D.D. Kulminskiy - Junior Research Scientist, Saratov branch of Kotelnikov IRE RAS. E-mail: kulminskydd@gmail.com A.S. Karavaev - Ph.D. (Phys.-Math.), Associate Professor, Saratov National Research State University named N.G. Chernyshevsky V.I. Ponomarenko - Dr.Sc. (Phys. Math.), Leading Research Scientist, Saratov branch of Kotelnikov IRE RAS M.D. Prokhorov - Dr.Sc. (Phys. Math.), Head of Laboratory, Saratov branch of Kotelnikov IRE RAS