Novel approach to wideband Jacobian computation for microwave imaging

We proposed a new spectral approach to the self-adjoint computation of the response Jacobian. It is designed to work with time-domain EM simulators thereby producing the Jacobian in a very wide frequency band. The new sensitivity formula operates on the spectral components of the E-field rather than on its time waveforms. The memory requirement is reduced by two to three orders of magnitude in comparison with our original approach. The proposed approach is well suited for wideband Jacobian computation in microwave tomography. It makes the electromagnetics-based optimization feasible. We also demonstrate the ability of wideband Jacobian distribution maps in a 3-D breast model to predict accurately the location of a scatterer in a known background medium.