US3195137A - Cassegrainian antenna with aperture blocking correction - Google Patents

Cassegrainian antenna with aperture blocking correction Download PDF

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Publication number
US3195137A
US3195137A US78364A US7836460A US3195137A US 3195137 A US3195137 A US 3195137A US 78364 A US78364 A US 78364A US 7836460 A US7836460 A US 7836460A US 3195137 A US3195137 A US 3195137A
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United States
Prior art keywords
reflector
paraboloid
signals
antenna
horn
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
US78364A
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English (en)
Inventor
Jr William C Jakes
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AT&T Corp
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Bell Telephone Laboratories Inc
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
Priority to NL272152D priority Critical patent/NL272152A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US78364A priority patent/US3195137A/en
Priority to FR881044A priority patent/FR1307590A/fr
Priority to GB22007/65A priority patent/GB1006219A/en
Priority to GB43805/61A priority patent/GB1006218A/en
Priority to DEW39552A priority patent/DE1257227B/de
Priority to DEW31245A priority patent/DE1225716B/de
Application granted granted Critical
Publication of US3195137A publication Critical patent/US3195137A/en
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
    • 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
    • H01Q19/02—Details
    • H01Q19/021—Means for reducing undesirable effects
    • H01Q19/027—Means for reducing undesirable effects for compensating or reducing aperture blockage
    • 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
    • H01Q19/195—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 a reflecting surface acts also as a polarisation filter or a polarising device

