Radar cross section of triangular trihedral reflector with extended bottom plate.

Brock, Billy C.; Doerry, Armin W.

doi:10.2172/984946

Cited by 15 publications

(12 citation statements)

References 4 publications

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“…Our reference targets are two triangular trihedral reflectors (also known as corner reflectors) composed of three orthogonal triangular conducting plates. Trihedral targets have a large RCS for their size and a low angular variability in RCS around their boresight (Atlas, 2002;Brock and Doerry, 2009;Chandrasekar et al, 2015). One reflector has a size parameter of 10 cm, with a maximum theoretical RCS at our radar operation frequency of 16.30 dBsm.…”

Section: Equations Used In Radar Calibrationmentioning

confidence: 99%

Absolute calibration method for frequency-modulated continuous wave (FMCW) cloud radars based on corner reflectors

et al. 2020

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Abstract. This article presents a new cloud radar calibration methodology using solid reference reflectors mounted on masts, developed during two field experiments held in 2018 and 2019 at the Site Instrumental de Recherche par Télédétection Atmosphérique (SIRTA) atmospheric observatory, located in Palaiseau, France, in the framework of the Aerosol Clouds Trace gases Research InfraStructure version 2 (ACTRIS-2) research and innovation program. The experimental setup includes 10 and 20 cm triangular trihedral targets installed at the top of 10 and 20 m masts, respectively. The 10 cm target is mounted on a pan-tilt motor at the top of the 10 m mast to precisely align its boresight with the radar beam. Sources of calibration bias and uncertainty are identified and quantified. Specifically, this work assesses the impact of receiver compression, temperature variations inside the radar, frequency-dependent losses in the receiver's intermediate frequency (IF), clutter and experimental setup misalignment. Setup misalignment is a source of bias, previously undocumented in the literature, that can have an impact of the order of tenths of a decibel in calibration retrievals of W-band radars. A detailed analysis enabled the quantification of the importance of each uncertainty source to the final cloud radar calibration uncertainty. The dominant uncertainty source comes from the uncharacterized reference target which reached 2 dB. Additionally, the analysis revealed that our 20 m mast setup with an approximate alignment approach is preferred to the 10 m mast setup with the motor-driven alignment system. The calibration uncertainty associated with signal-to-clutter ratio of the former is 10 times smaller than for the latter. Following the proposed methodology, it is possible to reduce the added contribution from all uncertainty terms, excluding the target characterization, down to 0.4 dB. Therefore, this procedure should enable the achievement of calibration uncertainties under 1 dB when characterized reflectors are available. Cloud radar calibration results are found to be repeatable when comparing results from a total of 18 independent tests. Once calibrated, the cloud radar provides valid reflectivity values when sampling midtropospheric clouds. Thus, we conclude that the method is repeatable and robust, and that the uncertainties are precisely characterized. The method can be implemented under different configurations as long as the proposed principles are respected. It could be extended to reference reflectors held by other lifting devices such as tethered balloons or unmanned aerial vehicles.

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Section: Equations Used In Radar Calibrationmentioning

confidence: 99%

Absolute calibration method for frequency-modulated continuous wave (FMCW) cloud radars based on corner reflectors

et al. 2020

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“…Furthermore, an azimuth deviation of less than 0.5° and elevation deviation of less than 0.5° could introduce no more than 0.5-dB RCS loss at the X-band. However, a pointing deviation of less than 0.5° in azimuth and elevation could make the resulting RCS within about 0.1 dB of the peak value for monostatic calibration [25]. By comparing the two results, we found that the RCS loss due to pointing deviation was more severe for bistatic calibration.…”

Section: Pointing Deviationmentioning

confidence: 84%

“…Consider a TCR with sides comprised of isosceles right triangles. With the geometry defined as per Figure 4, by using geometrical optics approximation theory, the RCS of a TCR can be formulated as [25]:…”

