Interdigital transducer analysis using equivalent PSpice model.

Interdigital transducers generating surface acoustic waves have found numerous applications. The present paper deals with an equivalent model of a single interdigital transducer as well as an SAW filter complying with the PSpice programme for the analysis of electronic systems. The suggested model makes it possible to take into account such effects as interelectrode reflections, losses along the acoustic path and the electromagnetic coupling between the transducers. The obtained results of the analysis of an interdigital transducer comply with the results obtained basing on an admittance model and delta-function model. The final aim is to model an SAW oscillator.

Sensor properties of lead phthalocyanine in a surface acoustic wave system.

The paper presents experimental results of the interaction of thin layers (83 and 310 nm) of lead phthalocyanine (PbPc) with trace amounts of toxic gas NO2 in a system with an acoustic surface wave on a LiNbO3 Y-Z substrate. PbPc films were prepared according to the usual vacuum evaporation method. Measurements of the sensor properties rely on changes in the differential frequency, deltaf, of the dual-delay line configuration, in one of which the investigated PbPc layer has been placed. Special stress has been put on the temperature dependence of the reversibility in the medium range, i.e. between 27 degrees C and 95 degrees C. Besides, one simple method for thin PbPc film regeneration in a low NO2 concentration range has been presented.