Definitions

  • This invention relates to antenna systems and more particularly to an improved, low-noise temperature Cassegrainian antenna.
  • Paraboloidal reflectors are frequently employed to convert spherical electromagnetic wave fronts to plane electromagnetic wave fronts, and vice versa.
  • Directional antennas in which an active feed element is located at the focus of a paraboloid have found wide application in radio communications as cheap and convenient means of intercepting and radiating directional signals.
  • Such antenna systems are, however, subject to distinct shortcomings which become more serious as the technology of the communications art advances. For example, in order to illuminate the paraboloid efficiently, an appreciable amount of energy is radiated or intercepted by the active feed element directly without reflection from the paraboloid. This spillover, as it is commonly called, causes an increase in the noise temperature in receiving antennas and accounts for a wasteful radiation of energy in a transmitting antenna.
  • the active feed element since the active feed element must be located at the focus of the paraboloid, the active components which are connected to the feed must normally be placed in the path of the antenna beam. These obstructions cause an increase in side lobe level of the antenna radiation pattern.
  • the conventional horn reflector antenna with a paraboloidal reflector eliminates both the problems of obstructions in the path of the beam and spillover.
  • a horn reflector having some desired gain is by necessity much more expensive and larger in size and weight than a paraboloidal antenna having a comparable gain.
  • the antenna sys tem of the present invention employs the classic Cassegrainian telescope principle.
  • a feed horn of relatively small size and having an ellipsoidal reflecting surface provides a source and collector of radio signals.
  • this feed horn is identical to the conventional horn reflector with the exception of the ellipsoidal reflector here substituted for the paraboloidal reflector.
  • This feed horn is located behind a large paraboloidal reflector and the focii of the ellipsoidal surfa-ce coincide with the paraboloid vertex and feed horn apex, respectively.
  • An intermediate reflector is located in front and centered about the axis of the paraboloid. Its surface exhibits a curvature which creates at the paraboloidal focus a virtual source or collector of signals to signals reflected from it, so that conversion of the signal toand from a plane wave front may be achieved.
  • the radio signal radiated from the feed horn passes through the hole in the paraboloid it diverges and impinges upon the intermediat' reflector from whence it is reflected, as though originating at the parabolic focus, toward the paraboloid.
  • a plane wave front is then developed by the paraboloid.
  • the beam radiated or intercepted by the feed horn is well defined for much the same reasons that the conventional horn reflector radiates and intercepts with such high directivity. Because the beam of the feed horn is so well controlled, very little energy is radiated or intercepted directly from beyond the periphery of the paraboloid and, hence, little spillover occurs. Still the antenna beam is developed by the paraboloid, however, and the advantages of size and cost derived therefrom are fully utilized.
  • the intermediate reflector may be made transparent to the ultimate antenna beam while performing its function of reflection between the feed horn and paraboloid.
  • the invention takes advantage of the fact that the rotation of the direction of polarization of circularly-polarized signals reverses upon reflection from the paraboloid. Hence, the rotation of the direction of polarization of the ultimate antenna beam signal is opposite that of the beam emerging from or collected by the horn.
  • the intermediate reflector is constructed to reflect circularly-polarized signals having one direction of rotation and to transmit signals having the opposite direction of rotation as though the intermediate reflector were not present, with the result that no shadow is created by the intermediate reflector.
  • the intermediate reflector may comprise three regions.
  • a region which reflects linearly-polarized signals of a given orientation and transmits linearly-polarized signals of the quadrature polarization lies between a pair of linear-to-circular polarization converters.
  • Circularlypolarized signals impinging upon the surface of the intermediate reflector are converted to linearly-polarized signals oriented in one of the two directions depending upon their original direction of rotation. Accordingly, the
  • linearly-polarized signals oriented in the given direction are reflected by the center region and reconverted to circularly-polarized signals having the original direction of rotation.
  • the linearly-polarized signals of the quadrature polarization are transmitted through the center region and also reconverted to circularly-polarized signals of their original direction of rotation.
  • An additional feature of the invention designed to conserve space, provides that the aperture of the feed horn be placed at right angles to the hole in the paraboloid and close to the paraboloid. A flat plate, then, directs the radio signal between the feed horn and the hole.
  • FIG. 1 is a side section of the complete antenna system of the invention
  • FIG. 2 is a front elevation of the feed horn illustrated in FIG. 1;
  • FIGS. 3A, 3B and 30 show the detailed construction of the intermediate reflector
  • FIGS. 4A and 4B illustrate a modification of the antenna system of FIG. I intended to save space.
