EP0268362A1 - Parabolantenne mit Heizung - Google Patents

Parabolantenne mit Heizung Download PDF

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Publication number
EP0268362A1
EP0268362A1 EP87308610A EP87308610A EP0268362A1 EP 0268362 A1 EP0268362 A1 EP 0268362A1 EP 87308610 A EP87308610 A EP 87308610A EP 87308610 A EP87308610 A EP 87308610A EP 0268362 A1 EP0268362 A1 EP 0268362A1
Authority
EP
European Patent Office
Prior art keywords
heater
antenna
assembly according
dish antenna
back surface
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
EP87308610A
Other languages
English (en)
French (fr)
Other versions
EP0268362B1 (de
Inventor
Pradeep Barma
Chi-Ming Chan
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.)
Raychem Corp
Original Assignee
Raychem Corp
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
Application filed by Raychem Corp filed Critical Raychem Corp
Priority to AT87308610T priority Critical patent/ATE79487T1/de
Publication of EP0268362A1 publication Critical patent/EP0268362A1/de
Application granted granted Critical
Publication of EP0268362B1 publication Critical patent/EP0268362B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/28—Adaptation for use in or on aircraft, missiles, satellites, or balloons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/02—Arrangements for de-icing; Arrangements for drying-out ; Arrangements for cooling; Arrangements for preventing corrosion

