Orientation Effect of the Electromagnetic Field Coupling for Device in a TEM Cell

In this article, the orientation effect of electromagnetic coupling for a device in a transverse electromagnetic (TEM) cell is explained in the frame of the model with intercoupling of equivalent electric and magnetic dipoles taken into account. Different from the widely used model, which predicts a half-circle period of the orientation effect, the proposed model predicts a full-circle period due to the introduced intercoupling. The intercoupling of the electric and magnetic field interaction inside the TEM cell and the full-circle period orientation effect is demonstrated first by simple straight and meander microstrip lines, which is then compared to a segment of an integrated circuit (IC). For the application of the proposed model to a complex device, a limited number of pairs of intercoupling electric and magnetic field dipoles can be introduced to predict the complicated orientation effect of a running large-scale IC in TEM cell measurement. The extracted dipoles are in good agreement with the near-field scanning results. The widely used Wilson model should be checked carefully in the application of field to line analysis.