1. a Faculty of Electronics, Telecommunications and Informatics, Department of Microwave and Antenna Engineering, Gdansk University of Technology, 11/12 Gabriela Narutowicza Street, Gdansk 80-233, Poland;, Email: wojmar@eti.pg.gda.pl
2. b Faculty of Electronics, Telecommunications and Informatics, Department of Microwave and Antenna Engineering, Gdansk University of Technology, 11/12 Gabriela Narutowicza Street, Gdansk 80-233, Poland