| 摘要 |
PROBLEM TO BE SOLVED: To materialize tuning adjustment of resonance characteristics without lowering a high Q-value essentially possessed by an antenna coil of small resistance loss, and to provide a circuit structure for a probe antenna with the number of turns increased and its mounting method, as to a nuclear magnetic resonance (NMR) measuring instrument. SOLUTION: A signal wire is led out of a substantially middle point of an antenna coil while trimmer capacitors of variable capacitance are connected to both sides of the antenna coil. A circuit is thereby formed wherein a series resonance circuit 1 on one side and a series resonance circuit 2 on the other side are parallel connected, with the substantially middle point of the antenna coil connected to the signal wire taken as a boundary point, the resonance circuit 1 comprising an antenna coil L<SB>1</SB>and a trimmer capacitor C<SB>1</SB>while the resonance circuit 2 comprising an antenna coil L<SB>2</SB>and a trimmer capacitor C<SB>2</SB>. By controlling resonance frequencies F<SB>1</SB>and F<SB>2</SB>of the resonance circuits 1 and 2, resonance characteristics are obtained wherein the parallel resonance frequency F<SB>0</SB>of the whole of an antenna circuit is tuned to a desired frequency and its impedance is adjusted to a specific value, e.g. 50Ω. COPYRIGHT: (C)2008,JPO&INPIT
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