Wide-Angle Radiation Due to Rough Phase Fronts

Nonuniformities in the phase fronts of electromagnetic and acoustical waves give rise to radiation in directions other than that desired. The magnitude of this effect is discussed here with special reference to quasi-random roughness. It is found that the level of wide-angle radiation is a strong function of the phase deviations and that reflecting surfaces, for example, should be held to tolerances of about ±0.01λ to prevent the level of the wide-angle radiation from exceeding twice that due to a perfectly smooth reflector