US3810187A - Capped antenna of the offset cassegrainian type - Google Patents

Capped antenna of the offset cassegrainian type Download PDF

Info

Publication number
US3810187A
US3810187A US00352332A US35233273A US3810187A US 3810187 A US3810187 A US 3810187A US 00352332 A US00352332 A US 00352332A US 35233273 A US35233273 A US 35233273A US 3810187 A US3810187 A US 3810187A
Authority
US
United States
Prior art keywords
antenna
reflector
cap
auxiliary reflector
screen
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
US00352332A
Other languages
English (en)
Inventor
N Hai
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.)
Thales SA
Original Assignee
Thomson CSF SA
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 Thomson CSF SA filed Critical Thomson CSF SA
Application granted granted Critical
Publication of US3810187A publication Critical patent/US3810187A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H01Q19/026—Means for reducing undesirable effects for reducing the primary feed spill-over
    • 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 to a very wide-band high-efficiency microwave antenna of the offset Cassegrainian type.
  • the purpose of the present invention is an offset Cassegrainian antenna in whichthe conventional position of the elements is so modified and the fixing system so arranged, that the screen, in addition to its double radio-electrical function (absorption of the diffracted waves and reflection of the external parasitic waves) affords a climatic protection, this without mechanical drawbacks.
  • the use of a radome surrounding the antenna and the resulting loss of energy may thus be avoided.
  • an offset Cassegrainian antenna comprising a chassis, a primary source having an aperture, an auxiliary reflector, a main reflector, a screen lined with a microwave absorber, and means respectively securing said primary source, said auxiliary reflector, said main reflector and said screen to said chassis; said aperture of said source and said auxiliary reflector being located above said main reflector; said screen having the form of a cap covering said auxiliary reflector and said primary source; and said means securing said screen to said chassis being independent from said means securing said auxiliary reflector to said chassis.
  • FIG. 1 is a schematic view of an antenna in accordance with the invention
  • FIG. 2 is a section through one of the elements of FIG. 1;
  • FIG. 3 is a more detailed view of a part of the antenna of FIG. I.
  • FIG. 1 illustrates a primary source, 1, of the horn type with a reflector.
  • An auxiliary reflector 2 and a main reflector 3, complete the radiating part of this offset Cassegrainian antenna.
  • the primary source 1 and the main reflector 3 are attached to a tubular chassis 4 by means of nut-bolt devices not shown.
  • the elements of the chassis 4 are welded together. They comprise three supports, a front one, 40, and two, 41 (only one of which can been seen), at the rear, these three supports being located at the apices of an isosceles triangle, the sides of which are formed by three horizontal tubes such as tube 45.
  • Two transverse tubes 42 (only one of which can be seen) leaning backward, have their first ends fixed to the support 40, while two other transverse tubes 43 (only one of which can be seen) leaning forward. have their first ends respectively secured to the two supports 41.
  • the two transverse tubes 42 have their second ends respectively fixed to the tubes 43, thus forming a V. Together with the two tubes 42, two small tubes 44 respectively secured to the two tubes 43, are used for supporting the main reflector 3.
  • a tubular frame 5 has a rear end secured to the tubes 43, and a front end supporting the auxiliary reflector 2.
  • the antenna is fitted with an element 6 which will be referred to as a cap.
  • This cap is attached to the tubular chassis 4.
  • the auxiliary reflector 2 and the aperture of the primary source 1, which faces the auxiliary reflector, are hidden by this cap which also covers the tubular frame 5; these hidden parts of the antenna have been illustrated in broken lines in FIG. 1.
  • the cap 6 is not directly fixed either to the primary source 1, or to the auxiliary reflector 2, or to the tubular frame 5, and can therefore shift under the effect of the wind without involving in its motion the tubular frame and the auxiliary reflector.
  • the cap has a curved surface, having two symmetry planes. Its section in the longitudinal symmetry plane has approximately the form of a half-ellipse subtended by its major axis, as shown in FIG. 1, and its section in the transverse symmetry plane approximately that of a semi-circle, as shown in FIG. 2 which is a section view of the cap through this latter plane, marked X-X in FIG. 1.
  • a microwave absorber 8 made up of graphite-filled urethane foam, the outer side of this absorber being formed by juxtaposed small cones;
  • a stratified polyester layer 10, used as a support for the metal layer, 9.
  • This fixing system is shown in FIG. 3. It comprises four curved tubular elements 11, 12, 13 and 14 the greatest part of which is located inside the wall of the cap, beneath the absorber layer. Those four elements are joined together, at one end, at the front part 15 of the cap, the other ends of the elements 11 and 12, which follow the edge of the cap, being respectively fixed to the two tubes 43 of the chassis 4.
  • the elements 13 and 14 form two arcs respectively located on either side of the longitudinal symmetry plane of the cap, and their second ends are also secured to the tubes 43.
  • the function of the cap is at the same time radioelectrical, mechanical and climatic. From the radioelectrical point of view, the cap, on the one hand, clue to its metal layer, forms a screen as concerns external parasitic radiations, and on the other hand, due to the absorber layer, intercepts virtually the whole of the energy radiated by the primary source 1 and not captured by the auxiliary reflector 2, and part of the energy diffracted by the edges of the primary source 1, by the edges of the auxiliary reflector 2 and by the tubular frame 5. The energy thus intercepted is either absorbed directly by the absorber 8, FIG. 2, or absorbed after reflection by the copper weave 9, FIG.
  • the cap makes it possible to reduce to 0.2 dB the undulation in the gain-frequency curve of the antenna, whereas it was around 1 dB in the operating frequency band of 3.8 to 7.l Gc/s in the antenna taken by example; it likewise makes it possible to reduce by dB the level of the radiated diffuse lobes, thus increasing the number of antennas of the described kind which it is possible to install at a junction of main telephone routes and, correspondingly, to increase the number of directions in which transmission can be made.
  • the mechanical function of the cap stems from the fact that due to its position, it protects against the effects of wind part of the primary source, the tubular assembly and the reflector; thus, the stresses produced by windloads on the auxiliary reflector being very much reduced, the diameters of the tubes used in the tubular assembly can be reduced correspondingly, bringing about a reduction in the parasitic diffraction effects for which these tubes are responsible.
  • the cap protects the auxiliary reflector against direct rain and snow, thus improving the reliability of operation of the antenna.
  • Antennas such as that just described, are intended more especially for radio links, but may also be used in the space and radar fields.
  • the invention is not limited to the embodiment described and it is possible, bu suitable arrangements, to continue the cap so that it covers that part of the main reflector 3 shown in FIG. 1, which is opposite the auxiliary reflector 2.
  • An offset Cassegrainian antenna comprising a chassis, a primary source having an aperture, an auxiliary reflector, a main reflector, a screen lined with a microwave absorber, and means respectively securing said primary source, said auxiliary reflector, said main reflector and said screen to said chassis; said aperture of said source and said auxiliary reflector being located above said main reflector; said screen having the form of a cap covering said auxiliary reflector and said primary source; and said means securing said screen to said chassis being independent from said means securing said auxiliary reflector to said chassis.

