Equivalent circuit model of the TEM cell electric and magnetic field coupling to microstrip lines

Electromagnetic compatibility (EMC) analysis of high-speed circuits is becoming mandatory due to the rapid increase in operating frequencies, RF interference and layout densities. Radiated susceptibility tests are important part of overall EMC analysis. In this paper the focus of investigation is on models of the coupling between a transverse electromagnetic (TEM) field generated by the TEM cell and the microstrip lines. In order to accurately model the coupling the models for microstrip lines, SMA connectors and TEM cell are developed. The coupling models are provided for transversal and longitudinal microstrip lines. The results for coupling capacitances are compared against results obtained by Method of Lines (MoL). The presented models are very accurate and include only passive elements, and therefore can be used for efficient coupling modelling between microstrip lines and the TEM cell septum.