The inverse source problem of electromagnetics: linear operator formalism and minimum energy solution

We address an inverse source problem consisting of finding the time-harmonic current distribution (source) with minimum L/sup 2/ norm (minimum energy) that generates a prescribed electromagnetic field provided outside the source's support. Using the well-known multipole expansion of the electromagnetic field we compute, via a linear operator formalism, the sought-after minimum L/sup 2/ norm current distribution consistent with the data.