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Intrinsic quality factor extraction of multi-port cavity with arbitrary coupling
1Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA.
The Review of Scientific Instruments
|January 30, 2021
Summary
New formulas extract the intrinsic quality factor (Q) of microwave cavities using S-parameter measurements. This method applies to both normal-conducting and superconducting cavities, even with non-ideal test fixtures.
Area of Science:
- Microwave Engineering
- Accelerator Physics
- Electromagnetics
Background:
- Accurate measurement of the intrinsic quality factor (Q) is crucial for optimizing microwave cavity performance.
- Existing methods may be limited by test fixture imperfections and cavity coupling complexities.
Purpose of the Study:
- To develop S-parameter based expressions for calculating the intrinsic quality factor of multiport microwave cavities.
- To evaluate the accuracy limitations of these expressions, particularly for superconducting accelerator cavities.
Main Methods:
- Derivation of S-parameter based analytical expressions for intrinsic quality factor.
- Analytical and simulation-based evaluation of expression accuracy for superconducting cavities.
- Validation against calibrated S-parameter measurements.
Main Results:
- Novel S-parameter based formulas for intrinsic quality factor extraction were derived.
- Accuracy limitations were quantified for superconducting accelerator cavities.
- The formulas demonstrated applicability to both normal-conducting and superconducting cavities.
Conclusions:
- The derived formulas provide a direct method for extracting intrinsic quality factor from S-parameter data.
- This approach is suitable for both normal-conducting and superconducting cavities, accounting for non-ideal test fixtures.
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