Inverse source in the near field: the case of a strip current

In this paper, we consider an inverse source problem in the near zone for a prototype configuration where the field radiated by a bounded strip magnetic current is observed over a rectilinear and parallel (to the source) observation domain. The study focuses on how the achievable performance depends on the configuration’s geometric parameters and the noise. In particular, we succeed in working out an approximation for the singular spectrum of the pertinent radiation operator that allows us to obtain analytical estimations for the resolution, the number of degrees of freedom, and the information content. Remarkably, the role of evanescent waves, which become relevant in the very near zone, is highlighted in connection to the available signal-to-noise ratio.