Radiation of the short waves by pair of plates backed by semiinfinite set of the ribbed stiffeners

Some acoustic diffraction problem is considered. The acoustic medium fills an upper semispace. Two semiinfinite thin plates are disposed on the boundary of the upper semispace. One of the plates is backed by the semiinfinite periodical set of the ribbed stiffeners. A source of the acoustic field is placed on the other plate. The problem is reduced to the infinite system of the linear algebraic equations. Such systems may be solved in the short waves limit. The expression for the field at the large distance of the junct of the plates is obtained. Bibliography: 4 titles.