Multiband ring focus antenna employing shaped-geometry main reflector and diverse-geometry shaped subreflector-feeds
First Claim
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1. An antenna comprising:
- a main reflector having a shaped surface of revolution about a boresight axis of said antenna and being operable at a plurality spectrally offset frequency bands;
a sub-reflector having a shaped non-linear surface of revolution about said boresight axis, said sub-reflector forming a ring-shaped focal point characteristic about said boresight axis; and
a feed element installed at a feed element location adjacent to a vertex of said sub-reflector on said boresight axis of said antenna; and
wherein at least said shaped sub-reflector has no continuous surface portion thereof shaped as a regular conical surface of revolution.
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Abstract
A multiband, shaped ring focus antenna architecture employs only a single or common main reflector, that is shaped such that it can be shared by each of a pair of interchangeable, diversely shaped close proximity-coupled, subreflector-feed pairs designed for operation at respectively different spectral bands. The operational band of the antenna is changed by swapping out the subreflector-feed pairs. Placement of the shaped subreflector in close proximity to the feed horn reduces the diameter of the main shaped reflector relative to a conventional ring focus structure, so as to facilitate installation within a constrained space facility, such as a shipboard-mounted satellite communication system.
55 Citations
35 Claims
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1. An antenna comprising:
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a main reflector having a shaped surface of revolution about a boresight axis of said antenna and being operable at a plurality spectrally offset frequency bands;
a sub-reflector having a shaped non-linear surface of revolution about said boresight axis, said sub-reflector forming a ring-shaped focal point characteristic about said boresight axis; and
a feed element installed at a feed element location adjacent to a vertex of said sub-reflector on said boresight axis of said antenna; and
whereinat least said shaped sub-reflector has no continuous surface portion thereof shaped as a regular conical surface of revolution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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- 19. A ring focus antenna having a main reflector of revolution shaped as a non-regular paraboloid about a boresight axis of said antenna, a sub-reflector of revolution shaped as a non-regular ellipsoid having a ring-shaped focal point characteristic about said boresight axis, and a feed element located less than two wavelengths of the frequency of operation of said antenna from said vertex of said sub-reflector.
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24. A method of configuring an antenna for operation at a selected one of a plurality of different frequency bands comprising the steps of:
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(a) providing a main reflector having a shaped, non-regular conical surface of revolution about a boresight axis of said antenna;
(b) locating a sub-reflector, having a shaped, non-regular conical surface of revolution about said boresight axis, in spaced apart relationship with said main reflector along said boresight axis, said shaped, non-regular conical surface of said sub-reflector having a ring-shaped focus characteristic about said boresight axis, said sub-reflector being selected from a plurality of respectively different sub-reflectors having shaped, non-regular conical surfaces of revolution about said boresight axis and configured for operation at spectrally different frequency bands; and
(c) locating a feed element adjacent to a vertex of said subreflector on said boresight axis, said feed element being selected from a plurality of different feed elements respectively configured for operation at said spectrally different frequency bands, said selected feed element being configured for operation at the band of operation of said selected sub-reflector. - View Dependent Claims (25, 26, 27, 28, 29, 30)
(d) configuring said antenna for operation at a frequency band different from said selected band by (d1) retaining said main reflector of step (a), (d2) replacing said selected sub-reflector of step (b) with another of said plurality of respectively different sub-reflectors, and (d3) replacing said selected feed element of step (c) with another of said plurality of a respectively different sub-reflector; and
whereineach of said another subreflector of step (d2) and said another feed element of step (d3) is configured for operation at said different frequency band.
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29. A method according to claim 28, wherein steps (a) and (b) comprise respectively shaping said main reflector and said plurality of sub-reflectors, so as to constrain sidelobes of said antenna'"'"'s directivity pattern to within a prescribed sidelobe specification at each of said respectively different bands of said selected sub-reflector of step (b) and said another sub-reflector of step (d2).
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30. A method according to claim 28, wherein said selected sub-reflector of step (b) and said feed element of step (c) are configured for operation at one of X band, C band, Ku band and Ka band, and said another sub-reflector of step (d2) and said feed element of step (d3) are configured for operation at another of X band, C band Ku band and Ka band.
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31. An antenna adapted to be operational at a selected one of a plurality of different frequency bands comprising:
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a main reflector having a shaped, non-regular conical surface of revolution about a boresight axis of said antenna;
a sub-reflector, having a shaped, non-regular conical surface of revolution about said boresight axis, located in spaced apart relationship with said main reflector along said boresight axis, said shaped, non-regular conical surface of said sub-reflector having a ring-shaped focus characteristic about said boresight axis, said sub-reflector being selected from a plurality of respectively different sub-reflectors having shaped, non-regular conical surfaces of revolution about said boresight axis and configured for operation at spectrally different frequency bands; and
a feed element located adjacent to a vertex of said sub-reflector on said boresight axis, said feed element being selected from a plurality of different feed elements respectively configured for operation at said spectrally different frequency bands, said selected feed element being configured for operation at the band of operation of said selected sub-reflector. - View Dependent Claims (32, 33, 34, 35)
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Specification