An analytical and experimental determination of the cutoff frequencies of higher-order TE modes in a TEM cell

In addition to the TEM mode, higher order TE and TM modes can propagate in a TEM cell. Since only the TEM mode is desired, the higher-order modes restrict the useful frequency range of the TEM cell. The cutoff frequency of the first higher-order mode is obtained both analytically and experimentally for several TEM cells of differing geometry. The difference between the experimental and theoretical results is shown to be only a few percent. In addition the field distribution of the first higher-order mode is found explicitly.