US3789417A
Expired / Lapsed
US
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Circularly symmetric retrodirective antenna
Assignee: United States Department of the Navy
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Filing: 1972-01-25
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Granted: 1974-01-29
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Expires: 1992-01-25
Abstract
Abstract A method and apparatus for obtaining automatic retrodirective performance from circularly symmetric arrays, and circular continuous aperture antennas. Phased mode sets are provided by a multimodal feed network as a result of modal interconnection methods. All modes in a particular mode set become in phase in the direction of an incoming signal, and as a result, a beam is made to reradiate in that direction. The method is applicable to two and three-dimensional retrodirective systems and includes both active and passive devices. Also, the reradiated beam width, beam power, and other reradiated beam characteristics including sidelobe functions, are capable of being controlled and adjusted.
Inventors
- 👤 H Coleman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:25
CPC Classifications
H; H01; H01Q; H01Q21/00; H01Q21/06; H01Q21/20; H01Q25/00; H01Q25/04; H01Q3/00; H01Q3/26; H01Q3/30; H01Q3/34; H01Q3/40
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
198 words
A method of providing retrodirective properties from a circular symmetric antenna system comprising: receiving a wavefront from a phi o direction, the antenna system being capable of maintaining substantially linearly varying phase mode properties around the antenna periphery; converting said wavefront into a corresponding first set of signals while maintaining amplitude and phase relationships of said first set of signals wherein the phase mode set is defined a set of n modes, each of which is a linear variation in phase around the antenna''s periphery such that for the nth mode of the set the phase changes by n X 360 electrical degrees as the angle phi changes by 360* around the antenna''s periphery; transposing said first set of signals into a first phase mode set with a multimodal network such that said first phased modE set provides a plurality of voltages to mode terminals corresponding to said first set of signals; interconnecting said mode terminals into associated mode terminals corresponding to a second mode set; reconverting said second mode set into a corresponding second set of signals; applying said second set of signals to the antenna such that a wavefront is generated to the phi o direction.
Claim 2
Independent Claim
198 words
A method of providing retrodirective properties from a circular symmetric antenna system comprising: receiving a wavefront from a phi o direction, the antenna system being capable of maintaining substantially linearly varying phase mode properties around the antenna periphery; converting said wavefront into a corresponding first set of signals while maintaining amplitude and phase relationships of said first set of signals wherein the phase mode set is defined a set of n modes, each of which is a linear variation in phase around the antenna''s periphery such that for the nth mode of the set the phase changes by n X 360 electrical degrees as the angle phi changes by 360* around the antenna''s periphery; transposing said first set of signals into a first phase mode set with a multimodal network such that said first phased modE set provides a plurality of voltages to mode terminals corresponding to said first set of signals; interconnecting said mode terminals into associated mode terminals corresponding to a second mode set; reconverting said second mode set into a corresponding second set of signals; applying said second set of signals to the antenna such that a wavefront is generated to the phi o direction.
Claim 3
Dependent Claim
183 words
A circular symmetric retrodirective antenna system comprising: circular symmetric antenna means; and multimodal feed network means having an even plurality of n mode terminals wherein n/2 mode terminals provide for a first phased mode set, and the remainder of said n mode terminals provide for an associated phased mode set, said multimodal feed network having the characteristic that if a unit voltage is applied to mode terminal n, the far field radiation pattern, E( phi ), is in the form En( phi ) An exp jn phi where An is the relative gain of mode n and phi is any selected angle; coupling means for coupling said antenna means to said feed network means such that the first phased mode set and said associated mode set are able to be established around the periphery of the antenna means; and intermodal connecting means for connecting a part of said n/2 mode terminals to an equal part of said remainder of said n mode terminals to effect selected mode pairs such that when a wavefront is presented to said antenna means retrodirectivity subsequently results therefrom.
Claim 4
Dependent Claim
183 words
A circular symmetric retrodirective antenna system comprising: circular symmetric antenna means; and multimodal feed network means having an even plurality of n mode terminals wherein n/2 mode terminals provide for a first phased mode set, and the remainder of said n mode terminals provide for an associated phased mode set, said multimodal feed network having the characteristic that if a unit voltage is applied to mode terminal n, the far field radiation pattern, E( phi ), is in the form En( phi ) An exp jn phi where An is the relative gain of mode n and phi is any selected angle; coupling means for coupling said antenna means to said feed network means such that the first phased mode set and said associated mode set are able to be established around the periphery of the antenna means; and intermodal connecting means for connecting a part of said n/2 mode terminals to an equal part of said remainder of said n mode terminals to effect selected mode pairs such that when a wavefront is presented to said antenna means retrodirectivity subsequently results therefrom.
Claim 5
Dependent Claim
18 words
The retrodirective antenna system as claimed in claim 2 wherein said multimodal feed network is a Butler matrix.
