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GB2236019A - Microwave focussing device - Google Patents

Microwave focussing device Download PDF

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Publication number
GB2236019A
GB2236019A GB9019031A GB9019031A GB2236019A GB 2236019 A GB2236019 A GB 2236019A GB 9019031 A GB9019031 A GB 9019031A GB 9019031 A GB9019031 A GB 9019031A GB 2236019 A GB2236019 A GB 2236019A
Authority
GB
United Kingdom
Prior art keywords
coating
tin oxide
glass
doped tin
fluorine doped
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
Application number
GB9019031A
Other versions
GB2236019B (en
GB9019031D0 (en
Inventor
David Raymond Goodall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pilkington Group Ltd
Original Assignee
Pilkington PLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from GB898920836A external-priority patent/GB8920836D0/en
Application filed by Pilkington PLC filed Critical Pilkington PLC
Priority to GB9019031A priority Critical patent/GB2236019B/en
Publication of GB9019031D0 publication Critical patent/GB9019031D0/en
Publication of GB2236019A publication Critical patent/GB2236019A/en
Application granted granted Critical
Publication of GB2236019B publication Critical patent/GB2236019B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/06Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using refracting or diffracting devices, e.g. lens
    • H01Q19/062Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using refracting or diffracting devices, e.g. lens for focusing
    • H01Q19/065Zone plate type antennas

Landscapes

  • Surface Treatment Of Glass (AREA)

Abstract

A microwave focussing device 1 for focussing microwave signals onto a collector 7 comprises a pane of glass 2 carrying a transparent patterned coating of fluorine doped tin oxide 4, which may, for example, be in the form of a Fresnel zone plate; it provides an unobtrusive means for focussing broadcast signals from satellites or broadcasting antenna used in local television stations onto a collector. <IMAGE>

