A.P. Trifonov - Honored Scientist of RF, Dr. Sc. (Eng.), Professor, Head of Department of Radiophysics, Voronezh State University E-mail: trifonov@phys.vsu.ru Yu.E. Korchagin - Dr. Sc. (Phys.-Math.), Associate Professor, Department of Radiophysics, Voronezh State University E-mail: korchagin@phys.vsu.ru S.V. Korolkov - Post-graduate Student, Department of Radiophysics, Voronezh State University E-mail: sergeik1991@rambler.ru