The present example considers a single resonator rectangular waveguide filter.
Single rectangular waveguide filter.
The filter is made on a 20 mm x 10 mm rectangular waveguide and its length is 67 mm. The structure is a resonator made of two thin irises placed in a rectangular waveguide.
Single resonator waveguide filter project in QW-Modeller.
This is an example of a very simple resonant structure, which shows the weakness of traditional Fourier transform processing of circuits with long impulse response. For those kind of problem QProny module is recommended. For the purpose of calculating reflection and transmission characteristics of the structure the S-Parameters postprocessing and QProny module are activated. The S-Parameters postprocessing is set from 10 GHz to 14 GHz with a frequency step of 0.01 GHz.
S-Parameters postprocessing configuration dialogue with QProny module activated.
QProny module control window with Calculation Status information (information about the model created after 2499 iterations).
For the purpose of getting the loaded Q-factor we press the Qf button. We have one resonant frequency in the considered band. This has been signalled during the building of the QProny model by the fact that the model was of order 2 (or in other words having one double complex pole). Thus only one frequency appears. The resonant frequency is being detected in each of the signals used by the differential method of S-parameter extraction. Since we consider 4 signals at each of the transmission line ports we have a total of 8 signals. The calculated values of the loaded Q-factor extracted from each of the signals may be slightly different due to errors of the extraction method used with limited number of samples. With increasing number of samples the values calculated from different signals should merge to the correct value of the Q-factor
Loaded Q-factor retrieved for model created after 2499 iterations.
The |S21| characteristic obtained from Fourier postprocessing (red) after 2500 iterations and QProny module result (blue) after 2499 iterations.
The |S21| characteristic obtained from Fourier postprocessing (red) after 25000 iterations and QProny module result (blue) after 2499 iterations.
Distribution of time-maximum envelope of Ez field component at 12.19 GHz.
Time dependent distribution of Ez field component at 12.19 GHz.
Distribution of time-maximum envelope of Ez field component at 11 GHz.
Time dependent distribution of Ez field component at 11 GHz.