A COUPLING-OF-MODES APPROACH TO THE ANALYSIS OF STW DEVICES

The dispersion characteristics of surface transverse waves (STW) on 36 degrees rotated Y-cut quartz have been analyzed numerically. A closed form dispersion relation has been derived and introduced in the equat ions of the coupling-of-modes (COM) theory to account for the variatio n of energy trapping with frequency. The transmission and reflection c oefficients at the finger edges have been determined from the stopband characteristics. Through the introduction of an electromechanical cou pling which varies linearly with the electrode mass loading, quantitat ive agreement with experimental results on two different types of two- port STW resonators has been achieved, and characteristic features hav e been explained.