Interaction of high-power microwave beams with metal-dielectric media

Results of experimental investigation of powerful microwave beams action on the metal-dielectric compositions are presented. Dielectric surfaces with introduced metallic grains as well as dielectric powder containing small admixtures of a metallic one have been explored as an objects of irradiation. At a relatively small microwave power ( mW) all investigated targets were practically completely transparent for incident electromagnetic wave. At a relatively high power (microwave generators based on the gyratrons and powerful magnetrons) the irreversible changes in the electric and radiophysical properties of metal-dielectric composites exposed to microwave radiation whose intensity is below the threshold intensity for plasma production have been observed (sharp increase of conductivity and microwave absorption coefficient).