Flat Adjustable Capacitor for MRI Scanner Antenna Tuning
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Solution Overview
Problem
Magnetic resonance scanner antennas face challenges in precise tuning due to manufacturing tolerances and environmental factors, requiring compensation capacitors that can handle high voltages and currents while minimizing ohmic and dielectric losses, within the limited space of a patient passage.
Innovation Solution
A compensation capacitor design featuring flat, parallel electrodes with high-voltage resistant insulation and low dielectric loss materials, allowing for variable capacitance adjustment through mechanical movement of the electrodes, enabling precise tuning and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional cylindrical capacitors are used for antenna tuning, then the antenna can be tuned, but the capacitor occupies excessive space in the limited patient passage
Solution Approach 1:
The patent transitions from a cylindrical capacitor design to a flat plate capacitor design, changing the geometric dimensionality from three-dimensional cylindrical volume to a two-dimensional plate structure with minimal thickness. This dimensional change allows the capacitor to fit within the constrained patient passage space while maintaining the necessary capacitance value through optimized plate area and separation distance.
Solution Approach 2:
The patent implements a variable capacitor design where the effective capacitance can be dynamically adjusted by changing the overlapping area between the parallel plates. This is achieved through mechanical movement of one plate relative to the other, allowing the tuning element to adapt to different antenna tuning requirements while occupying a compact space.
2Manufacturing precision
If the antenna is precisely tuned to compensate for manufacturing tolerances and thermal effects, then the antenna quality is improved, but the tuning elements are subjected to extreme voltage and current demands
Solution Approach 1:
The patent employs composite material construction for the capacitor, combining high-voltage resistant insulation material with low dielectric loss dielectric material between the parallel plates. This composite structure simultaneously provides the necessary electrical insulation for high voltage operation and minimizes dielectric losses that would otherwise degrade antenna quality factor, thereby addressing both reliability and tuning precision requirements.
3Loss of energy
If the capacitor is designed to minimize ohmic and dielectric losses, then the antenna quality is maintained, but the capacitor structure becomes more complex
Solution Approach 1:
The patent minimizes energy losses by optimizing key parameters: using extremely thin plate separation distance to reduce dielectric loss path length, selecting dielectric material with minimal loss tangent, and using highly conductive plate materials to minimize ohmic losses. These parameter optimizations achieve low loss performance without requiring complex structural arrangements.
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 design enhances the antenna's tuning capabilities, maintains high reliability and quality, and reduces the physical depth within the patient passage, addressing the limitations of existing capacitors in magnetic resonance scanners.
Implementation Method 1
An insulation material configured to resist high voltages is arranged between the first electrode and the second electrode
Implementation Method 2
a dielectric with low dielectric losses are arranged between the first electrode and the second electrode
Data Source
AI summary
The disclosure relates to a compensation capacitor for an antenna of a magnetic resonance scanner and a corresponding antenna with a compensation capacitor. The compensation capacitor has a first electrode and a second electrode arranged in parallel. An insulation material configured to resist high voltages and a dielectric with low dielectric losses are arranged between the first and the second electrode. The second electrode and/or the dielectric may be moved relative to the first electrode such that a surface area of a projection of the surface of the first electrode along the surface normal of the first electrode to the surface of the second electrode and/or the dielectric is variable.