  In this contribution we analyze the spectral properties of some commonly used
boundary integral operators in computational electromagnetics and of their
discrete counterparts, highlighting peculiar features of their spectra. In
particular, a comparison with the eigenvalues of the continuous operators will
be presented that highlights deviations in the high frequency regime and
impacts, in a peculiar way, the accuracy of the numerical solutions of each
formulation. A study and a proactive analysis of numerical results from
standard boundary element solvers and the predictions from the theoretical
analysis will corroborate the analytical framework employed and the validity of
our observations.
