FINITE-DIFFERENCE TIME-DOMAIN ANALYSIS OF INSET DIELECTRIC GUIDE AND ITS APPLICATION TO WAVE-GUIDE TRANSITIONS

A three-dimensional finite difference time-domain (FDTD) method is use d to characterise inset dielectric guide (IDG) and the rectangular wav eguide to IDG transition. Propagation constants and characteristic imp edances of the fundamental modes are calculated and subsequently used to obtain the S-parameters of the transition. Three different definiti ons of the characteristic impedance are applied and a simple averaging technique to compute the power flow along the guide is investigated. The transition is also characterised experimentally and good agreement between measured and numerical results is observed. Further, the fini te dimensions of the waveguide flange are investigated for the first t ime, and are seen to affect results.