EP0032604A1 - Radar-Reflektor - Google Patents

Radar-Reflektor Download PDF

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Publication number
EP0032604A1
EP0032604A1 EP80300155A EP80300155A EP0032604A1 EP 0032604 A1 EP0032604 A1 EP 0032604A1 EP 80300155 A EP80300155 A EP 80300155A EP 80300155 A EP80300155 A EP 80300155A EP 0032604 A1 EP0032604 A1 EP 0032604A1
Authority
EP
European Patent Office
Prior art keywords
elements
radar
reflector
group
groups
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.)
Withdrawn
Application number
EP80300155A
Other languages
English (en)
French (fr)
Inventor
Helge Varberg Selnes
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.)
VESTERALEN INDUSTRIER AS
Original Assignee
VESTERALEN INDUSTRIER AS
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 VESTERALEN INDUSTRIER AS filed Critical VESTERALEN INDUSTRIER AS
Priority to EP80300155A priority Critical patent/EP0032604A1/de
Publication of EP0032604A1 publication Critical patent/EP0032604A1/de
Withdrawn legal-status Critical Current

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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
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
    • H01Q21/20—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a curvilinear path

Definitions

  • radar reflectors which comprise a number of reflecting elements made of an electrically conductive material or at least having a reflective surface of electrically conductive material.
  • One form of radar reflector for use, for example, for marine purposes, comprises a plurality of hollow reflector elements each having an opening and an electrically conductive surface, the elements being arranged in a circular group with their openings facing radially outwards from an axis of symmetry of the group.
  • the reflector is generally mounted in use, with its axis of symmetry vertical or nearly so.
  • a radar reflector of this form is disclosed in United States Specification No. 3,117,318.
  • the hollow elements have a tetrahedral or pyramid-like shape.
  • the main object of the present invention is to provide an effective and reliable radar reflector of the form just. described for mounting for example on buoys, beacons, stationary fishing gear, booms, or on small vessels.
  • the radar reflector may also however, be used with advantage on land or in connection with aviation, for example, on objects which are, to some extent at least, movable in a manner corresponding to the uses at sea which are described above.
  • An important problem which the present invention aims to overcome is caused by the fact that the objects to which the reflector is fitted are often subjected to movement, for example because of wind and waves, so that the reflection conditions vary continuously.
  • a radar reflector of the form described is characterized in that each of the reflector elements has a substantially hemispherical shape with an opening of a diameter significantly larger than the wave length of a radar wave to be reflected.
  • each reflector element has a diameter significantly larger than the wave length of the radar wave which is to be reflected, means that preferably the diameter must be at least twice as large as the wave length. For common coastal navigation radar having a wave length of 3 cm. it is thus found practical to use a reflector element diameter of 7 cm. If the reflector is to be used in connection with radar having a wave length of for example 10 cm., the elements must be made correspondingly larger, for example with a diameter of 25 cm. A reflector having a larger diameter in relation to the wave length will give an improved radar echo.
  • the shape of the reflector elements is that at least one of these irrespective of the origentation of the group relative to the radar wave will have an area of its conductive reflecting surface which provides the desired reflection of the incident radar waves.
  • the element When each element has the shape substantially of a hemisphere, the element will cover a maximum angular range both in a horizontal plane, that is a plane normal to the axis of symmetry of the group, and in a vertical plane so that the reflection effect will be asmuch as possible independent of the orientation of the reflector at any moment and of movements to which it is subjected.
  • An additional substantial advantage of the radar reflector in accordance with the invention is that it may be constructed with comparatively small dimensions and small weight, which is of importance when the - reflector is to be mounted on spar buoys or the like, or on small craft.
  • the radar reflector comprises a central mounting tube 3 which carries four groups A, B, C and D of reflector elements one above the other.
  • the uppermost group A which is shown fully in plan in Figure 1 comprises four reflector elements la, lb, 1c and Id each having the shape of a hollow hemisphere. Each of these elements is attached to a supporting ring 2 by means of a central rivet 4 which is best shown in Figure 2.
  • the elements la to ld in group A thus form a circular arrangement in which the opening of each element is directed radially outwards with respect to an axis of symmetry 10 of the group.
  • the lower groups B, C and D are all similar to group A.
  • each group of elements is made as compact as is practicable and is also inexpensive and strong. At the same time a very good reflection effect for radar waves is obtained.
  • each reflector element As far as the geometrical shape of each reflector element is concerned, this need not necessarily be an exact hemisphere. Larger or smaller variations with respect to a mathematical hemispherical surface are possible. The advantageous effect is achieved by the substantially hemispherical double curvature concave-surfaced cup shape of the elements.
  • the reflector elements are made of aluminium sheet material, i.e. an electrically conductive material
  • each concave cup-shaped element may be made of an electrically non-conductive material which is provided with a thin electrically conductive reflective coating on its concave inner surface. The coating may also be on the outer surface of the element if the element is transparent to radar waves.
  • the mounting tube 3 is preferably made of glass fibre reinforced plastics material, for example a polyamide having a content of 20% glass fibres. However, other materials, including electrically conductive materials such as aluminium, may be used.
  • Each group of reflector elements is fixed on the tube 3 by means of a screw or like fastener through the supporting ring 2 of the group.
  • the number of groups used depends upon the range from a radar installation at which the reflector is required to be detectable. The larger the number of groups of reflecting elements that the reflector contains, the greater the range at which a reflection can be detected. As mentioned above, it is very important that the reflector should still provide reflection even though it assumes different orientations in relation to the radar installation. It is directly evident from Figure 2 that at least six of the reflector elements shown therein will present effective reflection surfaces or areas with respect to any given radar beam direction in a plane substantially normal to theaxis 10. In practice the radar scanning will in the overwhelming number of cases take place in a horizontal plane or very close to a horizontal plane. This means that the mounting tube 3 will generally be mounted in a vertical position on the object, the radar location of which is desired.
  • a housing 30 for this purpose is shown in Figure 3.
  • the housing 30 has a substantially cylindrical shape with end walls provided with central holes 33 and 34 respectively, corresponding to the diameter of the mounting tube 3. Further smaller holes 31 and 32 are provided in the end walls to equalize the pressures inside and outside the housing should the radar reflector get immersed in water. This can easily happen in rough weather if the reflector is mounted on a buoy or the like.
  • the material of which the container is made must of course be of such a kind that it does not give any significant attenuation of radar waves.
  • each group of elements may consist of a smaller number or preferably a higher number of elements than the four elements shown here, which is however the preferred number.
  • the arrangement of elements results in good flexibility which makes possible the adaption and adjustment of the radar reflector in a simple and inexpensive way according to requirements and conditions.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Aerials With Secondary Devices (AREA)
EP80300155A 1980-01-16 1980-01-16 Radar-Reflektor Withdrawn EP0032604A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP80300155A EP0032604A1 (de) 1980-01-16 1980-01-16 Radar-Reflektor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP80300155A EP0032604A1 (de) 1980-01-16 1980-01-16 Radar-Reflektor

