RESEARCH INTO NEW APPROACHES FOR VHF FILTER CRYSTALS.
Quarterly rept. no. 5, 1 May-31 Jul 64,
CLEVITE CORP CLEVELAND OHIO ELECTRONIC RESEARCH DIV
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Two-dimensional energy-trapping theory, used previously to explain the behavior of fundamental mode AT-cut quartz resonators, has been extended to include the harmonic overtone modes and the inharmonic overtone series associated with each harmonic. These results predict a slightly less than integer relationship between fundamental and harmonic mode frequencies, and the manner in which previous data on resonator design might be extended for use at the harmonics. An initial set of 3rd harmonic experiments, with electrode length as a parameter, shows reasonable agreement with theory. A 50 Mc 5th harmonic mode resonator, with relatively large circular electrodes, was designed and fabricated in accordance with energy-trapping principles. The resulting unit has a resonant resistance of 130 ohms, a Q sub m of 133,000 and is free of spurious responses. A total of twenty multi-electrode resonator samples were fabricated. Included were ten 30 Mc and eight 60 Mc 3rd harmonic mode resonators and two 20 Mc fundamental mode resonators. Each multi-electrode crystal consisted of 4 dot-resonators electrically connected in parallel. The motional characteristics of the individual resonators added in the predicted manner to yield a single multi-electrode resonator. Author
- Electrical and Electronic Equipment