BUILDING COMPONENTS

Abstract: The invention relates to a building component (1) adapted for absorbing incident electromagnetic energy in the radar range of frequencies particularly between 1 and 1.1 GHz, comprising a substrate in the form of a receptacle or tray (2) of material which is transparent to electromagnetic energy in said radar range, a reflector (3) of said energy and a separate absorber (4) of said energy. The arrangement of the device (1) is such that it may be installed in or on a structure as by suitable means such as hooks, adhesive or suction means.

Description: BUILDING COMPONENTS The invention relates to building cαiponents, particularly such c iponents -as -are us^ed to be .incorporated in or applied to a building, as by cladding, and which include radar energy absorptive properties. Air traffic ccxitrol and tlie difficulties inherent in an increasingly densely packed ccπroercial aircraft environment have been widely dis-cussed internationally. .Aircraft are controlled by ground per.sonnel using what are known as "Primary Radars". These operate in X-Band and are manufactured by many coπpanies. ϊheir main function is to plot the position and height of an aircraft; information which, us.ing software, is converted .into a peirmanently updated three dimensional track and is then presented to Air Traffic Controllers on the ground. The need to identify each aJLrcraft individually has been achieved through the use of "Secondary Radar" operating at a much lower frequency (between 1 and 1.1. ghz). This radar transmits on one frequency and receives on another and ag-ain through using software, is able to display automatically the individual track nmber of the aircraft alongside t±te three dimensional position known through the Primary Radar. This sytem is generally kncwn by the acronym IFF. Together these tv-ro systems provi-de course, speed, height and identity of all a-Lrborne contacts. Serious problems have arisen with Secondary Radars due to interference frαn structures, vehicles and otter solid objects which are irradiated naturally during operations. False and at times multiple radar returns -are presented to the operator which, in seme instances can be reduced by the i-ncαrporaticxi of very expensive software. The effects of these unwanted radar returns are to confuse the operator's picture and at times through πultipath effects to isidentify aircraft in the air traffic control system. The dangers inherent frcm tlese effects are obvious. It is an object of the invention to seek to obviate these disadvantages. According to the invention there is provided a building cαrponent adapted for absorbing incident electromagnetic energy in the radar range of frequencies, comprising a substrate of materi-al which is transparent to incident electromagnetic energy in the said range, a reflector of said energy and a separate absorber of said energy, the arrangement be.ing such that the device may be installed in or on a structure for absorbing said energy incident thereon. The substrate may comprise a receptacle of a material which is transparent to incident radar energy. The receptacle may preferably ccπprise a tray, which may be rectangular or of any other suitable or preferred configuration. The material of 1 e tray may comprise a polyester material or similar radar transparent material. The reflector may ccπprise a sheet aluminium reflector on the interior of the tray. Preferably the reflector may ccπprise a sheet of alimiinium foil, which may be loose in the tray, or may be secured to the interior of the tray as by glueing. The foam material may be a high density conductive foam, for exaπple a 1/4" (0.635cm) foam such as that sold under the Trade Mark Vitec. The pl-astic material may cαtprise a polycarbonate sheet, for exaitple a sheet of 57mm thickness, which may ccnpri.se a conductive foil, for exaitple a cast polycarbonate film filled with a disperser such as carbon black. Preferably, the film is relatively tough, and ther oformable. It will be understood that the various items of tlie ccπponent may be put up in the tray in v-arious order to provide a laminate type of structure which is light, robust, aesthetically pleasing and which is operationally effective and can be applied to a structure such as a building construction by any suit-able means such as hooks, adhesive or suction means. A plurality of the cαiponents can be applied as a mosaic cladding to a building surface. It will be understood that by varying the thickness of the polycarbonate sheeting and conductive foam, the performance can be varied accordingly. Suitably, there may be two panes of glass, and the reflector may be on a surface which is in use an inner surface of the unit, and the absOaTber may be on a surf-ace of tire otiier pane which faces into the air gap. The absorber may be an absorber of electromagnetic energy and may comprise a plastic sheet material such as bayfoil or baekert. The bayfoil may be opaque to incident electromagnetic energy, and the baekert may be transparent. The bayfoil may be of any desired colour when it is opaque, whereby to provide a pleasing aesthetic effect. The absorber may, in the alternative, be applied directly to the pane of glass as by fusing, vapour deposition or other suitable means. The reflector may be a coloured sheet of material such as plastic materi-al. The air gap may be 35mm wide. Such building ccrrponents, or double glazing units are often used on facades of buildings in glazing systems known as curtain glazing. Building components embodying the invention are hereinafter described, by way of exaπple, with reference to the -accαipanying drawings. Fig.l is a schematic transverse sectional view of one embodiment of building cαiponents according to the invention; Fig.2 is a schematic transverse sectional view of a second eπbodiment of building cαiponents in the form of a glazing unit according to the invention; and Fig.3, 4 and 5 are graphs of absorption of radar energy by building ccrrponents according to Figs. 1 and 2. Referring firstly to Fig.l of the drawings, there is shown a building ccπponent 1 adapted for absorbing incident electromagnetic energy in the radar range of frequencies particularly between 1 and 1.1 ghz, cαiprising a substrate in the form of a receptacle or tray 2 of material which is transparent to electromagnetic energy in said radar range, a reflector 3 of said energy and a separate absorber 4 of said*e ergy. The arrangement of the device 1 is such that it may be .installed in or on a structure as by suitable means such as hooks, adhesive or suction means. A plurality of the cαtponents 1 may be applied as a mosaic cladding to a building surface, so absorbing incident radar energy and providing avoidance of interference with say air traffic control radar. The reflector 3 is .in the embodiment a foil of aluminium secured to the inner surface of the tray 2 as by adhesive. The absorber 4 is a high density conductive foam of 1/4" (0.635cm) thick. There may be cover 5 of a polycarbonate material. Referring to Fig.2, there is shewn a second eπbodunent of building ccπponents in the form of a glazing unit 1, coπprising two substantially parallel panes 12 and 13 of glass separated by an air gap 14 of 34πm width in the eπtoodiment. There is a reflector in the form of a sheet 15 of material secured as by adhesive to the inner (in use) surf-ace of the inner pane 13 and an absorber 16 in the form of a sheet of bayfoil or baekert secured as by adhesive on the surface of the outer pane 12 of glass which is the surface whi-ch faces into the a^ gap 14. Thus, in use of the double glazing unit shown, when it is installed on a building, the absorber 16 is protected from tlie atmosphere outside the building, shown at "0" as it is in the (sealed) gap 14, while the reflector 15 is also protected by facing towards the inside "I" of the building. The absOaTber 16 absorbs incident radar energy and may thus be of resistance of about 35 Ohms and thus does not interfere with radar such as air traffic control. The reflector provides a desired aesthetic effect of the building if it is coloured as desired. The unit 11 includes a spacer 17, a drying agent 18 for air in the gap 14, a sealant 19 and an aluminium foil 20 edge protector.

