Axel Friedrich

CIRCULARLY POLARIZING LOCAL ANTENNA FOR A NUCLEAR MAGNETIC RESONANCE IMAGING APPARATUS

A local antenna system for generating and receiving circularly-polarized, high-frequency magnetic fields in a nuclear magnetic resonance imaging apparatus has two coil groups disposed to define an examination volume therebetween, with each coil group having two coils therein, with each coil having a middle axis disposed at an angle substantially less than 90° relative to the middle axis of the other coil in that group. The coil groups are disposed relative to the examination volume so that each coil in a coil group has a diagonally disposed counterpart coil in the other coil group. When the diagonally coils are respectively fed with currents which are phase-shifted by 90° relative to each other, they respectively generate circularly-polarized high-frequency magnetic fields in the examination volume which are in-phase. In a reception mode, the signals induced in the diagonally disposed coils are superimposed in-phase.