  We study the effects of random positional disorder in the transmission of
waves in a 1D Kronig-Penny model. For weak disorder we derive an analytical
expression for the localization length and relate it to the transmission
coefficient for finite samples. The obtained results describe very well the
experimental frequency dependence of the transmission in a microwave
realization of the model. Our results can be applied both to photonic crystals
and semiconductor super lattices.
