  We study composite D-wave superconductors consisting of randomly oriented and
randomly distributed superconducting droplets embedded into a matrix. In a
certain range of parameters the application of a small magnetic field enhances
the superconductivity in these materials while larger fields suppress
superconductivity as usual in conventional superconductors. We investigate the
magnetic field dependence of the superfluid density and the critical
temperature of such superconductors.
