Diagnostic magnetic resonance apparatus having a radio frequency shield between the radio frequency antenna and the gradient coil system

Claim 1

A diagnostic magnetic resonance apparatus comprising: means for defining an examination space for accepting at least part of an examination subject; means for generating a basic magnetic field in said examination space; gradient coil means for generating a plurality of gradient magnetic fields in said examination space superimposed on said basic magnetic field; radio frequency antenna means for transmitting excitation pulses into said examination subject in said examination space in the presence of said basic magnetic field and said gradient fields, and thereby causing said examination subject to produce magnetic resonance signals, and for receiving said magnetic resonance signals, said radio-frequency antenna means being disposed closer to said examination space than is said gradient coil means; and a radio-frequency shield disposed between said radio-frequency antenna means and said gradient coils means, said radio-frequency shield comprising a first electrically conductive layer and a second electrical conducive layer disposed opposite said first electrical conductive layer, a dielectric disposed between said first and second electrically conductive layers, each of said first and second electrically conductive layers having a plurality of interconnects disposed side-by-side and separated from each other by electrically insulating slots, said slots in the respective first and second electrically conductive layers being disposed offset relative to each other, and adjacent interconnects in at least one of said first and second electrically conductive layers being connected to each other by respective bridges which conduct high-frequency currents, said bridges being disposed in an arrangement preventing inducement of ring currents, having a resonant frequency approximating an operating frequency of the magnetic resonance apparatus, over a plurality of said interconnects, said bridges being disposed on the as least one electrically conductive layer causing currents induced in said at least one electrically conductive layer by said radio-frequency means to flow between said adjacent interconnects substantially only via said bridges.