EP0527714B1 - Cavity Antenna - Google Patents

Cavity Antenna Download PDF

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Publication number
EP0527714B1
EP0527714B1 EP92850148A EP92850148A EP0527714B1 EP 0527714 B1 EP0527714 B1 EP 0527714B1 EP 92850148 A EP92850148 A EP 92850148A EP 92850148 A EP92850148 A EP 92850148A EP 0527714 B1 EP0527714 B1 EP 0527714B1
Authority
EP
European Patent Office
Prior art keywords
cavity
antenna
dielectric
layers
hollow spaces
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
EP92850148A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0527714A1 (en
Inventor
Lars Wiklund
Erland Cassel
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.)
CelsiusTech Electronics AB
Original Assignee
CelsiusTech Electronics AB
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 CelsiusTech Electronics AB filed Critical CelsiusTech Electronics AB
Publication of EP0527714A1 publication Critical patent/EP0527714A1/en
Application granted granted Critical
Publication of EP0527714B1 publication Critical patent/EP0527714B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01Q13/10—Resonant slot antennas
    • H01Q13/18—Resonant slot antennas the slot being backed by, or formed in boundary wall of, a resonant cavity ; Open cavity antennas
    • 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
    • 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
    • H01Q19/06—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 refracting or diffracting devices, e.g. lens
    • H01Q19/09—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 refracting or diffracting devices, e.g. lens wherein the primary active element is coated with or embedded in a dielectric or magnetic material

Definitions

  • the present invention relates to an antenna for transmitting and/or receiving electromagnetic radiation comprising a cavity, an aperture arranged in front of the cavity, a feed element arranged in the cavity and a dielectric arranged in connection with the cavity.
  • Cavity antennas with a dielectric according to the above paragraph are well known to the expert in the antenna field.
  • the measurement results shown certainly apply to an airfilled cavity but it is apparent from the article that many cavity antennas have a dielectric filling.
  • the cavity antennas have a directional effect and are suitable for use as communication antennas within, for example, the UHF band.
  • the known cavity antennas have a number of characteristics in common which are unwanted, at least with certain applications.
  • the antenna has a relatively large radar target cross-section.
  • the large radar target cross-section is primarily caused by the corner reflectors inside the cavity.
  • the equipment has the smallest possible radar target cross-section.
  • Stealth technology is becoming more and more important in the construction of military equipment.
  • the antenna cavity is bulky and, in consequence, heavy.
  • the aim of the present invention is achieved by an antenna which is characterised by the fact that the dielectric is provided with hollow spaces and that these hollow spaces contain electrically conducting shells.
  • the radar target cross-section of the antenna is significantly reduced to a level comparable to the level of a plane plate.
  • the dielectric provided with holes forms a frequency-selective volume with low-pass characteristics.
  • the radar target cross-section produced by the corner reflectors within the cavity has been reduced to an acceptable level.
  • the dielectric provided with holes, with an electrically conducting shells and also called artificial dielectric hereinafter exhibits a change both of the dielectric constant and the permeability constant. This entails that also the index of refraction is changed, or, more accurately, increases.
  • the artificial dielectric also exhibits changed transmission and reflection characteristics. Low frequencies are transmitted and high frequencies are reflected.
  • the artificial dielectric can assume different frequency characteristics. For example, the artificial dielectric can be made to be mainly reflecting over a very large frequency range.
  • the dielectric used entails that its size and the size of the antenna cavity can be reduced without reducing the antenna frequency bandwidth. This thus results in a more compact antenna with unchanged performance.
  • the more compact format also makes possible a significant reduction in the weight of the antenna.
  • a further weight reduction is produced by the dielectric according to the invention which, through its hole structure, has a lower weight per volume unit than the dielectric used earlier.
  • the hole spaces in the dielectric are advantageously periodically arranged in a threedimensional matrix, which results in a dielectric with adequate low-pass characteristics.
  • the dielectric is divided up into a number of layers, each layer consisting of two part-layers with indentations arranged opposite one another in opposite surfaces of the part layers for forming hollow spaces.
  • a dividing of the dielectric into layers and part layers according to this embodiment provides the antenna with great flexibility and makes the installation of the electrically conducting shells relatively uncomplicated.
  • the shells are installed in the indentations of one part layer. After that the other cooperating part layer is installed.
  • Each pair of part layers will contain a plane with conducting shells.
  • the number of pairs of part layers comprised in the dielectric determines and corresponds to the number of planes with conducting shells.
  • the antenna 1 shown in Figure 1 and 2 comprises a cavity 2 mounted in a frame 3 in its open end.
  • the aperture 4 of the antenna is defined by the open end of the cavity and is rectangular in the embodiment shown.
  • a feed element 5 is arranged in the inside of the cavity 2 in its front part and has the shape of a T-shaped bar.
  • a feed cable 6 connects the feed element 5 and the cavity 2 to external units and is preferably constituted by a coaxial cable.
  • the major part of the cavity 2 is filled with a dielectric 7.
  • the dielectric 7 is divided into four layers 8, 9, 10, 11.
  • the number of layers can vary from only one to significantly more than the four layers shown, depending on what is suitable for the actual antenna. The choice is determined by the size of the cavity 2 and the requirements for the characteristics of the dielectric 7.
  • Figure 4 shows layer 11 in a perspective view.
  • Each layer 8, 9, 10, 11 is in turn divided into part layers, part layers 11a, 11b being shown for layer 11 in Figure 2 and 4.
  • the part layers 11a, 11b have a plane surface 12a and 12b, respectively.
  • symmetrically arranged indentations 13a and 13b with an essentially hemispherical shape are located.
  • a layer 11 with essentially spherical hollow spaces 14 is formed.
  • one part layer 11a is provided with electrically conducting spherical shells 15 in the hemispherical indentations 13a.
  • the shells 15 fill out the hollow spaces 14.
  • the shells are made of metallic or metallized shells and can be made, for example, of silver-coated celluloid balls.
  • the layers which enclose the electrically conducting shells are suitably made of material with low electromagnetic transmission losses for frequencies up to about 10 GHz and, for example, a material sold under the trademark Roasell, can be used.
  • the unwanted radiation is reduced which is otherwise reflected by the cavity in the direction of the incident radiation and is mainly caused by the corner reflectors in the interior of the cavity.
  • the artificial dielectric is placed in front of the cavity bottom.
  • the incident radiation is then reflected against the dielectric instead, since this is constructed for reflecting the frequencies or frequency ranges for which it is desired to reduce the radiation reflected by the cavity. If the normal to a three-dimensional matrix formed by the shells in the dielectric is not directed towards the incident radiation, the reflected radiation will be strongly reduced in the direction of incidence.
  • the known antenna contains a homogeneous dielectric without division into layers and inhomogeneity-creating hollow spaces filled with electrically conducting shells.
  • the cavity 2 has a significantly greater depth than the antenna according to the invention shown in the same section in Figure 2.
  • an artificial dielectric according to the invention By introducing an artificial dielectric according to the invention with hollow spaces, in which electrically conducting shells are placed, a number of positive effects are created.
  • the size of the cavity antenna can be reduced whilst retaining the frequency bandwidth, mainly due to the effect that the depth of the cavity can be reduced.
  • the antenna can be made lighter due to its reduced size and due to the fact that the artificial dielectric has a lower weight than the homogeneous dielectric previously used.
  • the artificial dielectric also reduces the monostatic radar target cross-section of the antenna.
  • the antenna aperture can be covered with a plane frequency-selective structure constructed of one or several parallel layers provided with metallic periodic patterns.
  • a plane layer 16 covering the aperture 4 of the cavity antenna in Figure 2.
  • the radome 16 is ideally transparent to the operating frequency band of the antenna and reflecting for all other frequencies.
  • the radar target cross-section of the antenna has changed appearance from being considered as a four corner reflector to being considered as a plane plate.

