Design of low frequency AT-cut quartz resonators

This paper covers the results of a study of CR-18/U crystal unit design in the frequency range 800 KC to 3000 KC. The choice of suitable design parameters for a plano-convex or a bi-convex plate of a given frequency involves finding a combination of plate diameter and surface curvature that will minimize the effects of unwanted modes of vibration within the operating temperature range. Satisfactory design parameters have been found for plano-convex plates in the frequency range 1400 KC to 3000 KC and for bi-convex plates down to 800 KC.