Description

FOCUSSING DEVICE The invention relates to a microwave focussing device for focussing microwave signals onto a collector.
Such focussing devices are used, for example, for focussing broadcast signals from satellites or broadcasting antenna which may be used in local television stations. They are best known in the form of parabolic "satellite dishes" which focus radiation onto a collector along the axis of the dish. However, it has also been proposed, in International Patent Publication Number WO 88/10521, to use, as a focussing device, a flexible plastics sheet bearing an opaque patterned absorbing or reflecting coating such as silver, nickel, aluminium or graphite ink or paint in the form of a Fresnel zone plate. The flexible plastics sheet, when not in use, is wound on a cylindrical roller behind a window in the building where the signal is to be focussed and collected.For use, the plastics sheet is unwound across the window and the pattern on the sheet focusses the microwave radiation onto a collector (described as a "waveguide horn feed") within the building. The invention provides a more aesthetically acceptable focussing means than the more conventional satellite dish, but still suffers from the disadvantage of being obtrusive when in use and requiring storage when not in use.
It has now been found, surprisingly, that satisfactory results can be achieved using in place of the opaque patterned coating, a patterned coating of fluorine doped tin oxide; such coatings are reflective to microwave radiation, have a high degree of transparency to visible light, and are already used, in continuous form, in architectural glazing applications. By using such fluorine doped tin oxide coatings, the obtrusive appearance of the prior art aerials may be avoided or at least substantially alleviated.
According to the present invention there is provided a focussing device for microwave radiation comprising a pane of glass carrying a transparent patterned coating of fluorine doped tin oxide to focus the microwave radiation onto a collector.
We have found that the fluorine doped tin oxide coatings on commercially available coated glass, for example glass as commercially offered as low emissivity glass for thermally insulating architectural glazing, are suitable for use in forming such focussing devices. This may be done, for example, by selectively etching the coating to provide the required pattern.
As indicated in International Patent Publication WO 88/10521 the pattern may be such that the focussing device constitutes a Fresnel zone plate. When the radiation to be collected is incident at 90" to the device, the pattern layer is in the form of concentric annular zones. When the radiation is incident at non-normal angles of incidence, the patterned layer may be in the form of a set of ellipses with centres displaced along a common major axis.
The commercially available low emissivity coated glasses with fluorine doped tin oxide coatings generally have coatings of fluorine doped tin oxide with a thickness in the range 150 nm to 1000 nm and may be used to form a patterned coated pane in accordance with the invention by selective etching, although we prefer to use coated glasses having a transparent fluorine doped tin oxide layer having a thickness in the range 250 nm to 400 nm.
The fluorine doped tin oxides are substantially transparent to visible light so that the patterned coating is not particularly obvious or obtrusive, and the glass focussing devices of the present invention can be glazed as windows of buildings, or behind existing windows as secondary sashes, where the radiation is to be collected without substantially detracting from the appearance of the windows. Unfortunately, particularly with thinner tin oxide coatings having a thickness of less than 800 nm, the coating is liable to exhibit iridescent colours which may be found objectionable.This effect can be overcome by using a coating with a colour suppressing underlayer (that is a layer which, when applied between the glass and an overlying layer which would otherwise exhibit iridescent reflected colours, suppresses those colours), for example of the type described in UK patent GB 2 015 983B or UK patent GB 2 031 756B.
The focussing effect of the device in accordance with the invention may be enhanced, in a manner known in principle, by placing a microwave reflective panel behind the focussing device.
This results in a more intense microwave signal being provided for collection at a point in front of the device i.e. on the same side of the device as the incident signal. It has been found that not only the fluorine doped tin oxide coatings used in patterned form in accordance with the present invention, but also other transparent semiconductor metal oxide coatings and transparent metallic coatings are reflective to microwave radiation and may be used in continuous form to provide such a microwave reflective panel. Thus according to a further aspect of the present invention there is provided a focussing device with a transparent patterned coating of fluorine doped tin oxide in accordance with the invention in spaced parallel relationship with a substantially continuous transparent coating reflective to microwave radiation.
The spacing between the patterned and substantially continuous coatings is preferably equal to 1/4 of the wavelength of the microwave radiation to be focussed.
When a transparent metallic coating is used as the substantially continuous coating, it will generally be composed of a very thin copper or silver layer, for example a layer having a thickness in the range 5 nm to 15 nm sandwiched between anti-reflection metal oxide layers. Suitable metal coated glasses are available from Pilkington Glass Limited of St. Helens, England, under the designations champagne KAPPAFLOAT glass and neutral KAPPAFLOAT glass (KAPPAFLOAT is a trade mark of Pilkington plc).
By the term "transparent" we mean a coating which reduces the visible light transmission of the coated substrate by not more than 30%. We especially prefer to use coatings such as coatings of fluorine doped tin oxide which reduce the light transmission of the coated substrate by not more than 105.
The substantially continuous coating may have the same fluorine doped tin oxide composition as the transparent patterned coatings disclosed herein, and may, if the glass pane is of suitable thickness, be applied on the opposite face of the glass to the patterned coating. Alternatively, the substantially continuous coating may be on a second pane of glass mounted in spaced parallel relationship with the pane having the patterned coating to provide either double glazing or, if an interlayer is used to bond the panes together, a laminate. This embodiment is illustrated, by way of example, in the accompanying drawing which shows, in diagrammatic form, a vertical section through a microwave focussing device.
Referring to the drawing, a laminate, generally designated 1, comprises first and second glass panes 2 and 3 of coated glass.
Pane 2, which is oriented towards the source of microwave radiation to be collected, has a transparent patterned coating of fluorine doped tin oxide in the form of a series of elliptical rings 4, while pane 3, oriented away from the source of microwave radiation, carries a continuous coating 5 of fluorine doped tin oxide on its surface facing the first pane. The panes are laminated together with a cast-in-place interlayer 6 of acrylic resin, polymerised in situ between the panes to bond them together, the spacing between the panes being chosen so that the thickness of the resin layer is equal to 1/4 of the wavelength in the resin of the microwave radiation to be focussed.
The microwave radiation reflected directly from the patterned coating, together with the radiation transmitted between the coated areas-of-the patterned coating, reflected by the continuous coating and transmitted between the coated areas of the patterned coating is focussed on a waveguide horn feed 7 in front of the laminate 1 for collection.
By using transparent fluorine doped tin oxide coatings (as for example the low emissivity coating on glass supplied by Pilkington Glass Limited of St. Helens, England, as Pilkington K Glass - trade mark), a laminate with a high light transmission (over 60%) over its whole area may be produced, having only a small difference in light transmission (less than 5%) between the coated and uncoated areas in the patterned coating so that the pattern is not unduly conspicuous.
While, in the drawing, the coatings have been shown on facing internal surfaces of the glass panes it will be appreciated that, provided it is of durable material (such as doped tin oxide) either (or both) of the coatings may be on an external exposed surface.
In this case, the thickness of the interlayer to be used should be calculated taking into account the thickness of the glass.
The production of a single pane focussing device in accordance with the invention is described but not limited by the following Example.
EXAMPLE A pane of 4 mm Pilkington K Glass (trade mark of Pilkington plc), a commercially available glass with a low emissivity coating of fluorine doped tin oxide and a colour suppressing underlayer, was cut to a size of approximately 100 cm x 110 cm and edge worked.
The base glass, that is without the coating, had a visible light transmission of 89% and the coated glass had a light transmission of 84%, so that the coating reduced the light transmission by 5%.
A pattern of rings, similar to that illustrated in Figure 2 of International Patent Publication WO 88/10521, in Reprochem etch resist WWA 75, a commercially available UV curable resin, was screen printed on to the glass and cured by exposure to UV light.
The printed glass was then used to form the base of a shallow trough with its printed surface upwards, and side walls constructed of thin strips of glass bonded to the base using RTV silicone sealant. After the sealant had cured, hydrochloric acid (approximately 20% weight/volume) was poured into the trough in an amount sufficient to cover the surface of the base and zinc dust applied over the liquid surface using a sieve to evenly distribute the particles over the liquid. The ensuing reaction was allowed to proceed for 30 seconds and then excess water was poured into the trough to terminate the reaction which was found to have etched the exposed transparent doped tin oxide coating off the glass. The reactants were drained off and the trough rinsed with water.
Sodium hydroxide solution (approximately 5%) was added to the trough to dissolve the resist which had protected the underlying doped tin oxide coating from etching and then drained off. The side walls of the trough were removed and the base glass, now carrying a patterned layer of transparent doped tin oxide with a colour suppressing underlayer, cleaned to provide a focussing device in accordance with the invention.
The fluorine doped tin oxide coatings used in the present invention are highly durable permitting the focussing device of the invention to be used and cleaned as a normal window, and thus providing a durable unobtrusive alternative to a satellite dish.
Moreover, the coating in the coated area of the glass will serve to reflect infra red radiation back into the building and, as an additional benefit, provide a window with improved heat insulation compared to normal uncoated glass.

