Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1997-01-08
2000-01-25
Jones, Deborah
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
4283159, 428378, 428433, 428469, 428472, 342 12, 205119, 205162, 205164, 205184, 205186, B32B 1500
Patent
active
060176288
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to chaff with transient radar absorbance and/or reflectance characteristics, having utility as an electronic warfare countermeasure useful in an absorbance mode for at least partial attenuation of radar signals, and useful in a reflectance mode as an electromagnetic detection decoy or for anti-detection masking of an offensive attack.
DESCRIPTION OF THE RELATED ART
In modern warfare, a wide variety of weapons systems are employed which operate across the electromagnetic spectrum, including radio waves, microwaves, infrared signals, ultraviolet signals, x-rays and gamma rays.
To counter such weapons systems, smoke and other obscurants have been deployed. In the past, smoke has been variously employed as a means of protection of ground-based military vehicles and personnel during conflict, to blind enemy forces, to camouflage friendly forces, and to serve as decoys to divert hostile forces away from the positions of friendly forces. With the evolution of radar guided missiles and increasing use of radar systems for battlefield surveillance and target acquisition, the obscurant medium must provide signal response in the millimeter wavelengths of the electromagnetic spectrum.
The use of "chaff", viz., strips, fibers, particles, and other discontinuous-form, metal-containing media to provide a signal response to radar, began during World War II. The first use of chaff involved metal strips about 300 millimeters long and 15 millimeters wide, which were deployed in units of about 1,000 strips. These chaff units were manually dispersed into the air from flying aircraft, to form chaff "clouds" which functioned as decoys against radars operating in the frequency range of 490-570 Megahertz.
Chaff in the form of aluminum foil strips has been widely used since World War II. More recent developments in chaff technology include the use of aluminum-coated glass filament and silver-coated nylon filament.
In use, chaff elements are formed with dimensional characteristics creating dipoles of roughly one-half the wavelength of the hostile electromagnetic system. The chaff is dispersed into a hostile radar target zone, so that the hostile radar "locks onto" the signature of the chaff dispersion. The chaff is suitably dispersed into the air from airborne aircraft, rockets or warheads, or from ground-based deployment systems.
The chaff materials which have been developed to date function effectively when deployed at moderate to high altitudes, but are generally unsatisfactory as obscuration media in proximity to the ground due to their high settling rates. Filament-type chaff composed of metal-coated fibers may theoretically be fashioned with properties superior to metal strip chaff materials, but historically the "hang time" (time aloft before final settling of the chaff to the ground) is unfortunately still too short to accommodate low altitude use of such chaff. This high settling rate is a result of large substrate diameters necessary for standard processes, typically on the order of 25 microns, as well as thick metal coatings which increase overall density. A further problem with metallized filaments is that typical metal coatings, such as aluminum, remain present and pose a continuing electrical hazard to electrical and electronic systems after the useful life of the chaff is over.
Although chaff has been highly successfully employed by the prior art, and is routinely used to decoy or divert radar guided threats away from military aircraft, successful exploitation of chaff typically requires precise synchronization of the chaff dissemination with an evasive maneuver. Thus, training is critical to the effective use of chaff for enhanced survivability against radar-based threats. Though the need for realistic training is universally accepted, environmental concerns over the effects of chaff pose a serious and growing threat to peacetime training in its use.
Considering the environmental impact of chaff material usage, in warfare as well as peacetime training applications, it
REFERENCES:
patent: 2818351 (1957-12-01), Nack et al.
patent: 2862783 (1958-12-01), Drummond
patent: 2920981 (1960-01-01), Whitehurst
patent: 2930105 (1960-03-01), Budd
patent: 3097941 (1963-07-01), Toulmin, Jr.
patent: 3129487 (1964-04-01), Whitacre et al.
patent: 3221875 (1965-12-01), Paquette
patent: 3372051 (1968-03-01), Stalego
patent: 3544997 (1970-12-01), Turner et al.
patent: 3549412 (1970-12-01), Frye et al.
patent: 3725927 (1973-04-01), Fielder
patent: 3765931 (1973-10-01), Kyri et al.
patent: 3952307 (1976-04-01), Nagler
patent: 3958066 (1976-05-01), Imamura et al.
patent: 4052530 (1977-10-01), Fonzi
patent: 4556507 (1985-12-01), Tomibe et al.
patent: 4738896 (1988-04-01), Stevens
patent: 4759950 (1988-07-01), Stevens
patent: 4852453 (1989-08-01), Morin
patent: 4859499 (1989-08-01), Savinet et al.
patent: 4942090 (1990-07-01), Morin
patent: 5034274 (1991-07-01), Stevens et al.
patent: 5039990 (1991-08-01), Stevens et al.
patent: 5087515 (1992-02-01), Stevens et al.
patent: 5129323 (1992-07-01), Park
patent: 5328717 (1994-07-01), Stevens et al.
patent: 5352519 (1994-10-01), Stevens et al.
patent: 5686178 (1997-11-01), Stevens et al.
Butters, Brian C. F., "Electronic Countermeasures/Chaff," IEEE Proceedings, vol. 129, Part F, No. 3, Jun. 1982, pp. 197-201.
Mack, C.L. Jr. and B. Reiffen, "RF Characteristics of Thin Dipoles," IEEE Proceedings, vol. 52, May 1964, pp. 533-542.
Van Vleck, J. H. et al., "Theory of Radar Reflection from Wires of Thin Metallic Strips," Journal of Applied Physics, vol. 18, Mar. 1947, pp. 274-294.
Grant, P. M. et al., "Introduction to Electronic Warfare," IEE Proc., vol. 129, Prt. F., No. 3, Jun. 1982, pp. 113-132.
Wickliff, R. G. and R. J. Garbacz, "The Average Backscattering Cross Section of Clouds of Randomized Resonant Dipoles," IEEE Trans. AP 22, May 1974, pp. 503-505.
Stevens Ward C
Sturm Edward A.
Alliant Defense Electronics Systems, Inc.
Hultquist Steven J.
Jones Deborah
Lam Cathy
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