US3165747A - Primary horn antenna feeding planar reflector through hole in focused curved reflector - Google Patents

Primary horn antenna feeding planar reflector through hole in focused curved reflector Download PDF

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US3165747A
US3165747A US258702A US25870263A US3165747A US 3165747 A US3165747 A US 3165747A US 258702 A US258702 A US 258702A US 25870263 A US25870263 A US 25870263A US 3165747 A US3165747 A US 3165747A
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reflector
planar
curved
unit
primary
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US258702A
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Wales Michael
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BAE Systems Electronics Ltd
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Marconi Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations 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 reflecting surfaces
    • H01Q19/18—Combinations 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 reflecting surfaces having two or more spaced reflecting surfaces
    • H01Q19/19—Combinations 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 reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • H01Q19/191—Combinations 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 reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface wherein the primary active element uses one or more deflecting surfaces, e.g. beam waveguide feeds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations 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 reflecting surfaces
    • H01Q19/18—Combinations 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 reflecting surfaces having two or more spaced reflecting surfaces
    • H01Q19/19—Combinations 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 reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • 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
    • H01Q3/16—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 for varying relative position of primary active element and a reflecting device
    • H01Q3/20—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 for varying relative position of primary active element and a reflecting device wherein the primary active element is fixed and the reflecting device is movable

