A new efficient excitation scheme for the FDTD method based on the field and impedance template

We have presented a new excitation scheme for the FDTD analysis of guided wave problems. Tangential E-field components in the input plane are driven by elementary sources with both amplitude and output impedance determined by the modal template. This permits accurate FDTD simulations using only short sections of input feeds. For typical microwave circuits such as a patch antenna considered in the present paper, a reduction in computer resources by a factor of two is achieved. The templates are established automatically by the 2DV FDTD algorithm operated in an optimization loop. By using the 2DV rather than 3D FDTD template generation, we can easily consider a fundamental mode or any higher mode, and distinguish between two propagating modes such as an odd and even mode in the presented example of asymmetrical coupled microstrip lines.