Landscapes

  • Aerials With Secondary Devices (AREA)
  • Details Of Aerials (AREA)
US00352332A 1972-04-21 1973-04-18 Capped antenna of the offset cassegrainian type Expired - Lifetime US3810187A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7214251A FR2180585B1 (is) 1972-04-21 1972-04-21

Publications (1)

Publication Number Publication Date
US3810187A true US3810187A (en) 1974-05-07

Family

ID=9097330

Family Applications (1)

Application Number Title Priority Date Filing Date
US00352332A Expired - Lifetime US3810187A (en) 1972-04-21 1973-04-18 Capped antenna of the offset cassegrainian type

Country Status (7)

Country Link
US (1) US3810187A (is)
JP (1) JPS5320342B2 (is)
CA (1) CA962342A (is)
DE (1) DE2319731C3 (is)
FR (1) FR2180585B1 (is)
GB (1) GB1359266A (is)
IT (1) IT980311B (is)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4126864A (en) * 1978-01-23 1978-11-21 Hopkins B Ice shield for micro-wave antenna
US4866457A (en) * 1988-11-08 1989-09-12 The United States Of America As Represented By The Secretary Of Commerce Covered inverted offset cassegrainian system
EP1635187A2 (en) * 2002-08-22 2006-03-15 Hitachi, Ltd. Millimeter wave radar with side-lobe absorbing radome
WO2019195700A1 (en) * 2018-04-05 2019-10-10 L3 Essco Incorporated A metal space frame radome

