Design and calibration of a TEM stripline for electromagnetic compatibility testing

Abstract

Electrical products are used in every aspect of our lives. Every electrically device has the potential of causing unintentional interference to other electrical devices. All unwanted currents or voltages that may arise in a system generate electrical noise. All kinds of unexpected radio-frequency (RF) energy produce this kind of noise. The term Electromagnetic Interference --EMI -- describes the situation that electrical noise destroys the functionality of systems. Therefore, emissions and immunity tests have to be performed according to the harmonized European norms like EN55020 standard. In this thesis, immunity to radiated fields testing will introduce and the basic requirements of the suggested test site which is a TEM stripline will also be mentioned. Stripline is a transmission line construction which provides a uniform electromagnetic field between its parallel plates. Radiated immunity can be defined as the product's ability to withstand EM energy that arrives via free-space propagation for its functionality. Design of a new TEM stripline for EMC testing is given in order to construct an alternative test site, a new stripline bigger than the one given by the standard was built. Main attention has been focused on the design parameters (characteristic impedance, field uniformity etc.) and calibration of the designed stripline. Defined stripline in the standard has 80 cm height but it is not sufficient for big equipments under test (EUTs). Then an alternative stripline can be used if it fulfills the specifications required by the standard.