Claim 6
Dependent Claim
22 words
The retrodirective antenna system as claimed in claim 2 wherein said intermodal connecting means comprises: passive lines each of a length l.
Claim 7
Dependent Claim
18 words
The retrodirective antenna system as claimed in claim 4 wherein gain networks are disposed in the passive lines.
Claim 8
Dependent Claim
19 words
The retrodirective antenna system as claimed in claim 2 wherein said antenna means comprises a plurality of individual elements.
Claim 9
Dependent Claim
22 words
The retrodirective antenna system as claimed in claim 6 wherein said individual elements are dipoles and are disposed around a conducting cylinder.
Claim 10
Dependent Claim
21 words
The system as claimed in claim 7 wherein gain networks are disposed in each of the passive lines of length l.
Claim 11
Dependent Claim
20 words
The system as claimed in claim 8 wherein a gain network is disposed in the open circuit center mode line.
Claim 12
Dependent Claim
172 words
A circular symmetric retrodirective antenna system comprising: circular symmetric antenna means; multimodal feed network having a center mode set consisting of one center terminal; a positive mode set and a negative mode set each having n terminals, said multimodal feed network having the characteristic that if a unit voltage is applied to mode terminal n, the far field radiation pattern, E( phi ), is in the form En( phi ) An exp jn phi where An is the relative gain of mode n and phi is any selected angle; coupling means for coupling said antenna means to said feed network such that the center, positive and negative mode sets are able to be established around the periphery of the antenna means; intermodal connecting means for interconnecting a portion of the n terminals of the positive mode set to an equal number of terminals in the negative mode set; and an open circuit line connected to said center mode terminal; so that when a wavefront is presented to the antenna means, retrodirectivity results.
Claim 13
Dependent Claim
172 words
A circular symmetric retrodirective antenna system comprising: circular symmetric antenna means; multimodal feed network having a center mode set consisting of one center terminal; a positive mode set and a negative mode set each having n terminals, said multimodal feed network having the characteristic that if a unit voltage is applied to mode terminal n, the far field radiation pattern, E( phi ), is in the form En( phi ) An exp jn phi where An is the relative gain of mode n and phi is any selected angle; coupling means for coupling said antenna means to said feed network such that the center, positive and negative mode sets are able to be established around the periphery of the antenna means; intermodal connecting means for interconnecting a portion of the n terminals of the positive mode set to an equal number of terminals in the negative mode set; and an open circuit line connected to said center mode terminal; so that when a wavefront is presented to the antenna means, retrodirectivity results.
Claim 14
Dependent Claim
15 words
The system as claimed in claim 10 wherein said multimodal network comprises: a Butler matrix.
Claim 15
Dependent Claim
29 words
The system as claimed in claim 10 wherein said intermodal connecting means comprises: passive lines, each of a length l, and said open circuit line is of length l/2.
Claim 16
Dependent Claim
34 words
The system as claimed in claim 10 wherein said antenna means comprises: a plurality of radiators. 14. The system as claimed in claim 13 wherein said radiators are dipoles disposed around a conducting cylinder.
Claim 17
Dependent Claim
177 words
A circular symmetric retrodirective antenna system comprising: circular symmetric antenna means; and Butler matrix network means having an even plurality of n mode terminals wherein n/2 mode terminals provide for a first phased mode set, and the remainder of said n mode terminals provide for an associated phased mode set, said Butler matrix having the characteristic that if a unit voltage is applied to mode terminal n, the far field radiation pattern, E( phi ), is in the form En( phi ) An exp jn phi where An is the relative gain of mode n and phi is any selected angle; coupling means for coupling said antenna means to said feed network means such that the said first phased mode set and said associated phased mode set are able to be established around the periphery of the antenna means; and intermodal connecting means for connecting a part of said n/2 mode terminals to an equal part of said remainder of said n mode terminals to effect selected mode pairs such that retrodirectivity results from said antenna means.
Claim 18
Dependent Claim
177 words
A circular symmetric retrodirective antenna system comprising: circular symmetric antenna means; and Butler matrix network means having an even plurality of n mode terminals wherein n/2 mode terminals provide for a first phased mode set, and the remainder of said n mode terminals provide for an associated phased mode set, said Butler matrix having the characteristic that if a unit voltage is applied to mode terminal n, the far field radiation pattern, E( phi ), is in the form En( phi ) An exp jn phi where An is the relative gain of mode n and phi is any selected angle; coupling means for coupling said antenna means to said feed network means such that the said first phased mode set and said associated phased mode set are able to be established around the periphery of the antenna means; and intermodal connecting means for connecting a part of said n/2 mode terminals to an equal part of said remainder of said n mode terminals to effect selected mode pairs such that retrodirectivity results from said antenna means.
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) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |