MODERN VHF FILTER CRYSTALS.
ARMY ELECTRONICS COMMAND FORT MONMOUTH N J
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With the advent of the trapped energy theory and experiments in which the electrode thickness was incorporated as an additional design criterion, design data are now available which permits the production of VHF filter crystals with a wide range of equivalent electric circuit parameters. It has been shown that in order to achieve consistent results when employing this technique, two factors must be rigorously adhered to 1 a high degree of accuracy must be maintained in the plating operation and 2 deviation from plate parallelism must be held to a minimum. The necessity of developing modern filter crystals in the VHF range is well dramatized in Figure 17 by showing the extent to which the crystal filter capabilities have been extended. In addition to the benefits which are obtained in the suppression of unwanted modes there is some indication that crystal Q can also be improved. Since the number of crystals measured possessing extremely parallel surfaces was limited, this data should not be taken as conclusive, but only to open the door to additional investigations of crystal Q-plate parallelism correlation. Author
- Electrical and Electronic Equipment