Pulse Propagation in Gigahertz Transverse Electromagnetic Cells

This paper deals with short electromagnetic pulse propagation in a large gigahertz transverse electromagnetic (GTEM) cell. The aim of the investigation is to analyze to what extent a voltage pulse with subnanosecond risetime, applied to the coaxial feeding port, is distorted when transformed into a field pulse in the testing volume. The analysis focuses on how the expected excitation of higher order modes results in a pulse distortion within GTEM cells. Therefore, an entire 3-D simulation model of the cell has been created and measurements have been conducted. Considering the GTEM cell as a linear time-invariant system, it is possible to calculate the impulse response in the time domain of each electromagnetic field component in the distinct observation points in the testing volume. The obtained simulation and measurement results are used to verify the proposed characterization of the GTEM cell. This method leads to a prediction of the pulse propagation of arbitrary transient excitation signals concerning both the pulse shape and the derived field magnitude.