Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/83—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with metals; with metal-generating compounds, e.g. metal carbonyls; Reduction of metal compounds on textiles
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06Q—DECORATING TEXTILES
  • D06Q1/00—Decorating textiles
  • D06Q1/04—Decorating textiles by metallising
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/14—Reflecting surfaces; Equivalent structures
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/14—Reflecting surfaces; Equivalent structures
  • H01Q15/18—Reflecting surfaces; Equivalent structures comprising plurality of mutually inclined plane surfaces, e.g. corner reflector
  • H01Q15/20—Collapsible reflectors

Definitions

• the object of the invention is to improve the recognizability of smaller objects with radar beams, particularly in the fields of sea and aviation and in the emergency services. It has now been found that the visibility by radar, especially in the case of small objects, is improved if metallized textile fabrics are attached to the objects, the metal after activation of the textile fabrics on them with a total metal layer thickness between 0.02 and 2.5 / has been electrolessly deposited by wet chemical means. Textile fabrics are understood to mean woven goods, knitwear and nonwovens. The invention relates to the use of metallized textile fabrics as a reflective material for micro and decimeter wave radiation.
• the polarization of the radiation reflected on stretched metallized tissues can be used to facilitate or increase the object recognition.
• a pulsating polarization of the reflected microwaves can be achieved by periodic stretching and unloading.
• the surface conductivity of the textile fabrics is considerably greater than if the same amount of metal had been applied by vapor deposition.
• the surface resistance measured according to DIN 54345 at 23 ° C and 50% rh, is in the order of magnitude at or below 1. 10 2 ⁇ . It is surprising that even layer thicknesses in the area of the skin depth still have a high reflectivity, which should be related to the textile base. For nickel layers, for example, the skin depth is 0.27 ⁇ m at 3 GHz and 0.16 ⁇ m at 9 GHz.
• the improved recognizability of even small objects increases security, particularly in the fields of shipping, aviation and rescue services.
• the light weight and the flexibility of the material are particularly advantageous when used according to the invention. It can be attached to uneven surfaces and can be cut to any size. It is so light that the additional weight hardly changes the total weight. It is a new, technical method to increase the reflection behavior of a non-metallic object for radar beams.
• the durability of the electrolessly deposited layer is also higher than would be expected with a vapor-deposited metal layer. It is also possible to coat the metal layer with a further protective layer, e.g. to be additionally protected by painting, lamination or coating.
• the reflectivity is very high in a range between 0.02 and 1000 GHz, that is in a far larger range than just the "classic" radar radiation.
• the textile fabric can consist of cotton, polyacrylonitrile, polyamide, aramid, polyester, viscose, modacrylic, polyolefin, polyurethane, PVC alone or in combination with one another.
• the electrolessly deposited metal layer preferably consists of nickel, cobalt, copper, silver, gold, also in combinations or as an alloy.
• the mesh size or crossing points of the weft and warp threads in fabrics should be less than half the wavelength of the radiation to be reflected; a textile fabric is preferred where the size of the mesh does not exceed one tenth of the wavelength.
• the reflection also depends on the shape of the textile construction. A textile construction that is as isotropic as possible will therefore be chosen if the reflection is to be isotropic.
• a loose, coarse-meshed textile fabric can be achieved by tensioning, so that the microwave rays are partially polarized after the reflection if unpolarized radiation is incident, or the reflection is particularly great for linearly polarized, incident radiation if the mechanical tension and the vector of the electric field strength are perpendicular to each other.
• the sample (dry weight 7.2 g) has approximately 3.1 g, ie approximately 40% by weight of nickel metal taken.
• the quick activation and the high metal deposition at room temperature are surprising.
• the nickel layer thickness on the fiber surface is 0.77 ⁇ m.
• textile fabrics coated with nickel were produced in different thicknesses and the reflection losses between 2 and 25 GHz were measured.
• the measurement method is sc h weig, for example, in H. Groll, Mikrowellenmeßtechnik, F. Vieweg & Sohn, Braunschweig 1969, p 353 ff described.
• the reflection loss is given in dB.
• a broadband frequency-modulated radiation of constant power for example 1.9 to 2.4 GHz, 7 to 8 GHz, is used to eliminate the effect of standing waves in the area in front of the measurement object (interface reflection).
• the textile fabrics are the same as in Example 1; they are also coated with nickel as in Example 1.
• the angle of incidence is 30 °.
