Classifications

• • 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
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/08—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a rectilinear path
  • H01Q21/10—Collinear arrangements of substantially straight elongated conductive units
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/30—Arrangements for providing operation on different wavebands
  • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
  • H01Q5/314—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors
  • H01Q5/321—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors within a radiating element or between connected radiating elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/40—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
  • H01Q9/28—Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines

Definitions

• the object of the invention relates to multiple antennas, used in particular, for radio communication equipment.
• the antennas according to the invention apply, for example, to equip vehicles and for a frequency band varying from 225 to 400 MHz. They can be spatial diversity, all antenna elements constituting the antenna then operating in the same frequency range.
• the antennas may also consist of several antenna elements operating in different frequency bands from each other. The position of the different antenna elements forming the antenna, relative to each other, depends on the application.
• An antenna according to the invention may be in the form of whip, better known by the acronym "low profile", provide at least two independent inputs or power supply, maintain an omnidirectional coverage and be predisposed to signal processing of space diversity type.
• the expression "low profile” corresponds to the transverse dimensions of the antenna itself, that is to say its section.
• FIGS. 1A and 1B represent an antenna system consisting of a first dipole 1 composed of an upper radiating element 1s and a lower radiating element 1b having the shape of a skirt, a second dipole 2, placed collinearly with the dipole 1 and composed of an upper radiating element 2s having the form of a counter skirt (upside-down skirt) and a lower element 2b also having the shape skirt, a first coaxial cable 3 passing through the assembly 2b, 2s, 1b and feeding the dipole 1 by the electrical connections of its core 5 with the element 1 s and its sheath 6 with the element 1b , a second coaxial cable 4 feeding the dipole 2 by the electrical connections of its core 7 to a quarter-wave trap 9, usually designated by its English terminology "stub" at point A and its sheath 8 with the element 2b.
• the disadvantages of this type of structure come from the use of the stub
• This antenna system consists of a first dipole 1 composed of an upper radiating element 1s connected to the core 1 1 of a multiaxial line 12 and of a radiating element lower 1b connected to the sheath 12i of the multiaxial line, a second dipole 2 composed of an upper radiating element 2s connected to the sheath 12i at point 10 and a lower radiating element 2b connected to the sheath 12 2 of
• a system if it is effective, has the disadvantage of having to use, to cover a wide frequency band, thick radiating elements, for example, cone sections, disks, etc. which lead to an increase in size of the antenna, which goes against one of the desired objectives, namely, to minimize the size of the antenna while maintaining a desired bandwidth.
• One of the objectives of the invention is to provide an antenna system capable of covering a wide frequency band from thin radiating elements and therefore of low profile.
• the structure of said present antenna makes it possible to feed dipoles in colinear arrangement without using "stubs" whose transverse dimensions are important when one wants to cover a broad band of frequencies.
• a dual antenna, produced according to the invention and operating in the UHF band of 225 to 400 MHz, is, for example, in the form of a whip of 2.5 m high and about 25 mm in diameter, while the equipment similar art market designed according to the prior art, have a diameter greater than 100mm.
• the object of the invention relates to a low-profile broadband multiple antenna comprising at least two dipoles, each dipole k designated D k consisting of a high antenna element D ks and a low antenna element D kb , said antenna being fed by a coaxial cable comprising a core and n sheaths arranged concentrically around the core with k varying from 1 to n, characterized in that it comprises at least the following elements arranged as indicated below:
• a dipole D 1 (k 1) disposed in the upper part of said antenna, said dipole D 1 comprising at least a first high antenna element D 1s connected to the core of said multiaxial cable comprising n sheaths and whose elementary element bottom D 1b is connected to the first sheath adjacent to the core,
• connection device positioned between a high element D ks of a dipole D k (k> 1) and the low element D k b of said dipole D k , the high element D ks is connected at a point to the sheath of index (k-1) of the multiaxial cable after the entire core and sheaths index (1 to k-1) wind in Q turns around a magnetic core and the base element D kb of the dipole D k is connected to the cladding of index k at a point, and in that said connection device comprises at least one monofilar winding of P turns disposed on the same magnetic core connects a low point of said low element D k b of said dipole D k to the cladding of index (k-1) at the point corresponding to the beginning of winding in order to achieve broadband impedance matching and feeding the dipole D k .
• the magnetic element is, for example, a torus or a tube. All dipoles D k constituting said antenna can operate in the same frequency range.
