EP4270642A1 - Verbesserte hornantenne - Google Patents

Verbesserte hornantenne Download PDF

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Publication number
EP4270642A1
EP4270642A1 EP23170140.0A EP23170140A EP4270642A1 EP 4270642 A1 EP4270642 A1 EP 4270642A1 EP 23170140 A EP23170140 A EP 23170140A EP 4270642 A1 EP4270642 A1 EP 4270642A1
Authority
EP
European Patent Office
Prior art keywords
horn
resistive film
horn antenna
ground plane
radome
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.)
Pending
Application number
EP23170140.0A
Other languages
English (en)
French (fr)
Inventor
Stéphane Mallegol
Yoann HENAFF
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
Thales 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 Thales SA filed Critical Thales SA
Publication of EP4270642A1 publication Critical patent/EP4270642A1/de
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/02—Waveguide horns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/48—Earthing means; Earth screens; Counterpoises
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • 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
    • 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

Definitions

  • the invention relates to that of wide frequency band horn antennas.
  • the dimensions of the horn are reduced, making such a solution compatible with integration constraints on supporting structures.
  • a horn antenna can thus be used alone as a high gain antenna or as an elementary antenna of a high gain array antenna with a directional beam for transmission or reception systems.
  • a horn antenna can also be used as an elementary antenna of a planar array antenna for an application in amplitude direction finding.
  • a horn antenna can finally be used as an elementary antenna of a multi-plane array antenna for an application in phase direction finding/interferometry.
  • a horn antenna comprises a waveguide whose flared end, constituting the horn of the antenna, crosses a ground plane so as to emerge above the latter in order to emit and/or receive main radiation A in the upper half-space above the ground plane.
  • creeping waves B are generated at the upper face of the ground plane and propagate radially away from the horn to the surface of the ground plane.
  • These creeping waves can be amplified C by physical and/or electromagnetic discontinuities, particularly at the edge of the ground plane.
  • the creeping waves can then combine with the main radiation A with the consequence of an alteration of the radiation pattern of the horn antenna evolved in the far field.
  • the radiation pattern shows pronounced oscillations of its main lobe (as shown on the CE1 and CH1 curves of the graphs of the figure 5 ). This is a serious alteration of the radiation pattern, which can lead to detection errors. It should be noted that the deterioration of the radiation pattern is all the more pronounced as the working frequency is high.
  • the creeping waves are also amplified by the presence of a radome, the presence of which is necessary to cover the horn of the antenna and avoid attacks from the external environment. More precisely, depending on its thickness and the real part of the relative permittivity of the material which composes it, the radome accentuates the creeping waves. It can also modify the period of these waves, for a given frequency and/or a given angular domain.
  • Another solution consists of making corrugations on the upper face of the ground plane in order to trap the creeping waves.
  • corrugations have a depth of ⁇ /4 and a step between two successive corrugations less than or equal to ⁇ /2 ( ⁇ being the wavelength associated with the central frequency of the working frequency range of the horn antenna considered ). These corrugations behave like resonators capable of absorbing surface waves.
  • this solution has the advantage of allowing effective trapping of creeping waves at the central frequency, it has numerous disadvantages: the working frequency range is reduced, since the absorption effect is optimized for the central frequency and that the effectiveness of these resonators is reduced as soon as we deviate too much from this central frequency (relative bandwidth between 15% and 20%); strong production constraints, since the thickness of the ground plane must be greater than the depth of the corrugations, the number of corrugations must be sufficient to effectively absorb surface waves, the machining precision of the corrugations must be high to avoid affecting the response of the antenna at high working frequencies, as the thinning of the ground plane raises mechanical resistance problems.
  • FSS surface is a layer made by arranging metallic elements in a periodic pattern.
  • the radome is made of a dielectric material. It has on a lower face (facing towards the horn and the ground plane) a first FSS surface and a second FSS surface on its upper face.
  • this solution has the following disadvantages: a loss of radiation efficiency, since the FSS surfaces to the right of the horn antenna absorb part of the radiated energy; a limited bandwidth, since the metallic elements constituting the FSS surfaces are dimensioned to be effective at the central frequency and the resonant effect on which the operation of an FSS surface is based decreases sharply when we deviate from the central frequency (relative bandwidth around 10%); a complexity of producing such a radome; the need to protect this composite radome by an additional radome covering the second FSS surface exposed to attacks; the need for a minimum distance between the radome and the mouth of the horn for the FSS surfaces to be effective, which increases the thickness of the horn antenna produced.
  • a HIS surface is composed of metallic elements arranged periodically and connected to the ground plane by a metallized via.
  • the present invention therefore aims to propose a solution to all or part of these problems.
  • the invention relates to a horn antenna comprising: a ground plane, delimiting an upper half-space; a horn, constituting one end of a waveguide, the horn crossing the ground plane so that a mouth of the horn is arranged at a predefined height above the ground plane in the upper half-space, characterized in that the horn antenna comprises at least one resistive film arranged around the horn, parallel to an upper face of the ground plane, the film resistive having an electrical resistance making it possible to limit creeping waves.
  • the horn antenna 11 comprises, along a Z axis, called vertical, a ground plane 12 and a horn 13.
  • the ground plane 12 has for example a rectangular parallelepiped exterior shape, with a square base and reduced thickness e.
  • the ground plane is cylindrical in shape.
  • This recess includes a central recess 21 of cylindrical shape, of radius R0 and depth p.
  • This recess has a bottom 22 and a peripheral edge 23.
  • the bottom 22 is the upper face of the ground plane where the creeping waves develop.
  • the ground plane 12 is provided with a central opening 24 through which the horn 13 passes.
  • the horn 13 has for example a constant cross section (that is to say along a plane orthogonal to the Z axis), for example of rectangular shape.
  • the horn section may have other shapes, for example being flared and/or circular.
  • the horn 13 is arranged so that its mouth 31 is placed above the bottom 22 of the recess 21 of the ground plane 12, at a height h above the latter.
