GB2058469A - Radiation-absorbing materials - Google Patents
Radiation-absorbing materials Download PDFInfo
- Publication number
- GB2058469A GB2058469A GB7930243A GB7930243A GB2058469A GB 2058469 A GB2058469 A GB 2058469A GB 7930243 A GB7930243 A GB 7930243A GB 7930243 A GB7930243 A GB 7930243A GB 2058469 A GB2058469 A GB 2058469A
- Authority
- GB
- United Kingdom
- Prior art keywords
- absorbing material
- radiation absorbing
- layer
- radiation
- resistive coating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000011358 absorbing material Substances 0.000 title claims abstract description 39
- 230000005855 radiation Effects 0.000 claims abstract description 45
- 239000011248 coating agent Substances 0.000 claims abstract description 22
- 238000000576 coating method Methods 0.000 claims abstract description 22
- 229920001247 Reticulated foam Polymers 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 10
- 238000005507 spraying Methods 0.000 claims abstract description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- 239000003973 paint Substances 0.000 claims description 11
- 229920003023 plastic Polymers 0.000 claims description 10
- 239000004033 plastic Substances 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 7
- 239000006260 foam Substances 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 229920005830 Polyurethane Foam Polymers 0.000 claims description 4
- 239000004645 polyester resin Substances 0.000 claims description 4
- 229920001225 polyester resin Polymers 0.000 claims description 4
- 239000011496 polyurethane foam Substances 0.000 claims description 4
- 239000004677 Nylon Substances 0.000 claims description 3
- 239000003989 dielectric material Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 claims description 3
- 229920001778 nylon Polymers 0.000 claims description 3
- 229920005749 polyurethane resin Polymers 0.000 claims description 3
- 230000002787 reinforcement Effects 0.000 claims description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 2
- 239000004744 fabric Substances 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims 1
- 238000001704 evaporation Methods 0.000 claims 1
- 230000006866 deterioration Effects 0.000 abstract description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 239000006096 absorbing agent Substances 0.000 description 6
- 229920000271 Kevlar® Polymers 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 239000004761 kevlar Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000002990 reinforced plastic Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 1
- QXJJQWWVWRCVQT-UHFFFAOYSA-K calcium;sodium;phosphate Chemical compound [Na+].[Ca+2].[O-]P([O-])([O-])=O QXJJQWWVWRCVQT-UHFFFAOYSA-K 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000004816 latex Substances 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000009931 pascalization Methods 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 239000005033 polyvinylidene chloride Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/005—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems using woven or wound filaments; impregnated nets or clothes
Landscapes
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Laminated Bodies (AREA)
Abstract
The invention provides a radiation absorbing material which will operate at a wide frequency range and is suitable for use in the vicinity of antennae to prevent deterioration of antennae radiation patterns and to prevent the unwanted return from objects in the path of radar beams and the like. The material comprises a layer of three dimensional netlike structure having an electrically resistive coating applied from one side only (e.g. by spraying) so that the resistivity across the thickness of the layer varies substantially exponentially. The layer is preferably a reticulated foam structure and is preferably impregnated with a low permittivity dielectric to impart structural strength to the layer. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to materials
This invention relates to radiation absorbing materials and methods of making radiation absorbing materials.
Radiation absorbing materials are of use in any application where the reflection of electromagnetic waves is required to be reduced, for example, in the vicinity of antennae to prevent deterioration of antennae radiation patterns and to prevent the unwanted return from objects in the path of radar beams and the like.
It is an object of the present invention to provide a radiation absorbing material which will operate at a wide frequency range.
According to the present invention a radiation absorbing material comprises a layer of three dimensional netlike structure having a resistive coating applied thereto, the resistive coating varying in resistivity across the thickness of the layer whereby the resistivity of the layer increases from one side of the layer to the other side.
Preferably the resistivity of the coating increases from one side of the layer to the other side substantially exponentially.
The layer may be impregnated with a low permittivity dielectric to impart structural strength to the layer.
Additional protection from environmental conditions for the layer may be achieved by the addition of a suitable thin skin whose thickness is preferably a small proportion of the wavelength of the incident radiation.
The netlike structure of the layer may be random but is preferably statistically uniform over dimensions of a wavelength.
