The effects of septum dimensions and positions on the characteristic impedance and fields of an asymmetric TEM cell

The paper deals with the numerical analysis of the effects of septum thickness and positions on the characteristic impedance and the electric field distribution in an asymmetric transverse electromagnetic (TEM) cell by using the method of moments (MOM). The distribution of the electric charge on the periphery of the conductors is determined using a quasi-static approximation for operation of the cell at frequencies well below its cut off frequency and by finding the Green's function for the structure. The impedance results are compared with those available in the literature and found to be in very good agreement. An investigation has also been carried out on the effects of the dimensions of the septum on the electric field distributions in the cross-section. The method has the advantage over others that no assumption is needed for the specific choice of the electric charge distribution on the conductors and the analysis considering the effects of the thickness of an offset septum becomes simpler and is most universal.