Parametric analysis and optimization of the shape of the transitions of a two-port rectangular TEM cell

The design of a two-port TEM cell has been numerically investigated with respect to the shape of the transitions connecting the small rectangular terminations, where connectors are fixed, and the TEM cell rectangular central part. At first, using a commercial code, the model has been developed and its validation has been done on an existing TEM cell. Then, starting from this TEM cell, a parametric analysis has been performed. The numerical results are shown and the effects of each parameter on the voltage standing wave ratio are discussed, with simple and practical diagrams useful for the design of a TEM cell. On the basis of the numerical analysis, modifications of the septum were performed on the TEM cell, and a substantial reduction of the highest values of VSWR has been obtained. Finally, a numerical optimized solution for the TEM cell with a maximum VSWR of 1.02 has been identified.