Scattering of a pulsed beam by a random medium over ground (Q2778766)

Electromagnetic backscattering from a layer of discrete random medium with a flat surface beneath, illuminated by a narrowband short radar pulse, is studied in the present paper. The transient response analysis is confined to a two-dimensional geometry, however, the same methodology of distorted Born approximation can be used to extend the results for the three-dimensional case. An aperture antenna with a Gaussian field distribution is assumed to be overlooking a medium which consists of small identical dielectric scatterers distributed randomly in space above a flat ground. The same antenna is used for both transmission and reception modes. The transmitted pulse train is assumed to be confined to a bandwidth significantly smaller than the carrier frequency. The received energy is decomposed into a coherent and an incoherent part associated respectively with the mean and fluctuating components of the received field at the antenna. An exact representation of the radiation patterns is achieved by means of the Gabor expansion [\textit{W. Schempp}, Harmonic analysis on the Heisenberg nilpotent Lie group, with applications to signal theory. Pitman Research Notes in Mathematics Series, Vol. 147, Longman Scientific and Technical, London (1986; Zbl 0632.43001)]. The background is assumed to be free space. The size of the particles is assumed to be small enough so that the incident beam does not decay or spread over any particle, and thus can be approximated by a local plane wave. NEWLINENEWLINENEWLINEThe problem can be considered as a simplified model for radar remote sensing of rain from space or remote sensing of ground covered with vegetation [\textit{J. Hyyppa} and \textit{M. Hallikainen}, A helicopter-borne eight-channel ranging scatterometer for remote sensing. II: Forest inventory. IEEE Geosci. Remote Sensing 31, 170-179 (1993); \textit{M. H. Newkirk} and \textit{G. S. Brown}, A waveform model for surface and volume scattering from ice and snow. IEEE Geosci. Remote Sensing 34, 444-456 (1996)]. Numerical results are presented and the behaviour of different scattering mechanisms is examined for various medium conditions.