Numerical T-matrix solution for polarized scattering from a cluster of spatially oriented, nonspherical scatterers

Abstract

A small low-cost anechoic chamber has been described. It has proved useful for undergraduate teaching and research applications. The method of chamber construction lends itself to the demonstration of antenna performance and measurement techniques and facilitates relocation if required. The total cost of both the chamber and positioner was found to be less than f3,000 sterling.By combining the chamber and positioner with a network analyzer and personal computer, an automated antenna measurement system that allows for the determination of antenna radiation patterns has been developed.Chamber characterization tests have indicated a reflectivity level of better than -52 dB in the range 18-30 GHz, implying a worst-case error of the order of 1 dB for pattern measurements within a dynamic range of 35-40 dB.It is felt that the chamber, and the associated measurement arrangement, offers a low-cost and simple method of assisting student understanding of antenna concepts, and at the same time provides an extremely useful facility for accurate antenna measurements, specifically in the range 18-30 GHz, for research applications. Received 2-1-96Microwave and Optical Technology Letters, 12/3, 150-154 ABSTRACT Because scatterer size is comparable with wauelength, a rigorous T-matrix solution is used to calculate scattering from the scatterer. When scatteren are nonuniformly clustered, the coherency of collective scattering f.om scatterers must be taken into account. We employ a multiplescattering formulation of the T-matrix method to develop numerical simulations of polarized scattering porn a cluster of spatially oriented, nonspherical particles. Numerical simulations are made for polarized bistatic backscattering, and for functional dependence on the particle shape, spatial distribution, orientation, and other parameters. Numerical results show (a) variations of complex scattering amplitude functions of clustered particles due to collective multiple scattering, (b) the scattering difference between clustered nonspherical and spherical particles, (c) the difference between collective& coherent and independent scattering; and (d) the effect due to the orientation distribution of clustered nonspherical particles. Numerical calculations compared well with the experimental data of a two-sphere cluster. ABSTRACTWe propose and design a novel EDFA equalizer based on a transmissive filter composed of two or more linearly chirped apodized fiber gratings (LCAFGs). 0 1996 John Wiley & Sons, Inc.

Efficient implementation of the invariant imbedding T-matrix method and the separation of variables method applied to large nonspherical inhomogeneous particles

“…Natural particulate matter has a tendency to aggregate and form single nonspherical particles. Scattering calculations for multiple nonspherical particles have been reported [56][57][58][59] based on the STMM. Fig.…”

Mind the gap: testing the Rayleigh hypothesis in T-matrix calculations with adjacent spheroids

“…This divergence would seem to provide another justification for the no-overlap condition, since two adjacent particles affect one another through their scattered field. Most derivations [4,27] and applications [28,29] of the STM method either explicitly start with the no-overlap assumption or abide by it implicitly by considering only sparse configurations [30,31]. While the assumption is irrelevant if all the constituent scatterers are spheres [11,32,33], it becomes increasingly more restrictive for highly anisotropic scatterers, effectively ruling out potential studies of densely packed aggregates.…”