Helicopter rotor-blade modulation of antenna radiation characteristics

Polycarpou, Anastasis C.; Balanis, C.A.; Stefanov, A.

doi:10.1109/8.929622

Cited by 23 publications

(6 citation statements)

References 12 publications

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“…The investigated memory effect is universal and can emerge in many wave-related disciplines and scenarios, e.g., optical, where molecules and even macroscopic structures are being rotated with laser beams [40][41][42][43][44] and optofluidics, where timedependent Purcell enhancements can emerge, 45,46 in radar, LIDAR, and sonar, where the micro-Doppler signatures produced by rotating blades of a helicopter are of interest, 34,47,48 and, even in astronomy, where neutron stars can be approximated by rotating dipoles. 49 Although the effects of rotation on scattering were comprehensively studied in the past (e.g., Refs.…”

Section: Summary and 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: Summary and Discussionmentioning

confidence: 99%

Memory effects in scattering from accelerating bodies

et al. 2020

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“…Similarly, the SNR with respect to a vibrating target, , can be described as in (12), shown at the bottom of the page. Based on (8), (10)- (12), the detection performance can be explicitly (12) Fig. 9.…”

Section: Target Detection Performance Analysismentioning

confidence: 99%

Effects of Non-Uniform Motion in Through-the-Wall SAR Imaging

Liu

Leung

Λαμπρόπουλος

2009

IEEE Trans. Antennas Propagat.

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Synthetic aperture radar (SAR) provides high resolution images that are well suited for through-the-wall target detection and recognition. As targets behind-the-wall undergo non-uniform motions, such as vibration, rotation and acceleration, their patterns can be recognized. To understand these signatures in through-the-wall SAR, we model and analyze the non-uniform motion-induced Doppler effect as well as the focused target SAR image. In particular, the wall effects on the focused SAR image and the micro-Doppler are formulated and analyzed. These analyses facilitate improving the target recognition performance by quantitatively estimating the parameters of the micro-Doppler signatures as well as the SAR imaging. We further analyze the detection performance of the non-uniform motion-induced target based on the generalized likelihood ratio test (GLRT) technique. The relationship between motion parameters and the detection performance allows us to evaluate the performance bound and the minimum detectable parameters.

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“…A vibrating structure is known to modulate reflected RF signals producing a received signal comprising the originally transmitted signal and sidebands offset by the frequency of vibration. This Doppler modulation is exploited in land mine detection [12], [13], but can be detrimental as in modulation by rotating helicopter rotor-blades [14]. The use of a standoff acoustic tone to drive mechanical vibrations subsequently detected by an RF signal has also been explored [13], [15].…”

Section: Introductionmentioning

confidence: 98%