US3821746A - Antenna system with distortion compensating reflectors - Google Patents

Antenna system with distortion compensating reflectors Download PDF

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Publication number
US3821746A
US3821746A US00303049A US30304972A US3821746A US 3821746 A US3821746 A US 3821746A US 00303049 A US00303049 A US 00303049A US 30304972 A US30304972 A US 30304972A US 3821746 A US3821746 A US 3821746A
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United States
Prior art keywords
reflector
reflectors
asymmetrical
rotationally
antenna
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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
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US00303049A
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English (en)
Inventor
M Mizusawa
Y Takeichi
S Betsudan
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Publication date
Priority claimed from JP9221071A external-priority patent/JPS5211871B2/ja
Priority claimed from JP9221171A external-priority patent/JPS5211872B2/ja
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
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Publication of US3821746A publication Critical patent/US3821746A/en
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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

Definitions

  • An antenna system has a reflector system comprising a plurality of reflectors having rotationally asymmetrical curved surfaces such as elliptic, hyperbolic or parabolic surface geometries.
  • asymmetrical curved surfaces such as elliptic, hyperbolic or parabolic surface geometries.
  • at least one pair of asymmetrical reflectors is arranged in facing relationship so that the differences in asymmetrical properties are compensated by the opposite radiation distribution characteristics of each reflector.
  • the reflectors are positioned apart so that among the reflectors the ratio between the product of the distances from each reflection point of each reflector t0 the focus of each reflected beam forms a constant ratio with the product of the distances from the reflection point to the focus of each incident beam. Accordingly, when an electromagnetic beam source with a rotationally symmetrical beam, is applied, a rotationally symmetrical radiation distribution characteristic results at an aperture of the antenna system even though the reflectors have rotationally asymmetrical curved surfaces.
  • This invention relates to an improvement of an antenna system having rotationally asymmetrical reflectors.
  • a rotationally asymmetrical reflector is meant a reflector which, due to its surface shape, causes an incident electromagetic field to be reflected asymmetrically so that an incident symmetrical electromagnetic field distribution loses its symmetry when it is reflected.
  • any of a parabolic reflector, a spherical reflector a hyprobolic reflector or an elliptic reflector are considered to be rotationally asymmetrical.
  • a flat reflector is considered to be rotationally symmetrical.
  • the Cassegrain antenna comprises a rotationally asymmetrical hyperboloid reflector la having a foci F F a rotationally asymmetrical paraboloid reflector lb having a focus F and a horn 2. Since a rotationally asymmetrical reflector is used, the electric field distribution on the aperture surface A-A' of the antenna is i a rotationally asymmetrical distribution when the beam reaches the antenna aperture surface A-A through the hyperboloid reflector la and the paraboloid reflector 1b, even though a rotationally symmetrical beam is fed from the horn 2.
  • the asymmetrical distribution at the'aperture A-A causes a deterioration of some antenna characteristics
  • FIG. 1 is a schematic view of a conventional antenna system having rotationally asymmetrical reflectors
  • FIG. 2 is a schematic view of an antenna to illustrate the function of the antenna of this invention
  • FIG. 3 is a schematic view of one preferred embodiment of the antenna in accordance with this invention.
  • FIG. 4 is a schematic view of another preferred embodiment of the antenna in accordance with this invention.
  • FIG. 5 is a schematic view of an embodiment using the system of this invention for an antenna primary feed system
  • FIG. 6 is a schematic view of a preferred embodiment using the system of this invention for a primary radiator of an elevation-azimuth mount type antenna.
  • FIG. 7 is a schematic view of a modification of the embodiment of the antenna system of FIG. 6.
  • Equation 1 The relation of power density between the incident beam to the reflector and the reflected beam is expressed by the Equation 1 as hereinafter shown.
  • the power contained in each of the solid angles d0, and dQ are P dfl andP dfl respectively. Since the powers are equal, the relationship can be expressed as wherein P designates the power density of an incident beam fed to the reflector per solid angle unit;
  • P designates the power density of a reflected beam per solid angle unit
  • d0 designates the differential solid angle bounded by the vectors F, M and F, M at the F 1 side;
  • dfl designates the differential solid angle bounded by the vectors F M and F M at the F side.
  • the angle 0 between the normal vector and the incident beam is the same as the angle ObetWeen the normal vector and the re-' flected beam.
  • F of FIG. 2 can be considered to be of an infinite distance.
  • the value F M can be considered constant for any beam. Accordingly, since the numerator in Equation 3 is constant the Equation 3 can be modified to PZ/PI I Hm The power density of the reflected beam changes depending upon the length F l M of the incident beam, and an asymmetrical beam results even if the incident beam is symmetrical.
  • P /P in Equation 3 should be constant for any beam.
  • P designates the power density of an arbitrary incident beam fed to a reflector 4a
  • P designates the power density of a corresponding beam reflected from the reflector 4b.
  • F ll in Equation 5 should be constant.
  • the reflectors are arranged to be symmetrical-about the point F accordingly,
  • Equation 5 is modified to A beam having the same shape as the beam from F 1 to M is radiated from the point F so that the symmetry of a symmetrical electric field distribution is not lost due to the rotationally asymmetrical reflectors 4a and 4b.
  • the ration P lP is constant when the ratio of the prodnets of the lengths in the numerator and denominator of the Equation 9 is designed to be constant for any beam, and rotational symmetry is not lost.
  • the antenna system of this invention can be used as a. primary feed system for other types of antennas or electromagnetic energy radiators e.g., a lens 5 as shown in FIG. 5. It should be understood that the antenna system of this-invention is also effective as a primary feed system for an antenna having fixed input and output ends and further having elevation and azimuth rotations.
