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High Q-factor Bragg-reflection sapphire-loaded cavity TE01delta mode resonators
John G Hartnett1, Michael E Tobar, Dominique Cros
1Frequency Standards and Metrology Research Group, School of Physics, University of Western Australia, Crawley, WA 6009, Australia. john@physics.uwa.edu.au
Summary
A novel method enhances the quality factor (Q-factor) of TE01delta cavity resonators using a monolithic sapphire dielectric tube and Bragg reflection. This technique significantly reduces surface losses, achieving a Q-factor of 1 x 10^5.
Area of Science:
- Electromagnetics and Microwave Engineering
- Materials Science and Engineering
Background:
- High-quality factor (Q-factor) resonators are crucial for advanced microwave devices.
- Traditional methods often face limitations in achieving superior Q-factors due to surface losses.
Purpose of the Study:
- To present an innovative method for enhancing the Q-factor of TE01delta cavity resonators.
- To utilize a monolithic sapphire dielectric tube and Bragg reflection for improved resonator performance.
Main Methods:
- Employing a Bragg reflection technique to confine electromagnetic energy.
- Utilizing a dielectric tube made of monolithic sapphire within a copper cavity.
- Optimizing cavity dimensions for maximum Q-factor through finite element simulations and experimental validation.
Main Results:
- Achieved a Q-factor of 1 x 10^5 for a TE01delta mode in a copper cavity at 8.78 GHz and 290 K.
- The achieved Q-factor is only 30% less than the theoretical limit imposed by the dielectric material's loss tangent.
- Demonstrated significantly reduced surface losses by confining energy away from cavity walls.
Conclusions:
- The presented method offers a significant enhancement in resonator Q-factor.
- Advantages include very low spurious mode density and a compact, single-piece sapphire design.
- Excellent agreement between finite element simulations and experimental data validates the technique.