  The basic theory underlying the realization of simple multiple-band
non-homogeneous dielectric resonators, whose spectral response is the overlap
of single-resonator frequency bands, is developed exploiting a general approach
discussed in the previous companion paper. The limit frequencies of the
proposed devices, given only by the dielectric properties of the involved
materials, can differ in principle by several decades. Experimental
confirmations have been obtained on a composite structure built up with teflon
and polyethylene; as predicted by the theory, the overall band includes
frequencies which range about from 20 GHz to more than 400 GHz, when high
frequency resonances are selectively excited. The localization of the higher
frequency radiation between the positive steps of the dielectric constant,
which is the basic properties of these non-homogeneous resonators, has been
experimentally verified by mapping the electromagnetic field intensity.
Possible applications of multiple-band Whispering Gallery dielectric resonators
are finally outlined.