Landscapes

  • Aerials With Secondary Devices (AREA)
  • Waveguide Aerials (AREA)
  • Details Of Aerials (AREA)
EP92850148A 1991-08-12 1992-06-17 Cavity Antenna Expired - Lifetime EP0527714B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9102349 1991-08-12
SE9102349A SE468873B (sv) 1991-08-12 1991-08-12 Kavitetsantenn med dielektrikum

Publications (2)

Publication Number Publication Date
EP0527714A1 EP0527714A1 (en) 1993-02-17
EP0527714B1 true EP0527714B1 (en) 1996-05-15

Family

ID=20383465

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92850148A Expired - Lifetime EP0527714B1 (en) 1991-08-12 1992-06-17 Cavity Antenna

Country Status (3)

Country Link
EP (1) EP0527714B1 (sv)
DE (1) DE69210711T2 (sv)
SE (1) SE468873B (sv)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8797222B2 (en) * 2011-11-07 2014-08-05 Novatel Inc. Directional slot antenna with a dielectric insert
US10158167B2 (en) 2012-07-24 2018-12-18 Novatel Inc. Irridium/inmarsat and GNSS antenna system
DE102022119696A1 (de) * 2022-08-05 2024-02-08 Tridonic Gmbh & Co Kg Gehäuse für eine Leuchte und Leuchte mit integrierter Funkschnittstelle

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2658145A (en) * 1946-01-07 1953-11-03 Dorne Arthur Cavity antenna
US2579324A (en) * 1947-05-16 1951-12-18 Bell Telephone Labor Inc Metallic structure for delaying propagated waves

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN,vol 9,No 193 (E-334)abstract of JP 60-062202,publ. 10 April 1985,MURATA SEISAKUSHO K.K *

Also Published As

Publication number Publication date
SE468873B (sv) 1993-03-29
DE69210711D1 (de) 1996-06-20
DE69210711T2 (de) 1997-01-30
SE9102349L (sv) 1993-02-13
SE9102349D0 (sv) 1991-08-12
EP0527714A1 (en) 1993-02-17

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