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US 3,983,560 AGranted
Cassegrain antenna with improved subreflector for terrestrial communication systems
AssigneeAndrew Corporation
InventorJames Bruce MacDougall
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AssigneeAndrew Corporation
InventorJames Bruce MacDougall
Estimating the term…
A Cassegrain antenna for use in terrestrial communication systems. The antenna has the conventional subreflector including a central area which provides tapered illumination of the entire main reflector, and a peripheral area which directs spillover from the central area onto the peripheral portion of the main reflector to improve the uniformity of illumination of the main reflector, thereby improving illumination efficiency and reducing gain loss due to spillover. The central and peripheral areas of the subreflector are preferably both surfaces of revolution of conic sections of the same kind, such as hyperboloids, ellipsoids or paraboloids, although the peripheral area may be a frustoconical surface if desired. The virtual focal points of the two conic sections of the subreflector are both coincident with the phase center of the feed horn.
A Cassegrain antenna for use in terrestrial communication systems, said antenna comprising the combination of a parabolic main reflector, a primary feed horn, and a subreflector illuminated by the primary feed horn including a central area forming the surface of revolution of a hyperbolic conic section for providing tapered illumination of the main reflector in the transmitting mode, said central area providing an antenna gain of less than about 40% and at least one peripheral area of the same kind of conic section as said central area, said areas both having virtual focal points coincident with each other and with the phase center of the primary feed horn, and orientation for directing spillover from said central area onto the peripheral portion of the main reflector to improve the uniformity of illumination of the main reflector.
Dependencies are inferred from the claim text.