Coupled micro-Doppler signatures of closely located targets

Kozlov, Vitali; Kosulnikov, Sergei; Filonov, Dmitry; Schmidt, Andrey; Ginzburg, Pavel

doi:10.1103/physrevb.100.214308

Cited by 7 publications

(6 citation statements)

References 26 publications

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“…This timescale separation approach, when applicable, is a powerful tool for numeric simulations, as it allows the use of off-the-shelf static simulators in order to solve time-dependent problems (see Refs. [20][21][22]. However, as all approximations do, they also must have inaccuracies and scenarios where they fail.…”

Section: Discussionmentioning

confidence: 99%

“…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. This time-scale separation approach, when applicable, is a powerful tool for numeric simulations, as it allows the use of off-the-shelf static simulators in order to solve time dependent problems (see for example [20]- [22]). However, as all approximations do, they also must have inaccuracies and scenarios where they fail.…”

Section: Discussionmentioning

confidence: 99%

“…In the second case of quasi-CW, the pulse length is effectively longer than the characteristic time scale of the motion, hence the phase and amplitude modulation is imposed on the carrier frequency directly. In this case it is more instructive to look at the micro-Doppler frequency comb in the frequency domain [20], [21], [34], which is the spectral content within the quasi-CW pulse. In both cases, time-scale separation techniques are frequently applied for the scattering analysis [16].…”

Section: Quasi-stationary Methods For Numeric Time Dependent Simulati...mentioning

confidence: 99%

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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%

Section: Discussionmentioning

confidence: 99%

Section: Quasi-stationary Methods For Numeric Time Dependent Simulati...mentioning

confidence: 99%

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Memory effects in scattering from accelerating bodies

et al. 2020

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“…It is important to note that a time scale separation method is used to derive Eq. ( 1 ) 32 , 33 . Here the assumption is that any time-dependent changes in the varactor’s capacitance are far slower than the carrier frequency of the exciting radiation.…”

Section: Theory and Modellingmentioning

confidence: 99%

Broadband radar invisibility with time-dependent metasurfaces

Kozlov

Vovchuk

Ginzburg

2021

Sci Rep

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Concealing objects from interrogation has been a primary objective since the integration of radars into surveillance systems. Metamaterial-based invisibility cloaking, which was considered a promising solution, did not yet succeed in delivering reliable performance against real radar systems, mainly due to its narrow operational bandwidth. Here we propose an approach, which addresses the issue from a signal-processing standpoint and, as a result, is capable of coping with the vast majority of unclassified radar systems by exploiting vulnerabilities in their design. In particular, we demonstrate complete concealment of a 0.25 square meter moving metal plate from an investigating radar system, operating in a broad frequency range approaching 20% bandwidth around the carrier of 1.5 GHz. The key element of the radar countermeasure is a temporally modulated coating. This auxiliary structure is designed to dynamically and controllably adjust the reflected phase of the impinging radar signal, which acquires a user-defined Doppler shift. A special case of interest is imposing a frequency shift that compensates for the real Doppler signatures originating from the motion of the target. In this case the radar will consider the target static, even though it is moving. As a result, the reflected echo will be discarded by the clutter removal filter, which is an inherent part of any modern radar system that is designed to operate in real conditions. This signal-processing loophole allows rendering the target invisible to the radar even though it scatters electromagnetic radiation.

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“…It is important to note that a time scale separation method is used to derive Eq. 1 31 . Here the assumption is that any time-dependent changes in the varactor's capacitance are far slower than the carrier frequency of the exciting radiation.…”

Section: Controlling the Scattered Phase From A Single Dipolementioning

confidence: 99%

Broadband Radar Invisibility with Time-Dependent Metasurfaces

Kozlov

Vovchuk

Ginzburg

2021

Preprint

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Concealing objects from interrogation has been a primary objective since the integration of radars into surveillance systems. Metamaterial-based invisibility cloaking, which was considered a promising solution, did not yet succeed in delivering reliable performance against real radar systems, mainly due to its narrow operational bandwidth. Here we propose an approach, which addresses the issue from a signal-processing standpoint and, as a result, is capable of coping with the vast majority of unclassified radar systems by exploiting vulnerabilities in their design. In particular, we demonstrate complete concealment of a 0.25 square meter moving metal plate from an investigating radar system, operating in a broad frequency range approaching 20% bandwidth around the carrier of 1.5GHz. The key element of the radar countermeasure is a temporally modulated coating. This auxiliary structure is designed to dynamically and controllably adjust the reflected phase of the impinging radar signal, which acquires a user-defined Doppler shift. A special case of interest is imposing a frequency shift that compensates for the real Doppler signatures originating from the motion of the target. In this case the radar will consider the target static, even though it is moving. As a result, the reflected echo will be discarded by the clutter removal filter, which is an inherent part of any modern radar system that is designed to operate in real conditions. This signal-processing loophole allows rendering the target invisible to the radar even though it scatters electromagnetic radiation.

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Coupled micro-Doppler signatures of closely located targets

Cited by 7 publications

References 26 publications

Memory effects in scattering from accelerating bodies

Memory effects in scattering from accelerating bodies

Broadband radar invisibility with time-dependent metasurfaces

Broadband Radar Invisibility with Time-Dependent Metasurfaces

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