Nuclear magnetic resonance probe

In an NMR probe system of the type comprising substantially electromagnetically orthogonal RF transmitter and receiver coils, the said transmitter coil being divided into two halves, a balancing coil intermediate between said halves that is in RF signal transfer relationship with the receiver coil and electromagnetically coupled to both of said halves so that RF voltages of opposite phase are induced therein from one and other of said halves, and electrical trimmers of RF amplitude and phase associated with each transmitter half, whereby adjustment of said trimmers enables in operation a dominant RF voltage to be set up in the balancing coil that is of the correct phase and amplitude substantially to cancel any spurious RF voltage in the receiver coil due to stray induction effects.

In an NMR probe system of the type comprising substantially electromagnetically orthogonal RF transmitter and receiver coils, the said transmitter coil being divided into two halves, a balancing coil similarly divided into two halves with the half of one coil intermediate between the two halves of the other coil and electromagnetically coupled thereto so that RF voltages of opposite phase are induced in each balancing coil half from one and other transmitter half, the two balancing coil halves being connected so that the dominant induced RF voltage in one half aids the dominant induced RF voltage in the other half and the connected halves being in RF signal transfer relationship with the receiver coil, and electrical trimmers of RF phase and amplitude associated with each transmitter coil half, whereby adjustment of said trimmers enables in operation dominant RF voltages to be set up in the balancing coil halves which together provide the correct phase and amplitude substantially to cancel any spurious RF voltage in the receiver coil due to stray induction effects.