US3737904A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin film polarization rotation microwave reflectors
Assignee: ABC Rail Corp
•
Filing: 1970-06-22
•
Granted: 1973-06-05
•
Expires: 1990-06-22
Abstract
Abstract A reflector target for reflecting an impinging microwave beam with a 90* change in polarization; the target comprises a layer of high dielectric constant material having a conductive backing and having one or more thin film conductive line grids on its front surface. The thickness of the dielectric layer is less than one-quarter wavelength, as measured in the dielectric, at the chosen microwave frequency, and the grid lines are oriented at 45* to the polarization of the impinging beam. The width of the conductive grid lines is about equal to or greater than the width of the inter-line spaces.
Inventors
- 👤 H Mori
- 👤 J Garcia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:30
CPC Classifications
H; H01; H01Q; H01Q15/00; H01Q15/14; H01Q15/22
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
128 words
A reflector target for an identification system of the kind in which the target is scanned by an incident microwave beam of given frequency polarized in a given direction, comprising: a thin layer of a dielectric material, having a dielectric constant substantially greater than unity, the thickness of the dielectric being substantially smaller than one-quarter wavelength, at said given frequency; at least one conductive line grid on the front surface of said dielectric facing said microwave beam, comprising a multiplicity of thin film conductive grid elements, said grid elements being aligned at an angle of about 45* to said direction of polarization; and a conductive backing on the other surface of said dielectric layer, said target affording a polarization rotation of approximately 90* in reflecting said microwave beam.
Claim 2
Dependent Claim
128 words
A reflector target for an identification system of the kind in which the target is scanned by an incident microwave beam of given frequency polarized in a given direction, comprising: a thin layer of a dielectric material, having a dielectric constant substantially greater than unity, the thickness of the dielectric being substantially smaller than one-quarter wavelength, at said given frequency; at least one conductive line grid on the front surface of said dielectric facing said microwave beam, comprising a multiplicity of thin film conductive grid elements, said grid elements being aligned at an angle of about 45* to said direction of polarization; and a conductive backing on the other surface of said dielectric layer, said target affording a polarization rotation of approximately 90* in reflecting said microwave beam.
Claim 3
Dependent Claim
45 words
A reflector target for a microwave identification system, according to claim 1, in which each conductive element of said grid Has a width D and is separated from adjacent grid elements by a space of width C and in which D > or = C.
Claim 4
Dependent Claim
29 words
A reflector target for a microwave identification system, according to claim 2, in which S D+C and in which S is less than one-quarter wavelength at said given frequency.
Claim 5
Dependent Claim
32 words
A reflector target for a microwave identification system, according to claim 1, including a plurality of said grids, each of given width in the scanning direction, representative of a given code quantity.
Claim 6
Dependent Claim
33 words
A reflector target for a microwave identification system, according to claim 4, in which the conductive grid elements of adjacent grids are consistently oriented at angles of approximately 90* relative to each other.
Claim 7
Dependent Claim
33 words
A reflector target for a microwave identification system, according to claim 1, in which the front surface of said target, including said grid, is covered by a thin protective film of dielectric material.
Claim 8
Dependent Claim
32 words
A reflector target for a microwave identification system, according to claim 1, in which said conductive backing comprises a self-supporting aluminum plate, and said dielectric layer is a layer of aluminum oxide.
Claim 9
Dependent Claim
30 words
A reflector target for a microwave identification system, according to claim 1, in which said dielectric material is fiberglass, and in which said conductive backing is a thin metal foil.
Claim 10
Dependent Claim
20 words
A reflector target for a microwave identification system, according to claim 1, in which said dielectric material is polyvinyl fluoride.
Claim 11
Dependent Claim
50 words
A reflector target for a microwave identification system, according to claim 2, in which D about 0.075 inch, C about 0.015 inch, the dielectric constant of the dielectric layer is about 9, and the total thickness of the dielectric layer is about 0.06 times the wavelength of the microwave beam.
Claim 12
Dependent Claim
52 words
A reflector target for a microwave identification system, according to claim 3, in which the basic dimensions of the target are determined in accordance with the expression (4S/Lg) ln (cosec pi C/2S) - cot 2 pi A/Lg 1/((Lg/S) cot2 ( pi C/S) -cot (2 pi A/Lg)) where Lg wavelength in the dielectric.
References Cited (Backward Citations)
US3161879A
Cited
US3366952A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |