US3787856A - Spherical microwave lenses - Google Patents

Spherical microwave lenses Download PDF

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Publication number
US3787856A
US3787856A US00272804A US3787856DA US3787856A US 3787856 A US3787856 A US 3787856A US 00272804 A US00272804 A US 00272804A US 3787856D A US3787856D A US 3787856DA US 3787856 A US3787856 A US 3787856A
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US
United States
Prior art keywords
lens
reflector
spherical
microwave
reflectors
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
US00272804A
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English (en)
Inventor
P Pyrah
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.)
BAC AND BRITISH AEROSPACE
BAE Systems PLC
Original Assignee
British Aircraft Corp 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 British Aircraft Corp Ltd filed Critical British Aircraft Corp Ltd
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Publication of US3787856A publication Critical patent/US3787856A/en
Assigned to BRITISH AEROSPACE PUBLIC LIMITED COMPANY reassignment BRITISH AEROSPACE PUBLIC LIMITED COMPANY CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE JAN. 2, 1981 Assignors: BRITISH AEROSPACE LIMITED
Assigned to BAC AND BRITISH AEROSPACE reassignment BAC AND BRITISH AEROSPACE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BRITISH AIRCRAFT CORPORATION LIMITED,
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H01Q15/23—Combinations of reflecting surfaces with refracting or diffracting devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/12—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems

