Experimental and Theoretical Mid-Series Characteristic Impedance of Acoustic Wave Filters

Abstract

The simplified theory of Stewart and the less approximate theory of Mason are compared with experimental measurements with respect to the mid-series characteristic acoustic impedance of a high-pass, a low-pass and a single-band-pass filters. The comparison is made over a large range of frequencies including a considerable portion of both the attenuation and transmission regions. There is remarkable agreement between theory and experiment, considering the approximations that are made in the theories. For the low-pass filter there seems to be no appreciable advantage of the more accurate theory of Mason. In the other two cases, however, there is a distinct superiority for this theory. For purposes of ascertaining cut-offs, and the characteristic impedance for the low-pass filter, the simpler theory of Stewart is more readily applicable.