EP0140598B1 - Antenne micro-ondes du type réflecteur à source cornet tapissé d'absorbant - Google Patents

Antenne micro-ondes du type réflecteur à source cornet tapissé d'absorbant Download PDF

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Publication number
EP0140598B1
EP0140598B1 EP19840306759 EP84306759A EP0140598B1 EP 0140598 B1 EP0140598 B1 EP 0140598B1 EP 19840306759 EP19840306759 EP 19840306759 EP 84306759 A EP84306759 A EP 84306759A EP 0140598 B1 EP0140598 B1 EP 0140598B1
Authority
EP
European Patent Office
Prior art keywords
horn
conical
absorber
reflector
plane
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
Application number
EP19840306759
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German (de)
English (en)
Other versions
EP0140598A1 (fr
Inventor
Charles M. Knop
Edward M. Ostertag
Yuk-Bun Cheng
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.)
Commscope Technologies LLC
Original Assignee
Andrew LLC
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 Andrew LLC filed Critical Andrew LLC
Publication of EP0140598A1 publication Critical patent/EP0140598A1/fr
Application granted granted Critical
Publication of EP0140598B1 publication Critical patent/EP0140598B1/fr
Expired 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
    • H01Q19/10—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
    • H01Q19/12—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 wherein the surfaces are concave
    • H01Q19/13—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 wherein the surfaces are concave the primary radiating source being a single radiating element, e.g. a dipole, a slot, a waveguide termination
    • H01Q19/132—Horn reflector antennas; Off-set feeding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/001—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems for modifying the directional characteristic of an aerial

Definitions

  • the present invention relates generally to microwave antennas and, more particularly, to reflector-type microwave antennas having conical feeds.
  • Conical feeds for reflector-type microwave antennas have been known for many years. For example, a 1963 article in The Bell System Technical Journal describes the selection of a conical horn-reflector antenna for use in satellite communication ground station (Hines et al, "The Electrical Characteristics of The Conical Horn-Reflector Antenna", The Bell System Technical Journal, July 1963, pp. 1187-1211). A conical horn-reflector antenna is also described in Daw- son U.S. Patent No. 3,550,142, issued December 22, 1970. Conical feed horns have also been used with large parabolic dish antennas.
  • a related object of this invention is to provide an improved conical feed which is capable of bringing the RPE's in both the E and H-planes even closer together.
  • a conical horn-reflector antenna comprising the combination of a paraboloidal reflector forming a paraboloidal reflecting surface for transmitting and receiving microwave energy, and a conical feed horn for guiding microwave energy from the focus of said paraboloidal reflecting surface to said reflector, the small end of the horn being located near and with its apex coincident with the focal point of the paraboloidal reflector, the lower portion of said horn having a smooth metallic interior wall defining a conical surface which, when projected onto the reflector, is intercepted by the paraboloidal reflecting surface thereof, the upper portion of said horn being lined with absorber on at least those portions of the interior wall which affect the E-plane field distribution so as to cause the radiation pattern envelope width in the E-plane to approach that in the H-plane, characterised by said absorber having its thickness located outside of the projection of said conical surface defined by said lower portion of said horn and having its exposed surface lying substantially on said conical surface projection.
  • the exposed surface of the absorber may be smooth or profiled in the form of multiple pyramids or convoluted cones.
  • a conical horn-reflector microwave antenna having a conical section 10 for guiding microwave signals to a parabolic reflector plate 11. From the reflector plate 11, the microwave signals are transmitted through an aperture 12 formed in the front of a cylindrical section 13 which is attached to both the conical section 10 and the reflector plate 11 to form a completely enclosed integral antenna structure.
  • the parabolic reflector plate 11 is a section of a paraboloid representing a surface of revolution formed by rotating a parabolic curve about an axis which extends through the vertex and the focus of the parabolic curve.
  • any microwaves originating at the focus of such a parabolic surface will be reflected by the plate 11 in planar wavefronts perpendicular to the axis 14.
  • the conical section 10 of the illustrative antenna is arranged so that its apex coincides with the focus of the paraboloid, and so that the axis 15 of the conical section is perpendicular to the axis of the paraboloid.
  • the cylindrical section 13 serves as a shield which prevents the reflector plate 11 from producing interfering side and back signals and also helps to capture some spillover energy launched from the conical section feed.
  • the conical section 10, the reflector plate 11, and the cylindrical shield 13 are usually formed of conductive metal (though it is only essential that the reflector plate 11 have a metallic surface).
  • the top of the reflector plate 11 is covered by a panel 20 attached to the cylindrical shield 13.
  • a radome 21 also covers the aperture 12 at the front of the antenna to provide further protection from the weather.
  • the inside surface of the cylindrical shield 12 is covered with an absorber material 22 to absorb stray signals so that they do not degrade the RPE.
  • absorber materials are well known in the art, and typically comprise a conductive material such as metal or carbon dispersed throughout a dielectric material having a surface in the form of multiple pyramids or convoluted cones.
  • the lower end portion of the inside surface of the conical feed horn is formed by a smooth metal wall, and the balance of the inside surface of the horn is formed by a layer of absorber material, the surfaces of the metal wall and the absorber material defining a single continuous conical surface.
  • the bottom section 10a of the conical feed horn 10 has a smooth inside metal surface.
  • the balance of the inside surface of the conical horn 10 is formed by an absorber material 30, with the innermost surfaces of the metal section 10a and the absorber material 30 defining a single continuous conical surface.
  • the metal wall adjoining the lower horn section 10a forms an outwardly extending shoulder 10b at the top of the section 10a, and then extends upwardly along the outside surface of the absorber 30.
  • the metal wall forms a second outwardly extending shoulder 10d to accommodate the greater thickness of the absorber material 22 which lines the shield portion of the antenna above the conical feed horn.
  • This recessed arrangement of the absorber material 30 permits further narrowing of the E-plane RPE and/or reductions in the gain drop of the antenna as compared with the structure shown in the aforementioned European Patent Publication No. 66455A. More specifically, for a given gain drop, the structure of the present invention permits the absober material to be extended farther down into the throat of the conical feed horn 10, thereby further narrowing the E-plane RPE.
  • the metal surface of the section 10 can be extended farther up from the bottom of the conical feed horn so that the narrowness of the E-plane RPE is essentially the same as that produced by the structure described in European Patent Publication No. 66455A, but at the same time reducing the gain drop relative to that of the structure described in said copending Application.
  • the lining 30 may be formed from conventional absorber materials, one example of which is AAP-ML-73 absorber made by Advanced Absorber Products Inc., 4 Poplar Street, Amesbury, Maine, U.S.A.
  • This absorber material has a flat surface, as illustrated in Fig. 4 (in contrast to the pyramidal or conical surface of the absorber used in the shield), and is about 3/8 inches (9.5 mm) thick.
  • the absorber material may be secured to the metal walls of the antenna by means of an adhesive.
  • the exemplary absorber material identified above it is preferably cut into a multiplicity of relatively small pads which can be butted against each other to form a continuous layer of absorber material over the curvilinear surface to which it is applied. This multiplicity of pads is illustrated by the grid patterns shown in Figs. 1-3.
  • the absorber material 30 is provided only on the two diametrically opposed regions of the interior walls of the conical horn 10 that affect the patterns of the antenna in the horizontal plane.
  • the only significant patterns of the antenna are those taken in the horizontal plane, which is the Y-Z plane in Fig. 3. That is, for a horizontally polarized signal, the Y-Z plane is the E-plane, and the X-Z plane is the H-plane; for a vertically polarized signal, the Y-Z plane is the H-plane, and the X-Z plane is the E-plane.
  • the portions of the conical feed horn 10 that principally affect the E-plane RPE (of a horizontally polarized signal) are the left and right hand walls of the horn through which the X-Y plane extends.
  • the absorber material 30 can be limited to diametrically opposed regions 40 of the inside surface of the feed horn. Restricting the absorber material in this manner reduces the cost of the antenna by reducing both the amount of absorber material required and the labour required to instal the absorber lining within the conical horn.
  • the absorber can be recessed (flush mounted) into the horn wall in the two regions 40 so as to maintain a single continuous conical surface on the inside of the horn 10.
  • the metal wall can form the entire conical surface, as in the structure described in the aforementioned European Patent Publication No. 66455A, and the absorber material 30 applied only to the limited regions 40 on the inner surface thereof.
  • the absorber material 30 within the conical section 10 causes the field distribution within the cone to taper off more sharply adjacent to the inside surface of the cone, due to the fact that the wall impedance of the absorber lining tends to force the perpendicular E field to zero. Furthermore, it does this while abstracting only a small fraction of the passing microwave energy propagating through the cone.
  • E8 (r, 8, 0) and E0 (r, 6, 0) be the polar and azimuthal components of electric field (with the origin at the apex of the cone, and 8 and 0 the polar and azimuthal angles, respectively) then, it can be shown that they can be mathematically expressed as:
  • An actual absorber has E differing from the no absorber case of 1.84 and the perfect absorber case of 2.39, with a hybridicity factor, Rs, neither zero (no absorber) or unity (perfect absorber). In general both will be complex with finite loss in the absorber.
  • the RPE improvements described above can be achieved over a relatively wide frequency band.
  • the improvements described above for the antenna illustrated in Figs. 1-3 can be realised over the common carrier frequency bands commonly referred to as the 4 GHz, 6 GHz and 11 GHz bands.
  • Absorber materials are generally characterised by three parameters: thickness, dielectric constant, and loss tangent.
  • the absorber used in the present invention must have a thickness and loss tangent sufficient to suppress undesirable surface (slow) waves.
  • Such surface waves can be readily generated at the transition from the metallic portion of the inside surface of the cone wall to the absober-lined portion of the cone wall, but these waves are attenuated by the absorber so that they do not interfere with the desired field pattern of the energy striking the reflector plate 11.
  • the end result is that all the improvements described above are attained without producing any undesirable distortion in the field patterns.
  • the narrowing E-plane effect can, in fact, be achieved with zero loss tangent material, but with no loss the surfaces waves are not attenuated and the operating bandwidth is reduced. Consequently, it is preferred to use an absorber material with some loss.
  • the invention has been described with particular reference to a horn-reflector antenna, it will be appreciated that the invention can also be used to advantage in a primary feed horn for a dish-type antenna. Indeed, in the latter application the substantially equal main beam widths in the E and H planes provided by the absorber lined feed horn are particularly advantageous because they provide symmetrical illumination of the parabolic dish. The consequent approximately equal second patterns with their reduced sidelobes, over a wide bandwidth, and with negligible gain loss, are also important in this primary feed horn application.

