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Ultra-wideband (UWB) radar imaging has attracted attention for use in security and intelligent transportation system (ITS) applications. Conventional UWB Doppler interferometry is an effective way to obtain high-resolution images while using a simple radar system. However, this method produces ghost images when multiple closely-spaced human targets are present. To resolve this problem, we propose...
The analysis of the Doppler signal returned by rotating targets is of great interest in the framework of target recognition and equipment monitoring. An analytical expression of such a signal already exists for the far-field case, based on the Jacobi-Anger expansion. An extension of this analytical expression is proposed for the near-field case. The solution involves a closed-form expression of each...
This paper summarizes the recent advances in using frequency-diverse metasurfaces for computational imaging in the microwave and millimeter wave regimes. Frequency-diverse apertures are defined as structures that can generate distinct radiation patterns as a function of frequency. Such waveforms can multiplex a scene information into a set of backscattered measurements, which can be decoded using...
The sky wave and the surface wave radars can be impacted by the instabilities of the ionosphere while they perform continuous surveillance of very large and far-off areas. When long-term integration is performed, those instabilities are leading to an increased false alarm rate. This is the typical case when detecting slow targets such as vessels. In this paper, we will discuss the case of a hybrid...
THz impulse communications is a new system concept based on an imaging radar that we have been developing for biomedical imaging applications the past ten years. Its hybrid architecture combines the high-peak-power and spread-spectrum of photoconductive-switch transmitters with the high-responsivity and broad-bandwidth (RF and video) of Schottky-rectifier receivers. The data is impressed by simple...
A null steering method for Forward-Looking Ground Penetrating Radar (FLGPR) is presented. The radar consists of two arrays (one at L-band and one at X-band) of wideband horns that form synthetic apertures at the vehicle advanced. The null steering method is applied to the SAR vertical view (intensity vs. range and height) image to compensate for the lack of vertical image resolution and help determine...
A near-field radar imaging technique is presented based on single-frequency measurements from a multiple-input multiple-output (MIMO) array. Such arrays are able to fully sample the κ-space of a region of interest. Advantageously, both range and cross-range information can be reconstructed, in contrast to conventional single-input multiple-output systems which require wideband frequency illumination...
Radar Cross Section analysis is the study of the scattering behavior of an object. The objective is to determine the main scatterers from measurements of the backscattered electric field. It is generally achieved by Radar Cross Section imaging. This leads to an ill-posed inverse problem because the system to solve is underdetermined. It is then necessary to regularize the problem by adding prior information...
The localization of buried targets using Ground Penetrating Radar (GPR) is dealt with. The bi-static GPR is made of two identical Vivaldi antennas operating from 0.5 GHz to 3.5 GHz and installed in front of a sand box. The experimental data acquired in a controlled laboratory environment are validated by electromagnetic simulation. Then, both synthetic and experimental data are processed to detect...
Turntable ISAR imaging systems generate radar images by rotating the radar target and performing measurements at various angles. The rotation leads to different perspectives onto the scattering centers of the target. This causes problems if polarimetric methods should be applied to the radar image. In this paper this problem is investigated and a correction technique suitable for two-dimensional imaging...
Magnetic modulated nanoparticles are a promising approach to enhance microwave breast cancer detection and imaging. Assuming that functionalized magnetic nanoparticles are able to accumulate selectively within tumorous tissue, this approach can increase the diagnostic reliability. This contribution deals with detecting and imaging of magnetic nanoparticles by means of ultra wideband sensing. Magnetic...
This contribution is based on an novel imaging system able to create real time radar images for personnel security screening recently presented. The imaging is performed as the person being screened continuously moves across a corridor populated with transmitters and receivers, and taking advantage of the person's movement to increase the number of observation angles. As part of a preliminary study...
The paper proposes a fast and interpolation-free method for near-field 3-D radar imaging. The scattered data are measured on 2-D planar antenna array with wideband stepped frequency signal. The near-field 3-D imaging procedure is indeed a nonuniform summation problem. Different from the conventional interpolation fast Fourier transform (FFT) method, the proposed method regards the imaging procedure...
Experimental evaluation of a Ground Penetrating Radar (GPR) system is presented. The method is based on an Underground-SAR imaging algorithm that takes into account the complex permittivity of the soil to compensate for the slower wave propagation so that buried objects are imaged at the correct depth. The proposed GPR imaging system is devoted to operate in C band, from 3.5 to 5.5 GHz, in order to...
We demonstrate a frequency-diverse imaging system using an air-filled cavity-backed antenna as a transceiver (cavity-to-cavity system layout) for the K-band (17.5–26.5 GHz) frequency regime. Leveraging the computational imaging concept, the frequency-diversity enables imaging in an all-electronic manner, without the need for mechanical raster scanning or active circuit components, minimizing the data...
Three-dimensional radar cross-section (RCS) images are a valuable support for understanding the scattering events occurring at a radar target. Traditional RCS measurement methods require a large angular range and many measurement points to provide sufficient resolution and unambiguousness. This paper proposes the usage of high-resolution techniques, enabled by taking only the polarimetric signal components...
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