EP0381037A1 - Système d'antenne - Google Patents

Système d'antenne Download PDF

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Publication number
EP0381037A1
EP0381037A1 EP90101435A EP90101435A EP0381037A1 EP 0381037 A1 EP0381037 A1 EP 0381037A1 EP 90101435 A EP90101435 A EP 90101435A EP 90101435 A EP90101435 A EP 90101435A EP 0381037 A1 EP0381037 A1 EP 0381037A1
Authority
EP
European Patent Office
Prior art keywords
reflector
antenna system
auxiliary
operating wavelength
auxiliary reflector
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.)
Withdrawn
Application number
EP90101435A
Other languages
German (de)
English (en)
Inventor
Gebhard Vogt
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.)
Siemens Schweiz AG
Original Assignee
Siemens Albis AG
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 Siemens Albis AG filed Critical Siemens Albis AG
Publication of EP0381037A1 publication Critical patent/EP0381037A1/fr
Withdrawn legal-status Critical Current

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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
    • H01Q19/10—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

  • the invention relates to an antenna system with a main reflector and an at least approximately hyperbolic auxiliary reflector, in the focus of which a primary radiator for the transmission and reception of electromagnetic waves with linear polarization is arranged, and in which the auxiliary reflector is designed such that it the polarization plane of the electromagnetic waves rotates by 90 °.
  • Such antennas are shown, for example, in European Patent 0 021 866 and are mostly intended for target radar systems.
  • Target tracking radar systems which are used to track one or more targets, require fast frequency hops in the entire transmission frequency bandwidth in certain tracking phases. This results in high demands on the uniformity of the radiation characteristics of the antenna system in the range of the operating frequency, which is limited in particular by diffraction effects of the incident electromagnetic waves at the auxiliary reflector.
  • the invention consists in that the auxiliary reflector consists of an at least approximately hyperbolic-shaped metallic support body, the surface of which faces the main reflector is provided with a layer of a low-loss dielectric of such thickness that it is at least approximated electrically corresponds to a quarter of the operating wavelength, and on the surface facing the main reflector, a parallel line grid of conductive wires is preferably applied at a grid spacing which corresponds electrically to about a sixth of the operating wavelength, and that the main reflector is also a line reflector, which consists of a plurality of parallel arranged conductive wires, which are attached to a dielectric absorbent support body, preferably with a grid spacing of the wires about a twelfth of the operating wavelength.
  • the sensitivity to the spillover and diffraction effect on the auxiliary reflector is largely reduced and thus the bandwidth of the radiation characteristics of the antenna system is increased.
  • the use of absorbent material for the carrier body of the main reflector has the advantage that those of the incident electromagnetic waves are absorbed, those whose polarization plane is not parallel to the conductive wires.
  • the inventive choice of the grid spacing on the main reflector largely achieves frequency independence in the reflection behavior of the electromagnetic waves for the working bandwidth, the polarization plane of which coincide with the direction of the wires.
  • the grid spacing on the auxiliary reflector is selected according to the invention so that the most exact possible phase rotation of the shafts by 90 ° can be maintained over the entire working bandwidth.
  • the diameter of the wires at the auxiliary reflector is 0.2 mm at an operating wavelength in the cm range, and the diameter of the wires at the main parabolic reflector is 0.25 mm.
  • the dielectric on the auxiliary reflector consists of polytetrafluoroethylene, the thickness of which is 3.55 mm at an operating wavelength in the cm range. This ensures rotation of the polarization plane by 90 ° of the electromagnetic waves over the entire working range.
  • the conductive wires of the main parabolic reflector and the auxiliary reflector consist of copper.
  • the copper wires can advantageously be coated with a protective layer in order to avoid chemical reactions on their surface.
  • the auxiliary reflector is carried by a conical plastic construction attached to the tapering end surface of the main parabolic reflector.
  • This conical support structure offers the advantage that the auxiliary reflector is extremely stable in position. Furthermore, this construction also offers weather protection for the antenna system.
  • the material of the plastic construction is chosen such that the incident or radiated waves are not affected.
  • the primary radiator consists of four individual radiators combined to form an overall radiator.
  • the overall radiator is rotated with respect to its horizontal axis of symmetry so that its polarization plane is rotated by 90 ° with respect to the polarization plane of the incident waves.
  • the total emitter has good cross-polarization suppression, it is insensitive to the waves diffracted at the auxiliary reflector, the polarization direction of which is rotated by 90 ° with respect to the emitted wave.
  • the antenna system shown in FIG. 1 comprises a primary radiator 1, a main reflector 3 and an auxiliary reflector 2.
  • the main reflector 3 forms a stable unit with a carrier body 6.
  • the auxiliary reflector 2 is connected to the end faces of the main reflector 3 via a conical carrier body 4, as a result of which the auxiliary reflector is fixed in its position in an extremely stable manner.
  • the primary radiator 1 is arranged such that its center of radiation coincides with the real focal point of the at least approximately hyperbolic auxiliary reflector 2.
  • the main reflector 3, which is designed as a paraboloid cut-out, is arranged such that its focal point coincides with the virtual focal point of the auxiliary reflector 2.
  • the exact shape of the reflectors and the primary radiator 1 are coordinated with one another in such a way that an at least approximately flat phase front results in the aperture plane of the main reflector 3.
  • the main reflector 3 is intended for the reflection of linearly polarized waves.
  • the auxiliary reflector 2 rotates the waves incident on it in such a way that the reflected waves are rotated by 90 ° in their polarization plane.
  • the main reflector 3 consists of a dielectrically absorbing carrier body 31, on the inside of which a line grid of conductive wires 32 is attached.
  • the direction of the line grid on the main reflector 3 is arranged such that it corresponds to the direction of the plane of polarization of the wave, which is reflected by the auxiliary reflector 2.
  • the grid spacing D of the conductive wires 32 on the main reflector 3 is preferably one twelfth of the mean operating wavelength. This advantageously results in a favorable reflection behavior of those waves whose polarization plane is parallel to the line pattern of the main reflector 3.
  • the value for the grid spacing D is advantageously 1.2 mm.
  • Optimal reflection behavior of the main reflector 3 largely independent of the wavelength selected within the working bandwidth, results from the fact that the diameter of the conductive wires 32 at the main reflector 3 is 0.25 mm. Since the carrier body 31 of the main reflector 3 consists of an absorbing dielectric, the main reflector 3 acts like a polarization filter. In this case, those waves whose polarization plane deviates from the direction of the conductive wires 32 are absorbed.
  • the auxiliary reflector 2 shown in an enlarged representation in FIG. 3 consists of a carrier body 21 which has an approximate hyperbolic surface. This surface is coated with a low-loss dielectric 22, the electrical thickness of which preferably corresponds to approximately a quarter of the mean operating wavelength.
  • This dielectric 22 preferably consists of polytetrafluoroethylene, which is known under the trade names "Teflon" from Dupont.
  • a line grid of conductive, parallel-guided wires 23 is applied to the dielectric 22 and is arranged in such a grid spacing d of adjacent wires 23 that this is approximately electrical corresponds to a sixth of the operating wavelength. For an operating wavelength in the cm range, this distance d is preferably 2.55 mm.
  • the choice of the preferred grid spacing d of the conductive wires 23 prevents the virtual reflection plane from penetrating into the dielectric 22, thereby avoiding a deterioration in the efficiency of the antenna system.
  • Teflon is used as the dielectric 22
  • the thickness of the dielectric layer for an operating wavelength in the cm range advantageously results in a value of 3.55 mm.
  • the direction of the line grid 23 is rotated by 45 ° with respect to the direction of the polarization plane of the primary radiator 1. Due to the advantageous design of the auxiliary reflector 2, a constant rotation of the polarization plane by 90 ° of the electromagnetic waves is largely achieved over the entire transmission bandwidth.
  • the carrier body 21 is preferably made of an aluminum alloy.
  • the carrier body 31 of the main reflector 3 is also of lightweight construction, i. H. that the absorbent dielectric 31 consists of a honeycomb structure.
  • the tapered end faces of the main reflector 3 are connected to the carrier body 21 of the auxiliary reflector 2 via a conical plastic construction 4.
  • This plastic construction consists of a material that enables unimpeded penetration of the electromagnetic waves.
  • the primary radiator 1 As shown in FIG. 4, consists of four individual radiators A, B, C, D combined to form an overall radiator.
  • the primary radiator 1 is then in its axis of symmetry 5 by 90 ° with respect to the plane of polarization falling shaft rotated.
  • the primary radiator 1 is insensitive to the radiation incident through diffraction and spill-over effects on the auxiliary reflector 2. In this way, the frequency dependence of the radiation diagrams is reduced to a minimum value.

