Electrically symmetric NMR coils with a plurality of windings connected in series
A nuclear magnetic resonance probe head comprising at least two orthogonal coil/resonator configurations A 1 and A 2 having different resonance frequencies, wherein at feast one of the coil/resonator configurations A 1 has two saddle-shaped coils S 1 and S 2 , wherein each coil has a window about which N windings are disposed which are connected in series, wherein N≧ 2 . Each coil S 1 and S 2 is formed mirror-symmetrically relative to a central plane of the respective coil, which is perpendicular to the window of the respective coil, wherein the central planes of the coils S 1 and S 2 are identical to minimize the electromagnetic coupling between the two coil/resonator configurations A 1 and A 2 at the resonance frequency of A 2 . The NMR probe head reduces coupling between the two coil/resonator configurations.
1. An NMR probe head, comprising:
at least two coil/resonator configurations A 1 and A 2 , wherein at least one of the coil/resonator configurations A 1 comprises two saddle-shaped coils S 1 and S 2 , wherein each coil S 1 and S 2 has one single window about which N windings, connected in series, are disposed, wherein N≧2 the coil/resonator configurations A 1 and A 2 being aligned perpendicularly to each other and having different resonance frequencies, wherein each coil S 1 and S 2 is mirror-symmetric relative to a central plane of a respective coil, said central plane being perpendicular to said window of said respective coil, wherein central planes of said coils S 1 and S 2 are identical to minimize electromagnetic coupling between said two coil/resonator configurations A 1 and A 2 at a resonance frequency or coil/resonator configuration A 2 .
2. The NMR probe head of claim 1 , wherein each coil S 1 , S 2 has at least N−1 crossing points between conductor sections thereof, wherein said crossing points are disposed on said central plane of said respective coil.
3. The NMR probe head of claim 2 , wherein at least one of the coils S 1 , S 2 has 2*J further crossing points between said conductor sections, wherein said further crossing points are disposed in pairs, symmetrically with respect to said respective central plane, wherein J≧1.
4. The NMR probe head of claim 3 , wherein at least one of the coils S 1 , S 2 is a sheet or a thin film coil, said crossing points or said further crossing points being formed using soldered or welded bridges.
5. The NMR probe head of claim 1 , wherein said coils S 1 , S 2 are formed such that, during resonant operation thereof, a potential on said respective coil S 1 , S 2 is distributed mirror-symmetrically, but equal and opposite, relative to said respective central plane.
6. The NMR probe head of claim 1 , wherein at least one of the coils S 1 , S 2 is a wire coil.
7. The NMR probe head of claim 1 , wherein at least one of the coils S 1 , S 2 is a sheet or thin film coil.
8. The NMR probe head of claim 7 , wherein at least one of the coils S 1 , S 2 is designed as a sheet coil of flexible PCB (printed circuit board) material.
9. The NMR probe head of claim 8 , at least one of the coils S 1 , S 2 is formed from at least N coil sections which are disposed on different planes, with at least N−1 through-contacts being provided through a dielectric, each electrically connecting two coil sections.
10. The NMR probe head of claim 9 , wherein one through-contact is not disposed on a crossing point in said respective coil S 1 , S 2 .
11. The NMR probe head of claim 1 , wherein said two coils S 1 , S 2 of said coil/resonator configuration A 1 are connected in parallel.
12. The NMR probe head of claim 1 , wherein said second coil/resonator configuration A 2 comprises at least one planar or saddle-shaped coil S 3 , said coil S 3 having a window about which N windings, connected in series, are disposed, wherein N≧2, said coil S 3 being mirror-symmetric relative to a central plane thereof which is perpendicular to said window.
13. The NMR probe head of claim 1 , wherein said coil/resonator configuration A 2 is a Birdcage resonator.
14. The NMR probe head of claim 1 , wherein impedances at feed lines of said coil/resonator configuration A 1 are selected such that, at a resonance frequency of said coil/resonator configuration A 2 , symmetric potentials form at said feed lines of said coil/resonator configuration A 1 .