  • FIG. 6 an embodiment is shown wherein the antenna system consists of a primary feed system having a horn 4a a flat reflector 4b, a paraboloid reflector 4c, a paraboloid reflector 4d, a flat reflector 4e, a sub-reflector 2 and a main reflector 3.
  • the two paraboloid reflectors 4c'and 4d have rotationally asymmetrical curved surfaces and the same surface-shape and are arranged so as to symmetrically face each other.
  • the sub-reflector 2 and the main-reflector 3 have respectively rotationally'symmetrical surfaces.
  • the flat reflector 4e, the subreflector 2 and the main-reflector 3 are turned around the elevation axis B-B'.
  • the horn 4a is fixed and all other reflectors are turned around the azimuth axis A-A.
  • the beam transmitted through the primary feed system is transmitted by focusing to the center line between the reflectors. Accordingly, no rotary joint is required as in aconventional antenna.
  • the beam fed from the input P is transmitted through the horn4a, the flat reflector 4b, the paraboloid reflector 4c, the paraboloid reflector 4d, the flat reflector 4e, the sub-reflector 2 the main reflector 3, and is finally radiated into space, as shown by the broken line in FIG. 6.
  • the electric field distribution of the beam from the horn 4a is rotationally symmetrical, and that of the beam fed from the flat reflector 4b to the paraboloid reflector 4c is also rotationally symmetrical.
  • the electric field distribution of the beam reflected from the paraboloid reflector 4c is rotationally asymmetrical.
  • the rotationally asymmetrical distribution is compensated by the asymmetrical structure of the paraboloid reflector 4d.
  • the electric field distribution of the beam reflected from the paraboloid reflector 4d becomes rotationally symmetrical.
  • the sub-reflector 2 and the main-reflector 3 are respectively rotationally symmetrical, so that the electric field distribution at the antenna aperture surface 8-8 is also rotationally symmetrical.
  • the elevation angle of the antenna is changed, the rotational symmetry of the field distribution of the beam reflected from the flat reflector 4e can be maintained because the reflector 4e turning with the elevation angle is a flat reflector in the embodiment.
  • FIG. 6 is effective when geometrical optics are applied. Instead of using the paraboloid reflectors 4c and 4d as shown in FIG. 6, it is possible to dispose a pair of ellipsoid reflectors 4c and 4d whose surfaces have the same curvature and face each other symmetrically as shown in FIG. 7. This replacementis effective for a system which is used in a relatively low frequency band and in which a consideration based on electromagnetic theory is required. That is, in the case wherein the incident wave to the reflector system and the reflected wave from the reflector are apt to largely diverge as shown by the broken line of FIG. 7, the system of FIG. 7 is effective.
  • the phase e enters of the incident wave on the ellipsoid reflector 4c and the reflected wave from the ellipsoid reflector 40', that is, the center F of the wave front of the incident wave and the center F of that of the reflected wave, are designated as the twofoci of the ellipsoid reflector 4c.
  • the relation between the incident wave and the reflected wave for any beam is not changed.
  • the incident wave having a rotationally symmetrical field distribution is fed into the reflector system, the reflected wave has a rotationally symmetrical field distribution.
  • the two rotationally asymmetrical reflectors face each other.
  • rotationally asymmetrical reflectors that is, more than two
  • a pair of the rotationally asymmetrical reflectors face each other through a pair of flat reflectors, the abovementioned relations and features can be maintained.
  • the relation between the power densities of the incident wave and of the reflected wave can be kept constant and a rotationally symmetrical field distribution can be provided, even though rotationally asymmetrical reantenna and decrease of side lobe and undesired polarized wave can be achieved.
  • An antenna system comprising a reflector system including:
  • a horn used as the primary radiator to generate a symmetrical electric field
  • At least one pair of asymmetrical reflectors arranged in facing relationship whereby the differences in asymmetrical properties are compensated by opposite radiation distribution characteristics so that the electric field distribution at an antenna aperture is rotationally symmetrical;
  • said plurality of reflectors positioned to provide a constant ratio between the product of the distances from each reflected point of each reflected beam on each reflector to each focus of the reflected beam and the product of the distances from said reflected points to each focus of each incident beam with regard to any beam passed from the horn and said reflectors to the antenna aperture.
  • An antenna system comprising:
  • a primary feed system including:
  • At least one pair of asymmetrical reflectors arranged in facing relationship whereby the differences in asymmetrical properties are compensated by opposite radiation distribution characteristics so that the electric field distribution at an antenna aperture is rotationally symmetrical; said horn having input and output ends fixed for elevation and azimuth rotation of the antenna wherein reflectors turning with an elevation rotation are flat reflectors while the reflectors independent of the elevation rotation are a plurality of rotationally asymmetrical curved surface reflectors said plurality of curved reflectors positioned to provide a constant ratio between the product of the distances from each reflected point of each reflected beam on each reflector to each focus of the reflected beam and the product of the distances from said reflected points to each focus of each incident beam in the primary feed system.
  • said antenna system further comprises a primary feed system including a horn, a first flat reflector, a paraboloid reflector, a paraboloid reflector, a second flat reflector, a sub-reflector and a main-reflector, the flat relfectors, the sub-reflector, and the main-reflector being tumable around an elevation axis, the said reflectors being tumable around an azimuth rotary'axis.
  • a primary feed system including a horn, a first flat reflector, a paraboloid reflector, a paraboloid reflector, a second flat reflector, a sub-reflector and a main-reflector, the flat relfectors, the sub-reflector, and the main-reflector being tumable around an elevation axis, the said reflectors being tumable around an azimuth rotary'axis.

