Gravitation

Bladel, J. Van

doi:10.1007/978-3-642-69198-0_8

Cited by 6 publications

(8 citation statements)

References 18 publications

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“…In particular, when the dipole is perpendicular to the polarization of the incident field, its moment will be identically zero, as is the case for the static dipole. This time scale separation method, also referred to as quasi-stationarity or adiabatic [10], [11], is reminiscent of similar approaches, such as the slowly varying amplitude approximation and short time Fourier transform (STFT) methods [15]. These approximations are especially prevalent in applied fields such as radar and sonar [16]- [19] , where the typical velocity of scatterers is far smaller than that of the velocity of the impinging waves.…”

Section: Discussionmentioning

confidence: 99%

Memory effects in scattering from accelerating bodies

et al. 2020

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Interaction of electromagnetic, acoustic, and even gravitational waves with accelerating bodies forms a class of nonstationary time-variant processes. Scattered waves contain intrinsic signatures of motion, which manifest in a broad range of phenomena, including Sagnac interference, and both Doppler and micro-Doppler frequency shifts. Although general relativity is often required to account for motion, instantaneous rest frame approaches are frequently used to describe interactions with slowly accelerating objects. We investigate theoretically and experimentally an interaction regime that is neither relativistic nor adiabatic. The test model considers an accelerating scatterer with a long-lasting relaxation memory. The slow decay rates violate the instantaneous reaction assumption of quasistationarity, introducing non-Markovian contributions to the scattering process. Memory signatures in scattering from a rotating dipole are studied theoretically, showing symmetry breaking of micro-Doppler combs. A quasistationary numeric analysis of scattering in the short-memory limit is proposed and validated experimentally with an example of electromagnetic pulses interacting with a rotating wire.

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Section: Discussionmentioning

confidence: 99%

Memory effects in scattering from accelerating bodies

et al. 2020

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“…For homogeneous and isotropic dielectric and magnetic materials, we have the following constitutive relations [17][18][19][20][21][22]…”

Section: Maxwell Equationsmentioning

confidence: 99%

Lorentz Transformation in Maxwell Equations for Slowly Moving Media

Sheng¹,

Li²,

Pu³

et al. 2022

Symmetry

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We use the method of field decomposition, a widely used technique in relativistic magnetohydrodynamics, to study the small velocity approximation (SVA) of the Lorentz transformation in Maxwell equations for slowly moving media. The “deformed” Maxwell equations derived using SVA in the lab frame can be put into the conventional form of Maxwell equations in the medium’s co-moving frame. Our results show that the Lorentz transformation in the SVA of up to O(v/c) (v is the speed of the medium and c is the speed of light in a vacuum) is essential to derive these equations: the time and charge density must also change when transforming to a different frame, even in the SVA, not just the position and current density, as in the Galilean transformation. This marks the essential difference between the Lorentz transformation and the Galilean one. We show that the integral forms of Faraday and Ampere equations for slowly moving surfaces are consistent with Maxwell equations. We also present Faraday equation in the covariant integral form, in which the electromotive force can be defined as a Lorentz scalar that is independent of the observer’s frame. No evidence exists to support an extension or modification of Maxwell equations.

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“…Te frame hopping method (FHM) is an analytical method based on the theory of relativity, which solves the scattering felds in the comoving frame and transforms the scattering felds back to the laboratory frame. Te FHM method is used to obtain the exact solution of the scattering from a perfectly conducting half plane in relativistic uniform motion in [18]. Despite signifcant progress in analytical and asymptotic methods, obtaining exact scattering solutions for arbitrarily shaped and composed moving objects remains a challenging task.…”

Section: Introductionmentioning

confidence: 99%

Relativistic Bistatic Scattering of a High-Speed Moving Plasma Coated Object

Ren

Kuang

Gao

et al. 2023

International Journal of Antennas and Propagation

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Accurate modeling of relativistic electromagnetic scattering characteristics from high-speed motion of plasma coated objects is crucial for the development of hypersonic aircraft and their applications in the identification and surveillance of moving stealth targets. Nevertheless, a solution for bistatic polarized radar cross sections (RCSs) from a 3-D object with plasma coated layer in motion has yet to be obtained. This manuscript proposes a solution to this problem by employing a combination of the auxiliary differential equation (ADE) method with Lorentz finite-difference time-domain (FDTD) method. Utilizing the Lorentz transformation, this paper presents the transformation of parameters of the incident plane wave and dimensions of the object between the laboratory system that remains static and the rest system that remains stationary relative to the object in high-speed motion. The near-zone electromagnetic fields near the object are computed using the ADE method in the rest system, after which the near-field to far-field (NF-FF) transformation is employed to obtain the far-zone polarized scattered field. By applying Lorentz transformation to the coordinates, this paper presents a solution for the polarized scattering from moving plasma coated objects. Especially, radial components of the polarized scatterings are analyzed. The proposed method is validated through several numerical experiments, demonstrating its efficiency and accuracy.

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Gravitation

Cited by 6 publications

References 18 publications

Memory effects in scattering from accelerating bodies

Memory effects in scattering from accelerating bodies

Lorentz Transformation in Maxwell Equations for Slowly Moving Media

Relativistic Bistatic Scattering of a High-Speed Moving Plasma Coated Object

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