Highly accurate fully-polarimetric radar cross section facility for mono- and bistatic measurements at W-band frequencies

Printed circuit metasurfaces have attracted significant attention in the microwave community for their capability of versatile wavefront manipulation. Despite their promising potential in telecommunications and radar applications, few transmissive metasurfaces have been reported operating at millimeter-wave frequencies. Several secondary effects including fabrication tolerances, interlayer near-field coupling and the roughness of conductors are more severe at such high frequencies and can cause significant performance degradation. Additionally, experimental characterization techniques reported previously are not accurate enough for the verification of such effects. In this work, we present highly efficient refracting metasurfaces operating at 83 GHz. We use a sophisticated synthesis technique that minimizes possible effects of performance degradation such as interlayer near-field coupling and the influence of fabrication tolerances. Additionally, we propose a new experimental technique for the characterization of periodic metasurfaces. Using this technique, we present for the first time an accurate determination of the intensity of propagating Floquet harmonics in a broad frequency range. The proposed method gives deep insight into the beam refraction problem as it accurately quantifies in which direction energy is scattering. Additionally, it verifies our numerical model.

Section: Introductionmentioning

confidence: 99%

High-Efficiency Refracting Millimeter-Wave Metasurfaces

Olk¹,

Macchi²,

Powell

2020

“…4. According to the four PSMs, the eight distortion parameters can be solved using (25) and (26). Finally, the four polarization return signals of a cylinder are simulated to illustrate how to detect the mutation using FEKO software [35].…”

Section: P R H P Arc P T H P Arc P R H M I M O P T Hmentioning

confidence: 99%

“…2) The calibrator sensitive to bistatic angles cannot be used, such as dihedral and trihedral reflectors, because the polarimetric MIMO array has different bistatic angles in near-field measurement. For the sake of bistatic polarimetric calibration, several solutions have been proposed in [25]- [28]. A polarimetric monostatic and bistatic RCS facility operating at W -band can be calibrated by a wire mesh with high cross-polarization level [25].…”

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confidence: 99%

“…For the sake of bistatic polarimetric calibration, several solutions have been proposed in [25]- [28]. A polarimetric monostatic and bistatic RCS facility operating at W -band can be calibrated by a wire mesh with high cross-polarization level [25]. A unidirectional conducting canonical object has been introduced in [26], which satisfies the requirements as a cross-polarized bistatic calibration device.…”

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confidence: 99%

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Calibration of a Polarimetric MIMO Array With Horn Elements for Near-Field Measurement

Kong

2020

Polarimetric multiple input and multiple output (MIMO) radar is capable of acquiring target's high-resolution images and polarization scattering matrix (PSM). In this article, calibration of a polarimetric MIMO array of an instrumentation radar for near-field measurement is achieved at X-band by using a rotatable double-antenna polarimetric active radar calibrator (RODAPARC) and a metal cylinder quickly and accurately. The theoretical PSM of the RODAPARC with different antenna rotation angles is derived from Huygens' radiation electric field which is applicable to different bistatic angles. A polarimetric signal model is adopted to reduce the impact of the RODAPARC on calibration. Experimental studies are conducted on a polarimetric MIMO array which is measured and divided into quasi-monostatic and bistatic transceiver channels for assessment on the calibration performance. Promising calibration results are obtained with a polarization isolation improvement of about 16 dB and great reduction of the polarization channel gain error less than ±0.5 dB in amplitude and ±3 • in phase. The calibrated polarization signatures for classic objects are consistent with the theoretical results. Index Terms-Multiple input and multiple output (MIMO) radar, polarimetric active radar calibrator (PARC), polarimetric calibration. I. INTRODUCTIONW ITH the explosive development of multiple input and multiple output (MIMO) technology, more and more MIMO radars have been presented in [1]-[6]. MIMO is an enabling technique capable of imaging a target using only one snapshot [6], which is different from rail synthetic aperture radar (SAR) and turntable inverse synthetic aperture radar (ISAR). Polarimetric MIMO radar images the target rapidly, while also providing the polarization scattering matrix (PSM) of the target. Crosstalk and polarization channel gain error distort the receive signal in polarimetric radars. This distortion will be more serious for polarimetric MIMO radars in terms of multiple transceiver channels. Therefore, polarimetric calibration serves an important role in polarimetric MIMO radars.According to the different polarimetric calibrators, polarimetric calibration can be divided into passive [7]-[9] and Manuscript

“…Generally, for full polarimetric calibration, at least two calibration scatterers (or at least two alignments of a depolarizing calibration scatterer) are needed. For example, common planar calibration scatterers are metallic plate [7], metallic circular disk [8], whereas the common 3D calibration scatterers are wire mesh [4], [8], [9], metallic sphere [8], [10], metallic cylinder [8], dihedral [3], [7], [8], and trihedral [7], [8]. The cylinder, the dihedral, the trihedral, and the wire mesh are depolarizing objects.…”

Section: Introductionmentioning

confidence: 99%

Augmented Depolarizing Scatterer Based on Resonant Elements for Polarimetric Radar Calibration

Ali

Perret

2022

A 3-in-1 depolarizing circular scatterer for the polarimetric radar calibration is proposed in this paper. The proposed scatterer is low cost, compact, planar circuit, and well suited for the radar operating in a compact range, for example, chipless RFID technology. By the virtue of its circular shape, the rear side of the proposed scatterer acts as a metallic disk with strong co polarization backscattered signals. The front side is composed of eight resonant dipoles which make it nondepolarizing and depolarizing scatterers at the inclination of 0° and 45°, respectively. The features of proposed circular scatterer are tested as reference calibration objects for single antenna based polarimetric radar calibration techniques. Two test objects are utilized: a dihedral tilted at 45° and a depolarizing multi resonant planar structure commonly called chipless RFID tag. The performance of proposed circular scatterer is also compared with the standard reference calibration objects: a metallic disk and a dihedral tilted at 22.5°. The performance of proposed circular scatterer is comparable to the standard reference calibration objects for the calibration techniques (namely Type 1 and Type 2). The proposed scatterer is potentially tolerant of displacement up to 1 cm and misalignment equals 2°.