Definitions

  • This invention relates to spherical microwave lenses which are provided with reflectors for reflecting electromagnetic waves used in radar systems.
  • a spherical microwave lens with a fixed metallic reflector by means of which incoming electromagnetic waves, after being brough to a focus on or close to the surface of the lens, may be reflected back along a path parallel to the path of the incoming waves.
  • Such reflectors generally consist of a part-spherical band or cap of sheet metal fixed on or close to the outer surface of the lens.
  • Such an arrangement of spherical lens and fixed reflector provides a reflected wave signal of constant amplitude and phase.
  • the object of the present invention is to provide a spherical lens and reflector arrangement, the reflected wave signal from which may be varied in terms of phase and/or amplitude.
  • a spherical microwave lens arrangement comprises a spherical microwave lens with a part-spherical reflector movable towards and away from the lens.
  • the lens has a focus outside the sphere, and the reflector is movable about a position co-incident with the focus point of the lens, towards and away from the surface of the lens on either side of the focus point whereby movement of the reflector produces a variation in the phase of a reflected wave.
  • the lens has a focus approximately on its surface, and a coating of an electrically resistive material extends over part of the outer surface of the lens, the reflector being mov able between a position where it lies against the resistive coating, and a position where it is spaced from the resistive coating by a distance of approximately one quarter of a wavelength, whereby movement of the reflector produces a variation in the amplitude of a reflected wave.
  • the electrically resistive material may be carbon loaded cloth, carbon loaded rubber or colloidal graphrte.
  • FIG. 1 shows in part-section one form of the invention in which two lenses and two reflectors are used, one of the reflectors being fixed relative to its associated lens and the other reflector being movable about the focus point of its associated lens so as to produce a variation in the phase of a reflected wave, and
  • FIG. 2 shows in part-section another form of the invention in which a single reflector is movable towards and away from a single lens which is provided with a re sistive coating over part ofits outer surface so as to produce a variation in the amplitude of a reflected wave.
  • a spherical microwave lens 1, 2 of dielectric material is mounted in each nose cone 3, 4 of a pair of fairings mounted on the wing tips of a tar get aircraft.
  • the lenses 1, 2 are designed to have a focus F at a distance of half of the wavelength away from the surface of the lens.
  • a reflector 5 in the nose cone 3 is of part spherical form and has an inside curvature approximately equal to the outside curvature of the lens 1. It is mounted on the end of a movable ram 6 extending from an electric actuator 7 which is thus able to move the reflector 5 towards and away from the lens 1 about the focus 7.
  • the actuator 7 is controlled by means of signals from a programme unit (not shown) in the aircraft.
  • a reflector 8 in the nose cone 4 is also of part spherical form and has an inside curvature approximately equal to the outside curvature of the lens 2.
  • This reflector is fixed to a bulkhead 9 at the rear of the nose cone. It is shown as being positioned with the focus point F of the lens 2 falling on its forward surface. This position may be adjusted to be forward of the focus point or to the rear of the focus point. The position would, however, be determined and fixed before use of the lenses.
  • both reflectors may be mounted so as to be movable in use, the extent of the movement being determined as follows:
  • the radar cross-section is reasonably constant.
  • the reflector 5 when placed at the focal point F and moved towardsand away from the lens 1 by a distance of one eighth of the wavelength is able to reflect substantially all of the received wave energy but, in so moving the reflector, the phase of the wave is changed. Movement of the reflector over the total range of one quarter of a wavelength produces a change in phase of the reflected wave energy of half a wavelength.
  • the distance over which the radar cross-section of a lens remains substantially constant is equal to a distance of approximately one quarter of a wavelength for most lenses, but this distance need not be equally spaced on either side of the focal point of the lens. For example, three quarters of the distance may be from the focal point towards the lens, the remaining quarter of the distance being from the focal point away from the lens.
  • the range of movement of a reflector is approximately one quarter of a wavelength, the range may be divided into movement either side of the focal point in many ways.
  • simple glint may be simulated.
  • this form of in vention lies in the testing of a radar system where variation of the phases of waves from a number of reflectors may be used to simulate glint from a target, i.e. where the reflected wave appears to come from a position other than from the target.
  • two or more spherical lenses would be employed spaced some distance apart and the phase change characteristics of each of them (i.e. the spacing of the reflectors from their respective lenses) is varied by means of a programme controlling the actuator so as to cause the resultant, combined reflected wave to appear to come from a position other than that of any of the lenses.
  • a resistive coating 11 such as a film, card or sheet of a material of suitable resistive value is placed upon the surface of a spherical lens 12 and a reflector 13 is mounted for movement towards and away from the coated surface of the lens along an axis through the centre of the lens.
  • the lens and reflector are mounted within a nose cone 10 of a target and the reflector is movable by means of an electric actuator 7 as in the arrangement shown in FIG. 1.
  • the focal point F of the lens in this case is on the surface of the lens.
  • the amount of energy reflected by the lens is at a maximum when the reflector is positioned against the resistivecoated lenssurface but the amount of wave energy reflected is reduced as the reflector is moved away from the focal point of the lens, as the resistive coating absorbs the energy, and the amount of movement may be as much as one quarter of a wavelength away from the focal point of the lens.
  • the amplitude of the reflected wave may be varied by movement of the reflector.
  • the reflector may be moved from a position where it lies adjacent to the resistive coating, to a position where it lies at a distance of one quarter of the wavelength in use away from the resistive coating.
  • suitable materials for the resistive coating which may be in the form of a sprayed coating, a film or sheet, are colloidal graphite, carbon loaded cloth, laminate or carbon loaded rubber sheet.
  • a reflector may be moved manually or remotely by any of various means such as a nut and sore mechanism, a solenoid operated mechanism etc., but such mechanisms are well known and to not form a part of the invention.
  • a microwave lens arrangement comprising a spherical microwave lens with a focus approximately on its surface and an electrically resistive material over part of its outer surface, and a part spherical reflector movable towards and away from the lens between posi tions where it is against the resistive coating or spaced from it by approximately one quarter of a wavelength, whereby movement of the reflector produces a variation in the amplitude of a reflected wave.
  • a microwave lens arrangement as in claim 1 wherein the electrically resistive material is carbon loaded rubber.
  • a microwave lens arrangement as in claim 1 wherein the electrically resistive material is colloidal graphite.
  • An apparatus for simulating the glint of an object illuminated by a radar beam including, in combination, two spherical microwave lenses spaced transversely to the radar beam, a fixed reflector associated with one lens, a movable reflector associated with the other lens, and means for moving the movable reflector towards and away from its associated lens thereby varying the phase difference between the beams reflected from the fixed and movable reflectors.
  • An apparatus for simulating the glint of an object illuminated by a radar beam including in combination two transversely spaced spherical microwave lenses, a separate reflector associated with each lens and movable towards and away from its associated lens and means for moving the reflectors independently of each other whereby movement of at least one of the reflectors produces a variation of the phase difference be tween the beams reflected by said reflectors.

