Modern radio physics has in recent years been characterized by rapid development of theory and engineering practice in the millimeter and submillimeter wave ranges. The dimensions of the systems, which are usually quite arbitrary in shape, are commensurate with or substantially in excess of the wavelength. This necessitates determination of the eigenvalues and eigenfunctions of regions with boundaries of complex form (waveguides, microstrip structures, resonators, etc.). One important problem is to lay the electrodynamic foundation for computer-aided design of microwave devices over a broad wavelength range [i]. A procedure for analytic description of the complex geometric shapes of real objects is especially important for development of the appropriate algorithm and their numerical implementation in computers. The theory of R functions, which is utilized in solving interior and exterior electrodynamic boundary value problems [2-11], is promising for this purpose.