Characterization of radar cross section of carbon fiber composite materials

Riley, Elliot J.; Lenzing, Erik H.; Narayanan, Ram M.

doi:10.1117/12.2176750

Cited by 3 publications

(4 citation statements)

References 4 publications

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“…The structure of the drone is designed to allow flight at high altitudes, e.g., thanks to long propellers (wingspan = 780 mm). Where possible, such as in the propellers and the lower part of the drone, carbon fiber parts are dropped in favor of high-quality plastics to reduce radar-wave absorption by carbon fiber [23]. We observed more noise when a GPR antenna is mounted on not-specifically designed drones, as in some of our (unpublished) tests with commercial drones.…”

Section: Drone Coupled With Gpr Antennasupporting

confidence: 55%

Drone-Borne Ground-Penetrating Radar for Snow Cover Mapping

2022

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Ground-penetrating radar (GPR) is one of the most commonly used instruments to map the Snow Water Equivalent (SWE) in mountainous regions. However, some areas may be difficult or dangerous to access; besides, some surveys can be quite time-consuming. We test a new system to fulfill the need to speed up the acquisition process for the analysis of the SWE and to access remote or dangerous areas. A GPR antenna (900 MHz) is mounted on a drone prototype designed to carry heavy instruments, fly safely at high altitudes, and avoid interference of the GPR signal. A survey of two test sites of the Alpine region during winter 2020–2021 is presented, to check the prototype performance for mapping the snow thickness at the catchment scale. We process the data according to a standard flow-chart of radar processing and we pick both the travel times of the air–snow interface and the snow–ground interface to compute the travel time difference and to estimate the snow depth. The calibration of the radar snow depth is performed by comparing the radar travel times with snow depth measurements at preselected stations. The main results show fairly good reliability and performance in terms of data quality, accuracy, and spatial resolution in snow depth monitoring. We tested the device in the condition of low snow density (<200 kg/m3) and this limits the detectability of the air–snow interface. This is mainly caused by low values of the electrical permittivity of the dry soft snow, providing a weak reflectivity of the snow surface. To overcome this critical aspect, we use the data of the rangefinder to properly detect the travel time of the snow–air interface. This sensor is already installed in our prototype and in most commercial drones for flight purposes. Based on our experience with the prototype, various improvement strategies and limitations of drone-borne GPR acquisition are discussed. In conclusion, the drone technology is found to be ready to support GPR-based snow depth mapping applications at high altitudes, provided that the operators acquire adequate knowledge of the devices, in order to effectively build, tune, use and maintain a reliable acquisition system.

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Section: Drone Coupled With Gpr Antennasupporting

confidence: 55%

Drone-Borne Ground-Penetrating Radar for Snow Cover Mapping

2022

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“…It is noted that most of the composites research is focused on the mechanical properties, which have been thoroughly studied and well documented. In comparison, the work on radar interference, radar cross section (RCS), lightning discharge and electromagnetic shielding were conducted by only measuring the electromagnetic (EM) responses (e.g., reflectance and absorption) of the composite structure [4][5][6]. The EM properties (or dielectric properties) of the materials were not fully investigated, which impedes their full use for radio frequency (RF) applications.…”

Section: Introductionmentioning

confidence: 99%

X-band microwave characterisation and analysis of carbon fibre-reinforced polymer composites

Haigh

Soutis

et al. 2019

Composite Structures

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In this paper, a detailed investigation of the electromagnetic (EM) properties of carbon fibre-reinforced polymer composites (CFRP) is presented. The electric permittivity, electrical conductivity, signal penetration and microwave absorption are discussed. Unidirectional composite laminate samples were characterised over X band (8-12 GHz) using the microwave transmission line technique. It is shown that the real part of the permittivity of the composites is not significantly anisotropic whereas the imaginary part is highly anisotropic. More microwave energy is reflected in the parallel case, while more energy is absorbed in the orthogonal case. These experimental results are studied at three geometric levels: macro-meso scale (laminate/lamina level) relating to lay-up and fibre direction dependence, microscale (fibre level) relating to the real part of permittivity and nanoscale level relating to imaginary part of permittivity. The findings can contribute to improved design of carbon fibre composites for electromagnetic applications, like shielding, curing and non-destructive inspection.

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“…There, the reflector is mounted in fixed orientations and material orientation is not considered. Riley et al present measurements of the radar cross section of twill-weave CFRP in [5], but only in a mono-static set-up and sample orientation was not considered. Artner et al estimate the conductivity of twill-CFRP from wave-guide measurements at 4-6 GHz with the Nicolson-Ross-Weir method in steps of 10 • [6].…”

Section: Introductionmentioning

confidence: 99%

“…Measurements of CFRP reflectivity and conductivity consider mostly unidirectional fibres and few material orientations [4][5][6]. High precision reflectivity measurements in the range of 110-200 GHz of unidirectional CFRP measured in the fibre direction and perpendicular to the fibre direction are conducted with a Fabry-Perot resonator in [4].…”

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confidence: 99%