Congreso: SET-160 Symposium on NCI/ATR in Air-Ground and Maritime Applications based on Radar and Acoustics (NATO) Lugar celebración: Atenas, Grecia. Fecha: 11/10/2010 – 12/10/2010

Autores: Arriba-Ruiz, I. de, Pérez-Martínez, F., Muñoz-Ferreras, J.M

Synthetic Aperture Radar (SAR) images a target region reflectivity function in the multi-dimensional spatial domain of range and cross-range. SAR synthesizes a large aperture radar so as to achieve a finer azimuth resolution than the one provided by any on-board real antenna. Furthermore, SAR is considered to be a mature consolidated technology capable of providing an all-weather, day/night capability to detect and locate targets. Conventional SAR techniques assume a single reflection of transmitted waveforms from targets. Nevertheless, today’s new scenes force SAR systems to work in urban environments. Consequently, multiple-bounce returns are added to direct-scatter echoes. We refer to these as ghost images, since they obscure true target image and lead to poor resolution. All this may involve a significant problem in applications related to surveillance and security. In this context, two kinds of multipath may be differentiated: the one owing to the reflected echo from Earth’s surface and the one that takes place in the target vicinity due to surrounding scatterers. By analyzing the quadratic phase error (QPE), this paper demonstrates that Earth’s curvature influences the defocusing degree of multipath returns. In addition to the QPE, other parameters such as integrated sidelobe ratio (ISLR), peak sidelobe ratio (PSLR), contrast (C) and entropy (E) provide us with the tools to identify direct-scatter echoes in images containing undesired returns coming from multipath.