Classifications

• • 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
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
  • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
  • H01Q1/246—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for base stations
• • 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
• • 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
  • H01Q9/285—Planar dipole

Definitions

• the present invention relates to antennas with vertical polarization, comprising a vertical carrier structure, of elongated shape, and dipoles situated at different levels along the structure and coupled to a coaxial power cable.
• Document WO 97/45892 discloses such an antenna, in particular an omnidirectional antenna in azimuth, having at least two dipoles located at the same level on the vertical structure.
• the dipoles and associated supply networks from the coaxial cable are integrated into the structure by constituting a balun assembly.
• the structure of this known antenna consists of two identical metal sections, which are parallel and at a well-defined distance from each other and are thus assembled by insulating joints. These sections each include a central part in the form of a longitudinal gutter and two opposite and flat lateral branches. They are assembled back to back, with the two gutters facing outwards and their flat branches arranged two by two face to face and separated by the distance defined between the profiles.
• the dipoles and their associated supply networks are machined in the flat branches of the two profiles, the two strands of each dipole being machined in two branches assembled face to face and being suitably folded to constitute the dipole during the assembly of the two profiles .
• the coaxial power cable terminates at one end of this structure. Its external conductor is electrically connected to a first of the two profiles. Its internal conductor is electrically connected to an auxiliary conductor, mounted in the gutter of this same first section and kept at a distance from the walls of this gutter to reconstitute the coaxial supply structure. It thus extends up to mid-height of the first profile, from where it is connected to the second profile by a coaxial connector, to allow symmetrically to feed the dipoles located on either side of the median transverse plane of the antenna structure by forming a balun assembly.
• Such an antenna generates a vertically polarized signal, which is omnidirectional in azimuth as soon as the antenna comprises at least two dipoles per vertical level. It generates a vertically polarized signal, which is directional in azimuth if the antenna has only one dipole at each vertical level.
• the vertically polarized azimuth signal from this antenna also has a crossed polarization component, which is horizontal and inherent in vertically polarized antennas fitted with dipoles and is due in particular to the radiation of horizontal metallic parts of the antenna.
• This horizontal component of polarization although weaker than the main vertical component and generally situated at a level of the order of 1 2 to 15 dB below this, is as such undesirable because susceptible to disrupt other types of neighboring antennas.
• the aforementioned known antenna is also relatively complex and expensive to produce. In addition, it can only be used at low and medium frequencies due to its realization in mechanical structure.
• the object of the present invention is to produce a vertical polarization antenna, the design of which is simple and makes it possible to minimize the crossed component of vertical polarization. It also aims to enable the antenna to be produced both in mechanical structure and in printed circuit, for its use at low and medium frequencies or at microwave frequencies.
• the present invention relates to a vertical polarization antenna, comprising a vertical carrier structure of elongated shape and dipoles located on said structure, at different levels along the latter, and coupled to a coaxial power cable, characterized in that it comprises only one of said dipoles per level and in that said dipoles are coplanar and substantially collinear, but are reversed relative to one another on one face of said structure, called the front of the antenna.
• Said antenna can also have at least one of the following additional characteristics: - Said dipoles are arranged in two groups and reversed from one group to another.
• the antenna has a lateral ground plane with respect to each group of dipoles and coplanar with them and a lateral supply line with respect to each group of dipoles and located in a plane distinct from the ground plane but parallel to this, said ground plane and said supply line each having a first section on a first side along one of said groups of dipoles, a second section on the other side along the other group and a middle section of continuity passing between the two groups, and further comprises projections provided on said first and second sections of said ground plane and said supply line and connected to said dipoles.
• Said coaxial supply cable extends against said ground plane to a midpoint of the median section of said ground plane and is connected to a corresponding midpoint of the median section of said supply line, by a coaxial outlet provided between said midpoints of said ground plane and said supply line.
• the antenna comprises a reflector associated with said dipoles and mounted opposite that of the faces of said structure which is opposite to that forming said front face of the antenna.
• FIGS. 1 and 2 are a front view and a rear view of an omnidirectional antenna according to the present invention
• FIG. 3 shows the radiation diagram in azimuth of the antenna of FIGS. 1 and 2
• FIG. 4 illustrates the operation of the antenna of FIGS. 1 and 2
• FIG. 5 represents an adaptation of the above-mentioned antenna of FIGS. 1 and 2, so as to constitute a directive antenna in accordance with the invention
• - Figure ⁇ is the radiation pattern of the directional antenna in Figure 5.
• the omnidirectional antenna illustrated in FIGS. 1 and 2 is shown made in printed structure. It can just as easily be produced in an assembled mechanical structure.
• It comprises an arrangement of six half-wave dipoles referenced 1 or 2, which are coplanar and substantially collinear and are inverted with respect to each other. These dipoles are printed on a front face of a dielectric substrate 3, of elongated shape and of suitable mechanical strength, constituting the carrying structure of the antenna.
• the dipoles are organized into two identical groups along the substrate, being designated by 1 or 2 depending on the group to which each of them belongs and being reversed from one group to another.
