The possibility to generate short spin waves (SWs) is of great interest in the field of magnonics nowadays.Wepresent an effective and technically affordable way of conversion of long SWs, which may be generated by conventional microwave antenna, to the short, sub-micrometer waves. It is achieved by grating-assisted resonant dynamic dipolar interaction between two ferromagnetic layers separated by some distance.Weanalyze criteria for the optimal conversion giving a semi-analytical approach for the coupling coefficient.Weshow by the numerical calculations the efficient energy transfer between layers which may be either of co-directional or contra-directional type. Such a system may operate either as a short spin wave generator or a frequency filter, moving forward possible application of magnonics.