1. Department of Electrical and Electronic Engineering, Faculty of Engineering and Technology (FET), University of Buea 1 , P.O. Box 63, Buea, Cameroon
2. Department of Rural Engineering, Faculty of Agronomy and Agricultural Sciences, University of Dschang 2 , P.O. Box 222, Dschang, Cameroon
3. Department of Physics, Alagappa Chettiar Government College of Engineering and Technology 3 , Karaikudi 630003, Tamilnadu, India
4. Department of Physics, Nehru Memorial College (Affiliated to Bharathidasan University, Tiruchirapalli 620024, Tamilnadu, India) 4 , Puthanampatti, Tiruchirapalli 621007, Tamilnadu, India
5. Department of Electrical and Electronic Engineering, College of Technology (COT), University of Buea 5 , P.O. Box 63, Buea, Cameroon
6. South-Polytech (Affiliated to École National Supérieur Polytechnique de Douala, Université de Douala, Douala, Cameroun), Institut Universitaire des Grandes Écoles des Tropiques 6 , P.O. Box 25080, Douala, Cameroun