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  • Aerials With Secondary Devices (AREA)
US00303049A 1971-11-17 1972-11-02 Antenna system with distortion compensating reflectors Expired - Lifetime US3821746A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP9221071A JPS5211871B2 (it) 1971-11-17 1971-11-17
JP9221171A JPS5211872B2 (it) 1971-11-17 1971-11-17

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US3821746A true US3821746A (en) 1974-06-28

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CA (1) CA969631A (it)
IT (1) IT970309B (it)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968497A (en) * 1974-03-19 1976-07-06 Thomas-Csf Antenna with a periscope arrangement
US4044361A (en) * 1975-05-08 1977-08-23 Kokusai Denshin Denwa Kabushiki Kaisha Satellite tracking cassegrainian antenna
DE2722373A1 (de) * 1976-05-18 1977-12-01 Mitsubishi Electric Corp Antennensystem
US4145695A (en) * 1977-03-01 1979-03-20 Bell Telephone Laboratories, Incorporated Launcher reflectors for correcting for astigmatism in off-axis fed reflector antennas
US4186402A (en) * 1976-05-18 1980-01-29 Mitsubishi Denki Kabushiki Kaisha Cassegrainian antenna with beam waveguide feed to reduce spillover
US4203105A (en) * 1978-05-17 1980-05-13 Bell Telephone Laboratories, Incorporated Scanable antenna arrangements capable of producing a large image of a small array with minimal aberrations
US4319250A (en) * 1977-06-29 1982-03-09 Nippon Telegraph & Telephone Public Corp. Offset dual-reflector aerial having tapered reflector segments in main reflector
US4339757A (en) * 1980-11-24 1982-07-13 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4343004A (en) * 1980-11-24 1982-08-03 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4343000A (en) * 1981-04-06 1982-08-03 The United States Of America As Represented By The Secretary Of The Navy Aircraft self-protection radar
US4356494A (en) * 1980-01-30 1982-10-26 Mitsubishi Denki Kabushiki Kaisha Dual reflector antenna
DE3302727A1 (de) * 1982-02-15 1983-09-01 Kokusai Denshin Denwa K.K., Tokyo Wellenleiter-strahlzufuehrung
US4482898A (en) * 1982-10-12 1984-11-13 At&T Bell Laboratories Antenna feed arrangement for correcting for astigmatism
US4491848A (en) * 1982-08-30 1985-01-01 At&T Bell Laboratories Substantially frequency-independent aberration correcting antenna arrangement
US4535338A (en) * 1982-05-10 1985-08-13 At&T Bell Laboratories Multibeam antenna arrangement
US4792811A (en) * 1985-04-19 1988-12-20 Thomson-Csf Device for reflecting the electromagnetic waves of a polarization and a method of construction of said device
US6225961B1 (en) 1999-07-27 2001-05-01 Prc Inc. Beam waveguide antenna with independently steerable antenna beams and method of compensating for planetary aberration in antenna beam tracking of spacecraft
US20070195000A1 (en) * 2006-02-23 2007-08-23 Peter Balling Multibeam antenna
US20110156948A1 (en) * 2007-03-16 2011-06-30 Mobile Sat Ltd. Vehicle mounted antenna and methods for transmitting and/or receiving signals

