1. Department of Electronics Engineering TechnologyCollege of Industrial Technology King Mongkut'sUniversity of Technology North Bangkok1518 Pracharat 1 Road, WongsawangBangsueBangkok10800Thailand
2. RF&Microwave Laboratory Electrical Metrology DepartmentNational Institute of Metrology (Thailand)3/4‐5 Moo 3, Klong 5, Klong LuangPathumthani12120Thailand