Section: Monostatic Bistatic Equivalence Theoremmentioning

confidence: 99%

Feasibility, Design, and Deployment Requirements of TCR for Bistatic SAR Radiometric Calibration

et al. 2018

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The trihedral corner reflector (TCR) is widely used as the calibration device in monostatic synthetic aperture radar (SAR) calibration, and the performance of the TCR in radiometric calibration has been studied and verified in depth. As for the bistatic SAR system calibration problem, there have been few published studies. There is a lack of knowledge regarding the exact bistatic radar cross-section (RCS) pattern of TCR with different bistatic angles, and it is also not clear whether the TCR can be used as the calibration target in bistatic SAR. Moreover, the bistatic and monostatic radar cross-section (RCS) characteristics of the TCR are different, even if the bistatic angle is very small. Therefore, the feasibility, design, and deployment requirements of the TCR for bistatic SAR calibration should be carefully investigated. In this paper, we outline the theoretical and practical requirements that need to be satisfied when choosing appropriate calibration devices for bistatic radiometric calibration. Based on these requirements, we analyzed the bistatic RCS patterns using electromagnetic simulation, and concluded that the TCR is feasible for bistatic SAR calibration under relatively small bistatic angles (less than 6°). The change of TCR boresight with the bistatic angle is not considered generally. However, we found that the TCR boresight and peak RCS will change with the bistatic angle. We have also proposed that the bistatic angle can be extended to 20° by taking the change of the TCR boresight into account. In this condition, we should get the TCR boresight according to the bistatic angle and then align it during the deployment. Both of these two conditions have their own unique advantages. Different error sources of TCR RCS from manufacture, misalignment, and deformation were investigated quantitatively with simulations, which can provide a theoretical basis for how to design a suitable TCR and guarantee the calibration accuracy for bistatic calibration. In addition, simulation results are different from those of monostatic calibration. Through experiments, we have further verified the feasibility by comparing the quality of bistatic SAR images and point target energy with several typical bistatic angles as the TCR boresight is considered or not. If the bistatic angle is larger than 6°, taking the TCR optimum boresight into account can improve imaging quality and point target energy.

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“…In principle, the reflector should be characterized by a reflectivity much higher than that of the surrounding scatterers [7]; that is to say, the reflector should have a high RCS for a relative small size. Some of the most common corner reflectors being used are flat plate, dihedral, triangular trihedral, and cubic trihedral, and their featured RCSs [11] are listed in Table 1. From the table, we can see that the circular trihedral offers the greatest RCS.…”

Section: The Shape Of Corner Reflectormentioning

confidence: 99%

The Design and Experiments on Corner Reflectors for Urban Ground Deformation Monitoring in Hong Kong

Qin

Perissin

Ling

2013

International Journal of Antennas and Propagation

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PSInSAR technology has been proved to be a powerful tool for monitoring urban ground displacement information to a millimetric accuracy. When it comes to the validation of PS-derived ground deformation, artificial corner reflector (CR) can be very useful due to its relative stability and high signal-to-noise ratio (SNR). In this paper, we will evaluate some general criteria for designing and setting up corner reflectors, including the shape, size, material, location, and others. An ideal prototype known as the rectangular trihedral with special designs is brought up in this paper, and validation experiments were conducted in Hong Kong to demonstrate the ability of the proposed prototype. The field data agreed with theoretical analysis, bringing up an economical and applicable approach for CR application in urban ground deformation monitoring.

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Radar cross section of triangular trihedral reflector with extended bottom plate.

Cited by 15 publications

References 4 publications

Absolute calibration method for frequency-modulated continuous wave (FMCW) cloud radars based on corner reflectors

Absolute calibration method for frequency-modulated continuous wave (FMCW) cloud radars based on corner reflectors

Feasibility, Design, and Deployment Requirements of TCR for Bistatic SAR Radiometric Calibration

The Design and Experiments on Corner Reflectors for Urban Ground Deformation Monitoring in Hong Kong

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