  The inverse source problem in electromagnetics has proved quite relevant for
a large class of applications. In antenna diagnostics in particular, Love
solutions are often sought at the cost of an increase of the dimension of the
linear system to be solved. In this work, instead, we present a reduced-in-size
single current formulation of the inverse source problem that obtains one of
the Love currents via a stable discretization of the Steklov-Poincar\'e
boundary operator leveraging dual functions. The new approach is enriched by
theoretical treatments and by a further low-frequency stabilization of the
Steklov-Poincar\'e operator based on the quasi-Helmholtz projectors that is the
first of its kind in this field. The effectiveness and practical relevance of
the new schemes are demonstrated via both theoretical and numerical results.