Claims (15)

1. A focussing device for microwave radiation comprising a pane of glass carrying a transparent patterned coating of fluorine doped tin oxide to focus the microwave radiation onto a collector.
2. A device as claimed in claim 1 wherein the coating comprises a fluorine doped tin oxide layer having a thickness in the range 150 nm to 1000 nm.
3. A device as claimed i-n claim 2 wherein the fluorine doped tin oxide layer has a thickness in the range 250 nm to 400 nm.
4. A device as claimed in any of the preceding claims wherein a colour suppressing underlayer, as hereinbefore defined, is provided on the glass substrate between the fluorine doped tin oxide layer and the glass.
5. A device as claimed in any of the preceding claims wherein the coated glass pane constitutes a Fresnel zone plate.
6. A device as claimed in any of the preceding claims wherein the patterned coating is in the form of concentric annular zones.
7. A device as claimed in any of claims 1 to 5 wherein the patterned coating is in the form of a set of ellipses with centres displaced along a common major axis.
8. A device as claimed in any of the preceding claims wherein the patterned coating is formed by selectively etching a continuous transparent fluorine doped tin oxide coating.
9. A focussing device for microwave radiation comprising a patterned layer of transparent fluorine doped tin oxide substantially as hereinbefore described in the Example.
10. A focussing device for microwave radiation comprising a device as claimed in any of the preceding claims with a substantially continuous transparent coating reflective to microwave radiation in spaced parallel relationship with the transparent patterned coating of fluorine doped tin oxide.
11. A device as claimed in claim 10 wherein the substantially continuous transparent coating is of semiconductor tin oxide.
12. A device as claimed in claim 11 wherein the substantially continuous transparent coating is of fluorine doped tin oxide.
13. A device as claimed in any of claims 10 to 12 in the form of a laminate comprising a pane of glass carrying the transparent patterned coating bonded by an interlayer to a second pane of glass carrying the substantially continuous transparent coating.
14. A focussing device for microwave radiation in the form of a glass laminate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
15. A window glazed with a pane of glass which is a focussing device for microwave radiation as claimed in any of the preceding claims.
GB9019031A 1989-09-14 1990-08-31 Microwave focussing device Expired - Fee Related GB2236019B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9019031A GB2236019B (en) 1989-09-14 1990-08-31 Microwave focussing device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898920836A GB8920836D0 (en) 1989-09-14 1989-09-14 Focussing device
GB9019031A GB2236019B (en) 1989-09-14 1990-08-31 Microwave focussing device

