USH484H
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polarization isolation and zero time-sidelobe pulse compression through group-complementary coding
Assignee: United States Department of the Army
•
Filing: 1987-08-20
•
Granted: 1988-06-07
•
Expires: 2007-08-20
Abstract
Abstract This concept makes use of the orthogonal nature of Group-Complementary Co to achieve improved polarization isolation between the vertical and horizontal radiation in a circularly polarized or dual linearly polarized antenna system while achieving zero time-sidelobe responses in pulse compression. Two channels of a radar system are established with each being encoded using an orthogonal Group-Complementary Code. One channel is associated with the vertical polarization of radiation while the second is devoted to the horizontal polarization. With a leading or lagging 90 degree phase relationship between the two channels, right hand or left hand circular polarization can be established according to the code of each channel which controls the relative phase. Such a technique of pulse compression and group complementary coding offers improved polarization isolation between channels while achieving zero-time sidelobes in pulse compression. The same isolation would be realized for a two channel system radiating simultaneous linear but orthogonal polarization.
Inventors
- 👤 Edward M. Holliday
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:20
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/08; G01S13/10; G01S13/26; G01S13/28; G01S7/00; G01S7/02; G01S7/024
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
280 words
A system for identifying target signatures comprising a source of radio frequency (RF) signals; divider means connected to said signals so as to divide the signals into first and second paths; first and second controllable bi-phase shifting means having first and second controlled input terminals; first and second main input terminals and first and second output terminals; said main input terminals being connected to the divider means such that the first and second paths flow respectable through said main input terminal and said output terminal of the first and second phase shift means; a code generator means connected to the controlled input terminals of the controllable phase shift means so as to cause a phase shift of the radio frequency signals in said paths at selected times in accordance to the code generated by the code generator; a 90 degree phase shifter connected between said divider means and the main input terminal of said first biphase shifting means; a dual polarized feed antenna having horizontal and vertical feeds connected to said first and second paths respectively; a phased detector having first and second inputs and an output; said dual polarized feed antenna transmitting radar signals in accordance to the phase shifted RF signals and detecting vertically and horizontal components of the signals reflected by targets and clutter; and first connection means connecting the vertical component to the first input of the phased detector and the horizontal component to the second input of the phased detector, whereby the output of the phased detector will be a signal which is an indicator of the target signature that reflected the RF signals and have a relative phase which is indentical to that transmitted.
Claim 2
Independent Claim
280 words
A system for identifying target signatures comprising a source of radio frequency (RF) signals; divider means connected to said signals so as to divide the signals into first and second paths; first and second controllable bi-phase shifting means having first and second controlled input terminals; first and second main input terminals and first and second output terminals; said main input terminals being connected to the divider means such that the first and second paths flow respectable through said main input terminal and said output terminal of the first and second phase shift means; a code generator means connected to the controlled input terminals of the controllable phase shift means so as to cause a phase shift of the radio frequency signals in said paths at selected times in accordance to the code generated by the code generator; a 90 degree phase shifter connected between said divider means and the main input terminal of said first biphase shifting means; a dual polarized feed antenna having horizontal and vertical feeds connected to said first and second paths respectively; a phased detector having first and second inputs and an output; said dual polarized feed antenna transmitting radar signals in accordance to the phase shifted RF signals and detecting vertically and horizontal components of the signals reflected by targets and clutter; and first connection means connecting the vertical component to the first input of the phased detector and the horizontal component to the second input of the phased detector, whereby the output of the phased detector will be a signal which is an indicator of the target signature that reflected the RF signals and have a relative phase which is indentical to that transmitted.
Claim 3
Dependent Claim
52 words
A system as set forth in claim 1 wherein said biphase shifting means shifts the phase by 180 degrees upon command from its controlled input terminal so as to provide either right circular polarized or left circular polarized radar signals of the antenna in accordance to the code on the code generator.
Claim 4
Dependent Claim
22 words
A system as set forth in claim 2 wherein the code generated by the code generator means is a group complementary code.
Claim 5
Dependent Claim
41 words
A system as set forth in claim 3 wherein said code generator means generates first and second codes which are orthogonal group complementary codes; and said first and second codes are fed respectively to said first and second controlled input terminals.
Claim 6
Dependent Claim
40 words
A system as set forth in claim 4 further comprising correlator means connected to the vertical component and horizontal component of the reflected radar signals and to said code generator means for correlating the reflected signals to the codes generated.
References Cited (Backward Citations)
US2551348A
Cited
US3517338A
Cited
US3686588A
Cited
US4276521A
Cited
US4329687A
Cited
US4353067A
Cited
US4472717A
Cited
US4513288A
Cited
US4580139A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-06-07 | 1991-12-07 | 1992-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-07 | 1995-12-07 | 1996-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-07 | 1999-12-07 | 2000-06-07 | $7700.00 | Window Closed / Lapsed |