Antenna device of a nuclear magnetic resonance (NMR) apparatus for exciting and/or receiving radio-frequency fields

摘要

The antenna device of a nuclear magnetic resonance apparatus contains for the purpose of exciting an at least largely homogeneous magnetic RF field and/or for receiving corresponding radio-frequency signals a hollow-cylindrical conductor sleeve which is sufficiently transmitting for low-frequency gradient fields. It contains, furthermore, inside the conductor sleeve a plurality of conductor groups made from a plurality of conductor elements which are connected in parallel and whose central axes lie on an imaginary lateral cylindrical surface concentric with the conductor sleeve, in addition means, reflecting the waves of the RF field, on the face ends of the device, as well as, finally, an external device for energy supply and/or signal processing. In this antenna device, the RF field is to be sufficiently homogeneous at least in the transverse direction. For this purpose, it is provided according to the invention that each conductor group (5, 6) contains conductor elements (8 to 17) of different conductor cross-section (q, q', q''). Inside each conductor group the conductor cross-sections of the conductor elements decrease at least substantially symmetrically when seen in the circumferential direction from the middle (plane S of symmetry) to the two edges. IMAGE