• the dipoles D k constituting the antenna can also be powered with different powers.
• the invention also relates to an antenna system comprising at least one antenna comprising two dipoles, a dipole k designated D k consisting of a high antenna element D ks and a low antennal element
• said antenna being fed by a coaxial cable comprising a core and two sheaths arranged concentrically around the core, with k equal to 1 or 2 characterized in that it comprises two separate coaxial cables and allowing the connection of said antenna with two radio channels disjoint, and in that the core of the first cable corresponds to the extension in the vehicle of the core of the invention and in that the sheath of this cable corresponds to the extension of a first sheath, a second sheath when it extends into the space Int only of sufficient length to be connected to the core of the second cable at a point F, said sheaths of the first and second cables are in contact with each other and are connected to a counter-skirt at a point M to form a quarter-wave balun system.
• the dipoles are, for example, adapted to operate in the frequency range [225-400 MHz].
• Other features and advantages of the device according to the invention will appear better on reading the description which follows of an example of embodiment given by way of illustration and in no way limiting attached to the figures which represent:
• FIGS. 1A and 1B a first example of an antenna using a "stub" according to the prior art
• FIG. 2 a second example of antenna structure according to the prior art
• FIGS. 3A, 3B an example of an antenna structure according to the invention
• FIG. 4 the detail of an exemplary embodiment for the power supply system
• FIGS. 5A and 5B other exemplary embodiments for the power supply system
• FIG. 6 an antenna incorporating means for limiting or even canceling leakage currents
• FIGS. 7A and 7B an exemplary embodiment of the device for connecting the antenna structure to the radio stations
• FIG. 8 a schematic representation of the application of the invention to an antenna structure comprising n dipoles
• FIG. 9 the detail of the supply system for the antenna example of FIG. 8.
• the description will be given by way of non-limiting example in the context of a low profile double antenna used for radio communication equipment, in particular in the UHF band ( Ultra High Frequency) 225-400MHz intended to be installed and used on vehicles that are stationary or in motion.
• the antenna can thus be used in a context of spatial diversity, that is to say that each antenna element operates in the same frequency range.
• the antenna can operate in transmission, reception or transmission / reception.
• the antenna structure can also be composed of a number of dipoles n with n greater than or equal to 2. Each dipole can be adapted to operate in the same frequency range, or in different frequency ranges.
• FIGS. 3A and 3B (respectively seen in perspective and sectional view) show an exemplary embodiment of a double antenna according to the invention.
• the antenna consists of a first dipole 1 composed of an upper radiating element 1s and a lower radiating element 1b forming a skirt (FIG. 3B), the cylindrical form for the radiating elements being taken from the example for ease of understanding the text, a second dipole 2, placed collinearly with the dipole 1 and composed of an upper radiating element 2s forming a counter skirt (upside-down skirt) and a lower element 2b also forming a skirt, of a triaxial cable 14 consisting of a core 140 , a first concentric sheath 14-, and a second concentric sheath 14 2 .
• a dielectric material such as polyethylene or Teflon
• the asymmetrical type of supply (known by the term "unbalanced") of the dipole 1 is achieved by the connection of the core 14 0 to the upper element 1 s and by the connection of the first sheath 14 1 to the lower element 1 b.
• the system may comprise a broadband impedance matching circuit known to those skilled in the art and interposed between the core 140 and the element 1 s which, for the sake of facilitating the understanding of the invention, n is not represented.
• the supply of the dipole 2 is also asymmetric type made by the connection of the second sheath 14 2 to the lower element 2b at point 27 and by the device 20 detailed in Figure 4, which is placed between the two elements 2s and 2b.
• the device 20 is, for example, composed of a winding 21 of the cable section in the form of Q turns, consisting of the portion of the core 140 and the sheath portion 14, located between these two elements 2s.
• a secondary winding formed by a monofilar cable 23 whose one end is electrically connected to the element 2b at point 24 and the other end is connected to the sheath 14i at the beginning of the winding 21 (considered starting from the antenna element 2b below the dipole) at point 25, and a connection 26 between the sheath 14-, and the upper radiating element 2s at the end of the winding 21.
• the monofilar cable 23 is itself wound around the magnetic core.
• any additional circuits known to those skilled in the art to improve the broadband adaptation of the impedance are not represented; for example, there may be mentioned the use of a LC plug circuit connecting the elements 2s and 2b, and / or an LC resonant circuit placed in series with the secondary winding 23.
• the element 20 has the particular function of providing a excitation by magnetic coupling and thus allow to expand the frequency band in which the antenna can operate, without having to use so-called antenna elements "thick" and in fact, without increasing the size of the antenna.
• FIG. 5A represents a first variant embodiment for which the magnetic element or magnetic core 22 is a torus 28.
