  The main purpose of this study is to review the Schenberg resonant antenna
transfer function and to recalculate the antenna design strain sensitivity for
gravitational waves. We consider the spherical antenna with six transducers in
the semi dodecahedral configuration. When coupled to the antenna, the
transducer-sphere system will work as a mass-spring system with three masses.
The first one is the antenna effective mass for each quadrupole mode, the
second one is the mass of the mechanical structure of the transducer first
mechanical mode and the third one is the effective mass of the transducer
membrane that makes one of the transducer microwave cavity walls. All the
calculations are done for the degenerate (all the sphere quadrupole mode
frequencies equal) and non-degenerate sphere cases. We have come to the
conclusion that the 'ultimate' sensitivity of an advanced version of Schenberg
antenna (aSchenberg) is around the standard quantum limit (although the
parametric transducers used could, in principle, surpass this limit). However,
this sensitivity, in the frequency range where Schenberg operates, has already
been achieved by the two aLIGOs in the O3 run, therefore, the only reasonable
justification for remounting the Schenberg antenna and trying to place it in
the sensitivity of the standard quantum limit would be to detect gravitational
waves with another physical principle, different from the one used by laser
interferometers. This other physical principle would be the absorption of the
gravitational wave energy by a resonant mass like Schenberg.
