| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi channel balanced/unbalanced (balun) circuit to prevent flow of leak RF current on the shield semiconductor in the coaxial RF cable in the magnetic resonance equipment. SOLUTION: The balanced/unbalanced circuit includes parallel combinations of the plural number of helicall coils that are coiled in different directions one another so as to cancel the voltage induced by outer RF field on the shielded transmission cables (L10, L12, L14, L16, L18 and L20). One capacitor is connected with each pair of helical coils in symmetric and parallel arrangement and the control capacitor (C12, C22) is fixed on the coil plug (86, 90) to re-control balanced/unbalanced circuit according to the needs. The multi channel balanced/unbalanced circuit (70, 72) enables control of the magnetic resonance equipment having odd or even number of channels without shield. Preferably, the balanced/unbalanced circuit (70, 72) is constructed on the single circuit board with a compact and space efficient closed packing and provides a good separation from transmission field.
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