

We perform microwave imaging using a dynamically reconfigurable aperture based on a tunable disordered cavity. The electrically large cavity is cubic with a spherical deformation and supports a multitude of distinct electromagnetic modes that vary as a function of excitation frequency. With a set of irises introduced into one wall of the cavity, the cavity modes couple to spatially distinct radiative modes that vary as a function of the driving frequency. To increase the diversity of the radiated fields, we replace one of the cavity walls with a variable impedance surface consisting of a set of varactor-populated mushroom structures grouped into pixels. The reflection phase of each pixel is independently changed with application of a voltage bias, effectively altering the surface impedance. We demonstrate high-fidelity imaging and examine the role of the impedance-tunable boundary condition, revealing superior performance in comparison with just frequency-diverse measurements. We also demonstrate single-frequency imaging, which can significantly reduce the demands on the required microwave source. The dynamic cavity imager may find relevance in security screening, through-wall imaging, biomedical diagnostics, and radar applications.

Original languageEnglish (US)
Article number054019
JournalPhysical Review Applied
Volume6
Issue number5
DOIs
StatePublished - Nov 29 2016
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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