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968497A (en) * 1974-03-19 1976-07-06 Thomas-Csf Antenna with a periscope arrangement
US4044361A (en) * 1975-05-08 1977-08-23 Kokusai Denshin Denwa Kabushiki Kaisha Satellite tracking cassegrainian antenna
DE2722373A1 (de) * 1976-05-18 1977-12-01 Mitsubishi Electric Corp Antennensystem
FR2352412A1 (fr) * 1976-05-18 1977-12-16 Mitsubishi Electric Corp Systeme d'antenne
US4186402A (en) * 1976-05-18 1980-01-29 Mitsubishi Denki Kabushiki Kaisha Cassegrainian antenna with beam waveguide feed to reduce spillover
US4145695A (en) * 1977-03-01 1979-03-20 Bell Telephone Laboratories, Incorporated Launcher reflectors for correcting for astigmatism in off-axis fed reflector antennas
US4319250A (en) * 1977-06-29 1982-03-09 Nippon Telegraph & Telephone Public Corp. Offset dual-reflector aerial having tapered reflector segments in main reflector
US4203105A (en) * 1978-05-17 1980-05-13 Bell Telephone Laboratories, Incorporated Scanable antenna arrangements capable of producing a large image of a small array with minimal aberrations
US4356494A (en) * 1980-01-30 1982-10-26 Mitsubishi Denki Kabushiki Kaisha Dual reflector antenna
US4339757A (en) * 1980-11-24 1982-07-13 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4343004A (en) * 1980-11-24 1982-08-03 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4343000A (en) * 1981-04-06 1982-08-03 The United States Of America As Represented By The Secretary Of The Navy Aircraft self-protection radar
DE3302727A1 (de) * 1982-02-15 1983-09-01 Kokusai Denshin Denwa K.K., Tokyo Wellenleiter-strahlzufuehrung
US4535338A (en) * 1982-05-10 1985-08-13 At&T Bell Laboratories Multibeam antenna arrangement
US4491848A (en) * 1982-08-30 1985-01-01 At&T Bell Laboratories Substantially frequency-independent aberration correcting antenna arrangement
US4482898A (en) * 1982-10-12 1984-11-13 At&T Bell Laboratories Antenna feed arrangement for correcting for astigmatism
US4792811A (en) * 1985-04-19 1988-12-20 Thomson-Csf Device for reflecting the electromagnetic waves of a polarization and a method of construction of said device
US6225961B1 (en) 1999-07-27 2001-05-01 Prc Inc. Beam waveguide antenna with independently steerable antenna beams and method of compensating for planetary aberration in antenna beam tracking of spacecraft
US6246378B1 (en) 1999-07-27 2001-06-12 Prc, Inc. Beam waveguide antenna with independently steerable antenna beams and method of compensating for planetary aberration in antenna beam tracking of spacecraft
US20070195000A1 (en) * 2006-02-23 2007-08-23 Peter Balling Multibeam antenna
US7522116B2 (en) * 2006-02-23 2009-04-21 Agence Spatiale Europeenne Multibeam antenna
US20110156948A1 (en) * 2007-03-16 2011-06-30 Mobile Sat Ltd. Vehicle mounted antenna and methods for transmitting and/or receiving signals
US8228253B2 (en) * 2007-03-16 2012-07-24 Mobile Sat Ltd. Vehicle mounted antenna and methods for transmitting and/or receiving signals

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IT970309B (it) 1974-04-10
CA969631A (en) 1975-06-17

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