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Complete S matrix in a microwave cavity at room temperature
Jérôme Barthélemy1, Olivier Legrand, Fabrice Mortessagne
1Laboratoire de Physique de la Matière Condensée, CNRS UMR 6622, Université de Nice-Sophia Antipolis, 06108 Nice, France.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 9, 2005
Summary
We studied resonance widths in microwave cavities, identifying two Ohmic loss mechanisms. These losses vary between modes due to field distribution, impacting resonance broadening.
Area of Science:
- Physics
- Electromagnetism
- Cavity Resonators
Background:
- Resonance widths in microwave cavities are crucial for understanding energy loss.
- Ohmic losses and antenna coupling are known contributors to resonance broadening.
Purpose of the Study:
- To experimentally determine the factors contributing to resonance width in 2D microwave cavities.
- To differentiate between antenna coupling and Ohmic loss contributions.
- To investigate the mechanisms of Ohmic losses and their impact on mode-dependent widths.
Main Methods:
- Experimental measurements of resonance widths in a 2D microwave cavity at room temperature.
- Development of a model to isolate the effect of coupling antennas.
- Application of S-matrix formalism for theoretical analysis.
Main Results:
- Successfully modeled and discriminated antenna coupling effects from Ohmic losses.
- Identified two primary Ohmic loss mechanisms: damping during propagation and absorption at the cavity contour.
- Demonstrated that contour absorption, dependent on field distribution, causes mode-to-mode width variations.
- Validated the theoretical model with measurements of hundreds of resonances.
Conclusions:
- Ohmic losses significantly influence resonance widths in microwave cavities.
- Mode-dependent resonance widths are primarily driven by field distribution-dependent contour absorption.
- The developed S-matrix theory accurately predicts these observed variations.