Stripline Balun RF Current Blocking via Integrated Capacitive Inductive Networks
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Solution Overview
Problem
Conventional coaxial baluns in MRI systems are large and inefficient in transforming signals across different transmission means, particularly failing to effectively block induced radio frequency current on ground conductors in stripline transmission lines.
Innovation Solution
The development of stripline baluns with capacitive and inductive networks on multi-layer signal carriers, featuring insulative elements, conductive layers, and vias to electrically couple conductors and ground conductors, effectively blocking induced RF current and transforming balanced/unbalanced signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coaxial baluns are used for signal transformation, then signal transformation between balanced and unbalanced transmission is achieved, but the device size becomes large and RF current blocking on ground conductors is ineffective
Solution Approach 1:
The patent replaces the traditional coaxial mechanical balun structure with an integrated stripline balun design where capacitive and inductive elements are fabricated directly on the circuit board. This substitution of mechanical assembly with integrated circuitry achieves compact size while maintaining effective RF current blocking through properly designed capacitor and inductor elements that provide the necessary impedance transformation and ground current blocking paths.
Solution Approach 2:
The patent merges multiple functions into a single integrated structure: the balun function, ground current blocking, and signal transmission are all achieved within the same stripline configuration. The capacitive circuit and inductive circuit are combined on the same circuit board with shared ground connections, creating a unified device that simultaneously performs signal transformation and RF current blocking without requiring separate components.
2Adaptability or versatility
If conventional coaxial baluns are used, then signal transformation is provided, but the device complexity and manufacturing difficulty increase for stripline integration
Solution Approach 1:
The patent segments the balun function into distinct capacitive and inductive circuit sections that can be independently designed and fabricated on the circuit board. Each section handles specific aspects of the signal transformation, allowing for modular manufacturing and easier integration into existing stripline configurations. The ground conductor blocking path is also segmented into discrete capacitive and inductive elements that can be independently optimized.
Solution Approach 2:
The patent utilizes parameter changes in the capacitive and inductive elements to achieve the desired signal transformation characteristics. By adjusting the capacitance and inductance values of the integrated circuits, the balun can be tuned for specific frequency ranges and impedance transformations. This parameter-based design allows for flexible adaptation to different stripline configurations without changing the fundamental structure.
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 stripline baluns provide a compact and efficient solution for blocking induced RF current, achieving higher impedance and improved signal transformation compared to coaxial cable baluns, enhancing the performance of MRI systems by reducing interference and improving signal processing.
Implementation Method 1
first and second capacitive circuits coupled to the conductive layers of each respective insulative element in the central region thereof
Implementation Method 2
a balun for blocking induced radio frequency current on ground conductors
Implementation Method 3
conductive material disposed in the vias electrically coupling a conductive layer on respective ends of the first and second elements with one another and with the ground conductors
Data Source
AI summary
Systems and devices for transmitting radio frequency signals to and from radio frequency coils in magnetic resonance imaging systems are provided. In one embodiment, a balun for blocking induced radio frequency current on ground conductors of a multi-layer signal carrier includes first and second insulative elements disposed on first and second sides of the signal carrier, respectively, a conductive layer partially surrounding ends of each insulative element with a central region of each insulative element not surrounded by the respective conductive layer, first and second capacitive circuits coupled to the conductive layers of each respective insulative element in the central region thereof, vias extending through the signal carrier, and conductive material disposed in the vias electrically coupling a conductive layer on respective ends of the first and second elements with one another and with the ground conductors.