Designing microstrip transitions into parallel-plate regions using the FDTD method

A design method is introduced for microstrip transitions between microstrip lines and parallel plate regions. The radiation impedance of an aperture radiating into a two‐dimensional region (i.e., parallel‐plate region) is obtained by the FDTD method, and then a multisection matched transition is designed between this aperture and a microstrip line. Numerical study of a sample design has shown that the 20 dB return loss bandwidth is about 40% for a two‐section transition. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 81–84, 1999