Landscapes

  • Aerials With Secondary Devices (AREA)
  • Waveguide Aerials (AREA)

Claims (3)

1. Antenne à réflecteur et cornet conique, comprenant la combinaison
d'un réflecteur paraboloïdal (11) formant une surface réfléchissante paraboloïdale pour émettre et recevoir une énergie de micro-ondes, et
d'un cornet d'alimentation conique (10) pour guider l'énergie de micro-ondes, à partir du foyer de ladite surface réfléchissante paraboloïdale, vers ledit réflecteur,
la petite extrémité du cornet (10) étant située près du point focal et de sorte que son sommet coïncide avec ce point focal du réflecteur paraboloïdal,
la partie inférieure (10a) dudit cornet (10), adjacente à la petite extrémité de celui-ci, ayant une paroi intérieure métallique lisse définissant une surface conique qui, lorsqu'elle est projetée sur le réflecteur, est interceptée par la surface réfléchissante paraboloïdale de ce dernier, et
la partie supérieure dudit cornet (10) étant revêtue d'une matière absorbante (30) sur au moins les parties de la paroi intérieure qui affectent la répartition du champ dans le plan E, de sorte que la largeur de l'enveloppe du diagramme de rayonnement dans le plan E se rapproche de la largeur dans le plan H,

caractérisée en ce que l'épaisseur de ladite matière absorbante (30) est située en dehors de la projection de ladite surface conique définie par ladite partie inférieure (10a) dudit cornet (10), et la surface apparente de ladite matière absorbante est située sensiblement sur ladite projection de surface conique.
2. Antenne à réflecteur et cornet conique, suivant la revendication 1, caractérisée en ce que la surface apparente de ladite matière absorbante (30) du côté intérieur dudit cornet d'alimentation conique (10) est sensiblement lisse.
3. Antenne à réflecteur et cornet conique suivant l'une ou l'autre des revendications précédentes, caractérisée en ce que ladite couche de matière absorbante (30) est prévue seulement sur les parois latérales opposées qui affectent l'enveloppe du diagramme de rayonnement dans le plan E d'un signal horizontalement polarisé.
EP19840306759 1983-10-17 1984-10-04 Antenne micro-ondes du type réflecteur à source cornet tapissé d'absorbant Expired EP0140598B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US54239683A 1983-10-17 1983-10-17
US542396 1983-10-17

Publications (2)

Publication Number Publication Date
EP0140598A1 EP0140598A1 (fr) 1985-05-08
EP0140598B1 true EP0140598B1 (fr) 1989-03-01

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EP19840306759 Expired EP0140598B1 (fr) 1983-10-17 1984-10-04 Antenne micro-ondes du type réflecteur à source cornet tapissé d'absorbant

Country Status (5)

Country Link
EP (1) EP0140598B1 (fr)
JP (1) JPH0626285B2 (fr)
BR (1) BR8405210A (fr)
CA (1) CA1223345A (fr)
DE (1) DE3476950D1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5317328A (en) * 1984-04-02 1994-05-31 Gabriel Electronics Incorporated Horn reflector antenna with absorber lined conical feed
GB9006752D0 (en) * 1990-03-27 1990-05-23 Ferguson Ltd Microwave antenna unit
JP3006602U (ja) * 1994-07-13 1995-01-31 ダイワ精工株式会社 魚釣用両軸受型リール

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4012738A (en) * 1961-01-31 1977-03-15 The United States Of America As Represented By The Secretary Of The Navy Combined layers in a microwave radiation absorber
US3936837A (en) * 1975-02-25 1976-02-03 The United States Of America As Represented By The Secretary Of The Navy Corrugated horn fed offset paraboloidal reflector
FR2396435A1 (fr) * 1977-06-28 1979-01-26 Thomson Csf Antenne a grand decouplage angulaire et a grande purete de polarisation
US4282530A (en) * 1979-12-26 1981-08-04 Bell Telephone Laboratories, Incorporated Cylindrical paraboloid weather cover for a horn reflector antenna with wave absorbing means
US4410892A (en) * 1981-05-26 1983-10-18 Andrew Corporation Reflector-type microwave antennas with absorber lined conical feed
US4423422A (en) * 1981-08-10 1983-12-27 Andrew Corporation Diagonal-conical horn-reflector antenna

Also Published As

Publication number Publication date
EP0140598A1 (fr) 1985-05-08
JPH0626285B2 (ja) 1994-04-06
CA1223345A (fr) 1987-06-23
BR8405210A (pt) 1985-08-27
DE3476950D1 (en) 1989-04-06
JPS60103804A (ja) 1985-06-08

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