Coaxial Resonator Assembly for Compact RF Filter Design
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Solution Overview
Problem
Existing radio-frequency filters face challenges in miniaturization while maintaining high Q-factor and frequency tunability, with conventional filters being too large for small cell base stations and costly for widespread deployment in high-power applications.
Innovation Solution
A resonator assembly with a unique configuration of distributed resonators, where each resonator consists of an inner and outer coaxial cylinder, arranged in inter-digitated configurations within a resonant chamber, allowing for magnetic field coupling and reduced physical size without compromising performance or frequency tunability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cavity resonators are used to achieve high Q-factor, then the Q-factor is improved, but the size of the filter increases
Solution Approach 1:
The patent applies nesting by placing one resonator inside another resonator chamber, with inner resonators positioned within outer resonators. This nested configuration allows multiple resonators to occupy overlapping spatial volumes, achieving compact filter miniaturization while maintaining the high Q-factor characteristics of cavity resonators.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by positioning resonators at different heights within the chamber (first resonator at first height, second resonator at second height). This vertical stacking approach enables compact filter design by exploiting the third dimension, reducing the filter's footprint while preserving high Q-factor performance.
2Reliability
If the order of the filter is increased to achieve high stop-band attenuation, then the stop-band attenuation is improved, but the insertion loss in the pass-band increases
Solution Approach 1:
The patent changes the physical parameters of the resonators, specifically their dimensions and positioning, to optimize the balance between stop-band attenuation and insertion loss. By adjusting resonator sizes, spacing, and heights, the filter achieves high stop-band rejection while minimizing pass-band insertion loss through precise parameter optimization.
3Volume of stationary object
If lumped components are used to achieve miniaturization, then the size is reduced, but the Q-factor decreases
Solution Approach 1:
The patent replaces traditional mechanical lumped components with electromagnetic cavity resonators. This substitution enables the filter to achieve miniaturization comparable to lumped element filters while maintaining the high Q-factor characteristics of cavity resonators, effectively bridging the gap between size reduction and performance preservation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves significant size reduction and increased Q-factor, enabling compact, high-performance filters suitable for small cell base stations and allowing for frequency retuning without the need for new filters, while maintaining low insertion loss and high power-handling capabilities.
Implementation Method 1
each resonator of the first set is for magnetic field coupling in proximity with at least one resonator of the second set
Data Source
Figure 1~2b
Figure 3~5b
Figure 6~7b
AI summary
A resonator assembly is provided comprising a resonant chamber, each chamber comprising a first wall, a second wall opposite the first wall, and side walls; in which the resonator chamber houses two or more resonators, each resonator comprising a first cylinder grounded on one of the first and second walls and extending into the chamber, and a second cylinder which is coaxial with the first cylinder and grounded on the other of the first and second walls and extending into the chamber; a first set of the resonators having their respective first cylinders grounded on the first wall and their respective second cylinders grounded on the second wall; a second set of the resonators having their respective first cylinders grounded on the second wall and their respective second cylinders grounded on the first wall; wherein each resonator of the first set is for magnetic field coupling in proximity with at least one resonator of the second set.