  • the antenna of the invention may, of course, receive signals as well in a manner reciprocally related to transmission and it is, in fact, as a receiving antenna that many features of the invention are fully exploited.
  • FIG. 1 illustrates the location of the three principle elements of the invention-a feed horn 10, a paraboloidal reflector 16 and an intermediate reflector 20.
  • Feed horn is similar to the conventional paraboloidal horn reflector with an ellipsoidal reflector 12 replacing the paraboloidal one.
  • FIG. 2 shows feed horn 10 in front elevation.
  • Paraboloidal reflector 16 is of the conventional type. Its surface is generated by rotating a parabola about an axis 18.
  • Feed born 10 is situated behind reflector 16, as shown in FIG. 1, so that its axis 17 lies perpendicular to and intersects axis 18.
  • An aperture 24 in the wall of feed horn 10 passes through axis 18 and faces the vertex of paraboloidal reflector 16. Further, the focii 11 and 21 of ellipsoidal section 12 are located at the apex of feed horn 10 on axis 17 and the vertex of reflector 16 on axis 18, respectively.
  • An ellipse is characterized as the locus of a point the sum of whose distances from a pair of focii is a constant.
  • feed horn 10 permits a great deal of control over the radiated signal.
  • the beam emanating from feed horn 10 is sharply defined and very little energy strays from the path of the beam.
  • FIG. 1 It can be seen from FIG. 1 that if the sizes of paraboloidal reflector 16 and intermediate reflector 20 are selected so that all of the biconical beam radiated from feed horn 10 is reflected from both reflectors 16 and 20, as indicated by ray lines 14, negligible energy is radiated in the form of spillover.
  • the significance of this feature of the invention is that very little thermal energy is collected from the surroundings and the effective noise temperature of the antenna contributed to the receiver system is small.
  • Feed horn 10 is relatively small and paraboloidal reflector 16 large so that the cost and size of feed horn 10 in comparison to the gain associated with the paraboloidal reflector 16 is reasonable.
  • the well-defined beam of feed horn 10 accounts for a small spillover not attainable with conventional paraboloidal antennas.
  • feed horn 10 and the cross section of surface 30 are circular in the embodiment of FIG. 1, they may both be rectangular as may be aperture 24, for ease of construction, in which case the envelope of the beam from feed horn 10 would be pyramidal. It is evident that this does not provide as eflioient an illumination of paraboloidal reflector 16 as the embodiment of FIG. 1.
  • intermediate reflector 20 may be made transparent to the antenna beam so that no shadow exists in the local antenna beam as would normally be expected from the presence of an obstruction such as intermediate reflector 20.
  • This facet of the invention takes advantage of the fact that circularly-polarized signals upon reflection from a conducting surface (in this instance paraboloidal reflector 16) reverse their direction of rotation of polarization.
  • Intermediate reflector 20 is capable of discriminating between circularly-polarized signals whose polarization is rotating in different directions in that signals rotating in one direction are reflected and signals rotating in the opposite direction are transmitted.
  • FIGS. 3A, 3B and 3C are side and front elevations, respectively, of reflector 20.
  • Section 20 is composed of square wave guide sections, as typified by wave guide sections 28, the cross sections of which are staggered in position to form an approximate spherical surface 30. This approximation is valid because the wavelength of the signal employed is normally large compared to the dimensions of the discontinuities of surface 30.
  • Each of sections 28 is composed of three regions as shown in FIG. 3C.
  • Linear-to-circular polarization converter regions 32 and 36 are connected by a middle region 34 which reflects linear-polarized signals oriented in a given direction and transmits linear-polarized signals oriented in the quadrature direction.
  • regions 32 and 36 are A90-degree sec-. tions with fins 38 and 42 oriented along opposite diagonals in regions 32 and 36, respectively.
  • Middle region 34 has a horizontal septum 40 placed therein.
  • counterclockwise-rotating circularly-polarized signals impinging upon intermediate reflector 20 are converted to linearly-polarized signals oriented in a horizontal direction after transmission through region 32.
  • these signals reach region 34 they are reflected therefrom and reconverted to counterclockwise-rotating circularlypolarized signals after the return trip through region 32, and radiated from surface 30.
  • clockwise signals are introduced into section 32, they are converted to linearly-polarized signals oriented in a vertical direction during transmission through region 32.
  • the vertically-polarized signals are transmitted through section 34 to section 36 in which they are reconverted t0 clockwise-rotating circularly-polarized signals and radiated as a portion of the antenna beam.
  • section 34 is adjusted to eflect a time lead through intermediate reflector 20 as a Whole with respect to free space which is an integral number of wavelengths of the signal.
  • Rotating region 34 by ninety degrees reverses the discriminatory characteristics of intermediate section 20.
  • Section 20 would then reflect clockwise-rotating circularly-polarized signals and transmit counterclockwise circularly-polarized signals.
  • feed horn is positioned at right angles to hole 22.
