1. Kotel’nikov Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, Vvedensky Square 1, Fryazino, Moscow Region 141190, Russia
2. Department of Electronic and Electrical Engineering, Trinity College Dublin, Dublin, Ireland
3. Electricity Supply Board, Engineering and Major Projects, Dublin 3, Ireland
4. Laboratoire de Mathématiques et Physique (EA 4217), Université de Perpignan Via Domitia, F-66860 Perpignan, France