Definitions

  • This invention relates to aerial systems and has for its object to provide improved and simplified wide aperture aerial systems which, when employed for transmission, will provide at the aperture a substantially parallel beam of radio energy from a localised primary source.
  • the invention provides aerial systems which will give much the same performance as the well known Cornucopia type of radiohorn but which are structurally much simpler and cheaper.
  • FIGURE 1 is a schematic side view of one embodiment
  • FIGURE 2 waveguide mouth-"2 (not shown in FIGURE 2), Opposite and facing the mouth 2 is a planar reflector 3.
  • mary radio unit are therefore intended to include localised primary radiation sources such, for example, as a waveguide mouth which is fed from a transmitter and which may, from the practical point of view, be regarded as approximating to apoint source, and localisedreceiver feeds such, forexample, as a similar Waveguide mouth feeding through a waveguide into a receiver.
  • localised primary radiation sources such as a waveguide mouth which is fed from a transmitter and which may, from the practical point of view, be regarded as approximating to apoint source
  • localisedreceiver feeds such, forexample, as a similar Waveguide mouth feeding through a waveguide into a receiver.
  • an aerial system comprises a curved reflector, a localised primary radio unit in a hole in said reflector and a planar reflector opposite and facing said primaryunit andin a plane at an angleto the curved reflector, the positioning of said planar reflector and the shapes and mutual arriangement of the two -rei flectors being such that radio energy followingvstraight line paths from said primary unit to the planar reflector twill'be reflected thereby to the curved reflector and reflected again from the curved reflector along paths parallel to one another and to the plane of the planar
  • an aerial system comprises a reflector of paraboloidal curvature, a
  • a planarreflector opposite and facing saidprimary Radial sidewalls 4 connect the curved edges of the reflector 1. with the adjacent edges of the reflector 3.
  • the cross indicated at 5 in FIGURE 1 represents the focus of the paraboloid. If the mouth of the horn 2 is in the curved surface of the reflector 1, the distance 2F (see FIGURE 1 should be twice the distance F. If, as illustrated, the horn mouth projects a little way in the direction of the reflector 3, the distance shown'as F should be correspondingly reduced.
  • the chain lines in FIGURE 1 represent energy paths from thehornvia the reflectors, 3 and 1 to form the final emergent parallel beam and are drawn on the assumption, which is near enough for prac H tical purposes, that the mouth 2 isa point source in then surface of the reflector ll.
  • the invention operates by the production of a virtual source (at the 'focus) unit and in a plane at an angle to the paraboloidal reflector, the distance of said planar reflector from said radio .unit being at least approximately one 'half the distance ofthe focus of theparaboloid from .saidunit, and a the two curved edges of the paraboloidal reflector and an adjacent edge of said planar reflector, the whole arrangement being such that radio energy following straight line paths from said unit to the planar reflector will be reflected thereby to the curved reflector and reflected again from the curved reflectoralong paths par- "pair of flat side walls which extend each between one of allel to one another and to the plane ofthe. planar refiector.
  • V virtual source
  • the localised primary radio unit' is, a small 'radio horn orflared waveguide mouth. Its mouth can lie in the general surface of the curved reflector but, if-
  • the axis of the localised primary radio unit is tilted'a few degrees, e.g., about 6, away from thesnorrnal to the flat reflector in the direction of the rear part of the curved reflector, i.e., in the direction tenuation is approximately constant.
  • the i V ing f from a real source (the mouth 2);, Electrically both the real and ,virtual sources Lare well within the".
  • the realsourc e 2 will normally be a small horn of the order of two wavelengths aperture sizeand the diffraction field will be'dorninant. This, however, does not seriously alter conclusions drawn from considering the operation in terms of geometricab optics with a,
  • the illumination in the vertical plane is optimised. for maximum aperture efficiency and (12) the reflections returned from the flat ⁇ reflector 3 to the primary horn aperture'are reduced.
  • the illumination in curvature is small and, as a consequence, the space at- FIGUREB shows the aperture illuminationin the yer-i tical plane (ordinates-mints offield intensity) of. the aperture fo r'the case where a.
  • beam tilt of-6" is made'by the primary horn 2 towards thewrear part-0f the surface the horizontal plane is approximately the primary horn illumination in this plane, as the degree of reflector abscissae are values of the Y (vertical) ordinate expressed in terms of F (focal length).
  • the flat reflector 3 intercepted about 85% of the primary horn energy in the case for which FIGURE 3. was obtained.
  • An aerial system comprising a curved reflector having a predetermined focus, a localised primary radio unit in a hole in said reflector, and a planar reflector opposite and facing said primary unit and in a plane at an angle tothe curved reflector, the distance of said planar reflector from said primary unit being at least approximately one-half the distance of said focus from said unit, and theshapes and mutual arrangement of the two reflectors being such that radio energy following straight line paths from said unit to the planar reflector will be reflected'thereby to the curved reflector and reflected 'again from the curved reflector along paths parallel to one another; and to'the plane of the planar reflector.
  • Anaerial system comprising a reflector of paraboloidal curvature, a localised radio unit in a hole in the paraboloidal reflector, a planar reflector opposite and facingsaid primary unit and in a plane at an angle to the paraboloidal reflector, the distance of said planar reflector from said'unit being at least approximately one-half the distance of the focus ,of the paraboloid from said unit, and a pair of flat side ,walls which extend each between one of, the two curved edges of the paraboloidal 1 reflector and an adjacent edge of said planar reflector,
  • planar reflector is hinged so as to be movable back and a forth over an are so that its angle'to the curved reflector is variable.

