NMR transmitting/receiving coil configuration
A nuclear magnetic resonance coil configuration having at least one flat or cylindrical coil ( 18 ), through which current flows in operation, which coil generates a high-frequency magnetic B 1 field at the location of a sample ( 16 ) which is oriented parallel to an x-axis, and which for the purpose of connection to a tuning network is connected to at least two electrical feed lines ( 11 ), through which in-phase currents flow in operation, and which generate a high-frequency magnetic B 2 field in the sample ( 16 ), the orientation of which encloses an angle α with the direction of the B 1 field, is characterized in that the following applies for the angle α: α=180°±Δα, where Δα<90°. In this way, a B 1 field profile, which is as rectangular as possible and is particularly steep on both sides, can be generated.
1. A nuclear magnetic resonance coil configuration for examination of a sample, the coil configuration comprising:
at least one flat or cylindrical coil through which a current flows in operation, said current flow in said coil generating a B 1 high-frequency magnetic field at a location of the sample, wherein said B 1 high-frequency magnetic field is oriented parallel to an x-axis; and
at least two electrical feed lines, said electrical feed lines being disposed, structured and dimensioned to connect said coil to a tuning network, wherein at least a fraction of said current generating said B 1 high-frequency magnetic field also flows through said electrical feed lines in operation, said current flow in said electrical feed lines thereby generating a B2 high-frequency magnetic field in the sample having a same phase as said B 1 high-frequency magnetic field, said B 2 high-frequency magnetic field being oriented at an angle α with respect to a direction of said B 1 high-frequency magnetic field, wherein α=180°±Δα, with Δα<90°.
2. The coil configuration of claim 1 , wherein Δα≤45°.
3. The coil configuration of claim 2 , wherein Δα≤15°.
4. The coil configuration of claim 1 , wherein at least two of said electrical feed lines have a crossing point.
5. The coil configuration of claim 1 , further comprising ring elements disposed in a bottom region of the coil configuration, wherein at least two of said electrical feed lines are electromagnetically coupled to said ring elements, said ring elements having a crossing point.
6. The coil configuration of claim 1 , further comprising at least one HF screen, said screen being disposed such that a sum of said B 1 and B 2 fields is substantially zero in at least a sub-region of the sample.
7. The coil configuration of claim 1 , wherein the coil configuration comprises at least four electrical feed lines forming at least two pairs of said at least two electrical feed lines, said at least four electrical feed lines generating B 2 i high-frequency fields in the sample during operation, wherein a sum of said B 2 i fields is substantially zero in at least in a sub-region of the sample.
8. The coil configuration of claim 7 , wherein at least pairs of electrical feed lines are fitted on opposite sides of the coil configuration.
9. The coil configuration of claim 1 , wherein the coil configuration comprises at least two coils which each generate a B 1 i high-frequency field in operation, said B 1 i fields being aligned to enclose an angle β between them, wherein |β|<10° or |β−180°|<10°.
10. The coil configuration of claim 9 , further comprising at least one HF screen, wherein, when operating at at least one measuring frequency, a sum of said B 1 i and said B 2 fields is substantially zero in at least a sub-region of the sample.
11. The coil configuration of claim 10 , wherein at least one said HF screen has openings.
12. The coil configuration claim 11 , wherein said openings are slots.