  • a flat reflector 44 directs the signals emanating from feed horn 10 through hole 22. This modification of the embodiment in FIG. 1 conserves space by situating feed horn 10 closer to reflector 16.
  • a paraboloidal reflector having a focus and a vertex, said paraboloid having a hole located at said vertex, a horn reflector located behind said paraboloid, said horn reflector having an ellipsoidal reflecting surface with one focus near the apex of said horn reflector, and a second reflector facing said paraboloid and located to create a virtual source and collector of signals at said focus of said paraboloid, said second reflector reflecting without changing the direction of rotation circularly-polarized signals rotatmg in one direction and transmitting circularly-polarized signals rotating in the opposite direction, said horn reflector oriented to permit coupling of signals between it .and said second reflector through said hole.
  • a paraboloidal reflector having a focus and a vertex, said paraboloid having a hole located at said vertex, a horn reflector located behind said paraboloid and directed in a line perpendicular to the axis of said paraboloid, said horn reflector having an ellipsoidal reflecting surface with one focus near the apex of said horn reflector, and a second reflector facing said paraboloid and located to create a virtual source and collector of signals at said focus of said paraboloid, said second reflector reflecting without changing the direction of rotation circularly-polarized signals rotating in one direction and transmitting circularly-polarized signals rotating in the opposite direction, and a flat reflector located behind said paraboloid to direct signals between said horn reflector and said hole.
  • a paraboloidal reflector having a focus and a vertex, a feed element accommodating circularly-polarized signals located near said vertex behind said paraboloid and directed to said focus of said paraboloid, and a second reflector facing said paraboloid and located to create a virtual source and collector of signals at said focus of said paraboloid, said second reflector comprising means for converting between circularly-polarized signals and linearly-polarized signals, means for reflecting linearly-polarized signals having a given direction of polarization and transmitting linearly-polarized signals having a direction of polarization orthogonal to said given direction, and means for converting between linearly-polarized signals and circularly-polarized signals, said last three means being located one adjacent to the' other in the order recited.
  • An antenna system comprising a paraboloidal reflector having a focus and a vertex, a hole in said paraboloid located at said vertex, a horn reflector located behind said paraboloid, said horn having an ellipsoidal reflecting surface with one focus near the apex of said horn reflector and the other focus at said vertex of said paraboloid and a second reflector facing said paraboloid and located to create a virtual source and collector of signals at said focus of said paraboloid, said horn reflector oriented to permit coupling of signals between it and said second reflector through said hole.
  • a paraboloidal reflector having a focus and a vertex, a hole in said paraboloidal reflector located at said vertex, a horn reflector comprising a horn for conveying electromagnetic waves along a longitudinal axis, said horn having an apex aperture and a side aperture in its wall, an antenna axis passing through said side aperture, and an ellipsoidal reflector of electromagnetic waves facing both said apertures, the ellipsoidal focii 1ying upon said antenna axis and said longitudinal axis at said vertex of said paraboloidal reflector respectively, and a second reflector facing said paraboloid and located to create a virtual source and collector of signals at said focus of said paraboloid.
  • a source of radio signals the signals of which impinge upon a microwave circuit device comprising a plurality of waveguide segments stacked one on top of the other to form a surface upon which microwave signals may be directed, said segments each comprising, in the order named, a A-degree section, a septum section, and a AQO-degree section.
  • An antenna system comprising a first reflector having an opening through it, a feed element accommodating circularly polarized signals located behind said reflector and directed at said opening, and a second reflector facing said first reflector and located to couple signals between said source and said first reflector, said second reflector reflecting without changing the direction of rotation circularly polarized signals having a given direction of rotation and transmitting circularly polarized signals having a direction of rotation opposite said given direction.
  • said wave transmission circuit device comprising the following elements located in succession in the order recited: means for converting said circularly-polarized wave when its polarization is rotating in one direction into a linearly-polarized wave the polarization of which is oriented in a given direction and for converting said circularly-polarized wave when its polarization is rotating in the other direction into a linearlypolarized wave the polarization of which is oriented orthogonally to said given direction, means for transmitting said linearly-polarized wave when its polarization is oriented in said given direction and for reflecting said linearlypolarized wave when its polarization is oriented orthogonally to said given direction, and means for converting said linearly-polarized wave when its polarization is oriented in said given direction into a circularly-polarized wave the polarization of which is rotating in said