  • the horn antenna 11 comprises a radome 14 which closes the recess 21 of the ground plane 12 and covers the mouth 31 of the horn 13.
  • the radome 14 essentially has the shape of a disk of radius R1, less than R0.
  • the horn antenna 11 integrates at least one resistive film 15.
  • the resistive film is arranged in a transverse plane. It is written in a disk of radius R1.
  • the resistive film 15 is thin. It has a thickness k, typically between 10 ⁇ m and 20 ⁇ m. Such a thickness allows integration without increasing the total thickness e of the horn antenna 11.
  • the resistive film 15 has a central opening 54, the cross section of which preferably corresponds to that of the horn 13, so that the resistive film 15 is positioned as close as possible to the horn (along a transverse plane), to maximize its effectiveness with respect to a reduction in creeping waves.
  • the horn antenna 11 advantageously comprises a support layer 16 capable of supporting resistive film 15.
  • layer 16 is arranged in a transverse plane. It is written in a disk of radius R1.
  • the layer 16 has a thickness enabling the resistive film 15 to be positioned slightly back from the mouth 31 of the horn 13 in the vertical direction. It also makes it possible to fill the recess 21 of the ground plane 12.
  • the material of layer 16 is preferably a dielectric or (magneto)dielectric material. It has a low dielectric constant, typically less than or equal to 2. It is a low-loss material. The choice of such a material contributes to the attenuation of creeping waves, in particular by not accentuating the propagation of creeping waves at the level of the underside of the radome.
  • the resistive film 15 is glued to the layer 16.
  • the glue film is referenced by the number 17 on the Figure 3 . It preferably has a thickness of between 50 ⁇ m and 250 ⁇ m. The glue film is actually thicker than the resistive film. She was not represented on the figure 2 .
  • the radome 14 and the assembly consisting of the resistive film 15 and the layer 16 are held in position on the ground plane 12 by a series of screws, one of which, is represented on the Figure 3 and bears the reference 18. Possibly tapped holes are provided in the components of the corner antenna 11 to receive these screws.
  • the radome, the central recess, the resistive film, and the support layer could have the shape of a rectangular parallelepiped.
  • the resistive film can for example be worn directly on the upper face of the ground plane 12.
  • the film is glued to this upper face.
  • the resistive film can for example be worn directly on the lower face 41 of the radome 14.
  • the film is glued to this lower face.
  • resistive films can for example be provided, arranged vertically one above the other. Two successive resistive films are advantageously separated by an intermediate layer similar to the support layer 16, but whose thickness is reduced so that the laminate thus produced does not negatively impact the total thickness of the horn antenna.
  • a layer such as the support layer 16 can be produced by the superposition of several elementary layers.
  • the horn antenna may possibly be non-planar.
  • the or each resistive film (and where appropriate each support layer) are shaped to follow the curvature of the ground plane.
  • the resistive film 115 is full. It forms a continuous circular surface of radius R1 with a central opening 154 adapted to the external contour of the horn.
  • a resistive film is made of a single material having a single resistive value, for example between 100 and 10,000 ⁇ /sq.
  • the resistive film can have other configurations.
  • the resistive film 215 results from the combination of two materials having different resistive values.
  • the first material forms a disc 221 with a central opening 254 and several concentric annular grooves, 222 and 223.
  • the second material fills said grooves.
  • annular grooves polygonal grooves can be provided.
  • the resistive film 315 is made up of the association of several concentric rings, 321 to 329, the external radius of one ring corresponding to the internal radius of the following ring and the material of each ring being chosen to create a radial resistive gradient with a minimum resistive value in the center, and a maximum resistive value at the periphery.
  • this makes it possible to guarantee optimal attenuation of creeping waves near the edge of the structure and, thus, limit the associated edge effects.
  • the resistive film 415 does not form a continuous surface, but a partial surface.
  • the resistive film does not completely cover the transverse plane around the mouth of the horn.
  • the resistive film 415 is for example composed of several full angular sectors, in this case two full angular sectors 431 and 432 along the plane E.
  • the two full angular sectors are therefore not contiguous.
  • the flare of the angular sectors can be adjusted to adjust the properties of the horn antenna. More precisely, such a configuration has the advantage of not degrading the radiation efficiency of the horn antenna (at the radiating mouth) while guaranteeing efficiency in trapping creeping waves over a wide frequency band. The effect of the latter on the undulations of the E-plane radiation diagram is then minimized.
  • the resistive film 515 does not form a continuous surface, but a partial surface.
  • the resistive film does not completely cover the transverse plane around the mouth of the horn.
  • the resistive film 515 is for example composed of several perforated angular sectors, in this case two perforated angular sectors 531 and 532 along the plane E and two perforated angular sectors 533 and 534 along the plane H, the perforated angular sectors being non-contiguous .
  • An openwork angular sector is for example made up of one or more arc(s) of concentric ring(s). The flare of the angular sectors can be adjusted to adjust the properties of the horn antenna, but also the geometry of the ring arcs (spacing, thickness, material used, etc.)
  • the resistive film 615 results from the combination of variants (d) and (e) with two solid angular sectors 631 and 632 along the plane E and two openwork angular sectors 633 and 634 along the the H plane.
  • the addition of resistive ring arcs making the junction between the continuous angular sectors makes it possible to accentuate the trapping of creeping waves and the reduction of the edge effects of the structure, in particular following the plane H.
  • the width of the resistive addition is preferably chosen to be less than or equal to ⁇ /4 (with ⁇ the wavelength chosen, usually, at the central operating frequency.
  • This sixth variant is preferable because it presents the advantages of the fifth variant (e) while retaining the interests of the full solution in plan E (fourth variant (d)). It is this variant which was chosen for the embodiment of the figures 1 And 2 .
  • resistive films can be optimized by electromagnetic simulation.
  • a resistive film can advantageously be produced by using a conventional screen printing process. Alternatively, it can be produced by an equivalent process: aerosol printing, 3D printing, etc.
  • the resistive film is for example made with a carbon-enriched polymer ink, a material suitable for screen printing.
  • the resistive film is a carbon-enriched thermoplastic, for example an ESD thermoplastic (for “ElectroStatic Discharge” in English), a material suitable for production by 3D printing.