Description

Jan. 12, 1965 M. WALES 3165,747
PRIMARY HORN ANTENNA FEEDING PLANAR REFLECTOR THRO IN FOCUSED CURVED REFLECTOR Filed Feb. 15, 1965 1 UGH HOLE Hal /-0 /-'2 /-'4 1 6 /'-a 2'-o 2-2 2 4 2 6 mu: 0F r ORB/NATE EXPRESSED IN F \NVENTOR mM in! 41M .2;
ATTORNEY-5 PRIMARY HGRN ANTENNA FEEDING PLANAR REFLEQTGR THRQUGH HGLE IN FGCUSED CURVED REFLECTUR Michaei. Wales, Durham, England, assignor to The Marconi Company Limited, a British company Filed Feb. 15, 1963, Ser. No. 258,702 Claims priority, application Great Britain, Apr. 4, 71%2,
Edd U62 i i Qfiiairns. (Cl. 343-361) This inventionrelates to aerial systems and has for its object to provide improved and simplified wide aperture aerial systems which, when employed for transmission, will provide at the aperture a substantially parallel beam of radio energy from a localised primary source. As will be apparent later, the invention provides aerial systems which will give much the same performance as the well known Cornucopia type of radiohorn but which are structurally much simpler and cheaper.
The invention will be described hereinafter with reference to transmission but, as will be obvious later, systems in accordance with this invention can equally well be used for reception. Expressions such as, localised pri- United States Patent Office Patented Jan. 12, 1%55 away from the mouth of the whole aerial system. The angle between the curved reflector and the planar reflector need not be fixed and constant but the said planar reflector may be hinged at one edge and moveable back and forth over an are so that said angle isvariable. Such an aerial system is useful, for example, in a height-finding radar.
The invention isillustrated in and further explained in connection with thedrawings, inwhich: FIGURE 1 is a schematic side view of one embodiment; FIGURE 2 waveguide mouth-"2 (not shown in FIGURE 2), Opposite and facing the mouth 2 is a planar reflector 3.
mary radio unitare therefore intended to include localised primary radiation sources such, for example, as a waveguide mouth which is fed from a transmitter and which may, from the practical point of view, be regarded as approximating to apoint source, and localisedreceiver feeds such, forexample, as a similar Waveguide mouth feeding through a waveguide into a receiver.
According to this invention, an aerial system comprises a curved reflector, a localised primary radio unit in a hole in said reflector and a planar reflector opposite and facing said primaryunit andin a plane at an angleto the curved reflector, the positioning of said planar reflector and the shapes and mutual arriangement of the two -rei flectors being such that radio energy followingvstraight line paths from said primary unit to the planar reflector twill'be reflected thereby to the curved reflector and reflected again from the curved reflector along paths parallel to one another and to the plane of the planar According to a feature of this invention, an aerial system comprises a reflector of paraboloidal curvature, a
localised radio unit in a hole in the paraboloidal reflector, a planarreflector opposite and facing saidprimary Radial sidewalls 4 connect the curved edges of the reflector 1. with the adjacent edges of the reflector 3. The cross indicated at 5 in FIGURE 1 represents the focus of the paraboloid. If the mouth of the horn 2 is in the curved surface of the reflector 1, the distance 2F (see FIGURE 1 should be twice the distance F. If, as illustrated, the horn mouth projects a little way in the direction of the reflector 3, the distance shown'as F should be correspondingly reduced. The chain lines in FIGURE 1 representenergy paths from thehornvia the reflectors, 3 and 1 to form the final emergent parallel beam and are drawn on the assumption, which is near enough for prac H tical purposes, that the mouth 2 isa point source in then surface of the reflector ll.
. The arrangement of FIGURES I and2," simple strucf turallythough it is, gives good performance and gain with high aperture efliciency and low noise characteristics approximating to those of the considerablymore expen I sive Cornucopia horn, though ,the bandwidth may be rather less. As will be appreciated the invention operates by the production of a virtual source (at the 'focus) unit and in a plane at an angle to the paraboloidal reflector, the distance of said planar reflector from said radio .unit being at least approximately one 'half the distance ofthe focus of theparaboloid from .saidunit, and a the two curved edges of the paraboloidal reflector and an adjacent edge of said planar reflector, the whole arrangement being such that radio energy following straight line paths from said unit to the planar reflector will be reflected thereby to the curved reflector and reflected again from the curved reflectoralong paths par- "pair of flat side walls which extend each between one of allel to one another and to the plane ofthe. planar refiector. V
Preferably the localised primary radio unit'is, a small 'radio horn orflared waveguide mouth. Its mouth can lie in the general surface of the curved reflector but, if-
desired, it can be allowed to project a little beyond said surface in the direction ofthe planar reflector which, in this case, should be shifted in correspondence with the shift of the horn or waveguide mouth with respect to the position it would occupy'were'it in said curved surface.