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2527545C3 (de) * 1975-06-20 1981-04-16 Naamloze Vennootschap Philips' Gloeilampenfabrieken, Eindhoven Im Spritzgußverfahren hergestellte Hornantenne
DE2749443C3 (de) * 1977-11-04 1980-06-04 Siemens Ag, 1000 Berlin Und 8000 Muenchen Mikrowellen-Breitbandrichtfunkantenne in Muschelbauweise
US4626863A (en) * 1983-09-12 1986-12-02 Andrew Corporation Low side lobe Gregorian antenna
EP0216768A1 (en) * 1984-05-31 1987-04-08 H.R. Smith (Technical Developments) Limited Anechoid chambers
GB8510724D0 (en) * 1985-04-26 1985-06-05 British Telecomm Controlled attenuation of microwave signals
DE3915280C2 (de) * 1989-05-10 1993-11-04 Berthold Lab Prof R Vorrichtung zur mikrowellen-transmissions- oder absorptionsmessung
GB9006752D0 (en) * 1990-03-27 1990-05-23 Ferguson Ltd Microwave antenna unit
DE19953271A1 (de) * 1999-11-06 2001-05-10 Airsys Navigation Systems Gmbh Sendeantenne

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1128952A (fr) * 1955-03-17 1957-01-14 Materiel Telephonique Antenne pour ondes ultra-courtes
US3733609A (en) * 1971-07-02 1973-05-15 Radiation Inc Shrouded offset parabolic reflector antenna

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1128952A (fr) * 1955-03-17 1957-01-14 Materiel Telephonique Antenne pour ondes ultra-courtes
US3733609A (en) * 1971-07-02 1973-05-15 Radiation Inc Shrouded offset parabolic reflector antenna

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4126864A (en) * 1978-01-23 1978-11-21 Hopkins B Ice shield for micro-wave antenna
US4866457A (en) * 1988-11-08 1989-09-12 The United States Of America As Represented By The Secretary Of Commerce Covered inverted offset cassegrainian system
EP1635187A2 (en) * 2002-08-22 2006-03-15 Hitachi, Ltd. Millimeter wave radar with side-lobe absorbing radome
EP1635187A3 (en) * 2002-08-22 2006-05-31 Hitachi, Ltd. Millimeter wave radar with side-lobe absorbing radome
WO2019195700A1 (en) * 2018-04-05 2019-10-10 L3 Essco Incorporated A metal space frame radome

Also Published As

Publication number Publication date
FR2180585B1 (is) 1974-12-20
JPS5320342B2 (is) 1978-06-26
DE2319731C3 (de) 1981-01-08
CA962342A (en) 1975-02-04
GB1359266A (en) 1974-07-10
FR2180585A1 (is) 1973-11-30
DE2319731B2 (de) 1980-04-24
JPS4922061A (is) 1974-02-27
IT980311B (it) 1974-09-30
DE2319731A1 (de) 1973-10-25

Similar Documents

Publication Publication Date Title
US3810187A (en) Capped antenna of the offset cassegrainian type
US5959590A (en) Low sidelobe reflector antenna system employing a corrugated subreflector
US6236375B1 (en) Compact offset gregorian antenna system for providing adjacent, high gain, antenna beams
US4282530A (en) Cylindrical paraboloid weather cover for a horn reflector antenna with wave absorbing means
US3936837A (en) Corrugated horn fed offset paraboloidal reflector
GB2166001A (en) Dual gridded reflector structure
US3733609A (en) Shrouded offset parabolic reflector antenna
US3178713A (en) Parabolic antenna formed of curved spaced rods
US4423422A (en) Diagonal-conical horn-reflector antenna
US3696436A (en) Cassegrain antenna with absorber to reduce back radiation
US5977926A (en) Multi-focus reflector antenna
US3706999A (en) Cassegraninian antenna having limited spillover energy
KR101877228B1 (ko) 복합재 결합 안테나
CN110739547A (zh) 一种卡塞格伦天线
US3122745A (en) Reflection antenna employing multiple director elements and multiple reflection of energy to effect increased gain
GB2120858A (en) Radome-covered reflector antennas
JP2626547B2 (ja) 反射波防止型パラボラ空中線
US6621461B1 (en) Gridded reflector antenna
JP3763428B2 (ja) 複反射鏡アンテナ装置
US4152706A (en) Log periodic zig zag monopole antenna
JPS62173804A (ja) 受信用アンテナ
JPS6128403Y2 (is)
JP3060947B2 (ja) コリニアアレイアンテナ
JPS6232712A (ja) パラボラアンテナ装置
JPS60157303A (ja) 複反射鏡アンテナ