Classifications

• • 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
  • H01Q15/22—Reflecting surfaces; Equivalent structures functioning also as polarisation filter
• • 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
  • H01Q15/141—Apparatus or processes specially adapted for manufacturing reflecting surfaces
• • 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
  • H01Q15/141—Apparatus or processes specially adapted for manufacturing reflecting surfaces
  • H01Q15/142—Apparatus or processes specially adapted for manufacturing reflecting surfaces using insulating material for supporting the reflecting surface

Definitions

• Electromagnetic wave reflector and method of manufacturing the same
• the present invention relates to electromagnetic wave reflectors made of an element made of an electrically conductive material, preferably having a convex face which defines a focal point for radio waves. They are most often antennas in the form of a spherical or parabolic cap, but they can also have any other shape giving focus.
• a metal antenna is already known which is made by stamping, in one or more passes, a spherical cap enabling the signals from a satellite to be focused at one point.
• the metal surface is radio opaque to the frequencies transmitted by the satellite and allows a theoretical reflection rate of 100%.
• the sheet must undergo several surface treatments in order to prevent corrosion. These treatments require repeats after stamping, in particular the application of a primer and a paint.
• DE 3911445 A also discloses antennas made of thermosetting material which require tools intended to obtain the desired shape, in particular parabolic.
• a metal frame is shaped manually in the tooling.
• a piece of material is then introduced into the tool above the frame.
• the tool is locked.
• Cooking is carried out in order to polymerize the material introduced.
• the tool is opened and the part is extracted from the mold. Due to molding technology, deburring must be performed followed by sanding, removing a primer, then painting on both sides.
• EP-595 418 an antenna is described comprising a metallic fabric coated by injection molding of thermoplastic resin.
• the wire mesh is given the desired shape before molding. It is very difficult to conform a metallic canvas into a parabola with great accuracy.
• Powder coating technologies do not allow for a large variation in color, without incurring disproportionate manufacturing costs due to the need to clean the manufacturing tool when switching from one color to another .
• the invention overcomes these drawbacks and makes it possible to obtain an electromagnetic wave reflector protected from corrosion, which is much easier to manufacture and which, in particular, allows the possible use of a paint which is easier and less expensive to use. and therefore to dispense with any painting operation with dusting and the cleaning operations that this entails.
• the subject of the invention is a method of manufacturing an electromagnetic wave reflector having a shape giving a focusing of the electromagnetic waves, in which an electrically conductive network is placed in a molding tool, material is put thermoplastic plastic in the molding tool and a reflector is removed from the mold, characterized in that the grating placed in the molding tool has a shape other than said shape giving focus of the electromagnetic waves, and the thermoplastic material is injected into the tool for molding under pressure such that it sets the network to said shape giving focus.
• the network of electrically conductive material may include wires arranged at a distance, preferably constant, from each other.
• the network is a canvas or a grid, in particular a plane.
• the manufacturing is done by injection molding of a thermoplastic material, preferably on a regular mesh grid of an electrically conductive material.
• the injection is carried out under high pressure, in particular greater than 50 bar and most often between 150 and 450 bar.
• the method consists in pinching between the two half-molds of an injection mold of thermoplastic material a network of an electrically conductive material of a size such that it exceeds the periphery of the imprint of the mold, - injecting thermoplastic material into the impression, demolding an injected part around the periphery of which protrudes the network, and cutting the network flush with the part.
• the network is thus well maintained during molding and the curvatures of the network and of the coating are not offset, the whole being obtained automatically by the usual molding operation.
• the coating of the wires is often almost complete and, in any case, takes place over more than 80% of the cross section of the wires.
• the wire generally has a diameter of 0.005 to 0.5 mm, it being understood that the wires can also have a cross section other than circular and that then the values indicated above are understood for the largest dimension of the cross section .
• thermoplastic material use may in particular be made of polyethylene, polypropylene or other polyolefins, ABS, polycarbonate, poly (methyl methacrylate) as well as any other injectable thermoplastic material.
• the thickness of plastic material injected is generally between 0.5 mm and 1 cm.
• the distance between the wires is between 0.003 mm and 1.5 cm.
• the desired color for the antenna is given to it by the fact that the plastic is dyed in the mass.
• the antenna can also be transparent.
• the invention also relates to an electromagnetic wave reflector comprising a network of an electrically conductive material coated with a sheet of thermoplastic material having a central part and a border, characterized in that in the central part the network appears punctually on one of the faces of the tablecloth, while on part of the border it is embedded in the tablecloth.
• FIG. 1 is a perspective view illustrating two half-molds according to the invention between which a wire mesh is inserted
• FIG. 2 shows the wire mesh at the stage where it is pinched between the two half-molds
• Figure 3 is an elevational view of an antenna according to the invention before the fabric has been cut
• Figure 4 shows the antenna with a drop of the fabric that has been cut
• Figure 5 is a partial sectional view of an antenna according to the invention
• Figure 6 is a partial sectional view of a variant of an antenna according to the invention.
• a flat metallic fabric 1 is retained on one of the two half-molds 2, 3 of an injection mold for thermoplastic material.
• Figure 2 shows that when the fabric 1 is pinched between the two half-molds 2, 3, it protrudes from the periphery of the cavity 4 of the mold.
• FIG. 3 represents the molded injected part 5 in which the fabric 1 is coated which protrudes by a part 6.
• FIG. 4 shows that the part 6 has been cut in the form of a drop 6 leaving a parabolic antenna in the shape of the imprint 4 which is made up, as shown in FIGS. 5 and 6, of the fabric 1 coated with a layer 7 of thermoplastic plastic.
• the antenna comprises a central part 8 in the form of a parabola and a peripheral border 9.
• the fabric 1 appears punctually on one of the faces of the sheet 7, while, on at least part of the border 9, the fabric 1 is embedded in the sheet 7.
• the antenna of the figure 5 was obtained when the direction of the injection current into the mold is directed vertically from bottom to top, while in FIG. 6, it was directed vertically from top to bottom.
• Polyethylene is introduced beforehand brought to a temperature of 260 ° C., so that it can flow through an injection point, into the cavity 4 of the mold which is in the shape of the reflector to be obtained and in which puts a flat aluminum canvas which protrudes from it.
• a pressure of 177 bar is applied to the plastic, the closing force of the two mold halves is 800 tonnes.
• 1.2 kg of polyethylene is injected into the imprint.
• the injection time is 7 seconds.
• the injection pressure is 117 bar.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Aerials With Secondary Devices (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Laminated Bodies (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Related Child Applications (1)

