US4356494A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual reflector antenna
Assignee: Mitsubishi Electric Corp
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Filing: 1981-01-23
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Granted: 1982-10-26
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Expires: 2001-01-23
Abstract
Abstract An earth station antenna is employed for telecommunicating with a satellite in combination with an automatic tracking apparatus. The antenna is a dual reflector antenna which comprises a main reflector, a sub-reflector and a primary radiator, and the used frequency band of the antenna is at least 1.8 octaves. A parameter t of the antenna, defined by a configuration of the primary radiator is less than 0.3 at the lowest operating frequency. The phase center of the primary radiator, at a low frequency within the operating frequency range, is made to correspond with the focus of the sub-reflector. The above parameter t is defined by: ##EQU1## where: λ: wavelength in free space, D h : aperture diameter of the primary radiator, L h : center axial length from the radiator apex to the radiator aperture plane, and L s : length from the radiator aperture plane to the bottom surface of the sub-reflector.
Inventors
- 👤 Takashi Katagi
- 👤 Shuji Urasaki
- 👤 Takashi Ebisui
- 👤 Katsuhiko Aoki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:56
CPC Classifications
H; H01; H01Q; H01Q19/00; H01Q19/10; H01Q19/18; H01Q19/19
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
179 words
In a dual reflector antenna having a usable frequency band of at least approximately 1.8 octaves, said antenna having a primary radiator having a radiating aperture for providing a radiated beam, said primary radiator including a horn having an apex, said antenna further comprising a main reflector and a sub-reflector for reflecting said radiated beam to said main reflector, said sub-reflector having a bottom surface which is closest to said primary radiator aperture, said antenna having a t parameter defined by: ##EQU3## λ: wave length in free space of said radiated beam, D h : diameter of the aperture of said primary radiator, L h : the axial length between said apex of the horn and said aperture, L s : the length between said aperture and said sub-reflector's bottom surface, the improvement comprising: the value of said t parameter being less than 0.3 at the lowest usable frequency of said antenna; and the phase center of said primary radiator being substantially coincident with the focal point of said sub-reflector at a low frequency within said usable frequency band.
Claim 2
Dependent Claim
179 words
In a dual reflector antenna having a usable frequency band of at least approximately 1.8 octaves, said antenna having a primary radiator having a radiating aperture for providing a radiated beam, said primary radiator including a horn having an apex, said antenna further comprising a main reflector and a sub-reflector for reflecting said radiated beam to said main reflector, said sub-reflector having a bottom surface which is closest to said primary radiator aperture, said antenna having a t parameter defined by: ##EQU3## λ: wave length in free space of said radiated beam, D h : diameter of the aperture of said primary radiator, L h : the axial length between said apex of the horn and said aperture, L s : the length between said aperture and said sub-reflector's bottom surface, the improvement comprising: the value of said t parameter being less than 0.3 at the lowest usable frequency of said antenna; and the phase center of said primary radiator being substantially coincident with the focal point of said sub-reflector at a low frequency within said usable frequency band.
Claim 3
Dependent Claim
36 words
A dual reflector antenna as claimed in claim 1, wherein the reflecting surface of at least one of said main reflector and sub-reflector is of a configuration defined by a portion of a conicoid of revolution.
Claim 4
Dependent Claim
34 words
A dual reflector antenna as claimed in claim 2, wherein said conicoid of revolution is one selected from the group of a hyperboloid of revolution, a paraboloid of revolution, or an ellipsoid of revolution.
Claim 5
Dependent Claim
32 words
A dual reflector antenna as claimed in claim 1, wherein the reflecting surface of at least one of said main reflector and sub-reflector is of a configuration defined by a shaped surface.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-25 | 1986-04-26 | 1986-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-25 | 1990-04-26 | 1990-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-25 | 1994-04-26 | 1994-10-26 | $7700.00 | Window Closed / Lapsed |