Analysis and compensation of metal resistivity effects in apodized SAW transducers

A method for the modeling of electrode resistance effects within apodized SAW (surface acoustic wave) transducers is presented The transducer is treated as a two-dimensional distributed network and analyzed by the standard methods of network theory. Electrostatic and acoustic interactions are fully taken into account. A full-scale numerical analysis based on a track division approach and an iterative solution of the network equations is presented. The computing time has been reduced to an acceptable level by using a quasi-equidistant track division scheme. The calculated deviation of the transfer function due to the resistivity of the metal is used to correct the result of the diffraction simulation. Metal resistivity and diffraction effects were compensated simultaneously in an in-line filter with a 40% relative bandwidth. The passband and stopband characteristics can be improved over those of an identical design compensated for diffraction only