Publications (1)

Family

ID=9531664

Family Applications (2)

Family Applications After (1)

Country Status (10)

Families Citing this family (3)

Family Cites Families (18)

• 1998
  • 1998-10-16 FR FR9813007A patent/FR2784804B1/fr not_active Expired - Fee Related
• 1999
  • 1999-10-12 BR BR9912233-2A patent/BR9912233A/pt not_active IP Right Cessation
  • 1999-10-12 EP EP99947544A patent/EP1119884A1/de active Pending
  • 1999-10-12 EP EP01201226A patent/EP1143561B1/de not_active Expired - Lifetime
  • 1999-10-12 WO PCT/FR1999/002450 patent/WO2000024086A1/fr not_active Application Discontinuation
  • 1999-10-12 JP JP2000577736A patent/JP2002528937A/ja active Pending
  • 1999-10-12 DE DE69923001T patent/DE69923001T2/de not_active Expired - Lifetime
  • 1999-10-12 AT AT01201226T patent/ATE286309T1/de not_active IP Right Cessation
  • 1999-10-12 CA CA002337810A patent/CA2337810A1/fr not_active Abandoned
  • 1999-10-12 AU AU60952/99A patent/AU6095299A/en not_active Abandoned
  • 1999-12-10 US US09/806,083 patent/US6486854B1/en not_active Expired - Fee Related

Non-Patent Citations (1)

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