1. Applied Electromagnetics and Telecommunication Research Group, Affiliated to the George Green Institute for Electromagnetics Research , University of Nottingham (UNMC) , Nottingham , UK
2. Faculty of Electrical Engineering , Czech Technical University in Prague , Technicka 2, 166 27 Prague , Czech Republic
3. Department of Electrical Engineering , California Polytechnic State University , San Luis Obispo , CA , USA