Definitions

  • This invention relates to dish antennas, eg. for receiving and/or transmitting signals from satellites or terrestrial microwave antennas, and in particular means for heating such antennas.
  • dish antennas particularly for receiving signals from satellites
  • Dish antennas vary widely in size, but many have diameters of 1 to 7 meters; for example, 1.2 meter and 1.8 meter aperture antennas are most frequently used for signals in the 12-14 GHz band which is widely used for private networks transmitting data, voice and video communications.
  • regulations eg. United States FCC Regulation 25.209, which set requirements, eg. radiation pattern sidelobe envelope requirements, for both transmit and receive antennas, and a major concern of antenna manufacturers and users is to ensure not only that antennas meet those requirements when first manufactured, but also that they do not become distorted subsequently, so that the requirements are no longer met.
  • dish antennas can be very satisfactorily heated, and thus kept free of ice and snow, by means of an electrical heater which is placed behind the antenna and spaced apart therefrom, so that the antenna is heated by radiation from the heater.
  • the present invention provides a dish antenna assembly which comprises
  • the heaters used in this invention preferably comprise a resistive element in the form of a sheet; however they can alternatively comprise one or more strip heaters secured to a thermally conductive sheet, preferably of metal. All such heaters are included in the term "sheet heater” or “heater in the form of a sheet” as used herein.
  • the sheet heater must be positioned so that it is substantially separated from the antenna by a medium which is substantially transparent to thermal radiation, usually air, so that heat generated by the heater radiates from the heater through the medium and strikes the back surface of the antenna.
  • a medium which is substantially transparent to thermal radiation usually air
  • heat generated by the heater radiates from the heater through the medium and strikes the back surface of the antenna.
  • the distance between the first surface of the heater and the back surface of the antenna is 3 to 6 inches (7.6 to 15.2 cm).
  • heating of the antenna takes place mainly or exclusively by conduction.
  • little or none of the heating of the antenna is the result of conduction and a substantial proportion, preferably at least 40%, particularly at least 60%, of the heating of the antenna is the result of radiation.
  • the antenna is generally also heated by free convection from air (or other gas) which lies between the antenna and the heater.
  • the air is preferably still air, i.e. any movement thereof is solely the result of convection currents.
  • the heat transferred by radiation from the heater to the antenna is not directly proportional to the temperature difference between them (as it is if the heat is transferred by conduction) but is proportional to T H 4-T A 4, where T H is the temperature of the first surface of the heater and T A is the temperature of the back surface of the antenna (in °K).
  • dish antennas generally comprise a plurality of ribs which extend from the back surface of the antenna.
  • an electrical resistance heater is to be placed in direct contact with the antenna, a large number of specially shaped and interconnected component heaters must be used, and they must contact substantially the whole of the antenna.
  • the heater can be positioned clear of the ribs, thus making it possible to use one or a relatively small number of sheet heaters, e.g. less than 8, for example 4 to 6, each of which has an easily manufactured shape, e.g. a rectangular shape.
  • the ratio of the area of the heater to the area of the back surface of the antenna should generally be at least 0.3, but it need not be (though of course it can be) as high as 1.0; thus the ratio is preferably 0.4 to 0.9, particularly 0.5 to 0.8.
  • Direct physical contact between the antenna and the heater is preferably minimized, especially when the antenna comprises ribs of metal or other thermally conductive material, since heating of the antenna by conduction through the ribs tends to cause irregular heating, and consequent distortion, of the front surface.
  • the heater is secured to ribs on the back surface of the antenna, it is preferably secured to the ribs by fasteners which are composed of polymeric material or other material of low thermal conductivity, which are spaced apart from each other, and which preferably prevent direct contact between the heater and the ribs.
  • the heater is secured to a back shell which is secured to the dish antenna around the perimeter thereof. The back shell is preferably environmentally sealed to the antenna, to minimize heat losses.
  • the first surface of the heater and/or the back surface of the dish antenna are preferably treated in some way which improves the emissivity thereof, for example by painting with a flat black paint.
  • the second surface of the heater is preferably such that its emissivity is low.
  • the second surface is preferably substantially covered by thermal insulation material, eg. a foamed polymer, fiberglass or other void-containing polymeric material, either alone or backed by a metallic foil.
  • any form of sheet heater can be used in this invention providing that it radiates heat sufficiently uniformly to warm the antenna without causing substantial distortion thereof.
  • the radiant thermal output preferably does not vary by more than ⁇ 20%, particularly not more than ⁇ 10%, from the average value, when the thermal load is the same at all points on the heater, i.e. when the antenna is at a uniform temperature.
  • Preferred heaters comprise a resistive element which is in the form of a sheet having electrodes secured (directly or indirectly) thereto.
  • each of the electrodes is also in the form of a sheet, eg. a metal foil, the resistive element lying between the electrodes so that the current passes normally through the resistive element; however, other electrode arrangements are also possible.
