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US 4,034,378 AGranted
Antenna with echo cancelling elements
AssigneeBell Telephone Laboratories, Incorporated
InventorEdward Allen Ohm
Life of this patent
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AssigneeBell Telephone Laboratories, Incorporated
InventorEdward Allen Ohm
Estimating the term…
A Cassegrainian antenna having a feed horn, a subreflector and a main reflector exhibits subreflector reflections back toward the feed horn. Some of this energy is reflected by the feed horn, and some by the main reflector adjacent to the feed horn, back toward the subreflector. This doubly reflected energy constitutes an echo which is reduced in the prior art by using a flat reflector plate mounted near the subreflector to cancel energy radiated by the subreflector back toward the region of the feed horn. Herein is disclosed the addition of a frequency sensitive reflecting wire grid between the flat plate and the feed horn. A combined reflection from the grid, plate, and subreflector provides echo cancellation in two frequency ranges. The plate may be recessed in a hole in the subreflector. A guard ring surrounding the plate prevents leakage through the subreflector hole.
An antenna having a main reflector, a subreflector and a feed system so arranged that radiation from said feed system is successively reflected from said subreflector and said main reflector, said antenna further having an essentially flat plate mounted near said subreflector so as to reflect some of said radiation back toward said feed system,
An antenna having a main reflector, a subreflector, and feed horn means in spatial relationship to each other such that radiation from said feed horn means is reflected from said subreflector and then from said main reflector, and
Dependencies are inferred from the claim text.