Publications (3)

Publication Number Publication Date
GB9019031D0 GB9019031D0 (en) 1990-10-17
GB2236019A true GB2236019A (en) 1991-03-20
GB2236019B GB2236019B (en) 1994-05-11

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9019031A Expired - Fee Related GB2236019B (en) 1989-09-14 1990-08-31 Microwave focussing device

Country Status (1)

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GB (1) GB2236019B (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2243490A (en) * 1990-03-02 1991-10-30 Pilkington Glass Ltd Dish antenna
GB2278020A (en) * 1993-04-02 1994-11-16 Nigel Frewin Antenna
US5389944A (en) * 1990-07-10 1995-02-14 Mawzones Developments Limited Phase correcting reflection zone plate for focusing microwave
EP0680111A1 (en) * 1994-04-29 1995-11-02 Hollandse Signaalapparaten B.V. Adjustable microwave antenna
NL9400863A (en) * 1994-05-26 1996-01-02 Hollandse Signaalapparaten Bv Adjustable microwave antenna
WO2000033414A3 (en) * 1998-11-03 2000-11-09 Arizona Board Or Regents Frequency selective microwave devices using narrowband metal materials
EP1213787A3 (en) * 2000-12-07 2002-07-17 Asahi Glass Company Ltd. Antenna device
WO2002060008A1 (en) * 2001-01-12 2002-08-01 Oorninki-Ohjelmistot Oy Antenna system
WO2006117004A1 (en) * 2005-05-03 2006-11-09 Carlsberg Breweries A/S A packaging object having a rfid tag

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988010521A1 (en) * 1987-06-16 1988-12-29 Thomas Michael Benyon Wright Collapsible receiving antenna

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU4810490A (en) * 1988-12-20 1990-07-10 Mawzones Developments Limited Focussing device for a microwave antenna

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988010521A1 (en) * 1987-06-16 1988-12-29 Thomas Michael Benyon Wright Collapsible receiving antenna

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2243490A (en) * 1990-03-02 1991-10-30 Pilkington Glass Ltd Dish antenna
GB2243490B (en) * 1990-03-02 1994-06-29 Pilkington Glass Ltd Coated glass
US5389944A (en) * 1990-07-10 1995-02-14 Mawzones Developments Limited Phase correcting reflection zone plate for focusing microwave
GB2278020A (en) * 1993-04-02 1994-11-16 Nigel Frewin Antenna
US5585812A (en) * 1994-04-29 1996-12-17 Hollandse Signaalapparaten B.V. Adjustable microwave antenna
EP0680111A1 (en) * 1994-04-29 1995-11-02 Hollandse Signaalapparaten B.V. Adjustable microwave antenna
US5736966A (en) * 1994-04-29 1998-04-07 Hollandse Signaalapparaten B.V. Adjustable microwave antenna
NL9400863A (en) * 1994-05-26 1996-01-02 Hollandse Signaalapparaten Bv Adjustable microwave antenna
WO2000033414A3 (en) * 1998-11-03 2000-11-09 Arizona Board Or Regents Frequency selective microwave devices using narrowband metal materials
US6473048B1 (en) 1998-11-03 2002-10-29 Arizona Board Of Regents Frequency selective microwave devices using narrowband metal materials
EP1213787A3 (en) * 2000-12-07 2002-07-17 Asahi Glass Company Ltd. Antenna device
US6473049B2 (en) 2000-12-07 2002-10-29 Asahi Glass Company, Limited Antenna device
EP1351335A1 (en) * 2000-12-07 2003-10-08 Asahi Glass Company Ltd. Antenna device
WO2002060008A1 (en) * 2001-01-12 2002-08-01 Oorninki-Ohjelmistot Oy Antenna system
WO2006117004A1 (en) * 2005-05-03 2006-11-09 Carlsberg Breweries A/S A packaging object having a rfid tag

Also Published As

Publication number Publication date
GB2236019B (en) 1994-05-11
GB9019031D0 (en) 1990-10-17

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19980831