Transmission Line RF Power Combiner With Capacitive Resonator Coupling
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Solution Overview
Problem
High-power RF systems face challenges in combining or dividing RF power efficiently due to size constraints, complexity, and additional losses when operating at frequencies below 300 MHz, particularly in particle accelerators and other applications, where existing techniques using coaxial cables and power vacuum tubes are cumbersome and costly.
Innovation Solution
A compact RF power combiner/divider design utilizing a transmission line resonator with a capacitive element that capacitively couples the inner and outer conductors, allowing for efficient power combination or division, and featuring adjustable coupling elements and a bandwidth adjuster to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If coaxial cables are wound in compact space to reduce size, then the size of the RF power combiner is reduced, but it becomes difficult to combine several RF power combiner units in one stage, necessitating several power-combining stages that add complexity, size, and additional RF losses
Solution Approach 1:
The invention divides the RF power combining function into multiple independent combiner units, each capable of handling multiple power sources in a single stage. This segmentation allows each unit to be compact while the system as a scale handles larger power requirements without proportionally increasing complexity or size.
Solution Approach 2:
The patent employs a nested structure where multiple coupling elements and resonant circuits are integrated within a compact coaxial cable arrangement. The coupling elements are positioned at specific locations along the wound coaxial cable, creating a space-efficient design that combines multiple functions in a single stage without requiring additional external components.
2Power
If the frequency range is less than 300 MHz, then the wavelength becomes relatively large (one meter or more), but the size of the RF power combiner must be proportional to the wavelength
Solution Approach 1:
The invention uses a wound or coiled configuration of the coaxial cable instead of a straight linear arrangement. This curvilinear geometry allows the combiner to fit a wavelength-proportional length into a much smaller physical volume, effectively reducing the footprint while maintaining the electrical length required for proper RF operation at frequencies below 300 MHz.
Solution Approach 2:
The patent transitions from a one-dimensional linear cable layout to a three-dimensional wound structure. By utilizing spatial dimensions vertically and radially through coiling, the design accommodates the required electrical length for low-frequency operation within a compact volume, decoupling physical size from wavelength proportionality.
3Reliability
If power vacuum tubes are used for high-power RF applications in lower RF frequency bands, then cost-effectiveness and overload tolerance are improved, but the system becomes more expensive and complex due to additional protection circuitry
Solution Approach 1:
The resonant circuit design inherently provides protection against overload conditions through its natural resonant properties. The circuit automatically reflects excess power back to the source when operating beyond its designed power level, eliminating the need for external protection circuitry while maintaining reliability and overload tolerance.
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
The solution provides a compact, adaptable, and low-loss RF power combiner/divider that reduces size and complexity while maintaining high power tolerance and phase stability, effectively addressing the limitations of existing systems.
Implementation Method 1
a capacitive element that capacitively couples the inner conductor and the outer conductor at a distal end of the transmission line resonator
Implementation Method 2
a transmission line resonator having an inner conductor, an outer conductor that surrounds the inner conductor, and a cavity between the inner conductor and the outer conductor
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Power combiner/divider (100) includes a transmission line (TL) resonator having an inner conductor (102), an outer conductor (104) that surrounds the inner conductor (102), and a cavity between the inner conductor (102) and the outer conductor (104). The inner conductor (102) and the outer conductor (104) are electrically connected at a proximal end of the TL resonator (101). The power combiner/divider (100) also includes coupling elements extending through respective openings of the outer conductor (104) and into the cavity. The power combiner/divider (100) also includes a capacitive element (130) connected to at least one of the inner conductor (102) or the outer conductor (104). The capacitive element (130) capacitively couples the inner conductor (102) and the outer conductor (104) at a distal end of the TL resonator (101).