  • Satisfactory heaters can also be made by combining one or more strip heaters with a sheet of metal, eg. aluminum, or other material of high thermal conductivity.
  • the strip heater(s) can be secured to one surface of the metal sheet, the opposite face then serving as the radiant surface, or can be sandwiched between two metal sheets, or can be embedded in the sheet.
  • the arrangement and spacing of the strip heater(s) should be such as to provide a sufficiently uniform radiant heat output.
  • one or more strip heaters can for example be arranged in serpentine fashion; or a plurality of strip heaters can for example be arranged parallel to each other, together with electrical bus connectors to feed power to the heaters.
  • the heater is preferably self-regulating, ie. the higher the thermal load at any particular point on the heater (or in any particular zone which is small in comparison with the overall size of the heater), the higher the heat output of the heater at that point (or in that zone); this avoids overheating of the antenna in areas which are not being cooled by ice or snow, and results in remarkable temperature uniformity of the dish antenna, and consequent minimization of distortion of the antenna.
  • the separation of the antenna and the self-regulating heater would be expected to result in a reduction of the sensitivity of the thermal output of the heater to the temperature of the antenna. In fact, however, the sensitivity is increased, and this apparently results from a combination of the self-regulating characteristic with the two factors discussed above (i.e. (1) a localized change in the temperature of the antenna is sensed not only by the portion of the heater directly opposite the change, but also by the adjacent parts of the heater, and (2) the heat transferred by radiation from the heater to the antenna is proportional to T H 4-T A 4).
  • Preferred self-regulating heaters for use in this invention comprise a PTC (positive temperature coefficient of resistance) conductive polymer composition which forms part or all of the resistive heating element or which acts as a control element for a ZTC (zero temperature coefficient) resistive heating element ie. a heating element whose thermal output is substantially independent of temperature, which may be composed of a conductive polymer composition or other material, e.g. a Nichrome or other resistive heating wire.
  • Self-regulation through other PTC materials or through other means e.g. the skin effect or the Curie point effect
  • thermostats may be used to control a ZTC heater.
  • FIGS. 1 and 2 show a dish antenna 1 having a concave front surface 11 and a convex back surface 12 and a plurality of ribs 13 extending from the back surface.
  • An electrical heater comprising four rectangular panels 2, 3, 4 and 5 is secured to the ribs by means of polymeric straps 6.
  • Figure 3 is similar to Figure 2, but shows an assembly further comprising a back shell 7, which is environmentally sealed to the periphery of dish antenna 1; the heater panels 2, 3, 4 and 5 are secured to the back shell 7 instead of to the ribs 13, and a layer 8 of fiberglass insulation secured to a metal foil 9 lies between the heater and the insulation.
  • the heater comprises metal foil electrodes 41 and 42, with a PTC conductive polymer resistive heating element 43 sandwiched between them.
  • the front surface of the heater has a coating 44 of flat black paint thereon.
  • Figure 5 shows an alternative form of sheet heater for use in the invention which comprises a metal, eg. aluminum, plate 100 having a strip heater 101 secured one surface thereof.
  • the first (radiant) surface of the heater is the opposite face.
  • Figure 6 is a cross-section through a preferred strip heater which comprises wire electrodes 61 and 62 embedded in a strip 63 of a PTC conductive polymer, and polymeric insulation 64 surrounding the strip 63.
  • the invention is further illustrated by the following Example.
  • a PTC conductive polymer powder was prepared by mixing 56% by weight of Marlex 50100 (high density polyethylene made by Phillips Petroleum), 43% by weight of Statex GH (carbon black made by Columbian Chemicals), and 1% by weight of an antioxidant in a Banbury mixer. The resulting compound was irradiated to a dose of 50 Mrads in a 3MeV electron beam and pulverized until all the particles were smaller than 187 micrometers (80 mesh). This PTC powder was tumble-blended with an equal weight of FA750 (high density polyethylene made by USI Chemicals), and the blend was extruded into a 12 inch by 0.040 inch (30.5 ⁇ 0.10 cm) sheet.
  • TEX-1 foil nickel/zinc passivated electro deposited copper made by Yates.
  • a heater for a 1.8 meter diameter antenna was made as follows. The laminated sheet was trimmed into five approximately 10 by 60 inch (25.4 by 152.4 cm) panels. Electrical busbars were attached to the two surfaces of each panel by soldering 0.020 by 0.5 inch (0.05 ⁇ 1.27 cm) copper strips terminated with 16 AWG copper conductor onto the copper foil. Adjacent panels were electrically connected in parallel using a standard connection suitable for attachment to a 120V power source. The panels and connections were electrically insulated by covering all surfaces completely with adhesive-backed Mylar tape. The first surface of the resulting heater (ie. the radiant surface) was then painted with flat black paint (Krylon) to enhance its thermal emissivity.
  • Krylon flat black paint
  • the heater was fastened with plastic straps to the back surface of the dish antenna, avoiding direct contact with all structural ribs.
  • a back shell for the antenna was mated to the antenna, placing polyurethane foam between the back of the heater and the back shell to reduce heat losses.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Details Of Aerials (AREA)
  • Surface Heating Bodies (AREA)
  • Aerials With Secondary Devices (AREA)
  • Resistance Heating (AREA)
EP87308610A 1986-09-30 1987-09-29 Parabolantenne mit Heizung Expired - Lifetime EP0268362B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87308610T ATE79487T1 (de) 1986-09-30 1987-09-29 Parabolantenne mit heizung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US91329086A 1986-09-30 1986-09-30
US913290 1992-07-14

