Resistive Losses in Acoustic Surface Wave Muitistrip Couplers

To analyze the effects of the finite resistivity of the metallic strips of a multistrip coupler for acoustic surface waves, the coupler is assumed to be composed of many parallel channels, each connected strip-by-strip through intervening lumped resistances. This method permits the calculation of the ohmic losses of couplers of arbitrary geometries even when that geometry is quite complicated. The method is applied here to many different examples such as J-type reflecting track changers, U-type reflectors, 90” corner reflectors, and unidirectional transducers. It is shown that for many of these coupler geometries there is an optimum aperture width in wavelengths which minimizes the ohmic losses. The calculated losses are consistent with measured values.