• Dense tissue is therefore required to achieve good reflection at short wavelengths.
• a textile fabric according to Example 1 is coated with a 0.2 ⁇ m nickel coating as described there. Immediately after rinsing, it is placed in a gold cyanide bath at 78 ° C. while still wet. The gold bath based on potassium gold cyanide is adjusted to a pH of 10.5 at 4 g / l with ammonia. After 20 seconds, a shiny gold metal film is deposited on the shiny nickel layer. The gold layer thickness on the nickel-plated surface is 0.2 / ⁇ m within 5 minutes. The reflection losses in dB with vertical incidence are shown below.
• the degree of reflection depends on mechanical stresses.
• Linearly polarized microwave radiation falls vertically onto a knitted fabric of an acrylonitrile copolymer on which a 0.75 ⁇ m thick nickel layer is deposited.
• Line II shows the reflection losses in dB, if the knitted fabric is not mechanically stressed.
• Line I shows the losses under tensile stress (stress direction parallel to the E-vector).
• a periodic variation in the tensile stress leads to a periodic variation in the reflected microwave intensity.
• the detectability of an object sought by radar can be increased considerably within an isotropic or at least constant reflecting environment (rescue service, friend / enemy detection, etc.).
• Either a linearly polarized radiation is used and the intensity variation of the reflector is assessed, or circularly polarized radar radiation is used, the reflected signal having a periodic variation in the ellipticity of the polarization, which can be detected by an analyzer on the receiving side.
• a polyethylene paper ie a nonwoven made of polyolefin staple fibers, is provided with an electrolessly deposited nickel layer as described above. With a 0.4 ⁇ m thick nickel layer, the following reflection losses result in dB:
• This metallized, textile fabric is particularly suitable as recognition material, for example as a cross for search helicopters. Because of its light weight, it can easily be carried on expeditions.
• a polyester-cotton blend fabric consisting of 65 wt .-% polyester staple fibers based on polyethylene terephthalate and 35 wt .-% cotton, shows at a 0.7 / um thick nickel layer provided below the reflection losses in dB.
• This metallized material is suitable for tents, backpacks or clothing for skiers and hikers.
• the fabric has only become imperceptibly heavier due to the metallization; it has not lost its textile elastic properties. If you can with a plasticized PVC layer coats, to make it resistant to rain, it may additionally be provided with W arntician. People who carry such backpacks or clothing can be found with radar equipment if they are lost in desert areas or on the tundra.
• a balloon tissue for example arngewebe g of a polyester filament or nylon 6,6 fabric is coated with an approximately 0.7 micron thick stranlos deposited nickel layer. It is also given a protective coating made of PVC, rubber or polyurethane varnish. This subsequent lamination does not interfere with the reflectivity of the fabrics. In line I the reflection losses in dB of this fabric are given if it is only provided with a 0.7 / um thick nickel layer, in line II the losses with an additional rubber coating. A free balloon made of such material can be easily located using the on-board radar of a commercial aircraft.
• the fabric can also be embedded as the last layer in polyester resin, which increases the radar location of gliders.
• a polyamide or polyester filament yarn fabric is provided with an approximately 0.65 ⁇ m thick nickel layer.
• line I of the table below the reflection losses are given in dB, by lamination with a PVC coating (line II) or with a polyethylene coating (line III) the reflectivity of the metallized fabric is practically unchanged.
• Life jackets can be advantageously produced from this metallized fabric, which can also be provided with the prescribed warning color RAL 2002.
• the fabric can also be attached to life rafts. If the fabric is attached to the mast tips of sailboats, they are easier to locate with radar without the sailboat becoming top-heavy.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Aerials With Secondary Devices (AREA)
• Laminated Bodies (AREA)
• Woven Fabrics (AREA)
• Chemically Coating (AREA)
• Decoration Of Textiles (AREA)

Priority Applications (1)

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Publications (2)

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Family Applications (1)

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Cited By (8)

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Citations (10)

Family Cites Families (8)

• 1978
  • 1978-11-02 DE DE19782847485 patent/DE2847485A1/de not_active Withdrawn
• 1979
  • 1979-10-22 AT AT79104077T patent/ATE989T1/de not_active IP Right Cessation
  • 1979-10-22 DE DE7979104077T patent/DE2962730D1/de not_active Expired
  • 1979-10-22 EP EP79104077A patent/EP0010711B1/fr not_active Expired
  • 1979-10-30 US US06/089,712 patent/US4320403A/en not_active Expired - Lifetime
  • 1979-11-02 JP JP14139279A patent/JPS5566106A/ja active Granted
• 1981
  • 1981-07-06 US US06/282,105 patent/US4420757A/en not_active Expired - Fee Related

Patent Citations (10)

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