Publications (2)

Publication Number Publication Date
EP0268362A1 true EP0268362A1 (de) 1988-05-25
EP0268362B1 EP0268362B1 (de) 1992-08-12

Family

ID=25433136

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87308610A Expired - Lifetime EP0268362B1 (de) 1986-09-30 1987-09-29 Parabolantenne mit Heizung

Country Status (6)

Country Link
EP (1) EP0268362B1 (de)
JP (1) JPS6390204A (de)
KR (1) KR880004597A (de)
AT (1) ATE79487T1 (de)
CA (1) CA1292800C (de)
DE (1) DE3781096T2 (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0326744A2 (de) * 1987-11-25 1989-08-09 Andrew Corporation System zur Enteisung des Reflektors von Mikrowellenantennen
GB2234117A (en) * 1989-07-19 1991-01-23 David Scott Satellite reception window
WO1997040646A1 (en) * 1996-04-19 1997-10-30 Thermion Systems International Method for heating the surface of an antenna dish
US5942140A (en) * 1996-04-19 1999-08-24 Thermion Systems International Method for heating the surface of an antenna dish
US9398642B2 (en) 2012-10-22 2016-07-19 Thales Canada Inc Removable heater for communication antenna
DE202017002725U1 (de) 2017-05-23 2017-06-13 Dynamic Solar Systems Ag Heizpanel mit gedruckter Heizung

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7747319B2 (en) 2006-03-17 2010-06-29 Zoll Medical Corporation Automated resuscitation device with ventilation sensing and prompting
US20230135141A1 (en) * 2021-11-01 2023-05-04 Amphenol Thermometrics, Inc. Antenna heater and methods for preventing ice formation on electromagnetic wave antennas

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2163168A1 (de) * 1971-01-18 1972-10-05 Inst Fuer Nachrichtentechnik Anordnung zur Beheizung einer in Strahlungsrichtung angebrachten Abdeckung einer Parabolantenne
FR2426343A1 (fr) * 1978-05-16 1979-12-14 Bony Gilbert Panneau degivrant pour reflecteur de faisceaux hertziens
GB2059155A (en) * 1979-08-17 1981-04-15 Raychem Corp PTC heater assembly
US4304987A (en) * 1978-09-18 1981-12-08 Raychem Corporation Electrical devices comprising conductive polymer compositions
DE3525488A1 (de) * 1985-07-17 1987-01-29 Dynamit Nobel Ag Elektrisch beheizbare flaechenreflektor-antenne

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2163168A1 (de) * 1971-01-18 1972-10-05 Inst Fuer Nachrichtentechnik Anordnung zur Beheizung einer in Strahlungsrichtung angebrachten Abdeckung einer Parabolantenne
FR2426343A1 (fr) * 1978-05-16 1979-12-14 Bony Gilbert Panneau degivrant pour reflecteur de faisceaux hertziens
US4304987A (en) * 1978-09-18 1981-12-08 Raychem Corporation Electrical devices comprising conductive polymer compositions
GB2059155A (en) * 1979-08-17 1981-04-15 Raychem Corp PTC heater assembly
DE3525488A1 (de) * 1985-07-17 1987-01-29 Dynamit Nobel Ag Elektrisch beheizbare flaechenreflektor-antenne

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 7, no. 62 (E-164)[1207], 15th March 1983; & JP - A - 57 208 702 (MITSUBISHI DENKI) 20-12-1982 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0326744A2 (de) * 1987-11-25 1989-08-09 Andrew Corporation System zur Enteisung des Reflektors von Mikrowellenantennen
EP0326744A3 (de) * 1987-11-25 1989-08-23 Andrew Corporation System zur Enteisung des Reflektors von Mikrowellenantennen
GB2234117A (en) * 1989-07-19 1991-01-23 David Scott Satellite reception window
WO1997040646A1 (en) * 1996-04-19 1997-10-30 Thermion Systems International Method for heating the surface of an antenna dish
US5942140A (en) * 1996-04-19 1999-08-24 Thermion Systems International Method for heating the surface of an antenna dish
US9398642B2 (en) 2012-10-22 2016-07-19 Thales Canada Inc Removable heater for communication antenna
DE202017002725U1 (de) 2017-05-23 2017-06-13 Dynamic Solar Systems Ag Heizpanel mit gedruckter Heizung

Also Published As

Publication number Publication date
DE3781096D1 (de) 1992-09-17
CA1292800C (en) 1991-12-03
JPS6390204A (ja) 1988-04-21
KR880004597A (ko) 1988-06-07
EP0268362B1 (de) 1992-08-12
ATE79487T1 (de) 1992-08-15
DE3781096T2 (de) 1993-03-11

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