  The modulation with magnetic field of the sheet inductance measured on
proximity effect Josephson-junction arrays (JJAs) is progressively vanishing on
lowering the temperature, leading to a low temperature field-independent
response. This behaviour is consistent with the decrease of the two-dimensional
penetration length below the lattice parameter. Low temperature data are
quantitatively compared with theoretical predictions based on the XY model in
absence of thermal fluctuations. The results show that the description of a JJA
within the XY model is incomplete and the system is put well beyond the weak
screening limit which is usually assumed in order to invoke the well known
frustrated XY model describing classical Josephson-junction arrays.
