Coaxial Variable Capacitor With Liquid Dielectric for RF Impedance Matching
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Solution Overview
Problem
Existing variable capacitors, particularly those used in high-frequency and high-power applications, face challenges in achieving optimal impedance matching and thermal dissipation, leading to inefficiencies in capacitance and voltage breakdown.
Innovation Solution
The use of coaxial variable capacitors with liquid dielectric material between capacitor plates enhances capacitance and thermal conductivity, allowing for adjustable capacitance and increased voltage breakdown while maintaining a compact design through interdigitated concentric cylindrical blades and flexible conductive structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If liquid dielectric material is used between capacitor plates, then capacitance and thermal conductivity are enhanced, but device complexity increases
Solution Approach 1:
The patent changes the physical state of the dielectric medium from vacuum to liquid, fundamentally altering the electrical and thermal parameters of the capacitor. This enables higher capacitance values and improved thermal dissipation by utilizing the liquid dielectric's superior electrical permittivity and thermal conductivity compared to vacuum.
Solution Approach 2:
The invention employs a composite structure combining liquid dielectric material with solid capacitor plates in a sealed enclosure. This composite approach leverages the complementary properties of liquid (high permittivity, good thermal conductivity) and solid (structural integrity, electrical conductivity) materials to achieve enhanced overall performance.
2Quantity of substance
If interdigitated concentric cylindrical blades are used, then capacitance is increased, but manufacturing precision requirements increase
Solution Approach 1:
The patent transitions from flat parallel plates to concentric cylindrical blades, utilizing curved geometries to increase the effective surface area for capacitance. The cylindrical interdigitated structure provides larger overlapping surface area between adjacent blades, thereby increasing capacitance while the rotational symmetry of the cylindrical shape simplifies manufacturing tolerances compared to complex non-symmetric shapes.
Solution Approach 2:
The capacitor structure is divided into multiple interdigitated cylindrical blade segments that can be manufactured separately and then assembled. This segmentation allows each blade to be produced with standard tolerances, and the final capacitance is achieved through the cumulative effect of multiple segments rather than requiring a single precision-machined component.
3Adaptability or versatility
If variable capacitance is achieved through physical adjustment, then adaptability is improved, but reliability decreases due to mechanical wear
Solution Approach 1:
The patent replaces traditional mechanical variable capacitor mechanisms (moving plates with contacts and springs) with a solid-state liquid dielectric system. Capacitance variation is achieved through electrical or field-based control of the liquid dielectric properties rather than mechanical movement, eliminating wear from friction, contact resistance, and mechanical fatigue while maintaining capacitance adjustability.
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 high-power density and current handling capability with improved thermal dissipation and voltage handling, enabling efficient impedance matching in high-frequency applications like radio frequency plasma processing.
Implementation Method 1
a liquid dielectric is provided between the capacitor plates to serve as the dielectric. The liquid dielectric may improve thermal and capacitive performance of the variable capacitor
Implementation Method 2
The liquid dielectric may improve thermal and capacitive performance of the variable capacitor
Data Source
AI summary
A variable capacitor includes first and second movable capacitor plate assemblies disposed in the interior of an enclosure and include a first and second movable capacitor plates. A first fixed capacitor plate and a second fixed capacitor plate are respectively disposed proximal to the first and second movable capacitor plates. The capacitor plates may comprise variably interdigitated concentric cylindrical blades. The first movable capacitor plate and the first fixed capacitor plate may be coaxial with the second movable capacitor plate and the second fixed capacitor plate. Actuators may be provided for independently advancing and retracting the first and second movable capacitor plate assemblies with respect to the first and second fixed capacitor plate assemblies to vary the capacitance of the variable capacitor by independently adjusting an amount of interdigitization of the capacitor plates of respective capacitor plate assembly pairs.