Electrical Effects of Snow and Ice Coatings on Reflector Antennas.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO
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In recent years, the effects of icing on reflector antenna systems used in precision approach radars has become an ever increasing problem of interest. This paper presents a simple technique that may be used for the analysis of the icing on such reflector systems. For simplicity, the ice is assumed to have a uniform vertical thickness over the upper side of exposed surfaces. Beginning with a uniform phase front in the beam direction for the uniced reflector, one can trace rays back to the reflector using geometrical optics to determine the angle of incidence at each point on the reflector. The phase and amplitude of the rays for the iced reflector are computed by local plane wave analysis and used to calculate the far field in the manner of physical optics. This technique gives downward beam shifts of up to 30 milliradians for some typical reflectors. This technique modifies the array aperture function. The full pattern can obtained from the convolution of the computed pattern with the pattern of the original system. Author
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