A.P. Trifonov - Dr. Sc. (Eng.), Honored Scientist of RF, Professor, Head of Department of Radiophysics, Voronezh State University. E-mail: trifonov@phys.vsu.ru E.V. Litvinov - Ph. D. (Phys.-Math.), Assistant, Department of Radiophysics, Voronezh State University. E-mail: elitvinov@list.ru