[1] We address the problem of extracting the maximum amount of information on an electromagnetic field over a domain D O from field sample measurements on a domain D I , with a priori information on the source (or scatterer). The problem is faced in two steps. In the first one, the source reconstruction is dealt with by taking into account the available a priori information and the optimal probe positioning is determined as that optimizing the singular value dynamics of the involved linear radiation operator. The second step consists of reconstructing the field on D O as that radiated by the retrieved source. An extensive numerical analysis highlights the performance of the approach.Citation: Capozzoli, A., C. Curcio, A. Liseno, and P. Vinetti (2010), Field sampling and field reconstruction: A new perspective, Radio Sci., 45, RS6004,
The diagnosis of the faulty elements of a planar array from noisy far-field power pattern data is considered in the case of "on-off" faults. The possible ambiguities of the solutions are considered both in the theoretical and practical sense and are shown to be intrinsically less relevant than in the widely studied continuous case. The probability of the occurrence of the practical ambiguities is inferred from a number of numerical examples and is shown to be negligible in all cases of interest. An effective algorithm is presented here based on an intersection set finding approach and involving the minimization of a suitable objective functional. The global minimization of the functional has been successfully performed by applying a properly modified genetic algorithm. A number of numerical examples shows the effectiveness of the approach whose computational complexity essentially increases linearly with the array size.Index Terms-Fault diagnosis, phased-array antennas.
Abstract-A phase-only power pattern synthesis technique for flat (aperiodic) microstrip reflectarrays with elements arranged on a nonregular lattice is presented. The approach mitigates the typical design issues of reflectarray antennas related to the computational burden and to the possible occurrence of suboptimal solutions which are here even more significant due to the non-regular element lattice. This is done by a convenient two-stage procedure for choosing the starting point of the iterations and by proper representations of the unknowns of the problem. Design constraints on the element positions are also imposed to avoid overlapping as well as too large spacings. The algorithm, accelerated by parallel programming on Graphics Processing Units, has been analyzed against the cases of a pencil-beam and of a shapedbeam involving a typical South America coverage. In order to properly characterize the performance of the synthesis algorithm, it has been applied also to the design of reflectarrays with elements located on a non-regular lattice. The results show that in the case of non-regular lattice better directivities, better coverage behavior and better sidelobe levels are achievable as compared to reflectarrays characterized by a regular lattice.
Abstract-We introduce and discuss a parallel SAR backprojection algorithm using a Non-Uniform FFT (NUFFT) routine implemented on a GPU in CUDA language.The details of a convenient GPU implementation of the NUFFT-based SAR backprojection algorithm, amenable to further generalizations to a multi-GPU architecture, are also given.The performance of the approach is analyzed in terms of accuracy and computational speed by comparisons to a "standard", parallel version of the backprojection algorithm exploiting FFT + interpolation instead of the NUFFT. Different interpolators have been considered for the latter processing scheme. The NUFFT-based backprojection has proven significantly more accurate than all the compared approach, with a computing time of the same order. An analysis of the computational burden of all the different steps involved in both the considered approaches (i.e., standard and NUFFT backprojections) has been also reported.Experimental results against the Air Force Research Laboratory (AFRL) airborne data delivered under the "challenge problem for SAR-based Ground Moving Target Identification (GMTI) in urban environments" and collected over circular flight paths are also shown.
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