Data-driven linearizing approach in inverse scattering.

Direct or forward wave scattering admits three classical regimes in which the map from scatterer properties or scattering potential to the data is linear, namely, the Born, Rytov, and physical optics approximations. In this paper we derive a new decomposition of the forward scattering map which reveals a previously unknown approximate bilinear forward scattering relation. The latter is data-driven, i.

Generalized likelihood ratio test change detection with optical theorem constraint.

We demonstrate a new application of the optical theorem to enhance the detection, from noisy scattering data, of an unknown scatterer embedded in an unknown background medium. The proposed methodology is based on a generalized likelihood ratio test detector with an additional constraint that must be obeyed by the scattered field data if the scatterer is known to be passive, lossless, or active. The constraint in question is based on the classical optical theorem, which is used throughout this paper in its most general form applicable to arbitrary probing fields and background media.

Nonuniqueness of optical theorem detectors.

We demonstrate and discuss the multitude of ways in which the extinct power of a scatterer can be measured. To tie some of the developed results to the classical statement of the optical theorem involving the imaginary part of the forward-scattering amplitude, particular attention is given to plane wave excitation. On the other hand, the general results apply to more general probing fields including near fields carrying evanescent components.

Radiation enhancement due to metamaterial substrates from an inverse source theory.

In this paper the formalism of the electromagnetic inverse source theory is used to investigate radiation enhancement due to antenna substrates. Particular attention is given to sources that are confined within a spherical volume and are embedded within two nested spheres of arbitrary materials. Emphasis is given to the special case when the two nested spheres are made up of materials with oppositely signed constitutive parameters.

Illustration of the role of multiple scattering in subwavelength imaging from far-field measurements.

Recently it has been proposed that the classical diffraction limit could be overcome by taking into account multiple scattering effects to describe the interaction of a probing wave and the object to be imaged [Phys. Rev. E73, 036619 (2006)].

Intensity-only signal-subspace-based imaging.

A signal-subspace method is derived for the localization and imaging of unknown scatterers using intensity-only wave field data (lacking field phase information). The method is an extension of the time-reversal multiple-signal-classification imaging approach to intensity-only data. Of importance, the derived methodology works within exact scattering theory including multiple scattering.

Time-reversal MUSIC imaging of extended targets.

This paper develops, within a general framework that is applicable to rather arbitrary electromagnetic and acoustic remote sensing systems, a theory of time-reversal "MUltiple Signal Classification" (MUSIC)-based imaging of extended (nonpoint-like) scatterers (targets). The general analysis applies to arbitrary remote sensing geometry and sheds light onto how the singular system of the scattering matrix relates to the geometrical and propagation characteristics of the entire transmitter-target-receiver system and how to use this effect for imaging. All the developments are derived within exact scattering theory which includes multiple scattering effects.

Noniterative analytical formula for inverse scattering of multiply scattering point targets.

This paper derives, in the exact framework of multiple scattering theory for point targets, a noniterative analytical formula for the nonlinear inversion of the target scattering strengths from the scattering or response matrix that can be applied after the target positions have been estimated in a previous step via, e.g., time-reversal multiple signal classification or another approach.

Generalized power-spectrum Larmor formula for an extended charged particle embedded in a harmonic oscillator.

The nonrelativistic Larmor radiation formula, giving the power radiated by an accelerated charged point particle, is generalized for a spatially extended particle in the context of the classical charged harmonic oscillator. The particle is modeled as a spherically symmetric rigid charge distribution that possesses both translational and spinning degrees of freedom. The power spectrum obtained exhibits a structure that depends on the form factor of the particle, but reduces, in the limit of an infinitesimally small particle and for the charge distributions considered, to Larmor's familiar result.

Observations on "nonradiating surface sources": comment.

The proof, established in a recent paper [A. J. Devaney, "Nonradiating surface sources," J.

Nonradiating sources with connections to the adjoint problem.

A general description of localized nonradiating (NR) sources whose generated fields are confined (nonzero only) within the source's support is developed that is applicable to any linear partial differential equation (PDE) including the usual PDEs of wave theory (e.g., the Helmholtz equation and the vector wave equation) as well as other PDEs arising in other disciplines.