Breast tumor detection with TR-DORT based on multilayered Green's function theory

Ultrawideband (UWB) time-reversal techniques are widely used in microwave imaging systems to detect and localize breast tumors. Measuring the scattering electromagnetic fields from a breast phantom can be time-reversed and back-propagated to refocus on a tumor. In this study, a Debye model was applied to the breast phantom. Using the decomposition of the time-reversal operator (TR-DORT), images were obtained in the UWB frequency range of 3.1–10.6 GHz. The conventional TR imaging method employs the free-space Green's function to refocus on the tumor, which degrades refocusing in a lossy and dispersive breast phantom. We propose the use of the cylindrical dyadic Green's function in a three-layer medium for TR imaging. The excitation system consists of a circular array of spiral antennas. The imaging results of the proposed Green's function in TR-DORT were subsequently calculated, indicating successful tumor detection in different application scenarios of the lossy and dispersive breast phantom.