Rough surface RCS measurements and simulations using the Physical Optics Approximation

International audienceThe objective of this article is to develop innovative approaches to obtain analytical expressions of the Radar Cross Section (RCS) of perfectly-conducting random rough surfaces under the Physical Optics (PO) approximation. The led approaches take into account the specific geometrical properties of the considered surfaces to calculate their RCS. The objective is to reduce the computing time with respect to the numerical PO technique, which requires two numerical integrations. All developed approaches are validated by comparison with a commercial code (the MLFMM of FEKO), used as a reference, and with measurements performed on three selected rough surfaces samples

Accuracy of Singularity Expansion Method in Time and Frequency Domains to Characterize Antennas in Presence of Noise

International audienceIn this paper, the accuracy of the singularity expansion method (SEM) used for antenna characterization is investigated. A well-known limitation of the SEM is that pole extraction is very sensitive to noise. A comparison between two main methods of pole extraction is presented. The matrix pencil (MP) method and the Cauchy's method are used to extract poles from the radiated fields of a dipole antenna and two bowtie antennas. Results are presented for simulated fields, and the robustness to a white Gaussian noise is also analyzed. We show that the MP method allows working with lower SNR than Cauchy's method and is more accurate for field reconstruction

Window increasing technique to discriminate mathematical and physical resonant poles extracted from antenna response

International audienceThis letter presents a new approach called window increasing technique (WIT) to discriminate mathematical and physical poles extracted from a noisy antenna response. The principle of the WIT is to apply a pole extraction method on several windows of the response and then to observe the stability of the extracted poles. In order to compare the WIT to the classical window moving technique (WMT), we apply these two techniques on the electric far field backscattered by a dipole antenna. We show that, in presence of noise, the WIT allows finding more physical poles with a good accuracy than the WMT

A new algorithm of 3D image reconstruction of radar targets from ramp responses in low frequency

International audienc

Ramp response radar imaging: Analysis of frequency parameters

International audienc

Low frequency imaging of separated objects using the ramp response technique

International audienc

Characterization of details of large targets with the low-frequency ramp response technique

International audienc

Caractérisation des pôles de résonance d'objets éclairés par une onde électromagnétique large bande

En zone de résonance, la réponse d une cible radar à une onde électromagnétique large bande présente des singularités appelées pôles de résonance. Ces pôles de résonance sont intrinsèques à chaque objet et peuvent, par conséquent, être utilisés dans un processus d identification. Sont étudiées dans cette thèse : une analyse du caractère résonant des objets à partir du facteur de qualité, une procédure de sélection des pôles de résonance qui suffisent pour caractériser un objet, la détermination des dimensions caractéristiques d objets à partir des pôles de résonance, la caractérisation de cibles diélectriques, etc.In resonance region, the radar scattering response of any object can be modelled by poles of resonance. The mapping of these poles in the complex plane gives useful information for the discrimination of a radar target, as its general shape, its characteristic dimension and its constitution. This thesis presents several studies such as: an analysis of the resonant behaviour of targets with the quality factor, a procedure for selecting the poles that actually contribute to the scattering response, the determination of characteristic dimensions of targets with the resonance poles, the characterisation of dielectric targets, etc.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Resonance behaviour of radar targets with aperture. Example of an open rectangular cavity

International audienc