1. Electrical Engineering Department, Federal University of Juiz de Fora, Juiz de Fora, Brazil
2. Electrical Engineering Department, Federal University of Paraná, Curitiba, Brazil
3. Electronics Department, Federal Institute of Education, Science and Technology of the Southeast of Minas Gerais, Campus Juiz de Fora, MG, Brazil
4. Wireless and Optical Dpt. of Peraton Labs, NJ, USA
5. Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, USA