An NMR marginal oscillator for measuring magnetic fields below 50 mT

In order to measure or control magnetic fields in the flux density range from 50 mT down to 1 mT by means of NMR technique, a novel marginal oscillator has been developed. By observing proton resonance in an aqueous CuSO4 solution of about 2 cm3 sample volume, a signal-to-noise ratio of 50 dB has been obtained in a field with a flux density of 15 mT.