V.V. Zajtsev - Ph. D. (Phys.-Math.), Professor, Department of Radiophysics, Samara State University. E-mail: zaitsev@ssu.samara.ru Ar.V. Karlov - Post-graduate Student, Department of Radiophysics, Samara State University. E-mail: ar.karlov@gmail.com I.V. Stulov - Post-graduate Student, Department of Radiophysics, Samara State University. E-mail: stulov.i.v@mail.ru