Influence of ballistics to diffusion transition in primary wave propagation on parametric antenna operation in granular media.
A model of parametric transmitting antenna in granular media is developed, which takes into account velocity dispersion, frequency-dependent absorption, and frequency-dependent scattering of acoustic waves in granular media. The latter process may induce a transition from the ballistics to the diffusion regime of pump (primary) high-frequency wave propagation with increasing frequency. The conditions under which the transition from ballistics to diffusion manifests itself in the change of the demodulated (rectified) low-frequency acoustic pulse profile are established. It is demonstrated that parametric low-frequency radiation contains information on both absorption and scattering of high-frequency acoustic waves.
Tournat
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Laboratoire d'Acoustique de l'Université du Maine UMR-CNRS 6613, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans cedex 09, France.
Gusev
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Castagnède
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B