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US78364A 1960-12-27 1960-12-27 Cassegrainian antenna with aperture blocking correction Expired - Lifetime US3195137A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL272152D NL272152A (enrdf_load_stackoverflow) 1960-12-27
US78364A US3195137A (en) 1960-12-27 1960-12-27 Cassegrainian antenna with aperture blocking correction
FR881044A FR1307590A (fr) 1960-12-27 1961-12-05 Dispositif d'antenne
GB22007/65A GB1006219A (en) 1960-12-27 1961-12-07 Improvements in or relating to antenna systems
GB43805/61A GB1006218A (en) 1960-12-27 1961-12-07 Improvements in or relating to antenna systems
DEW39552A DE1257227B (de) 1960-12-27 1961-12-09 Cassegrain-Antenne
DEW31245A DE1225716B (de) 1960-12-27 1961-12-09 Cassegrain-Antenne

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US78364A US3195137A (en) 1960-12-27 1960-12-27 Cassegrainian antenna with aperture blocking correction

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US3195137A true US3195137A (en) 1965-07-13

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US78364A Expired - Lifetime US3195137A (en) 1960-12-27 1960-12-27 Cassegrainian antenna with aperture blocking correction

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US (1) US3195137A (enrdf_load_stackoverflow)
DE (2) DE1257227B (enrdf_load_stackoverflow)
GB (2) GB1006219A (enrdf_load_stackoverflow)
NL (1) NL272152A (enrdf_load_stackoverflow)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3271771A (en) * 1962-02-15 1966-09-06 Hazeltine Research Inc Double-reflector, double-feed antenna for crossed polarizations and polarization changing devices useful therein
US3281850A (en) * 1962-03-07 1966-10-25 Hazeltine Research Inc Double-feed antennas operating with waves of two frequencies of the same polarization
US3340535A (en) * 1964-06-16 1967-09-05 Textron Inc Circular polarization cassegrain antenna
US3414904A (en) * 1966-05-16 1968-12-03 Hughes Aircraft Co Multiple reflector antenna
US3448455A (en) * 1964-03-20 1969-06-03 Thomson Houston Comp Francaise Armoured structure antenna
US3500419A (en) * 1966-09-09 1970-03-10 Technical Appliance Corp Dual frequency,dual polarized cassegrain antenna
US3510873A (en) * 1965-10-18 1970-05-05 Comelit Comp Elettro It Horn-reflector antenna
US3514779A (en) * 1966-02-25 1970-05-26 Csf Antennae with focusing devices
US3641577A (en) * 1968-03-12 1972-02-08 Comp Generale Electricite Scanning antenna having a spherical main reflector with moveable subreflector
US3953858A (en) * 1975-05-30 1976-04-27 Bell Telephone Laboratories, Incorporated Multiple beam microwave apparatus
US4689632A (en) * 1985-05-30 1987-08-25 Rca Corporation Reflector antenna system having reduced blockage effects
US4977407A (en) * 1981-07-23 1990-12-11 Crane Patrick E Optical collimator
US5003321A (en) * 1985-09-09 1991-03-26 Sts Enterprises, Inc. Dual frequency feed
US10879619B2 (en) 2009-06-04 2020-12-29 Ubiquiti Inc. Microwave system
CN113659346A (zh) * 2021-07-30 2021-11-16 中国航空工业集团公司济南特种结构研究所 一种天线罩电厚度测试天线及使用方法

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Publication number Priority date Publication date Assignee Title
NL278997A (enrdf_load_stackoverflow) 1961-07-31
DE2628713C2 (de) * 1976-06-25 1987-02-05 Siemens AG, 1000 Berlin und 8000 München Rotationssymmetrische Zweispiegelantenne
DE2947987C2 (de) * 1979-11-28 1982-03-04 Siemens AG, 1000 Berlin und 8000 München Cassegrain-Antenne
US4568329A (en) * 1982-03-08 1986-02-04 Mahurkar Sakharam D Double lumen catheter
US4692141A (en) 1982-03-08 1987-09-08 Mahurkar Sakharam D Double lumen catheter
US4583968A (en) * 1983-10-03 1986-04-22 Mahurkar Sakharam D Smooth bore double lumen catheter
US5197951A (en) 1983-12-14 1993-03-30 Mahurkar Sakharam D Simple double lumen catheter
US4623327A (en) * 1985-02-12 1986-11-18 Mahurkar Sakharam D Method and apparatus for using dual-lumen catheters for extracorporeal treatment
US4770652A (en) * 1985-02-12 1988-09-13 Mahurkar Sakharam D Method and apparatus for using dual-lumen catheters for extracorporeal treatment
US4808155A (en) 1986-02-27 1989-02-28 Mahurkar Sakharam D Simple double lumen catheter
GB2234858A (en) * 1988-09-02 1991-02-13 Thorn Emi Electronics Ltd Cassegrain antenna
US5374245A (en) 1990-01-10 1994-12-20 Mahurkar; Sakharam D. Reinforced multiple-lumen catheter and apparatus and method for making the same
US5221255A (en) 1990-01-10 1993-06-22 Mahurkar Sakharam D Reinforced multiple lumen catheter
US5690642A (en) 1996-01-18 1997-11-25 Cook Incorporated Rapid exchange stent delivery balloon catheter

