Orientation Effect of Field-to-Line Coupling in a TEM Cell

In this paper, we study the orientation effect of magnetic and electric field-to-line coupling (FtLC) between a microstrip line and a TEM cell by using a square-shaped transmission line pulse as an interference source. With the detections at enough orientations, the electric and magnetic FtLCs can be extracted with high accuracy. It is found that in the TEM cell, the ratio of electric to maximum magnetic FtLC is dominated by the characteristic impedance of the studied microstrip line due to the determined value of width-to-distance. For a certain ratio of electric to maximum magnetic FtLC, there is a singular angle at which the microstrip line gives no response for any electromagnetic interference excitation. Meanwhile, at the supplementary angle, the response of the microstrip line shows no dependence on the termination load.