Characterizing Resonators with S-Parameter Network Analyzers

Resonators, such as quartz crystal, surface acoustic wave (SAW) grooved reflectors, and dielectric resonators are widely used in frequency control, timing, and filter applications. However, inadequate understanding of these devices usually results in designs that do no live up to expectations; whether they operate at unwanted frequencies, have an unexpected "Q", or are less reliable or manufacturable. What follows is a description of an accurate and repeatable technique for converting transmission and reflection measurements ( in the form of S-parameters ) of resonators into an equivalent electrical circuit. The equivalent electrical circuit parameters can then be used to specify the characteristics of resonator. These parameters are also extremely useful in the design of filters and oscillators which use resonators.