| 摘要 |
PURPOSE: To suppress the degradation of beam convergence performance by reducing the focal distance of a basic parabolic mirror surface corresponding toδwhen a direction equally bisecting an angle formed by the mirror axes of two basic parabolic mirror surfaces, for which the directions of mirror axes are most separated, is defined as a (z) axis and an angle formed by the mirror axes and the (z) axis is defined asδ. CONSTITUTION: Concerning an antenna mirror surface 2, its opening diameter is 46λ×60λ, its beam directionθis 0 deg.,±10 deg. and±20 deg., the focal distance of each basic parabolic mirror surface is changed by f0×(2cosθ-1) when the focal distance ofθ=0 deg. is defined as f(), and the average value of focal distance is 60λ, for example. In this case, the weight coefficients of respective basic parabolic mirror surfaces consisting of the mirror surface 2 are set at the same value. Then, the average value of the opening efficiency of main antenna mirror surface becomes 54.5% and is excellent in comparison with the average value 48.4% of the opening efficiency of antenna mirror surface in the conventional case of designing the antenna while fixing the focal distance of basic parabolic mirror surface. Thus, the degradation of beam convergence performance can be suppressed.
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