Thus the layer may comprise a reticulated foam structure, a honeycomb structure or a knitted filament structure.
The reticulated foam is preferably made from a polyurethane resin.
The honeycomb structure may be formed from a dielectric material and the knitted filament structure may be formed from nylon filaments.
The resistive coating preferably comprises paint which is electrically resistive.
Preferably the paint contains carbon in fine particulate form or the carbon may be in the form of fibres.
Alternatively, the resistive coating may comprise an evaporated conductive metal deposit such as a nickel-chromium alloy.
The low permittivity dielectric may be polyurethane foam, a syntactic foam or a solid plastic material.
The thin skin may comprise plastic having a low permittivity. Preferably this plastic comprises a reinforced polyester resin.
The layer may have a radiation reflecting backing sheet which preferably comprises a silver loaded conductive paint or a reinforced plastic layer using a conductive reinforcement such as carbon fibres or a carbon cloth.
The invention also comprises a method of making a radiation absorbing material comprising applying a resistive coating to one side only of a layer of three dimensional netlike structure such that the thickness of the resistive coating reduces across the thickness of the layer and hence the resistivity of the layer increases across the thickness of the layer.
Preferably the resistive coating is applied by spraying.
Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:
Figure 1 is a cross-sectional view of a radiation absorbing material in its basic form comprising a coated reticulated foam according to the invention.
Figure 2 is a cross-sectional view of a layer of coated reticulated foam impregnated with a low permittivity dielectric.
Figure 3 is a cross-sectional view as Figure 2 with a strengthening thin skin attached,
Figure 4 is a cross-sectional view as Figure 3 with a further skin attached to the other side of the layer,
Figure 5 is a graph showing a typical curve of normal incidence reflection coefficient against radiation frequency for a coated reticulated foam and,
Figure 6 is a graph showing a typical curve as in Figure 5 of a coated reticulated foam impregnated with a low permittivity dielectric.
The radiation absorbing material as shown in Figure 1 comprises a reticulated foam layer 10 of polyurethane resin having a three-dimensional netlike structure to which has been applied, by spraying from one side 20 of the layer only, a resistive coating. Since it is sprayed from the side 20 only, the coating varies in thickness across the layer, being thickest on the sprayed side 20 and gradually becoming thinner towards the other side 22. This distribution gives the layer a resistivity or complex permittivity of an approximate exponential form, the resistivity increasing towards the side 22.
The reticulated foam can have various cell sizes and for an absorber operating up to 20 GHz 10 pores per inch has been found to be satisfactory. For higher frequencies a smaller pore size should be adopted.
Instead of the reticulated foam a dielectric honeycomb can be used. Again the limitation is the frequency up to which a honeycomb of a given size will operate. For frequencies up to 20 GHz a cell size of 3/1 6 of an inch has been found to be satisfactory. Alternately, a large cell honeycomb with reticulated foam inserted into the cells can be used.
Other suitable materials are knitted nylon monofilament and "Enkamat" (Registered Trade Mark) which is a thick (0.010") filament made up to give a random open three dimensional structure.
Essentially the material should be a suitable three dimensional netlike structure which can be random but is statistically uniform over dimensions of a wavelength.
The resistive coating can comprise various types of resistive paints. Suitable compositions for the paint are
(1) PVDC emulsion (30% solid) 100 grams
Dispersion of carbon (18% solid) 166 grams
Water + 20% ammonia 12 cc approx.
(2) Copylymer latex (41.5% solid) 100 grams
Dispersion of carbon (18% solid) 230 grams
Water + 20% ammonia 1 6.5 cc approx.
The quantity of water + ammonia in these compositions may be varied to adjust the viscosity to make the paint suitable for spraying.
(3) Polyester resin 100 grams
Carbon 100 grams
Solvent (Xylene) 100 grams
Again the quantity of solvent may be varied to adjust viscosity.
The required pick up of dry paint is 38g/sqaure foot for a " thick layer of reticulated foam.
Other materials can be used instead of a carbon dispersion to give the required resistivity such as carbon fibres.
Alternatively, an evaporated metal layer of, for example, nickel-chromium alloy can be deposited on the layer of reticulated foam.
