V.V. Shunaev – Ph.D.(Phys.-Math.), Senior Lecturer, 

Department of Radiotechnique and Electrodynamics, Saratov State University named after N.G. Chernyshevsky E-mail: vshunaev@list.ru

O.E. Glukhova – Dr.Sc.(Phys.-Math.), Professor, Head of the Department of Radiotechnique and Electrodynamics,  Saratov State University named after N.G. Chernyshevsky E-mail: GlukhovaOE@info.sgu.ru