Characterization of a single-step microstrip discontinuity in a substrate using the finite-difference time-domain method

A single‐step microstrip discontinuity in a substrate is characterized using the finite‐difference time‐domain (FDTD) method, and an equivalent circuit model has been developed. The microstrip discontinuity newly introduced in this paper has a substrate thickness change in the longitudinal direction with a uniform strip width. The discontinuity has applications in patch antenna feed design and interconnections between microwave circuit modules. The simulation results are compared with those computed by HFSS to show good agreement. An equivalent circuit developed from the FDTD results, which is accurate within 2.4% in magnitudes of S11 and S21, can be applied for computer‐aided designs. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 245–248, 2000.