A microwave technique has been developed for obtaining total cross sections and angular distributions for the scattering of electromagnetic radiation by nonspherical particles whose size is of the order of the wavelength. The scattering by spheroidal and cylindrical refracting particles has been measured for three orthogonal orientations of the symmetry axis. Comparison of the results with exact and approximate theoretical calculations for spheres, spheroids, and finite and infinite cylinders indicates the possibility of developing useful approximation methods. Some interesting effects have been noted, particularly a very large resonance in the scattering by finite cylinders. The results have been given preliminary application to the problem of the nature of the interstellar material which absorbs and polarizes starlight.

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The scattering from a thin conducting wire is computed by representing the induced current as a sum of driven and resonant terms, the latter with complex propagation constant mk perturbed from its free space value k. Using Galerkin’s method, the central problem of determining m reduces to a minimization problem. For the limiting cases of highly conducting or highly absorbing wires simplifications are found. For short wires the Rayleigh cross sections are obtained; for longer wires with high absorption, accurate cross section formulas are constructed based on the unperturbed infinite wire currents. For general wire lengths and conductivities the method is computationally very simple and results are in excellent agreement with independent computations of both current and far field quantities, as well as experimental measurements.

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