US3795003A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Schwarzschild radar antenna with a unidirectional turnstile scanner
Assignee: United States Department of the Army
•
Filing: 1973-02-26
•
Granted: 1974-02-26
•
Expires: 1993-02-26
Abstract
Abstract A Schwarzschild Antenna includes feed horns respectively mounted on a turnstile waveguide switch. During transmission, as each horn passes a particular arc of rotation, microwave energy is emitted from the horn onto an adjacent mirror that reflects the energy to the antenna reflectors. The result is a unidirectional scan in the far field. A tracking mode of operation is also provided. Either of the two modes of operation may be selected by the operator.
Inventors
- 👤 J Meek
- 👤 C Ravilious
- 👤 W Heinard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 01:06
CPC Classifications
H; H01; H01Q; H01Q3/00; H01Q3/12; H01Q3/16; H01Q3/18; H01Q19/00; H01Q19/10; H01Q19/18; H01Q19/19; H01Q19/191
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
136 words
A Schwarzschild antenna system having main and subreflectors, the system comprising: a plurality of waveguide pipes extending radially from a central rotating hub; window means formed in the hub for insuring passage of energy through only one pipe at a time; a rotatable mirror positioned adjacent a central aperture formed in the main reflector for transmitting microwave energy to and from the aperture; and means disposed adjacent the rotatable mirror for directing microwave energy in the pipes along a direction coincident with the mirror; whereby microwave energy flowing through the hub during transmission will sequentially energize each pipe, as each pipe passes through a preselected arc of rotation, the sequential energization of the pipes resulting in the reflection of a unidirectional sector scan from the mirror, the subreflector, and the main reflector to the far field.
Claim 2
Dependent Claim
136 words
A Schwarzschild antenna system having main and subreflectors, the system comprising: a plurality of waveguide pipes extending radially from a central rotating hub; window means formed in the hub for insuring passage of energy through only one pipe at a time; a rotatable mirror positioned adjacent a central aperture formed in the main reflector for transmitting microwave energy to and from the aperture; and means disposed adjacent the rotatable mirror for directing microwave energy in the pipes along a direction coincident with the mirror; whereby microwave energy flowing through the hub during transmission will sequentially energize each pipe, as each pipe passes through a preselected arc of rotation, the sequential energization of the pipes resulting in the reflection of a unidirectional sector scan from the mirror, the subreflector, and the main reflector to the far field.
Claim 3
Dependent Claim
51 words
The subject matter set forth in claim 1 wherein the plurality of waveguide pipes are mounted 90* apart, to form a turnstile scanner, each pipe curving along an outward end portion and further wherein the microwave energy directing means comprises a feed horn connected to an outward end of each pipe.
Claim 4
Dependent Claim
41 words
The subject matter of claim 1 wherein the plurality of waveguide pipes are radially mounted 90* apart to form a turnstile scanner, each pipe terminating outwardly in a horn, and further wherein the microwave energy directing means comprises an organ-pipe transition.
Claim 5
Dependent Claim
35 words
The subject matter of claim 2 together with a microwave lens positioned between a feed horn traversing the arc and the mirror; whereby the lens optimizes directivity of a beam reflected from the rotatable mirror.
Claim 6
Dependent Claim
24 words
The structure of claim 4 wherein the lens may be fabricated from a plurality of adjacently spaced metal plates having varying channel lengths therebetween.
Claim 7
Dependent Claim
23 words
The structure of claim 4 wherein the lens may be fabricated from a plurality of adjacently spaced metal plates having varying gaps therebetween.
Claim 8
Dependent Claim
24 words
The subject matter of claim 4 wherein the lens may be fabricated from a plurality of adjacently spaced dielectric plates that have varying lengths.
Claim 9
Dependent Claim
26 words
The subject matter of claim 4 wherein the lens may be fabricated from a plurality of adjacently spaced dielectric plates that have varying indices of refraction.
Claim 10
Dependent Claim
27 words
The structure of claim 1 wherein the hub forms a portion of an R.F. turnstile switch, the switch being connected through a rotatable joint to a transmitter-receiver.
Claim 11
Dependent Claim
14 words
The structure set forth in claim 1 wherein the main reflector is a twistflector.
Claim 12
Dependent Claim
11 words
The structure of claim 1 wherein the subreflector is a transflector.
Claim 13
Dependent Claim
24 words
The system defined in claim 1 wherein the rotatable mirror has beveled tapering edges to render the rotatable mirror more compact for rapid switching.
Claim 14
Dependent Claim
45 words
The subject matter of claim 3 together with means for generating a conical scan, said means located adjacent the rotatable mirror, the mirror transmitting the conical scan to the subreflector and to the main reflector when the mirror is repositioned in a second angular orientation.
References Cited (Backward Citations)
US3680141A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |