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Reliable electromagnetic simulators are of prime importance for the design of radar sounder instruments and for supporting the subsequent analysis of their data. In this paper, we present a coherent, facet method-based simulator that can compute radar echoes from the subsurface of a target area with an arbitrary number of geological layers, thus going beyond the surface-only or the two-layer descriptions so far implemented in coherent ray-tracing radar sounder simulators. Propagation of fields throughout the subsurface is computed according to Snell’s law following a ray-tracing approach. For each ray interacting with the surface, be it a direct reflection or a refracted ray coming from the subsurface, the phase contribution of each facet is calculated through the linear phase approximation, while the total field received at the antenna is computed using Huygen’s principle. Validation simulations have been performed against the radar data of lunar and martian areas characterized by a multilayer nature and collected by the Lunar Radar Sounder instrument of JAXA’s Kaguya lunar probe and the Shallow Radar instrument onboard NASA’s Mars Reconnaissance Orbiter, respectively. Results confirm the effectiveness of the proposed simulator. [ABSTRACT FROM AUTHOR]

An approach to the detection of specific polarimetric SAR signatures is presented. The polarimetric response in a resolution cell can be viewed as a sample of the electromagnetic scattering matrix for that resolution cell. Through the use of multiple coherent apertures, multiple samples of the scattering matrix can be obtained. With the use of a suitable decomposition and a weighted log-likelihood formulation, it is possible to estimate the relative likelihoods that the observed scattering matrix responses match known electromagnetic signatures. [ABSTRACT FROM AUTHOR]

This paper extends prior work by Cameron and Rais to define new multidimensional representations of the reciprocal scatterer space and the general polarization scatterer space, including distance metric definitions for these representations. The relationship between the maximum symmetric scatterer type and the maximum value that can be attained by the asymmetry parameter is derived to determine the shape of the polarization reciprocal scatterer space. Moreover, a metric is derived for this space that reduces to the symmetric scatterer space metric when the asymmetry parameter is zero. These results are extended to the general polarization scatterer space by defining a metric on the polarization scatterer space that reduces to the polarization reciprocal scatterer metric when the reciprocity parameter \thetarec is zero. [ABSTRACT FROM AUTHOR]

An alternate definition of the asymmetry parameter \tau, appearing in the Cameron decomposition is presented. The new definition is signed as \taus, but in absolute value, it is equivalent to the previous definition. The Cameron decomposition signed asymmetry parameter \taus is given in terms of the Huynen decomposition parameters, including but not limited to the Huynen helicity (asymmetry) parameter. It is demonstrated that the Huynen decomposition asymmetry parameter is a poor indicator of scatterer symmetry. The relationship between the Cameron and Huynen decomposition parameters is examined for special cases. [ABSTRACT FROM PUBLISHER]

The Kennaugh-Huynen scattering matrix con-diagonalization is projected into the Pauli basis to derive a new scattering vector model for the representation of coherent target scattering. This model permits a polarization basis invariant representation of coherent target scattering in terms of five independent target parameters, the magnitude and phase of the symmetric scattering type introduced in this paper, and the maximum polarization parameters (orientation, helicity, and maximum return). The new scattering vector model served for the assessment of the Cloude-Pottier incoherent target decomposition. Whereas the Cloude-Pottier scattering type α and entropy H are roll invariant, βand the so-called target-phase parameters do depend on the target orientation angle for asymmetric scattering. The scattering vector model is then used as the basis for the development of new coherent and incoherent target decompositions in terms of unique and roll-invariant target parameters. It is shown that both the phase and magnitude of the symmetric scattering type should be used for an unambiguous description of symmetric target scattering. Target helicity is required for the assessment of the symmetry-asymmetry nature of target scattering. The symmetric scattering type phase is shown to be very promising for wetland classification in particular, using polarimetric Convair-580 synthetic aperture radar data collected over the Ramsar Mer Bleue wetland site to the east of Ottawa, ON, Canada. [ABSTRACT FROM AUTHOR]