The discussion focuses on determining the resonant frequencies of two coaxial cylinders, emphasizing that the resonant frequency is influenced by the length of the cylinders and their configuration. The resonant wavelength differs for closed and open-ended cylinders, with the cavity between them requiring specific formulas. Key factors include the type of connector used, the impedance of the connecting cable, and whether the ends of the assembly are open or shorted. The impedance of the coaxial assembly can be calculated using a specific formula, and the lowest resonant frequency is identified as the 1/4 wave frequency. Overall, understanding the impedance and configuration is crucial for accurately determining the resonant frequencies in coaxial cylinders.