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A fast Gaussian beam shooting (GBS) algorithm for monostatic scattering over a range of angles is developed. The algorithm exploits the beam localization in the near- and far-fields with only few beams contributing to the back scattered field. The results are compared to those of iterative physical optics.
Frame-based Gaussian Beam Shooting is presented as an alternative to ray-based methods, when reliable and accessible knowledge of propagated electromagnetic fields is required at all points in built-up environments.
In the context of ground based Radar or wireless communications, non line of sight situations occuring in suburban type built environments are particularly demanding regarding the accuracy of field simulations. This communication presents new developments of the frame-based Gaussian beam shooting method to address some of the diffraction problems encountered in the presence of buildings. The presentation...
Frame decomposition is conventionally used to perform decomposition of fields radiated by large planar apertures into a half plane, in a rigorous and stable way. An algorithm based on a spectral partitioning concept has been developed to extend frame-based Gaussian beam launching to omnidirectional and non directive sources. Frame decomposition is applied in six planes in the spectral domain, starting...
Frame decomposition has been introduced into Gaussian Beam Shooting (GBS) algorithms to perform decompositions of fields radiated by large planar apertures into a half plane in a rigorous and stable way. This work proposes a generalization of frame-based GBS to situations when fields are radiated into all directions in 3d space. Frame decomposition is applied in six planes in the spectral domain,...
A fast and adaptive near-field physical optics algorithm is developed for the analysis of general multi-reflector antenna systems. The algorithm is applied to the radiation pattern computation of an extremely large antenna of RATAN-600 radio telescope operating at mm-wave frequencies. Near-field reflector to reflector field propagation and far-field radiation pattern computation results will be presented...
Radiated or scattered fields are represented as being radiated by a number of limited plane wave spectra obtained by subdividing the 3D spectrum into spectra defined in several planes, using a partition of unity technique. Gabor frame decomposition can be used in each spectral domain, to decompose the field spectrum into Gaussian windows radiating in the form of Gaussian beams. The summation of all...
A fast and adaptive near-field physical optics algorithm is developed for the analysis of general multi-reflector antenna systems. The algorithm is applied to the radiation pattern computation of an extremely large antenna of RATAN-600 radio telescope operating at mm-wave frequencies.
Geometrical optics (GO) based methods are widely used for modeling and parameters determination of big reflector antennas in the millimeter wave band, when the diffraction effects are small enough, and computations using methods that are more precise would take excessively long time. In this report, the result of GO modelling and optimization of the modified optical system of RATAN-600 radiotelescope...
Results of simulations of RATAN-600 radio telescope focusing optics are given. It is shown that due to suboptimal shape of the secondary mirror, the total energy loss amounts to 10%??15% at low elevations and 2??4% at high elevations. New ways of focusing optics optimization, which allow to compensate for up to 80% of the energy loss caused by the non-optimal shape of the secondary mirror, are proposed...
A multilevel algorithm for the statistical characterization of the radiation patterns of beam steered conformal arrays is presented. The algorithm can be used to obtain average complex field patterns and power patterns in the presence of random amplitude and phase excitation errors. The computational scheme is based on a hierarchical decomposition of the array into smaller sub-arrays. At the finest...
Gaussian beam shooting is proposed as an alternative to the Parabolic Equation method or to ray-based techniques, in order to compute backscattered fields in the context of Non-Line-of-Sight ground-based radar. Propagated fields are represented as a superposition of Gaussian beams, which are launched from the emitting antenna and transformed through successive interactions with obstacles. In this...
The multilevel fast physical optics (MLPO) algorithm attains a computational complexity comparable to that of the fast Fourier transform (FFT) based techniques by using hierarchical domain decomposition and phase compensated interpolation approach. In this communication we present an optimized distributed memory algorithm, obtained by partitioning not only the radiating aperture but also the grid...
This paper illustrates the ability of Gaussian beam shooting techniques to accommodate large propagation problems in multipath contexts. Frame based decomposition of fields provides a flexible and efficient tool to perform beam launching. Channel transfer matrices are defined, which allow for a complete description of multidimensional channels through a limited number of coefficients. A beam re-expansion...
The proposed fast time domain physical optics (TDPO) scheme is based on a domain decomposition of the scattering surface or radiating aperture into smaller patches. The scheme exploits the fact that, asymptotically, the number of samples required to describe the scattered or radiated fields in time and angular domains, is proportional to the size of the patch. Therefore the radiation patterns are...
An original ray tube launching and tracking technique, based on the discretized plane-wave spectrum of source fields is proposed. This technique is well suited to compute fields in contexts where multiple reflections have to be taken into account. The validity of the method is demonstrated in the case of wave propagation in open-ended waveguides and cavities
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