1. Department of Physics, National and Kapodistrian University of Athens, Zografou University Campus, Athens, Greece
2. Department of Aerospace Science and Technology, National and Kapodistrian University of Athens, Euripus Campus, Psachna, Evoia, Greece
3. Karlsruhe Institute of Technology, Institut für Hochleistungsimpuls -und Mikrowellentechnik (IHM), Eggenstein-Leopoldshafen, Germany