There are many reasons, other than that of excluding local disturbance
s, for using more gravitational antennas at the same time. In fact a n
etwork of resonant antennas allows the detection of radiation coming f
rom any direction and in any polarization state (sky coverage problem)
. the estimate of some parameters of the source (information gain). th
e verification of the predictions of general relativity regarding the
features of gravitational waves (e.g. their propagation velocity, thei
r quadrupole nature etc.) and the existence of celestial objects which
cannot be observed other than through the gravitational effects they
produce (e.g. black holes). the enhancement of the noise rejection cap
ability of the instrument thus enhancing its sensitivity (network filt
ering). Regarding this feature, some very interesting characteristics
are exhibited by local networks of equal antennas (gravitational array
s). In this paper the major issues related to these problems will be p
resented and discussed and the experimental and theoretical results wi
ll briefly be reviewed. Some new ideas will also be introduced.