CHARACTERIZATION OF 3-DIMENSIONAL OPEN DIELECTRIC STRUCTURES USING THE FINITE-DIFFERENCE TIME-DOMAIN METHOD

Millimeter and submillimeter wave three-dimensional (3-D) open dielect ric structures are characterized using the finite-difference time-doma in (FDTD) technique, The use of FDTD method allows for the accurate ch aracterization of these components in a very wide frequency range, The first structure characterized through FDTD for validation purposes is a mm-wave image guide coupler, The derived theoretical results for th is structure are compared to experimental data and show good agreement , Following this validation, a sub-mm wave transition from a strip-rid ge line to a layered ridge dielectric waveguide (LRDW) in open environ ment is analyzed, and the effects of parasitic radiation on electrical performance are studied, The transition is found to be very efficient over a wide sub-mm frequency band which makes it useful for a variety of applications. In addition to the transition, a sub-mm wave distrib uted directional coupler made of the LRDW is extensively studied using the FDTD method as an analysis tool, Furthermore, an iterative proced ure based on the FDTD models is used to design a 3-dB coupler with a c enter frequency of 650 GHz and negligible radiation loss, This success ful design shows that the FDTD technique can be used not only as an an alysis method, but also as a design tool to provide designs which take into account all high frequency parasitic effects.