Mutual Influence Between the Equipment Under Test and TEM Cells

This paper provides a generalized approach for investigating the reactive effects of the gigahertz transversal electromagnetic cell using the method of moments. This method is based on a framework recently developed. Thin dipoles are used as canonical equipment under test (EUT) to provide a basic understanding of the effects of the interaction between the cell and EUT. Emphasis is put on the impedance variation and on the overall current distribution on the EUT, which are a measure par excellence of this coupling. The impact of the phenomenon of illumination and re-illumination along with the role of evanescent modes on the EUT has been demonstrated. It is shown that even for small EUTs the contribution of the fields excited by induced currents on the EUT and scattered back from cell walls cannot be, in general, neglected, as they contribute to the total field. The appeal of the approach resides in its simplicity and in imparting deep insights into the physics behind the mutual influence between the cell and the EUT.