O.E. Glukhova - Dr.Sc. (Phys.-Math.), Associated Professor, Head of the Department of Radio-Technique and Electrodynamics, Physical Faculty, Saratov State University named after N.G. Chernyshevsky. E-mail: graphene@yandex.ru V.V. Mitrofanov - Post-graduate Student, the Department of Radio-Technique and Electrodynamics, Physical Faculty, Saratov State University named after N.G. Chernyshevsky. E-mail: ip.boyar@gmail.com