Optimization of the GTEM cell wideband termination

The suppression of non-essential modes is investigated in this work upon applying the network analysis. A simplified equivalent circuit model of the cell allowing separation of TEM and TM₁₁ modes is developed. This approach enables the determination of the reflected power, power absorbed in the pyramid absorbers and dissipated in the lumped elements as well as separate evaluation of the attenuation for each mode although there is an energy transfer from one mode to another. The expected poor absorption character of the lumped elements with respect to essential higher order mode and the postulated high midway frequency of cells lined with pyramid absorbers are confirmed. Further, determination of the performance of each element of the circuit permits optimization of the cell's parameters, thus enabling the enlargement of the overall usable test volume.