The frequency range of the absorber is a function of the thickness of the reticulated foam. A typical curve of normal incidence reflection coefficient vs frequency is shown in Figure 5 for an absorber thickness of 1.25 mm.
Figure 2 shows an absorber in which the reticulated foam is impregnated with a low permittivity dielectric foam 12 to give structural strength, such as a polyurethane foam. Some degradation of the electrical performance results depending upon the permittivity of the infilling dielectrics. A typical performance curve of a 1.25 mm thick impregnated sheet is shown in Figure 6.
Instead of polyurethane foam the dielectric can be a syntactic foam made up from hollow spheres of glass or plastic or other suitable material embedded in a plastic base.
A typical mix is;
glass spheres 30 grams
epoxy resin 90 grams
hardener 10 grams
The spheres are simply mixed into the liquid resin which is cured to give a finished product having a specific gravity of usually about 0.5. This type of foam has high strength and is capable of withstanding high hydrostatic pressures and yet gives a reasonably low value of permittivity.
A solid plastic with a low dielectric constant could be used to impregnate the reticulated foam. In general this would not be so good electrically as a foamed material because the permittivity would be higher.
Figure 3 shows an impregnated reticulated foam layer having a thin skin 14 for environmental protection, the thickness of the skin being a small proportion of the wavelength. The skin 14 has a sufficiently low permittivity to give an acceptable low reflection at the highest frequency range of the absorber. A suitable material for the skin 14 is polyester resin reinforced with Kevlar (Registered Trade
Mark) which typically has a permittivity of 3.24.
If the criterion is 1% power reflection at 20 GHz then a thickness of 0.22 mm is suitable. At lower frequencies the reflection would be correspondingly less.
Figure 4 shows an absorbing layer having a skin 14 as the front half of a sandwich structure, the rear layer 1 6 of which is a reinforced plastic layer using carbon, Kevlar (Registered Trade Mark) or glass.
Kevlar and glass require a conductive coating so as to provide a reflecting surface.
The core of the sandwich comprises a reticulated foam 10 or a honeycomb structure, or comprises a large cell honeycomb into the cells of which the reticulated absorber has been inserted. The reticulated foam 10 or other structure can be impregnated with a low dielectric honeycomb 12.
Claims (31)
1. A radiation absorbing material comprising a layer of three dimensional netlike structure having a resistive coating applied thereto, the resistive coating varying in resistivity across the thickness of the layer whereby the resistivity of the layer increases from one side of the layer to the other side.
2. A radiation absorbing material as claimed in claim 1 in which the resistivity of the coating increases from one side of the layer to the other side substantially exponentially.
3. A radiation absorbing material as claimed in claims 1 or 2 in which the layer is impregnated with a low permittivity dielectric to impart structural strength to the layer.
4. A radiation absorbing material as claimed in any preceding claim in which the layer has a thin skin whose thickness is a small proportion of the wavelength of the incident radiation.
5. A radiation absorbing material as claimed in any preceding claim in which the netlike structure of the layer is random.
6. A radiation absorbing material as claimed in any preceding claim in which the netlike structure of the layer is statistically uniform over dimensions of a wavelength.
7. A radiation absorbing material as claimed in any preceding claim which the layer comprises a reticulated foam structure.
8. A radiation absorbing material as claimed in any of claims 1 to 6 in which the layer comprises a honeycomb structure.
9. A radiation absorbing material as claimed in any of claims 1 to 6 in which the layer comprises a knitted filament structure.
10. A radiation absorbing material as claimed in claim 7 in which the reticulated foam is made from a polyurethane resin.
11. A radiation absorbing material as claimed in claim 8 in which the honeycomb structure is formed from a dielectric material.
12. A radiation absorbing material as claimed in claim 9 in which the knitted filament structure is formed from nylon filaments.
1 3. A radiation absorbing material as claimed in any preceding claim in which the resistive coating comprises paint which is electrically resistive.
14. A radiation absorbing material as claimed in claim 1 3 in which the paint contains carbon in fine particulate form.
1 5. A radiation absorbing material as claimed in claim 1 3 in which the paint contains carbon in fibrous form.
1 6. A radiation absorbing material as claimed in any one of claims 1 to 1 2 in which the resistive coating comprises an evaporated metal deposit.
1 7. A radiation absorbing material as claimed in claim 1 6 in which the metal comprises a nickelchromium alloy.
