Frequency extension method of TEM cells based on slotted waveguide antenna

In order to break through limitatiions in actual testing, the extension method of frequency range of a transverse electromagnetic (TEM) cell is studied. Using the theory of electromagnetic field and microwave technology, the influence of adding slots to the cell on the higher order modes is analyzed, and the suppressing effect of slots on the higher order modes is reinterpreted by summarizing the variation of the distribution of surface current. According to the principle of slotted waveguide antenna, a new method has been proposed to design the slotted surface of the TEM cell. Along with the numerical simulation of electromagnetic field, the paper validates the effectiveness of an engineering method to suppress higher order modes and evaluates the accuracy of the control parameters and the constraint conditions. The effect of the new method is further verified by processing a real cell and its measurement. The simulation and test results show that, without reducing the test space and affecting the main mode, the engineering method of slotted cell can extend the bandwidth by 42.9% by suppressing higher order modes.