A close-form approximate to calculate the resonance frequency in asymmetric TEM cell

A simple semi-analytical method was presented to calculate the resonance frequencies in asymmetric TEM cell by estimating the equal inhomogeneous transmission line resonance frequencies in condition of open circuit and short circuit at terminal. The moment method was used to calculate the capacitance of cross-section, then characteristic impedance along transverse axis was obtained. The numerical results were obtained in a table by solving the combined equation of transmission line impedance transfer equation and terminal input impedance expression in gas capacitance.