Wideband characterisation of air coupled transducers

This paper describes a theoretical and experimental study on the use of wideband piezopolymer transducers (PVDF) for the determination of the through-air system impulse response, in both transmission and reception. A linear systems model was used to design a PVDF transmitter/receiver possessing a unipolar, planar and wideband impulse response for operation in air. The devices were tested in a water environment, to confirm the theoretical modelling approach, and then the model was utilised to predict the response-in air. The influence of frequency dependent airborne attenuation is included within the model to assist in the correlation between through water and through air calibration data. Good agreement between theory and experiment has been observed through the application of this modified model. The PVDF devices were then applied for evaluation of the impulse response of a range of through air transducers, including piezoceramics, piezocomposites and capacitive devices