[en] Questions of wave propagation and investigations of superthermal particles in a plasma with strong small-scale irregularities have recently acquired urgency in connection with experiments on the interaction of high-power radio signals with the ionospheric plasma. In these experiments strong density variations which are small in scale compared with the wavelength of the incident electromagnetic wave are observed, resulting from the excitation of thermal and ponderomotive parametric instabilities close to the pump wave reflection point. The theoretical study of the problem of electromagnetic wave propagation in such a medium encounters a number of fundamental difficulties. These are related to finding the effective field under resonant conditions in a complex medium such as a plasma with small-scale irregularities imbedded in it. An important advance was made where renormalization of the field was used to approach the plasma resonance quite closely. However, the iteration technique used to find the effective dielectric function is inapplicable in the immediate vicinity of the resonance. On the other hand, experimental and theoretical studies reveal that when the pump wave power is high enough the irregularities acquire the form of cavitons: localized structures separated fairly far from one another. The Born approximation is no longer suitable for describing such a medium; but on the other hand for analytical calculations one can use the small parameter n that characterizes the packing density of these irregularities in space. In the present work the authors study the resonant properties of such a medium in the approximation n much-lt 1. In particular, they find the effective dielectric function var-epsilon ^eff by taking into account the geometrical resonances of the individual irregularities. 3 refs