22 August 2000 Acoustic and electromagnetic wave interaction: a technique for detection of buried objects
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Abstract
The idea of using acoustically induced Doppler spectra as a means for target detection and identification is introduced. To demonstrate feasibility of such a technique, an analytical solution for the calculation of the bistatic scattered Doppler spectrum from an acoustically excite, vibrating dielectric circular cylinder is presented. In this paper, the incident plane wave is assumed to be polarized along the axis of the cylinder is presented. In this paper, the incident plane wave is assumed to be polarized along the axis of the cylinder. A perturbation method is developed to calculate the electromagnetic scattering from a slightly deformed and inhomogeneous dielectric cylinder. Then, assuming the vibration frequency is much smaller than the frequency of the incident electromagnetic wave, a closed form expression for the time-frequency response of the bistatic scattered field is obtained. The solution for acoustic scattering from a solid elastic cylinder is applied to give the displacement on the surface as well as the compression and dilation within the cylinder. Both the surface displacement and the variation in material density within the cylinder contribute to the Doppler component of the of the electromagnetic scattered field. Results indicate that the scattered Doppler frequencies correspond to the mechanical vibration frequencies of the cylinder, and the sidelobe Doppler spectrum level is, to the first order, linearly proportional to the degree of deformation and is a function of bistatic angle. Moreover, the deformation in the cylinder, and thus the Doppler sidelobe level, only becomes sizeable near frequencies of normal modes of free vibration in the cylinder. These resonant frequencies are found to depend only on the object properties and are independent of the surrounding medium. Utilizing the information in the scattered Doppler spectrum could provide an effective means of buried object identification, where acoustic waves are used to excite the mechanical resonances of a buried object.
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Kamal Sarabandi, Daniel E. Lawrence, "Acoustic and electromagnetic wave interaction: a technique for detection of buried objects", Proc. SPIE 4038, Detection and Remediation Technologies for Mines and Minelike Targets V, (22 August 2000); doi: 10.1117/12.396305; https://doi.org/10.1117/12.396305
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