Focus broadening by astigmatism of large microwave parabolic antennas.
The primary astigmatism of a parabolic antenna of an aperture of 10(3) lambda and of f/D = 0.43 was investigated. The measured astigmatic aberration is caused predominantly by large span surface deformations. In the case described, the focus of a Cassegrain system of 11.85 magnification is broadened up to 153 mm at the secondary and up to 2 mm at the primary focus. This aberration effect accounts for 5%-6% of the total intensity.
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