Preferably also the axis of the localised primary radio unit is tilted'a few degrees, e.g., about 6, away from thesnorrnal to the flat reflector in the direction of the rear part of the curved reflector, i.e., in the direction tenuation is approximately constant. In FIGURE 3 the i V ing f from a real source (the mouth 2);, Electrically both the real and ,virtual sources Lare well within the". aperture p 1 plane of the paraboloidal sector and there is good screeni v om extraneous radiation (primarily back radiation) and high gainand efficiency. f i
In practice, the realsourc e 2 will normally be a small horn of the order of two wavelengths aperture sizeand the diffraction field will be'dorninant. This, however, does not seriously alter conclusions drawn from considering the operation in terms of geometricab optics with a,
point source (real source), as is done in drawing the chainline paths of FIGURE 1, provided, of course, that a unique phase centre is preserved and the secondary aperture amplitude pattern is modifled in accordance. with the amplitude pattern obtained from the primary horn.
of the paraboloid sector. This tilt is desirable for two reasons (a) the illumination in the vertical plane is optimised. for maximum aperture efficiency and (12) the reflections returned from the flat {reflector 3 to the primary horn aperture'are reduced. The illumination in curvature is small and, as a consequence, the space at- FIGUREB shows the aperture illuminationin the yer-i tical plane (ordinates-mints offield intensity) of. the aperture fo r'the case where a. beam tilt of-6" is made'by the primary horn 2 towards thewrear part-0f the surface the horizontal plane is approximately the primary horn illumination in this plane, as the degree of reflector abscissae are values of the Y (vertical) ordinate expressed in terms of F (focal length). The flat reflector 3 intercepted about 85% of the primary horn energy in the case for which FIGURE 3. was obtained.
shown in full lines in its central position and in dotted lines in its-two'extreme positions. The-result of swing-- ing the planar reflector is, of course, to swing the emer-; gent beam up and down over an arc in the plane of the paper in FIGURE 4. Side plates (not shown in FIG- URE 4) may be provided as at 4 in FIGURE 2 but, it pro- ,vided they cannot of course be fixed to the side edges of the reflector 3 which swings between them with as small a clearance therefrom as is convenient to permit of swinging.
I claim:
1. An aerial system comprising a curved reflector having a predetermined focus, a localised primary radio unit in a hole in said reflector, and a planar reflector opposite and facing said primary unit and in a plane at an angle tothe curved reflector, the distance of said planar reflector from said primary unit being at least approximately one-half the distance of said focus from said unit, and theshapes and mutual arrangement of the two reflectors being such that radio energy following straight line paths from said unit to the planar reflector will be reflected'thereby to the curved reflector and reflected 'again from the curved reflector along paths parallel to one another; and to'the plane of the planar reflector.
1 2. Anaerial system comprising a reflector of paraboloidal curvature, a localised radio unit in a hole in the paraboloidal reflector, a planar reflector opposite and facingsaid primary unit and in a plane at an angle to the paraboloidal reflector, the distance of said planar reflector from said'unit being at least approximately one-half the distance of the focus ,of the paraboloid from said unit, and a pair of flat side ,walls which extend each between one of, the two curved edges of the paraboloidal 1 reflector and an adjacent edge of said planar reflector,
the whole arrangement being such that radio energy following straight line paths from said unit to the planar reflector will be reflected thereby to the curved reflector 5 and reflected again from the curved reflector along paths.
parallel to one another and to the plane of the planar reflector.
a 3. An aerial system as claimed in claim 1 wherein the radio unit is a small radio horn.
4. An aerial system-as claimed in claim 1 wherein the radio unit has a mouth lying in the general surface of the curved reflector.
(a? 5. An aerial systemas claimed in clairn 1 wherein the radio unit has a mouthprojecting a small distance be- 5 yond the general'surface of the curved reflector in the direction of the planar reflector, the position of the planar reflector being shifted in correspondence with the shift.
of the horn or waveguide mouth with respect to the position it would occupy were it in said curved surface.
' 6. An aerial system as claimed in claim 1 wherein the axis of the localised primary radio unit istilted a few degrees away from the normal to the planar reflector in the direction of the rear part of the curved reflector.
7. An aerial system as claimed in claim 1 wherein the planar reflector is fixed.
. 8. An aerial system as claimed in claim 1 wherein the planar reflector is hinged so as to be movable back and a forth over an are so that its angle'to the curved reflector is variable.
"9. An aerial system as claimed in claim 1 wherein the radio unit is a flared waveguide mouth.
HERMAN KARL SAALBACH, 215mm Examiner.

