Flat MRI Transmission Antenna for Localized Field Generation
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Solution Overview
Problem
Magnetic resonance imaging devices generate circularly polarized transmission magnetic fields in a larger volume than necessary, leading to higher power dissipation and inefficiency.
Innovation Solution
A transmission antenna apparatus with flat antennas, including butterfly and loop antennas, is designed to generate a locally delimited transmission magnetic field by configuring the antennas in a space-saving manner and using a feed apparatus to create phase-shifted magnetic field components, allowing for efficient circular polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional transmission antennas are used to generate circularly polarized transmission magnetic fields, then the magnetic resonance imaging device can excite magnetic resonances, but the transmission magnetic field is generated in a substantially larger volume region than necessary, leading to higher power dissipation
Solution Approach 1:
The transmission antenna is divided into multiple separate flat antennas arranged in a specific geometric pattern. Each flat antenna generates a linearly polarized magnetic field, and through coherent combination with appropriate phase relationships, these segmented components create the desired circularly polarized field only in the targeted examination volume, rather than a large surrounding volume
Solution Approach 2:
The patent configures multiple flat antennas with specific orientations and feed phase relationships to create a transmission magnetic field that is locally concentrated in the examination volume. The field strength is deliberately localized to where it is needed for MRI excitation, while minimizing field generation in surrounding regions, thereby reducing unnecessary power dissipation
2Area of stationary object
If flat antennas are used to save space and integrate into the patient couch, then the device complexity is reduced and space is saved, but generating a circularly polarized field requires multiple antennas with specific phase relationships
Solution Approach 1:
Multiple flat antennas are merged into a single integrated transmission antenna system with a unified feed network. The individual flat antennas are arranged in a compact geometric configuration and fed with coherent signals having specific phase relationships, combining their individual linearly polarized fields to produce the desired circularly polarized field in the examination volume
Solution Approach 2:
The flat antennas serve multiple functions: they generate linearly polarized magnetic fields, contribute to forming the circularly polarized transmission field through coherent combination, and are integrated into the patient couch structure. This multi-functionality reduces the need for separate components and simplifies the overall system design
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 enables the generation of a locally delimited transmission magnetic field, reducing power dissipation and improving field homogeneity, while being integrated into a patient couch without additional space requirements.
Implementation Method 1
The transmission antenna apparatus includes a feed apparatus configured to feed the loop antenna and butterfly antenna with a phase difference of 90°. Using the loop antenna and the butterfly antenna, transmission magnetic field components that are phase shifted by 90° and perpendicular to one another and, in combination, result in a circularly polarized transmission magnetic field may thus be generated.
Data Source
AI summary
The transmission antenna apparatus is configured for emitting transmission magnetic fields in magnetic resonance imaging devices and includes one or more flat antennas. A magnetic resonance imaging device includes such a transmission antenna apparatus.