Two-dimensional square arrays of short Josephson junctions are investi
gated using a model which includes both the lumped Josephson circuit e
lements and an equivalent inductance for the superconducting loops. We
have supposed that all junction parameters and the inductances are id
entical. The analysis of the Gibbs thermodynamic potential shows the e
xistence of energy barriers for a basic process for the diamagnetic be
havior of the array: The motion of a flux quantum in the interior of t
he array. These barriers have been numerically evaluated as a function
of the array parameters. The effect of the bias current is discussed
and the critical current of the array has been estimated.