G01R 33/3635 (20130101)
A double-tuned NMR sample excitation coil has a first end connected through a first balancing inductor to ground and a second end connected through a second balancing inductor to a low-frequency (LF) capacitor tuning and matching network. Two two balancing inductors have inductance less than 50% but greater than 10% that of the excitation coil. Each balancing coil is tuned by a capacitor network to an independent resonant frequency when disconnected from the sample coil that is less than 95% but greater than 60% of the final high frequency (HF) resonance. Moreover, both such independent resonant frequencies are equal within 10%. Broadband operation is possible under a variety of temperatures and the circuit works with high-speed sample spinners.
Doty; F. David (Columbia, SC)