Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Research Article Analysis of Approximations and Aperture Distortion for 3D Migration of Bistatic Radar Data with the Two-Step Approach | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 192378 9 pages doi 2010 192378 Research Article Analysis of Approximations and Aperture Distortion for 3D Migration of Bistatic Radar Data with the Two-Step Approach Luigi Zanzi and Maurizio Lualdi Dipartimento di Ingegneria Strutturale Politecnico di Milano Piazza Leonardo Da Vinci 32 20133 Milano Italy Correspondence should be addressed to Luigi Zanzi Received 31 December 2009 Accepted 7 June 2010 Academic Editor Joao Manuel R. S. Tavares Copyright 2010 L. ZanziandM. Lualdi. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. The two-step approach is a fast algorithm for 3D migration originally introduced to process zero-offset seismic data. Its application to monostatic GPR Ground Penetrating Radar data is straightforward. A direct extension of the algorithm for the application to bistatic radar data is possible provided that the TX-RX azimuth is constant. As for the zero-offset case the two-step operator is exactly equivalent to the one-step 3D operator for a constant velocity medium and is an approximation of the one-step 3D operator for a medium where the velocity varies vertically. Two methods are explored for handling a heterogeneous medium both are suitable for the application of the two-step approach and they are compared in terms of accuracy of the final 3D operator. The aperture of the two-step operator is discussed and a solution is proposed to optimize its shape. The analysis is of interest for any NDT application where the medium is expected to be heterogeneous or where the antenna is not in direct contact with the medium . NDT of artworks humanitarian demining radar with air-launched antennas . 1. Introduction In 1983 Gibson et al. 1 introduced the fast .
