Study on Available Condition of Static Circuit Parameters Applied to Predict the Transmission Characteristics of Step Microstrip Line

The static circuit parameters extracted from the field results of non-uniform microstrip line provides an efficient way to predict dynamic effect of non-uniform structure. The predictable frequency range of the static circuit parameters on prediction of the transmission characteristics of step microstrip line is researched in this paper. The circuit parameters are extracted from the full wave results of step line, respectively, at three frequencies (9 GHz, 15 GHz and 20 GHz). On one hand, the time domain transmission characteristics of step line can be solved from the equivalent circuit constructed by these extracted circuit parameters. On the other hand, the frequency domain S-parameter can be derived by the static distributed characteristic impedance. By comparing these time and frequency domain results obtained from the static circuit parameters with those obtained directly from the full wave method, the available condition of the static circuit parameters of the step microstrip line can be analyzed. This comparison shows that the static circuit parameters can be used in frequency bands from DC up to 20 GHz. To verify the accuracy of the static parameters used to predict the transmission characteristics of step line, the measured S-11 is also given for comparison.