1 8. A radiation absorbing material as claimed in claim 3 in which the low permittivity dielectric comprises a polyurethane foam.
19. A radiation absorbing material as claimed in claim 3 in which the low permittivity dielectric comprises a syntactic foam.
20. A radiation absorbing material as claimed in claim 3 in which the low permittivity dielectric comprises a solid plastic material.
21. A radiation absorbing material as claimed in claim 4 in which the thin skin comprises plastic having a low permittivity.
22. A radiation absorbing material as claimed in claim 21 in which the plastic comprises a reinforced polyester resin.
23. A radiation absorbing material as claimed in any preceding claim having a radiation reflecting backing sheet.
24. A radiation absorbing material as claimed in claim 23 in which the backing sheet comprises a silver loaded conductive paint.
25. A radiation absorbing material as claimed in claim 23 in which the backing sheet comprises a plastic layer having a conductive reinforcement.
26. A radiation absorbing material as claimed in claim 25 in which the conductive reinforcement comprises carbon cloth.
27. A method of making a radiation absorbing material comprising applying a resistive coating to one side only of a layer of three dimensional netlike structure such that the thickness of the resistive coating reduces across the thickness of the layer and hence the resistivity of the layer increases across the thickness of the layer.
28. A method as claimed in claim 27 in which the resistive coating is applied by spraying.
29. A method as claimed in claim 27 in which the resistive coating is applied by evaporation of a .metal.
30. A radiation absorbing material constructed and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.
31. A method of making a radiation absorbing material substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7930243A GB2058469B (en) | 1979-08-31 | 1979-08-31 | Radiation-absorbing materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7930243A GB2058469B (en) | 1979-08-31 | 1979-08-31 | Radiation-absorbing materials |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2058469A true GB2058469A (en) | 1981-04-08 |
| GB2058469B GB2058469B (en) | 1983-12-14 |
Family
ID=10507527
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7930243A Expired GB2058469B (en) | 1979-08-31 | 1979-08-31 | Radiation-absorbing materials |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2058469B (en) |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3900856A1 (en) * | 1989-01-13 | 1990-07-26 | Messerschmitt Boelkow Blohm | FACADE CONSTRUCTION OF BUILDINGS |
| DE3900857A1 (en) * | 1989-01-13 | 1990-07-26 | Messerschmitt Boelkow Blohm | FACADE BUILDING OF BUILDINGS IN THERMAL INSULATION TRAINING AND METHOD FOR PRODUCING THERMAL INSULATION |
| DE3918383A1 (en) * | 1989-06-06 | 1990-12-20 | Messerschmitt Boelkow Blohm | FACADE CONSTRUCTION OF BUILDINGS |
| DE3936291A1 (en) * | 1989-11-01 | 1991-05-02 | Herberts Gmbh | MATERIAL WITH RADAR ABSORBING PROPERTIES AND THE USE THEREOF IN METHODS FOR CAMOUFLAGE AGAINST RADAR DETECTION |
| DE4014453A1 (en) * | 1990-05-06 | 1991-11-14 | Gruenzweig & Hartmann | ELECTRICALLY CONDUCTIVE SURFACE ELEMENT AND METHOD FOR PRODUCING THE SAME |
| DE4035460A1 (en) * | 1990-11-08 | 1992-05-14 | Messerschmitt Boelkow Blohm | Large surface, sandwiched sound insulating wall - has extra material layer on side exposed to impingement for narrow band suppression |
| DE4142480A1 (en) * | 1991-12-20 | 1993-07-01 | Kerasorb Keramik Gmbh | Absorber element used to absorb electro-magnetic waves - comprises base made of electrically insulating material contg. finely divided dielectric and/or magnetic material |
| FR2688345A1 (en) * | 1988-11-18 | 1993-09-10 | Thomson Csf | STRUCTURE ABSORBING ELECTROMAGNETIC WAVES. |