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FR911045A (fr) * 1943-09-28 1946-06-26 Color Metal A G Réflecteurs cylindriques produisant un faisceau lumineux en forme de coin
US2736895A (en) * 1951-02-16 1956-02-28 Elliott Brothers London Ltd High frequency radio aerials
US2741744A (en) * 1951-05-08 1956-04-10 Driscoll Clare Microwave apparatus for circular polarization
US2825032A (en) * 1953-03-10 1958-02-25 Alford Andrew Wave guide mode transformer
US2952017A (en) * 1956-02-23 1960-09-06 Decca Record Co Ltd Waveguide type radar apparatus having polarization converter
US2972743A (en) * 1957-06-19 1961-02-21 Westinghouse Electric Corp Combined infrared-radar antenna
US2983918A (en) * 1956-09-11 1961-05-09 Magneti Marelli Spa Bilateral transmission system
US3089137A (en) * 1959-07-01 1963-05-07 Bell Telephone Labor Inc Polarization tracking receiver

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US2032588A (en) * 1931-09-12 1936-03-03 Jr Herman Potts Miller Communication and detection system
FR898352A (fr) * 1942-06-24 1945-04-20 Telefunken Gmbh Perfectionnements aux systèmes de production simultanée ou alternative de deux rayonnements dirigés
FR911045A (fr) * 1943-09-28 1946-06-26 Color Metal A G Réflecteurs cylindriques produisant un faisceau lumineux en forme de coin
US2736895A (en) * 1951-02-16 1956-02-28 Elliott Brothers London Ltd High frequency radio aerials
US2741744A (en) * 1951-05-08 1956-04-10 Driscoll Clare Microwave apparatus for circular polarization
US2825032A (en) * 1953-03-10 1958-02-25 Alford Andrew Wave guide mode transformer
US2952017A (en) * 1956-02-23 1960-09-06 Decca Record Co Ltd Waveguide type radar apparatus having polarization converter
US2983918A (en) * 1956-09-11 1961-05-09 Magneti Marelli Spa Bilateral transmission system
US2972743A (en) * 1957-06-19 1961-02-21 Westinghouse Electric Corp Combined infrared-radar antenna
US3089137A (en) * 1959-07-01 1963-05-07 Bell Telephone Labor Inc Polarization tracking receiver

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3271771A (en) * 1962-02-15 1966-09-06 Hazeltine Research Inc Double-reflector, double-feed antenna for crossed polarizations and polarization changing devices useful therein
US3281850A (en) * 1962-03-07 1966-10-25 Hazeltine Research Inc Double-feed antennas operating with waves of two frequencies of the same polarization
US3448455A (en) * 1964-03-20 1969-06-03 Thomson Houston Comp Francaise Armoured structure antenna
US3340535A (en) * 1964-06-16 1967-09-05 Textron Inc Circular polarization cassegrain antenna
US3510873A (en) * 1965-10-18 1970-05-05 Comelit Comp Elettro It Horn-reflector antenna
US3514779A (en) * 1966-02-25 1970-05-26 Csf Antennae with focusing devices
US3414904A (en) * 1966-05-16 1968-12-03 Hughes Aircraft Co Multiple reflector antenna
US3500419A (en) * 1966-09-09 1970-03-10 Technical Appliance Corp Dual frequency,dual polarized cassegrain antenna
US3641577A (en) * 1968-03-12 1972-02-08 Comp Generale Electricite Scanning antenna having a spherical main reflector with moveable subreflector
US3953858A (en) * 1975-05-30 1976-04-27 Bell Telephone Laboratories, Incorporated Multiple beam microwave apparatus
US4977407A (en) * 1981-07-23 1990-12-11 Crane Patrick E Optical collimator
US4689632A (en) * 1985-05-30 1987-08-25 Rca Corporation Reflector antenna system having reduced blockage effects
US5003321A (en) * 1985-09-09 1991-03-26 Sts Enterprises, Inc. Dual frequency feed
US10879619B2 (en) 2009-06-04 2020-12-29 Ubiquiti Inc. Microwave system
CN113659346A (zh) * 2021-07-30 2021-11-16 中国航空工业集团公司济南特种结构研究所 一种天线罩电厚度测试天线及使用方法
CN113659346B (zh) * 2021-07-30 2023-11-21 中国航空工业集团公司济南特种结构研究所 一种天线罩电厚度测试天线及使用方法

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Publication number Publication date
DE1225716B (de) 1966-09-29
NL272152A (enrdf_load_stackoverflow)
GB1006219A (en) 1965-09-29
DE1257227B (de) 1967-12-28
GB1006218A (en) 1965-09-29

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