Publications (1)

Publication Number Publication Date
EP0032604A1 true EP0032604A1 (de) 1981-07-29

Family

ID=8187079

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80300155A Withdrawn EP0032604A1 (de) 1980-01-16 1980-01-16 Radar-Reflektor

Country Status (1)

Country Link
EP (1) EP0032604A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4833485A (en) * 1985-05-17 1989-05-23 The Marconi Company Limited Radar antenna array
FR2727573A1 (fr) * 1994-08-08 1996-05-31 Centre Nat Etd Spatiales Etalon artificiel passif pour radar a tres haute resolution

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB582168A (en) * 1941-09-17 1946-11-07 George William Walton Improvements in or relating to means for navigation, aerostation and like determination of the movements of vehicles relative to their surroundings
US2520008A (en) * 1940-04-05 1950-08-22 Bell Telephone Labor Inc Radio marker system
DE837972C (de) * 1950-10-19 1952-05-05 Eugen Schellenbach Rueckstrahler fuer Wegehindernisse, Fahrzeuge od. dgl.
GB696834A (en) * 1950-12-13 1953-09-09 Marconi Wireless Telegraph Co Improvements in or relating to radar reflector systems for use on buoys and other floating structures
US3117318A (en) * 1960-04-29 1964-01-07 Stanley T Lovejoy Radar reflector
US3413636A (en) * 1967-01-31 1968-11-26 Philip N. Migdal Radar cross section augmenter
DE2524684A1 (de) * 1975-06-04 1976-12-23 Mueller Hartwig Westa App Radar-reflektor
US4148033A (en) * 1977-06-20 1979-04-03 Speckter Hans E Radar reflector for buoys and other floating objects

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2520008A (en) * 1940-04-05 1950-08-22 Bell Telephone Labor Inc Radio marker system
GB582168A (en) * 1941-09-17 1946-11-07 George William Walton Improvements in or relating to means for navigation, aerostation and like determination of the movements of vehicles relative to their surroundings
DE837972C (de) * 1950-10-19 1952-05-05 Eugen Schellenbach Rueckstrahler fuer Wegehindernisse, Fahrzeuge od. dgl.
GB696834A (en) * 1950-12-13 1953-09-09 Marconi Wireless Telegraph Co Improvements in or relating to radar reflector systems for use on buoys and other floating structures
US3117318A (en) * 1960-04-29 1964-01-07 Stanley T Lovejoy Radar reflector
US3413636A (en) * 1967-01-31 1968-11-26 Philip N. Migdal Radar cross section augmenter
DE2524684A1 (de) * 1975-06-04 1976-12-23 Mueller Hartwig Westa App Radar-reflektor
US4148033A (en) * 1977-06-20 1979-04-03 Speckter Hans E Radar reflector for buoys and other floating objects

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4833485A (en) * 1985-05-17 1989-05-23 The Marconi Company Limited Radar antenna array
FR2727573A1 (fr) * 1994-08-08 1996-05-31 Centre Nat Etd Spatiales Etalon artificiel passif pour radar a tres haute resolution

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): BE DE FR GB LU NL SE

17P Request for examination filed

Effective date: 19811002

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19830214

RIN1 Information on inventor provided before grant (corrected)

Inventor name: SELNES, HELGE VARBERG