| WO1994013878A1 (en) * | 1992-12-04 | 1994-06-23 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Radar attenuating textiles |
| EP0742095A3 (en) * | 1995-05-12 | 1998-05-06 | Oto Melara S.p.A. | Composite material structure able to absorb and dissipate incident electromagnetic radiation power, in particular for air, water and land craft and for fixed ground installations |
| EP1107355A3 (en) * | 1999-11-30 | 2002-06-26 | LINTEC Corporation | Sheet antenna |
| GB2394361A (en) * | 1988-10-21 | 2004-04-21 | Marconi Electronic Devices | Energy absorbing compositions |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2215346C1 (en) * | 2002-02-06 | 2003-10-27 | Игнатьков Сергей Николаевич | Radio absorbing coating |
-
1979
- 1979-08-31 GB GB7930243A patent/GB2058469B/en not_active Expired
Cited By (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2394361B (en) * | 1988-10-21 | 2004-09-15 | Marconi Electronic Devices | Energy absorbing compositions |
| GB2394361A (en) * | 1988-10-21 | 2004-04-21 | Marconi Electronic Devices | Energy absorbing compositions |
| FR2688345A1 (en) * | 1988-11-18 | 1993-09-10 | Thomson Csf | STRUCTURE ABSORBING ELECTROMAGNETIC WAVES. |
| US5083127A (en) * | 1989-01-13 | 1992-01-21 | Messerschmitt-Bolkow-Blohm Gmbh | Thermal barrier facade construction of high rise structures and a process for fabrication of a thermal barrier |
| DE3900856A1 (en) * | 1989-01-13 | 1990-07-26 | Messerschmitt Boelkow Blohm | FACADE CONSTRUCTION OF BUILDINGS |
| US5084705A (en) * | 1989-01-13 | 1992-01-28 | Messerschmitt Bolkow-Blohm Gmbh | Facade construction in high rise structures |
| DE3900857A1 (en) * | 1989-01-13 | 1990-07-26 | Messerschmitt Boelkow Blohm | FACADE BUILDING OF BUILDINGS IN THERMAL INSULATION TRAINING AND METHOD FOR PRODUCING THERMAL INSULATION |
| DE3918383A1 (en) * | 1989-06-06 | 1990-12-20 | Messerschmitt Boelkow Blohm | FACADE CONSTRUCTION OF BUILDINGS |
| US5121122A (en) * | 1989-06-06 | 1992-06-09 | Messerschmitt-Bolkow-Blohm Gmbh | Facade construction for high structures |
| DE3936291A1 (en) * | 1989-11-01 | 1991-05-02 | Herberts Gmbh | MATERIAL WITH RADAR ABSORBING PROPERTIES AND THE USE THEREOF IN METHODS FOR CAMOUFLAGE AGAINST RADAR DETECTION |
| DE4014453A1 (en) * | 1990-05-06 | 1991-11-14 | Gruenzweig & Hartmann | ELECTRICALLY CONDUCTIVE SURFACE ELEMENT AND METHOD FOR PRODUCING THE SAME |
| DE4035460A1 (en) * | 1990-11-08 | 1992-05-14 | Messerschmitt Boelkow Blohm | Large surface, sandwiched sound insulating wall - has extra material layer on side exposed to impingement for narrow band suppression |
| DE4142480A1 (en) * | 1991-12-20 | 1993-07-01 | Kerasorb Keramik Gmbh | Absorber element used to absorb electro-magnetic waves - comprises base made of electrically insulating material contg. finely divided dielectric and/or magnetic material |
| GB2287836A (en) * | 1992-12-04 | 1995-09-27 | Secr Defence | Radar attenuating textiles |
| AU672074B2 (en) * | 1992-12-04 | 1996-09-19 | Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland, The | Radar attenuating textiles |
| US5817583A (en) * | 1992-12-04 | 1998-10-06 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Radar attenuating textiles |
| GB2287836B (en) * | 1992-12-04 | 1996-09-18 | Secr Defence | Radar attenuating textiles |
| WO1994013878A1 (en) * | 1992-12-04 | 1994-06-23 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Radar attenuating textiles |
| EP0742095A3 (en) * | 1995-05-12 | 1998-05-06 | Oto Melara S.p.A. | Composite material structure able to absorb and dissipate incident electromagnetic radiation power, in particular for air, water and land craft and for fixed ground installations |
| EP1107355A3 (en) * | 1999-11-30 | 2002-06-26 | LINTEC Corporation | Sheet antenna |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2058469B (en) | 1983-12-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19980831 |