• This form advantageously makes it possible to obtain a "tighter” magnetic coupling and in this way facilitates the transfer of the RF power ( radio frequency) to the radiating elements of the dipole.
• FIG. 5B shows another alternative embodiment for which the magnetic element or magnetic core 22 is a tube 29.
• This form allows the use of a cable 14 of rigid type which is not arranged to be wound.
• FIG. 6 represents an embodiment variant which makes it possible, in particular, to improve the decoupling between the two elementary antennas 1 and 2.
• this type of arrangement is more particularly suitable in the case of use in a multi-channel system .
• the idea is to add ferrite sleeves 13 by placing them around the sheath 14i located between the antennas 1 and 2. The effect of inductance thus produced limits or cancels the leakage currents or return in surface of the sheath, and thus increases the decoupling between the two elementary antennas.
• FIGS. 7A and 7B represent an example of an asymmetric-asymmetrical connection device making it possible to connect the antenna to two transceiver stations with two separate coaxial cables.
• Ext denotes the space corresponding to the outside of the carrier vehicle where a low profile is requested and Int inside the vehicle.
• a preferred embodiment is to position only the antenna part according to the invention in the space Ext and to install the supply device 30 allowing the connection of two radio stations in the space Int where no drastic constraint of dimension n is imposed.
• the device 30 comprises two separate coaxial cables 15 and 16 which allow the connection of the antenna according to the invention to two disjointed radio channels.
• a preferred embodiment is that the core 15 of the cable 15 0 corresponds to the extension in the vehicle of the core 14 0 of the invention and 15i sheath of the cable 15 corresponds to the extension of the sheath 14- ,.
• Sheath 14 2 when it extends into the space Int only of sufficient length to be connected to the core 16 0 of the cable 16 at point F.
• the sheaths 15i and 16i of the cables 15 and 16 are in contact between them and are connected to a counter-skirt 31 at the point M to form a system usually designated by the skilled quarter-wave balancer.
• FIG. 8 diagrammatically represents the case where the antenna comprises n dipoles fed by a multiaxial cable composed of a core and concentric ducts in this example, the antenna is at n broadband access.
• a dipole k designated D k in Figure 8 consists of a low element D k b and a high element D ks , as indicated for example by the elements 2b and 2s of the previous figures.
• the antenna comprises a dipole D 1 at the top of the antenna whose antenna top 1w D element is connected to the core 14 0 a multiaxial cable comprising n concentric ducts to each other and therefore not fed this last, and whose elementary element low D 1b is connected to the first sheath 14- ⁇ adjacent to the core 14 0 .
• the first sheath is the sheath that is disposed closest to the core
• the second sheath 14 2 of the multiaxial cable is the sheath disposed between the first and the third sheath 14 3 and so on. This provision is only a convention used for the example of the description.
• the device 40 (FIG. 9) corresponding to the device 20 previously described is used to connect the other dipoles.
• This device 40 is positioned between the high element D ks of the dipole k or D k and the low element D kb of the dipole D k .
• the high element D ks is connected at point 46 to the index cladding (k-1) of the multiaxial cable after the set of sheaths of index (1 to k-1) and of the core wind up.
• a double antenna consists of 2 elementary antennas of collinear dipole type with skirt, placed one above the other; each elemental antenna having its own input.
• the broadband antenna is a two-input antenna, this will, for example:
• the antenna can be implemented using the usual realization techniques of broadband antennas for mobiles, in particular the antennas of the VHF-FM (Very High Frequency Frequency Modulation), namely:
• connection system which will be placed at the base of the antenna and will have no noticeable influence on the profile and the size of the antenna.
• the antenna or radiating structure according to the invention is a multiple structure of fine collinear dipole type. It implements elements of small transverse dimensions, so low profile, able to operate in a wide frequency band. She has a more profile weak than broadband antennas known by implementation of thin dipole structure and an adaptation circuit instead of so-called "thick" structure. It offers an optimization of the physical dimensions of the multiaxial cable and magnetic coupling system instead of a stub feeding. It also offers the possibility of adding complementary circuits to improve impedance matching. Its structure is adapted for use on moving vehicles, for tactical multi-use. It also offers the possibility of coupling to the emission: + 3dB of directivity, a possibility of spatial diversity at reception: fight against fading, a phenomenon better known by the abbreviation Anglo-Saxon "fading".

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)
• Details Of Aerials (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=41320077

Family Applications (1)

Country Status (6)

Families Citing this family (8)

Family Cites Families (11)

• 2009
  • 2009-04-24 FR FR0902008A patent/FR2944917B1/fr active Active
• 2010
  • 2010-02-23 SG SG2011078227A patent/SG175349A1/en unknown
  • 2010-02-23 EP EP10706982.5A patent/EP2422403B9/de active Active
  • 2010-02-23 US US13/265,818 patent/US8922445B2/en not_active Expired - Fee Related
  • 2010-02-23 WO PCT/EP2010/052303 patent/WO2010121851A1/fr active Application Filing
• 2011
  • 2011-10-23 IL IL215829A patent/IL215829A/en active IP Right Grant

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events