The problem of calculation of fields with fine well-conductive screens has many important ways of application and has been methodically developed during two centuries. It gave birth to new mathematical approaches to solution of the field theory problems including methods based on factorization of analytical functions [1-3]; and also to the idea of iterative interreflections of waves emerging on the edge of the screens (beginning with Swarzschild's work).

The results of the solution of a new problem with the Hskind-Vainstein method, that is, passage of E-waves through thr transversal slot in the wall of the plane waveguide are represented in the report.