Research and Development Program on NMR-EPR Communication Receiver-II.
Abstract
An investigation was made to develop further the state-of-the-art of audio frequency comb filters utilizing magnetic resonance techniques. The optically pumped vapor of Hg(199) was selected as an investigative medium because of the narrow bandedness (1Hz) and large signal-to-noise power ration (75 dB/Hz). Sample cells were improved so that a NMR S/N of 70 dB/Hz could be achieved for room temperature cells. A general theory and reduction to practice is presented for achieving arbitrary multi-passband filters through modulation of the static magnetic field. A parametric amplifier system investigated can be described as employing conventional Hg(199) NMR instrumentation plus a low level of modulation of H(o) field (to form a sideband structure on the spin precessional frequency spectrum) and an H1 field which is coincident with the sidebands nearest the carrier. Deviation from the theory occurs when H(1) > 100 H(1s). Suggestions are made for reducing these effects. Importantly, the parametric amplifier, similar to the Hg(199) NMR, was found to be Johnson noise limited and sensitive to a field of 0.066 micro-G/(Hz to the 1/2 power). (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1969
- Accession Number
- AD0853694
Entities
People
- Glenn E. Conklin
- Joseph R. Desanto