Space–Frequency Ultrawideband Time-Reversal Imaging

We introduce time-reversal ultrawideband (UWB) imaging functionals based on the simultaneous utilization of spatial and UWB frequency data acquired by limited-aspect antenna arrays. The targets are discrete scatterers embedded in homogeneous or continuous random inhomogeneous media. Singular value decomposition is applied to space-frequency multistatic scattering data matrices indexed by sensor location and frequency data, and the resulting singular values and vectors are employed to construct time-domain excitation signals for UWB imaging of the embedded scatterer(s) via synthetic backpropagation (reverse migration). Spatial information needed for focusing on the embedded scatterer(s) is provided by either the left singular vectors or the eigenvectors of the space-space multistatic data matrices. The resulting UWB imaging functionals can yield statistical stability in random media.