1. Universidade Federal de Minas Gerais (UFMG),Graduate Program in Electrical Engineering,Belo Horizonte,MG,Brazil
2. Universidade Federal de Minas Gerais (UFMG),Dep. of Electronics Engineering,Belo Horizonte,MG,Brazil
3. Universidade Federal de São João del-Rei (UFSJ),Dep. of Technology,Ouro Branco,MG,Brazil
4. Instituto Tecnológico de Aeronáutica (ITA),SP,Brazil