Abstract: A shim coil assembly for positioning shim coils in a narrow gap between magnetic poles of miniature NMR devices around the magnetic center includes electric traces on multiple levels of printed circuit board layers in various, overlapping configurations. Mirror image shim coils can be connected in series in a symmetric sense or connected in series in a antisymmetric sense.

Abstract: A method is provided for acquiring multiple NMR response signal data in rapid succession for averaging NMR spectral data from a sample. The fluid sample is placed in a capillary that extends through the magnetic field of the NMR spectrometer, including through the center of the magnetic field to place a segment of the sample in the magnetic center. After the sample fluid, initially magnetized by the magnetic field, is activated to emit an NMR pulse signal, the fluid in the capillary is advanced rapidly to put another pre-magnetized segment of the sample fluid in the fluid center, acquiring an NRM pulse signal, and continuing the cycle until a desired number of NMR response data signals from the sample have been acquired. Those response data from multiple acquisitions are then averaged.

Abstract: A capillary cartridge assembly for positioning a sample fluid at a geometric center between juxtaposed pole pieces of a NMR magnet assembly for NMR analysis comprises a capillary captured in a channel in a printed circuit board assembly that is sized to fit between the pole pieces. The assembly includes a RF coil surrounding a portion of the capillary. Electric traces shaped to function as shim coils can be included in the printed circuit board. An end of the printed circuit board includes electrically conductive contacts that plug into a receptacle to connect the RF coil and traces to external electrical circuitry when the RF coil is in the geometric center. The capillary can be a continuous flow-through capillary or a closed cartridge.

Abstract: A single-pole, double-throw, transmit/receive switch for switching a NMR coil between a transmit mode and a receive mode comprises two diode bridge switches on opposites sides of a node the is common with the two diode bridges and the NMR coil. One of the two diode bridges is positioned between the coil and a preamplifier for signals received from the coil, and the other diode bridge is positioned between the coil and a RF signal transmitter for connecting and disconnecting transmitted signals to and from the coil. The NMR coil is connected to the switches through a resonant impedance matching network.