ELECTRICAL MULTIPORT TRANSFER-FUNCTIONS AND EFFICIENCY IN LAYERED MEDIA OF PIEZOELECTRIC AND OR NONPIEZOELECTRIC MATERIALS

Electrical impedance parameters of a layered structure tapped at its interfaces and composed of piezoelectric and/or nonpiezoelectric strata are determined using the chain matrix approach. The method, within certain constraints, is applicable, whether the layers are disks, rings, or plates since the constraints ensure that each stratum behaves, to an approximation of negligible error, as a thickness vibrator. The most general case requires that the transverse dimensions of each layer be large in comparison to its thickness, insuring that the acoustical propagating modes are predominantly dilatational. The method is accurate for layers that are composed of uniaxially poled ceramics or when certain electrode geometries are used, since for these cases the dilatational modes are respectively uncoupled or very weakly coupled. Transducers and the acoustically coupled, piezoelectric core electrical transformer, or PT, are some of the devices that can be implemented from structures of layered media so that power and efficiency considerations are addressed within the context of multiple port networks.