Cylindrical coordinate system-based full wave FDTD computation for resonant frequency calculation of circular cavity resonator

In this paper, a full wave finite difference time domain (FDTD) computation method based on cylindrical coordinate system is proposed for calculating the resonant frequency of circular cavity resonator. The use of FDTD method with cylindrical coordinate system instead of Cartesian coordinate system is considered due to the geometry shape of analyzed structure, i.e. circular cavity resonator. In the computation, a hollow circular cavity resonator made of perfect conductor with the radius of 50mm and length of 100mm is discretized based on cylindrical coordinate system and numerically computed to determine its resonant frequencies. To verify the proposed method, the theoretical approach for the cavity is carried out by calculating its resonant frequencies for correspondent resonance mode. In addition, a simulation for determining resonant frequencies of the cavity is also conducted using finite element method (FEM) commercialized software. It shows that the FDTD computation result demonstrates an acceptable accuracy compared to the theoretical approach with the discrepancy less than 5% although it is worse than the result of FEM commercialized software.