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  • Aerials With Secondary Devices (AREA)
  • Radar Systems Or Details Thereof (AREA)
US00272804A 1971-07-26 1972-07-18 Spherical microwave lenses Expired - Lifetime US3787856A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3499071 1971-07-26

Publications (1)

Publication Number Publication Date
US3787856A true US3787856A (en) 1974-01-22

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Application Number Title Priority Date Filing Date
US00272804A Expired - Lifetime US3787856A (en) 1971-07-26 1972-07-18 Spherical microwave lenses

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US (1) US3787856A (fr)
FR (1) FR2147235B1 (fr)
GB (1) GB1348672A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4287519A (en) * 1980-04-04 1981-09-01 The United States Of America As Represented By The Secretary Of The Navy Multi-mode Luneberg lens antenna
US4419669A (en) * 1971-01-04 1983-12-06 Trw Inc. Controlled scintillation rate decoy
WO1995034922A1 (fr) * 1994-06-16 1995-12-21 Hann Lenn R Procede et appareil de modulation d'un signal radar doppler
US5673049A (en) * 1996-01-26 1997-09-30 Kitchen; William J. Police radar jammer
US5883602A (en) * 1996-06-05 1999-03-16 Apti, Inc. Wideband flat short foci lens antenna
US10338187B2 (en) * 2017-01-11 2019-07-02 Raytheon Company Spherically constrained optical seeker assembly
US11726169B1 (en) * 2019-03-14 2023-08-15 The United States Of America, As Represented By The Secretary Of The Navy System for augmenting 360-degree aspect monostatic radar cross section of an aircraft

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2194391B (en) * 1986-06-23 1991-02-27 Secr Defence A passive radar target

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2716746A (en) * 1950-10-31 1955-08-30 Rca Corp Focusing of radar beams for a tracking radar
US2866971A (en) * 1956-09-05 1958-12-30 Kenneth S Kelleher Radiant energy reflector
US3116486A (en) * 1961-12-29 1963-12-31 Anton M Johnson Luneberg lens system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2716746A (en) * 1950-10-31 1955-08-30 Rca Corp Focusing of radar beams for a tracking radar
US2866971A (en) * 1956-09-05 1958-12-30 Kenneth S Kelleher Radiant energy reflector
US3116486A (en) * 1961-12-29 1963-12-31 Anton M Johnson Luneberg lens system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4419669A (en) * 1971-01-04 1983-12-06 Trw Inc. Controlled scintillation rate decoy
US4287519A (en) * 1980-04-04 1981-09-01 The United States Of America As Represented By The Secretary Of The Navy Multi-mode Luneberg lens antenna
WO1995034922A1 (fr) * 1994-06-16 1995-12-21 Hann Lenn R Procede et appareil de modulation d'un signal radar doppler
US5508704A (en) * 1994-06-16 1996-04-16 Hann; Lenn R. Method and apparatus for modulating a doppler radar signal
US5673049A (en) * 1996-01-26 1997-09-30 Kitchen; William J. Police radar jammer
US5883602A (en) * 1996-06-05 1999-03-16 Apti, Inc. Wideband flat short foci lens antenna
US10338187B2 (en) * 2017-01-11 2019-07-02 Raytheon Company Spherically constrained optical seeker assembly
US11726169B1 (en) * 2019-03-14 2023-08-15 The United States Of America, As Represented By The Secretary Of The Navy System for augmenting 360-degree aspect monostatic radar cross section of an aircraft

Also Published As

Publication number Publication date
GB1348672A (en) 1974-03-20
FR2147235A1 (fr) 1973-03-09
FR2147235B1 (fr) 1977-04-01

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AS Assignment

Owner name: BRITISH AEROSPACE PUBLIC LIMITED COMPANY, DISTRICT

Free format text: CHANGE OF NAME;ASSIGNOR:BRITISH AEROSPACE LIMITED;REEL/FRAME:004080/0820

Effective date: 19820106

Owner name: BRITISH AEROSPACE PUBLIC LIMITED COMPANY

Free format text: CHANGE OF NAME;ASSIGNOR:BRITISH AEROSPACE LIMITED;REEL/FRAME:004080/0820

Effective date: 19820106

AS Assignment

Owner name: BAC AND BRITISH AEROSPACE, BROOKLANDS RD., WEYBRID

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BRITISH AIRCRAFT CORPORATION LIMITED,;REEL/FRAME:003957/0227

Effective date: 19811218