Analysis of waveguide aperture coupling using the finite-difference time-domain method

The finite-difference-time-domain (FDTD) method is applied to an interior propagation and coupling problem given in the form of aperture coupled waveguides. This problem demonstrates the method´s ability to model a rather complex problem where energy not only propagates in a waveguide, but couples to and then propagates within a second waveguide. The coupling consists of a single and a double aperture. The first case establishes modeling requirements and the second case is compared to experiment. Agreement is typically within experimental error, thereby validating the method for this application. Results showed little sensitivity to either mesh dimensions or simulation duration and were achieved using 32 cells for the broad side of the waveguide, 12 cells for the aperture diameter, and 8192 timesteps.<>