• This antenna is planar and achieves the combination of two elementary antenna systems, each having the same number of dipoles or two times less dipoles than the resulting antenna, to obtain an almost omnidirectional diagram of the resulting antenna. of this combination.
• the antenna can include any number of dipoles for the desired gain.
• the substrate 3 also carries dipole supply networks, generally designated by the reference 4 and printed on the two faces of the substrate. These supply networks define a ground plane 5 on the front face and an actual supply line 6 on the rear face of the substrate. They are provided laterally in correspondence along the two groups of dipoles and have substantially quarter-wave horizontal projections 7 and 8 for supplying the dipoles.
• the ground plane 5 and the supply line ⁇ each comprise two opposite analogous sections, which are produced along and substantially over the m i- length of the first edge and of the second edge of the substrate, respectively, and a median section of continuity , which is made slightly at an angle from the first to the second preceding section, passing between the two groups of poles.
• the horizontal projections 7 which start from the ground plane are provided two by two side by side and said to be double and thus end directly at the two strands of the dipoles.
• the horizontal projections 8 which start from the supply line are simple and connected to only one of the strands of the dipoles, by welded metal inserts 9 passing through the substrate.
• a coaxial cable 10 ensures the supply of power to a midpoint 11 of the antenna. It extends along the ground plane 5 to this midpoint, being masked by this ground plane. It is welded to the ground plane for its mechanical strength and the electrical connection of its external conductor to the ground plane. Its inner conductor is connected by welding to the supply line ⁇ , through a coaxial outlet which is provided at the midpoint 11 and designated by the same reference of this midpoint.
• This coaxial output is produced by a passage through the substrate and a corresponding but slightly larger local demetallization of the ground plane.
• the antenna is thus supplied at its center, directly by the coaxial supply cable, to then ensure symmetrical and phase supply of the different dipoles.
• the two groups of dipoles have a small center distance d between them.
• This spacing d makes it possible to align the phase centers of the dipoles of the two groups, to compensate for their slight offset due to the effect of the ground plane on the dipoles.
• the value of this center distance is very low and of the order of a few mm. It depends on the frequency of use of the antenna and is in practice adjusted as a function of it. This thus adjusted center distance minimizes the ripples of the signal radiated by the antenna, making them less than 2 dB relative to the maximum radiation of the antenna.
• This antenna is mounted in a protective radome, not shown but as commonly used.
• This radome of cylindrical shape can be provided with a surge arrester point connected by a section of cable to the ground plane of the antenna.
• Figure 3 shows the antenna radiation pattern in azimuth, given with a scale of 5 dB per division. It shows that its radiation in azimuth is quasi-omnidirectional, presenting only weak ripples limited and less than 2 dB compared to the maximum radiation, on the two sides of the antenna corresponding to the angular positions noted 90 ° and - 90 ° .
• FIG. 4 illustrates the obtaining of the vertical polarization of the signal radiated by the antenna, which results from the addition to each other of the vertical components Ev of polarization of the signals of its different dipoles. It also highlights that the horizontal components Ec of polarization of the signals of two inverted dipole elements are opposite and thus tend to cancel each other out.
• This in practice makes it possible to obtain a vertical polarization antenna, the cross or horizontal component of which is very small and is situated at a level of the order of 20 dB below the vertical polarization.
• This antenna can be used at all frequencies where the dipole elements are achievable, thus for example in mechanical structure at low and medium frequencies and in printed structure at microwave frequencies.
• the planar shape of the antenna makes it compact and light.
• the dimensions of the printed circuit antenna, used at 3.5 GHz are 330 x 60 x 1.5 mm.
• FIG. 5 represents a directional antenna, which is produced by the addition of a reflector 20 to the omnidirectional antenna of FIGS. 1 and 2, the main references of the above-mentioned omnidirectional antenna being shown in this FIG. 5.
• This reflector 20 is placed at the rear of the substrate 3 while being close to the latter. It is in this figure 5 of U-shaped cross section, the edges of its lateral branches substantially flush with the substrate.
• the reflector can alternatively be placed in front of the substrate. Under these conditions, the radiation of the dipole elements crosses the substrate.
• the radiation pattern in azimuth of the antenna of this figure 5 is made directive, by deformation and precise orientation of the omnidirectional radiation diagram as illustrated in figure 3 of the initial antenna without this reflector.
• this directive antenna makes it possible to deform more or less the omnidirectional radiation pattern of the initial antenna in order to obtain the desired directional diagram in azimuth.
• the signal from this directional antenna is vertically polarized and has a very low level of cross polarization, like that of the initial omnidirectional antenna without associated reflector.
• This directional antenna also has the same advantages as the above-mentioned omnidirectional antenna.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)
• Support Of Aerials (AREA)
• Details Of Aerials (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9545401

Family Applications (1)

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Cited By (1)

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Family Cites Families (5)

• 1999
  • 1999-05-10 FR FR9905924A patent/FR2794290B1/fr not_active Expired - Fee Related
• 2000
  • 2000-05-09 US US09/959,842 patent/US6529171B1/en not_active Expired - Fee Related
  • 2000-05-09 DE DE60019412T patent/DE60019412T2/de not_active Expired - Fee Related
  • 2000-05-09 EP EP00925416A patent/EP1181744B1/de not_active Expired - Lifetime
  • 2000-05-09 ES ES00925416T patent/ES2240094T3/es not_active Expired - Lifetime
  • 2000-05-09 AT AT00925416T patent/ATE293293T1/de not_active IP Right Cessation
  • 2000-05-09 AU AU44146/00A patent/AU4414600A/en not_active Abandoned
  • 2000-05-09 WO PCT/FR2000/001241 patent/WO2000069019A1/fr active IP Right Grant

Non-Patent Citations (1)

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