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  • Waveguide Aerials (AREA)
EP23170140.0A 2022-04-27 2023-04-26 Verbesserte hornantenne Pending EP4270642A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR2203946A FR3135170A1 (fr) 2022-04-27 2022-04-27 Antenne cornet améliorée

Publications (1)

Publication Number Publication Date
EP4270642A1 true EP4270642A1 (de) 2023-11-01

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP23170140.0A Pending EP4270642A1 (de) 2022-04-27 2023-04-26 Verbesserte hornantenne

Country Status (4)

Country Link
US (1) US20230352844A1 (de)
EP (1) EP4270642A1 (de)
FR (1) FR3135170A1 (de)
IL (1) IL302270A (de)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102810743A (zh) * 2011-06-29 2012-12-05 深圳光启高等理工研究院 一种衰减天线表面爬行波的装置
US20170273562A1 (en) * 2010-11-03 2017-09-28 Sensible Medical Innovations Ltd. Electromagnetic probes, and methods for using such electromagnetic probes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170273562A1 (en) * 2010-11-03 2017-09-28 Sensible Medical Innovations Ltd. Electromagnetic probes, and methods for using such electromagnetic probes
CN102810743A (zh) * 2011-06-29 2012-12-05 深圳光启高等理工研究院 一种衰减天线表面爬行波的装置

Also Published As

Publication number Publication date
IL302270A (en) 2023-11-01
US20230352844A1 (en) 2023-11-02
FR3135170A1 (fr) 2023-11-03

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