Claims: CLAIMS 1. A building component adapted for absorbing incident electromagnetic energy in the radar range of frequencies, cαiprising a substrate of material which is transparent to incident electromagnetic energy in the said range, a reflector of said energy and a separate absorber of said energy, the arrangemsnt being such that the device may be installed in or on a structure for absorbing said energy incident thereon. 2. A building component according to Claim 1, the substrate cαtprising a receptacle of material which is transparent to said energy. 3. A building component according to Claim 2, the absorber cαtprising a foam insert in the tray. 4. A building cαiponent according to Claim 3, the receptacle cαtprising a tray. 5. A building component according to Claim 4, the material of the tray cαtprising a polyester or similar radar transparent material. 6. A building cαiponent according to any of Claims 2 to 5, the reflector cαrprising a sheet aluminum reflector. 7. A building cαtponent according to Claim 6, the sheet aluminium reflector being secured to tlie receptacle. 8. A building ccttponent according to any preceding claim, including a cover of a sheet of plastic material. 9. A building cαtponent according to Claim 8, the plastic material cαtprising a polycarbonate sheet material. 10. A building cαtponent according to Claim 1, the substrate cαtpriSaing a plurality of panes of glass, there being a reflector on one surface of one pane and an absorber an one surface of an adjacent pane. 11. A building component according to Claim 10, adjacent panes being separated by an air gap. 12. A building ccπponent according to Claim 11, there be.ing two panes of glass, forming a glazing unit, the reflector being an a surface which in use is an inner surface of the unit, and the absorber being on a surface of the other pane which faces into the a^ gap. 13. A building cαtpαnent according to Claim 12, tine absorber being applied directly to the respective pane. 14. A building cαiponent according to Claim 12 or 13, the reflector cαιpris.ing a coloured sheet of plastic material.

Inventors: TUSCH KLAUS NORBERT, TUSCH, KLAUS, NORBERT
Applicants: COLEBRAND LTD, COLEBRAND LIMITED
Application year: 1991
Main classification: H01Q17
IPC codes: H01Q17