A. P. Trifonov - Dr. Sc. (Eng.), Professor, Honoured Scientist of the Russian Federation, Head of Department of Radiophysics of Voronezh State University. E-mail: trifonov@phys.vsu.ru, trirad@mail.ru
A. V. Kharin - Post-graduate Student of Department of Radiophysics of Voronezh State University. E-mail: phys.vsu@gmail.com