Аннотация:When a supernova remnant expands, hot gas that is swept up will compress density fluctuations in the interstellar medium, and shock waves will be generated in them. The resulting compression of the magnetic field and relativistic particles in the fluctuations can cause the fluctuations to produce nonthermal radio emission whose combined power is comparable to that observed in supernova remnants. The fluctuations will be strongly compressed in a thin layer behind the shock front, accompanied by radiative cooling. Cooling of the fluctuations because of their high gas density may also occur during the adiabatic expansion phase of the remnant. In the model of compressed fluctuations the relation between the surface brightness of the nonthermal radio emission and the radius of the remnant is a power law with an exponent of -17/4, which is similar to that inferred from the statistics of well-observed remnants. The thickness of the radio envelope of supernova remnants and their polarization are discussed.