FDTD modelling of IDG structures

A three-dimensional Finite-Difference Time-Domain (FDTD) technique is applied to characterise deep slot and shallow slot inset dielectric guide (IDG), and the rectangular waveguide to IDG transition. Characteristic impedance of an IDG is defined and calculations presented for the first time and it is then used to determine S-parameters of the transition. The described method utilises pulsed excitation so that wideband results are available from a single FDTD computation. A graded mesh is used for computational efficiency. Comparisons are made between experimental and theoretical results and good agreement is found.