  Leonhardt demonstrated (2009) that the 2D Maxwell Fish Eye lens (MFE) can
perfectly focus 2D Helmholtz waves of arbitrary frequency, i.e., it can
perfectly transport an outward (monopole) 2D Helmholtz wave field, generated by
a point source, towards a "perfect point drain" located at the corresponding
image point. Moreover, a prototype with \lambda/5 super-resolution property for
one microwave frequency has been manufactured and tested (Ma et al, 2010).
However, software simulations or experimental measurements for a broad band of
frequencies have not been reported. Here we present simulations with a
non-perfect drain for a device equivalent to the MFE, called the Spherical
Geodesic Waveguide (SGW), that predict up to \lambda/500 super-resolution close
to discrete frequencies. These frequencies are directly connected with the
well-known Schumann resonance frequencies of spherical symmetric systems. Out
of these frequencies, the SGW does not show super-resolution in the analysis
performed.