Claims (1)

1. AN AERIAL SYSTEM COMPRISING A CURVED REFLECTOR HAVING A PREDETERMINED FOCUS, A LOCALISED PRIMARY RADIO UNIT IN A HOLE IN SAID REFLECTOR, AND A PLANAR REFLECTOR OPPOSITE AND FACING SAID PRIMARY UNIT AND IN A PLANE AT AN ANGLE TO THE CURVED REFLECTOR, THE DISTANCE OF SAID PLANAR REFLECTOR FROM SAID PRIMARY UNIT BEING AT LEAST APPROXIMATELY ONE-HALF THE DISTANCE OF SAID FOCUS FROM SAID UNIT, AND THE SHAPES AND MUTUAL ARRANGEMENT OF THE TWO REFLECTORS BEING SUCH THAT RADIO ENERGY FOLLOWING STRAIGHT LINE PATHS FROM SAID UNIT TO THE PLANAR REFLECTOR WILL BE REFLECTED THEREBY TO THE CURVED REFLECTOR AND REFLECTED AGAIN FROM THE CURVED REFLECTOR ALONG PATHS PARALLEL TO ONE ANOTHER AND TO THE PLANE OF THE PLANAR REFLECTOR.
US258702A 1962-04-04 1963-02-15 Primary horn antenna feeding planar reflector through hole in focused curved reflector Expired - Lifetime US3165747A (en)

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GB12954/62A GB976253A (en) 1962-04-04 1962-04-04 Improvements in or relating to aerial systems

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3284802A (en) * 1963-11-12 1966-11-08 Bell Telephone Labor Inc Folded horn-reflector antenna wherein primary reflector is nonreflective at portion where specular reflection to feed would otherwise occur
US3357022A (en) * 1963-12-05 1967-12-05 Bell Telephone Labor Inc Folded horn-reflector antenna structure
US3683387A (en) * 1970-12-28 1972-08-08 Us Army Compact scanning radar antenna
JPS5028255A (en) * 1973-07-11 1975-03-22
JPS55179403U (en) * 1980-03-13 1980-12-23

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5117786Y1 (en) * 1970-03-31 1976-05-13

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531454A (en) * 1942-02-04 1950-11-28 Sperry Corp Directive antenna structure
US2579140A (en) * 1946-03-13 1951-12-18 Crawford Walter Freeman Wave projector
US2595271A (en) * 1943-12-20 1952-05-06 Kline Morris Antenna lobe shifting device
US2597391A (en) * 1946-04-30 1952-05-20 Us Sec War Antenna
US2656464A (en) * 1945-11-05 1953-10-20 Charles V Robinson Feed locus for semiparabolic reflector
US2705754A (en) * 1945-01-24 1955-04-05 Bell Telephone Labor Inc Directive antenna systems

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531454A (en) * 1942-02-04 1950-11-28 Sperry Corp Directive antenna structure
US2595271A (en) * 1943-12-20 1952-05-06 Kline Morris Antenna lobe shifting device
US2705754A (en) * 1945-01-24 1955-04-05 Bell Telephone Labor Inc Directive antenna systems
US2656464A (en) * 1945-11-05 1953-10-20 Charles V Robinson Feed locus for semiparabolic reflector
US2579140A (en) * 1946-03-13 1951-12-18 Crawford Walter Freeman Wave projector
US2597391A (en) * 1946-04-30 1952-05-20 Us Sec War Antenna

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3284802A (en) * 1963-11-12 1966-11-08 Bell Telephone Labor Inc Folded horn-reflector antenna wherein primary reflector is nonreflective at portion where specular reflection to feed would otherwise occur
US3357022A (en) * 1963-12-05 1967-12-05 Bell Telephone Labor Inc Folded horn-reflector antenna structure
US3683387A (en) * 1970-12-28 1972-08-08 Us Army Compact scanning radar antenna
JPS5028255A (en) * 1973-07-11 1975-03-22
JPS55179403U (en) * 1980-03-13 1980-12-23

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SE302783B (en) 1968-08-05
DE1929064U (en) 1965-12-16
GB976253A (en) 1964-11-25

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