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  • Aerials With Secondary Devices (AREA)
EP90101435A 1989-01-31 1990-01-25 Système d'antenne Withdrawn EP0381037A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH315/89 1989-01-31
CH31589 1989-01-31

Publications (1)

Publication Number Publication Date
EP0381037A1 true EP0381037A1 (fr) 1990-08-08

Family

ID=4184207

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90101435A Withdrawn EP0381037A1 (fr) 1989-01-31 1990-01-25 Système d'antenne

Country Status (1)

Country Link
EP (1) EP0381037A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161879A (en) * 1961-01-05 1964-12-15 Peter W Hannan Twistreflector
US3235870A (en) * 1961-03-09 1966-02-15 Hazeltine Research Inc Double-reflector antenna with polarization-changing subreflector
CH634691A5 (en) * 1978-11-20 1983-02-15 Contraves Ag Radar reflector
EP0088681A1 (fr) * 1982-03-02 1983-09-14 Thomson-Csf Antenne à double réflecteur à transformateur de polarisation incorporé
EP0101533A1 (fr) * 1982-08-19 1984-02-29 Siemens-Albis Aktiengesellschaft Antenne radar

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161879A (en) * 1961-01-05 1964-12-15 Peter W Hannan Twistreflector
US3235870A (en) * 1961-03-09 1966-02-15 Hazeltine Research Inc Double-reflector antenna with polarization-changing subreflector
CH634691A5 (en) * 1978-11-20 1983-02-15 Contraves Ag Radar reflector
EP0088681A1 (fr) * 1982-03-02 1983-09-14 Thomson-Csf Antenne à double réflecteur à transformateur de polarisation incorporé
EP0101533A1 (fr) * 1982-08-19 1984-02-29 Siemens-Albis Aktiengesellschaft Antenne radar

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