  With analytical (generalized Mie scattering) and numerical
(integral-equation-based) considerations we show the existence of strong
resonances in the scattering response of small spheres with lossless impedance
boundary. With increasing size, these multipolar resonances are damped and
shifted with respect to the magnitude of the surface impedance. The
electric-type resonances are inductive and magnetic ones capacitive.
Interestingly, these subwavelength resonances resemble plasmonic resonances in
small negative-permittivity scatterers and dielectric resonances in small
high-permittivity scatterers. The fundamental dipolar mode is also analyzed
from the point of view of surface currents and the effect of the change of the
shape into a non-spherical geometry.
