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Design and Fabrication and Parameter Extraction of Q-band Waveguide Filter with Transmission Zeros

Pourmohammad, Sara | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45307 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Banai, Ali
  7. Abstract:
  8. E-plane waveguide filters are good choices due to highly manfacturing accuracy in Q-band microwave devices.To increase the attenuation slop or selectivity of such filters one need to synthesis transmission zeros with cross coupled resonators.With this method for constanst degree and return loss, attenuation slop increases in comparison to direct coupled resonators.
    In this thesis we designed and fabricated a Q-band 4th degree filter,with center frequency at 42.1746 GHz and bandwidth of 350 MHz with two transmission zeros. Results of simulations and measurments are given in chapters 3 and 5.
    Microwave filters using coupled resonators are important components in microwave systems. Various methods for the synthesis of these filters have been well developed.However, the practical implementation and fabrication of these filters inevitably lead to performances that differ from the designed frequency responses. As a result, microwave filters usually go through the tuning and optimization process that becomes more time consuming and expensive as the number of resonators increases in highorder filters. In the tuning process of the filters, the key step is parameter extraction to extract the coupling coefficients and resonant frequencies of individual resonators from the measured frequency responses or simulation. Careful comparison between the extracted parameters and the synthesized (designed) values will then lead to pinpointing the resonators that need to be tuned and optimized. In this thesis, a robust and efficient model based parameter extraction (MBPE) technique is utilized to extract the coupling matrix from the filter response which is based on rational interpolation of polynomials. The proposed method is very fast and robust and can be used, with good accuracy, for low loss filters. In order to test and verify the method in this research and to demonstrate its capabilities,a 9th degree combline filter was tuning and results of tuning is given in chapter4
  9. Keywords:
  10. E-Plane Waveguide Filter ; Cross Coupling the Resonators ; Coupling Matrix ; Transmission Zeros ; Model Base Parameter Extraction ; Rotational Interpolation

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