Modified Dipole MRI Receiving Coil for Low-Loss Gain Matching
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Solution Overview
Problem
The gain of MRI receiving coils is limited due to restricted size, as increasing the number of loop coils reduces coil diameter, weakening the magnetic field strength, and conventional matching circuits for shortened dipoles increase loss and reduce sensitivity.
Innovation Solution
Incorporating a modified dipole with a parasitic element inside the loop coil, utilizing a split ring and linear elements to achieve impedance matching without lumped-parameter elements, enhancing antenna gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of loop coils is increased to improve gain, then the gain increases, but the coil diameter becomes smaller and magnetic field strength becomes weaker
Solution Approach 1:
The patent combines a loop coil and a dipole coil into a single coil element, creating a hybrid structure that leverages the strengths of both configurations. The loop coil provides magnetic field generation while the dipole coil enhances signal reception, achieving improved gain without sacrificing magnetic field strength or requiring reduced coil dimensions.
Solution Approach 2:
The coil element uses a composite structure combining conductive materials in different geometric configurations (loop and dipole). This composite approach allows the single coil element to perform multiple functions - generating magnetic field through the loop portion and receiving signals through the dipole portion - thereby improving overall gain while maintaining adequate coil size.
2Quantity of substance
If the coil diameter is reduced to fit more loop coils, then the number of loop coils increases, but the magnetic field strength becomes weaker
Solution Approach 1:
By merging the loop coil and dipole coil into a single hybrid coil element, the patent effectively increases the functional number of coils without physically reducing individual coil dimensions. Each hybrid element contributes both to magnetic field generation and signal reception, allowing more functional elements to be arranged in the array while maintaining adequate size for sufficient magnetic field strength.
3Reliability
If conventional matching circuits are used for shortened dipoles, then impedance matching is achieved, but loss increases and sensitivity decreases
Solution Approach 1:
The patent extracts and eliminates the conventional matching circuit from the shortened dipole structure. Instead of using external matching components that introduce loss, the design accepts the inherent impedance characteristics of the shortened dipole and integrates it directly with the loop coil, achieving the desired performance without additional lossy matching elements.
Solution Approach 2:
The hybrid coil element is designed to be self-sufficient, where the loop coil and dipole coil portions work together intrinsically to achieve both magnetic field generation and signal reception. The structure self-adjusts its electromagnetic characteristics through the coupling between the two coil types, eliminating the need for external matching circuits that would increase loss.
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 modified dipole configuration enhances coil sensitivity and gain by suppressing loss, allowing effective MR signal reception despite reduced coil dimensions.
Implementation Method 1
a main dipole configured to receive a radio-frequency 'RF' signal and output a reception signal
Implementation Method 2
a parasitic element that includes a split ring having a gap in part of a ring shape
Implementation Method 3
a plurality of coil elements, wherein: at least one of the plurality of coil elements includes a loop coil and a modified dipole disposed inside the loop coil
Data Source
AI summary
In one embodiment, a receiving coil includes a plurality of coil elements, wherein: at least one of the coil elements includes a loop coil and a modified dipole disposed inside the loop coil; and the modified dipole includes a main dipole configured to receive a radio-frequency “RF” signal and output a reception signal and a parasitic element that includes a split ring having a gap in part of a ring shape.