| 摘要 |
A five-horn Cassegrain antenna is disclosed comprising a main dish, an up-taper subreflector set on the boresight axis of the main dish, and including a sum horn positioned on the boresight axis between the subreflector and the main dish with four error horns set therearound. The aperture of the sum horn is relatively large to substantially eliminate radiation spillover at the up-taper subreflector. The error horns are positioned around this large aperture sum horn such that the radiation patterns of paired error horns will crossover in their sidelobes. These error horns are provided with a high aspect ratio with the narrow dimension of each error horn being located in the plane of its tracking crossover with the radiation pattern of the other error horn with which it is paired. The foregoing antenna design combination results in a high illumination efficiency antenna wherein the radiation patterns of the error horns crossover in substantially increased sidelobes of the respective patterns thereby facilitating the accurate determination of a difference null.
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