Patent US3821741A successfully refreshed from Google Patents.
US3821741A
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Tracking system with pointing error detector
Assignee: Italtel SpA
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Filing: 1972-11-22
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Granted: 1974-06-28
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Expires: 1992-11-22
Abstract
Abstract A tracking system, e.g. for following the course of a communications satellite, has a horn-reflector antenna working into a generally cylindrical coupler with three axially spaced circular waveguide sections interconnected by frustoconical transition sections, i.e. a large-diameter section propagating the dominant mode TEo11 and two higher modes TMo01, TEo21, an intermediate-diameter section propagating only the TEo11 and TMo01 modes, and a small-diameter section cutting off all except the TEo11 mode. The two higher modes TMo01 and TEo21, coming into existence only when the incoming beacon wave is disaligned with the horn axis, provide a measure of the pointing error the antenna; for correcting this disalignment, a first error signal corresponding to the TMo01 mode is extracted from the intermediate-diameter waveguide section by a first pair of diametrically opposite rectangular waveguide branches with major sides transverse to the cylinder axis whereas a second error signal corresponding to the TEo21 mode is extracted from the large-diameter waveguide section by a second pair of diametrically opposite rectangular waveguide branches, offset from the first pair by 90*, whose major sides are parallel to the cylinder axis. The two error signals are isolated by additively combining the outputs of the first pair of rectangular waveguide branches and subtractively combining the outputs of the second pair of rectangular waveguide branches with the aid of a first and a second magic T, respectively, working together into a third magic T whose summing and differential outputs deliver corrective voltages to a controller for the antenna.
Inventors
- 👤 Oro E D
- 👤 L Salari
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:21
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/146; H; H01; H01P; H01P1/00; H01P1/16; H01Q; H01Q25/00; H01Q25/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
457 words
In a system for tracking a target emitting high-frequency radiation, including a reflector antenna provided with control means for keeping same trained upon the target to receive said radiation, the combination therewith of: a tubular conductive structure of circular cross-section connected to said antenna for excitation thereby, said structure having an output section remote from said antenna, a first coupling section closer to said antenna and a second coupling section proximal to said antenna, said output section, first coupling section and second coupling section being of progressively larger diameter, said output section being dimensioned to sustain only a dominant circular mode TE*11 of wave propagation at the frequency of said radiation, said first coupling section being dimensioned to sustain said dominant mode and one higher mode TM*01 of wave propagation at said frequency, said second coupling section being dimensioned to sustain said dominant mode, said one higher mode and one other higher mode TE*21 of wave propagation at said frequency; first waveguide means of rectangular cross-section connected to said first coupling section, said first waveguide means being oriented and dimensioned to pick up said one higher mode to the substantial exclusion of said dominant mode and said other higher mode; second waveguide means of rectangular cross-section conjugate to said first waveguide means and connected to said second coupling section, said second waveguide means being oriented and dimensioned to pick up said other higher mode to the substantial exclusion of said dominant mode and said one higher mode; and output circuitry connecting said first and second waveguide means to said control means for delivering thereto corrective signals tending to cancel a pointing error of said antenna giving rise to said higher modes; each of said waveguide means comprising a pair of aligned waveguide branches extending from diAmetrically opposite sides of the corresponding coupling section of said structure, the first pair of aligned waveguide branches having major surfaces transverse to the axis of said first coupling section, the second pair of aligned waveguide branches having major surfaces parallel to the axis of said second coupling section, said first pair of waveguide branches being joined to said first coupling section at locations offset by 90* from the locations at which said second pair of waveguide branches are joined to said second coupling section; said output circuitry including a first T junction with lateral inputs connected to said first pair of waveguide branches, a second T junction with lateral inputs connected to said second pair of waveguide branches, and a third T junction with lateral inputs respectively connected to a summing output of said first T junction and to a differential output of said second T junction, said third T junction having summing and differential outputs connected to said control means.
Claim 2
Dependent Claim
457 words
In a system for tracking a target emitting high-frequency radiation, including a reflector antenna provided with control means for keeping same trained upon the target to receive said radiation, the combination therewith of: a tubular conductive structure of circular cross-section connected to said antenna for excitation thereby, said structure having an output section remote from said antenna, a first coupling section closer to said antenna and a second coupling section proximal to said antenna, said output section, first coupling section and second coupling section being of progressively larger diameter, said output section being dimensioned to sustain only a dominant circular mode TE*11 of wave propagation at the frequency of said radiation, said first coupling section being dimensioned to sustain said dominant mode and one higher mode TM*01 of wave propagation at said frequency, said second coupling section being dimensioned to sustain said dominant mode, said one higher mode and one other higher mode TE*21 of wave propagation at said frequency; first waveguide means of rectangular cross-section connected to said first coupling section, said first waveguide means being oriented and dimensioned to pick up said one higher mode to the substantial exclusion of said dominant mode and said other higher mode; second waveguide means of rectangular cross-section conjugate to said first waveguide means and connected to said second coupling section, said second waveguide means being oriented and dimensioned to pick up said other higher mode to the substantial exclusion of said dominant mode and said one higher mode; and output circuitry connecting said first and second waveguide means to said control means for delivering thereto corrective signals tending to cancel a pointing error of said antenna giving rise to said higher modes; each of said waveguide means comprising a pair of aligned waveguide branches extending from diAmetrically opposite sides of the corresponding coupling section of said structure, the first pair of aligned waveguide branches having major surfaces transverse to the axis of said first coupling section, the second pair of aligned waveguide branches having major surfaces parallel to the axis of said second coupling section, said first pair of waveguide branches being joined to said first coupling section at locations offset by 90* from the locations at which said second pair of waveguide branches are joined to said second coupling section; said output circuitry including a first T junction with lateral inputs connected to said first pair of waveguide branches, a second T junction with lateral inputs connected to said second pair of waveguide branches, and a third T junction with lateral inputs respectively connected to a summing output of said first T junction and to a differential output of said second T junction, said third T junction having summing and differential outputs connected to said control means.
Claim 3
Dependent Claim
30 words
The combination defined in claim 1 wherein a differential output of said first T junction and a summing output of said second T junction are connected to respective dummy loads.
Claim 4
Dependent Claim
13 words
The combination defined in claim 2 wherein said dummy loads are short circuits.
Claim 5
Dependent Claim
27 words
The combination defined in claim 2 wherein said dummy loads are resistances substantially equaling the characteristic impedances of said first and second pairs of waveguide branches, respectively.
Claim 6
Dependent Claim
31 words
The combination defined in claim 1 wherein said output section, first coupling section and second coupling section are coaxially cylindrical and are separated from one another by substantially frustoconical transition sections.
Claim 7
Dependent Claim
33 words
The combination defined in claim 1 wherein said antenna comprises a horn with a converging throat adjoining said second coupling section, the latter having a diameter equaling the minimum diameter of said throat.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |