EP0582793B1 - Load materials for use in microwave lenses - Google Patents

Load materials for use in microwave lenses Download PDF

Info

Publication number
EP0582793B1
EP0582793B1 EP19930108308 EP93108308A EP0582793B1 EP 0582793 B1 EP0582793 B1 EP 0582793B1 EP 19930108308 EP19930108308 EP 19930108308 EP 93108308 A EP93108308 A EP 93108308A EP 0582793 B1 EP0582793 B1 EP 0582793B1
Authority
EP
European Patent Office
Prior art keywords
resin
hardener
iron powder
carbonyl iron
load
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.)
Expired - Lifetime
Application number
EP19930108308
Other languages
German (de)
French (fr)
Other versions
EP0582793A1 (en
Inventor
Jack Alan Poyner
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.)
BAE Systems Defence Systems Ltd
Original Assignee
Siemens Plessey Electronic Systems Ltd
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 Siemens Plessey Electronic Systems Ltd filed Critical Siemens Plessey Electronic Systems Ltd
Publication of EP0582793A1 publication Critical patent/EP0582793A1/en
Application granted granted Critical
Publication of EP0582793B1 publication Critical patent/EP0582793B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

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
    • H01Q15/02—Refracting or diffracting devices, e.g. lens, prism
    • H01Q15/08—Refracting or diffracting devices, e.g. lens, prism formed of solid dielectric material

Definitions

  • the present invention relates to materials, commonly known as load materials which are for use in the manufacture of microwave lenses.
  • load materials used in microwave systems are hard and have a low glass transition temperature which normally causes their insulation properties to drop in high temperature environments. This drop in insulation makes the materials more conductive and often causes disruption in the microwave system.
  • a further object of the invention is to provide a flexible insulative material which may be moulded to shapes having 'knife-edges'.
  • load materials for use in microwave lenses comprising carbonyl iron powder and resin with which resin said carbonyl iron powder is mixed, characterised in that a mix of resin and hardener is in a ratio of 3:1 carbonyl iron powder to resin/hardener mix, said resin having a low glass transition temperature, which together with the ratio of carbonyl iron powder to resin/hardener gives a load material that is flexible over a predetermined temperature range.
  • the load materials may be moulded into shapes having 'knife-edges'.
  • the flexible insulative material comprises carbonyl iron powder manufactured to the grades of E, TH or SF. This powder is mixed together with an epoxy resin which consists of a resin which may be resin Cy1300 and a hardener which may be a hardener Hy1308. These materials are well known in the art and are obtainable from known suppliers.
  • the resin has a low glass transition temperature Tg (°C). This is the temperature at which on heating, the polymer chains are caused to vibrate in a coordinated manner (ie become plastic) and the polymer chains become rigid and glassy.
  • Tg glass transition temperature
  • the mix is made in a ratio of 3:1 of carbonyl iron powder to resin/hardener. The combination of the mix ratio and the resin having a low Tg temperature gives a very flexible material.
  • a method of manufacturing the mix will now be described.
  • a suitable mould is used which corresponds to the size and shape of microwave lens required.
  • the mould is cleaned with industrial alcohol and sprayed with a release agent over the relevant parts of the mould.
  • the mould is assembled ensuring that respective parts mate correctly.
  • the carbonyl iron powder is pre-dried in an oven at 45 to 55° C.
  • the weights are determined by the size of the microwave lens required and will vary accordingly, however, the mix ratio is in the order of 3:1.
  • 300 gm of carbonyl iron powder are used together with 50 gm of resin Cy1300 and 50 gm of hardener Hy1308.
  • the resin and the hardener are mixed together and the carbonyl iron powder is added and mixing continues until a smooth consistent paste is obtained.
  • the mixture is then de-aerated in a vacuum encapsulation plant down to a vacuum of 5 Torr, and is subjected to a dwell period of 5 minutes before the vacuum is released.
  • the mixture is then poured into the mould until the mould is full, and the mould is placed in encapsulation unit, and operated down to a vacuum of 5 Torr and allowed to dwell for 5 minutes before the vacuum is released.
  • the load mix is then allowed to stand for a period of 24 hours at room temperature.
  • the mould is then demounted from the encapsulation unit and the load is carefully extracted.
  • the load may then be affixed to a backing strip for transport.
  • the material is aptly suitable for moulding into shapes having 'knife-edges' and because of its flexibility does not have a tendency to fracture.
  • the flexible material produced by the above method is aptly suitable for use in microwave components which are placed in a temperature environment ranging from + 85° C to - 30° C.

Description

  • The present invention relates to materials, commonly known as load materials which are for use in the manufacture of microwave lenses.
  • Hitherto, load materials used in microwave systems are hard and have a low glass transition temperature which normally causes their insulation properties to drop in high temperature environments. This drop in insulation makes the materials more conductive and often causes disruption in the microwave system.
  • An article in the IEEE Transactions on Magnetics, Vol 10, No 1, March 1974, pages 96 to 97, entitled 'Method of Forming Ferrite Impregnated Resins for Microwave Measurements', by William L Wade Jr, and Aubrey Raffalovich, discloses the use of ferrite and carbonyl iron impregnated polyethylene for fabricating microwave absorbing elements.
  • However, hardness of known materials make them particularly vulnerable to fracture, particularly when the materials were moulded to shapes having 'knife-edges'.
  • It is an object of the present invention to provide a flexible insulative material for use in microwave systems which operate over a wide temperature range.
  • A further object of the invention is to provide a flexible insulative material which may be moulded to shapes having 'knife-edges'.
  • According to the present invention there is provided load materials for use in microwave lenses comprising carbonyl iron powder and resin with which resin said carbonyl iron powder is mixed, characterised in that a mix of resin and hardener is in a ratio of 3:1 carbonyl iron powder to resin/hardener mix, said resin having a low glass transition temperature, which together with the ratio of carbonyl iron powder to resin/hardener gives a load material that is flexible over a predetermined temperature range.
  • It will be appreciated that various grades of material may be used, and that the choice of materials and their quantities provide the desired flexibility in the temperature range of +85° C to -30° C.
  • The load materials may be moulded into shapes having 'knife-edges'.
  • An embodiment of the present invention and a method of manufacturing the load materials will now be described.
  • The flexible insulative material comprises carbonyl iron powder manufactured to the grades of E, TH or SF. This powder is mixed together with an epoxy resin which consists of a resin which may be resin Cy1300 and a hardener which may be a hardener Hy1308. These materials are well known in the art and are obtainable from known suppliers. The resin has a low glass transition temperature Tg (°C). This is the temperature at which on heating, the polymer chains are caused to vibrate in a coordinated manner (ie become plastic) and the polymer chains become rigid and glassy. The mix is made in a ratio of 3:1 of carbonyl iron powder to resin/hardener. The combination of the mix ratio and the resin having a low Tg temperature gives a very flexible material.
  • A method of manufacturing the mix will now be described. A suitable mould is used which corresponds to the size and shape of microwave lens required. The mould is cleaned with industrial alcohol and sprayed with a release agent over the relevant parts of the mould. The mould is assembled ensuring that respective parts mate correctly.
  • The carbonyl iron powder is pre-dried in an oven at 45 to 55° C. In the example that follows, the weights are determined by the size of the microwave lens required and will vary accordingly, however, the mix ratio is in the order of 3:1. In the present example, 300 gm of carbonyl iron powder are used together with 50 gm of resin Cy1300 and 50 gm of hardener Hy1308. The resin and the hardener are mixed together and the carbonyl iron powder is added and mixing continues until a smooth consistent paste is obtained. The mixture is then de-aerated in a vacuum encapsulation plant down to a vacuum of 5 Torr, and is subjected to a dwell period of 5 minutes before the vacuum is released. The mixture is then poured into the mould until the mould is full, and the mould is placed in encapsulation unit, and operated down to a vacuum of 5 Torr and allowed to dwell for 5 minutes before the vacuum is released. The load mix is then allowed to stand for a period of 24 hours at room temperature. The mould is then demounted from the encapsulation unit and the load is carefully extracted.
  • The load may then be affixed to a backing strip for transport.
  • The material is aptly suitable for moulding into shapes having 'knife-edges' and because of its flexibility does not have a tendency to fracture.
  • The flexible material produced by the above method is aptly suitable for use in microwave components which are placed in a temperature environment ranging from + 85° C to - 30° C.
  • It will be readily appreciated by those skilled in the art that the use of other types of ingredients for the mix may be used which give the same flexibility.

Claims (5)

  1. Load materials for use in microwave lenses comprising carbonyl iron powder and resin with which resin said carbonyl iron powder is mixed, characterised in that a mix of resin and hardener is in a ratio of 3:1 carbonyl iron powder to resin/hardener mix, said resin having a low glass transition temperature, which together with the ratio of carbonyl iron powder to resin/hardener gives a load material that is flexible over a predetermined temperature range.
  2. Load materials as claimed in Claim 1, which remain flexible in the temperature range of + 85° to - 30° C.
  3. Load materials as claimed in Claim 1 or Claim 2, wherein the carbonyl iron powder may be in the grades E, TH or SF.
  4. Load materials as claimed in any preceding Claim, wherein the resin is resin Cy1300 and the hardener is hardener Hy1308.
  5. Load materials as claimed in any preceding Claim, wherein the material may be moulded into shapes including 'knife-edges'.
EP19930108308 1992-08-11 1993-05-22 Load materials for use in microwave lenses Expired - Lifetime EP0582793B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9216992A GB2269594B (en) 1992-08-11 1992-08-11 Load material for use in microwave lenses
GB9216992 1992-08-11

Publications (2)

Publication Number Publication Date
EP0582793A1 EP0582793A1 (en) 1994-02-16
EP0582793B1 true EP0582793B1 (en) 1997-10-22

Family

ID=10720152

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930108308 Expired - Lifetime EP0582793B1 (en) 1992-08-11 1993-05-22 Load materials for use in microwave lenses

Country Status (3)

Country Link
EP (1) EP0582793B1 (en)
DE (1) DE69314723T2 (en)
GB (1) GB2269594B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7301504B2 (en) 2004-07-14 2007-11-27 Ems Technologies, Inc. Mechanical scanning feed assembly for a spherical lens antenna

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109517559B (en) * 2018-10-30 2022-04-08 成都飞机工业（集团）有限责任公司 Fast-curing wave-absorbing edge sealing adhesive
CN109517558B (en) * 2018-10-30 2022-04-08 成都飞机工业（集团）有限责任公司 Preparation method of fast-curing wave-absorbing edge sealing adhesive

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1278791A (en) * 1969-06-12 1972-06-21 Armstrong Cork Co Shaped charge blending method and product
US3843593A (en) * 1972-06-05 1974-10-22 Du Pont Radar absorptive coating composition of an acrylic polymer,a polyester and an isocyanate cross-linking agent
GB2196343B (en) * 1983-10-03 1988-09-14 Courtaulds Plc Microwave-absorbing fibres and filaments
DE3381770D1 (en) * 1983-11-07 1990-08-30 Dow Chemical Co LOW DENSITY ABSORPTION COMPOSITIONS FOR ELECTROMAGNETIC RADIATION.
JPS6173400A (en) * 1984-09-18 1986-04-15 ティーディーケイ株式会社 Radio wave absorbing gasket

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7301504B2 (en) 2004-07-14 2007-11-27 Ems Technologies, Inc. Mechanical scanning feed assembly for a spherical lens antenna

Also Published As

Publication number Publication date
DE69314723D1 (en) 1997-11-27
DE69314723T2 (en) 1998-02-19
GB2269594B (en) 1995-08-30
GB9216992D0 (en) 1992-09-23
EP0582793A1 (en) 1994-02-16
GB2269594A (en) 1994-02-16

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