Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/24—Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/24—Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
  • H01Q21/26—Turnstile or like antennas comprising arrangements of three or more elongated elements disposed radially and symmetrically in a horizontal plane about a common centre

Definitions

• Broadband radiating element with double polarization generally square in shape.
• the invention relates to antennas and their radiating elements.
• a radiating element with double polarization can be formed of two radiating dipoles, each dipole being constituted by two strands of collinear conductors. The length of each strand is substantially equal to a quarter of the working wavelength.
• the dipoles are mounted on a structure allowing their supply and their positioning above a reflector (ground plane). This allows, by reflection of the rear radiation of the dipoles, to refine the directivity of the radiation diagram of the assembly thus formed.
• the dipoles can radiate or receive electromagnetic waves according to two polarization channels, for example a horizontal polarization channel and a vertical polarization channel or also according to two polarization channels offset by an angle of ⁇ 45 ° from the horizontal or vertical.
• two polarization channels for example a horizontal polarization channel and a vertical polarization channel or also according to two polarization channels offset by an angle of ⁇ 45 ° from the horizontal or vertical.
• a radiating element with two orthogonal polarization pathways each having a unidirectional radiation diagram and whose aperture at half power in the diagonal planes, ie planes located at + / - 45 ° from the main planes E and H of each dipole. is substantially less than 90 °.
• the invention aims to improve the situation.
• each dipole comprises a pair of coplanar conductive plates, of the same geometry in the general shape of a square; the two plates of each pair are positioned with their diagonals substantially aligned on the same alignment axis for each pair; and the axes of alignment of the two pairs of plates intersect at right angles at a crossing point situated between the plates of each dipole.
• the plates are arranged with respect to each other so that two vertices of a square of a plate, opposite on a diagonal of the square, are aligned along the same alignment axis with two opposite vertices on a diagonal of the square of the other plate of the same pair.
• FIG. 1 is a top view of a first embodiment of a radiating element according to the invention
• FIG. 2 is a view along section AA of the radiating element of FIG. 1,
• FIGS. 3, 4 and 5 illustrate a top view of three alternative embodiments of the radiating element shown in FIGS. 1 and 2,
• FIG. 6 is a perspective view of a linear network composed of several radiating elements according to the invention.
• FIGS. 7a and 7b are top views of a radiating element according to the invention, shown schematically, in which are shown the electric field distributions.
• Figure 1 shows a virtual dotted square outline 1, the side length of which is "a”.
• the radiating element shown comprises four metallic radiating plates 2a, 2b, 2c, 2d, of square shape, the side length of which is "c". These four plates are juxtaposed in the same plane inside the virtual square 1.
• the square plates 2a and 2c have a common diagonal, that is to say located substantially on the same alignment axis 3; similarly, the plates 2b and 2d have a common diagonal, that is to say located substantially on the same alignment axis 4.
• alignment axes 3, 4 which constitute diagonals common to both pairs of plates, intersect at right angles at a crossing point "O" located between the plates of each pair or dipole.
• the alignment axes 3 and 4 also form the diagonals of the dotted virtual square 1.
• Each pair of plates, respectively; 2b, 2d, is supplied by means of a balun.
• the pair of plates 2a, 2c forms a symmetrical dipole radiating a polarized electric field, and this in a plane perpendicular to that of the plates 2a, 2b, 2c, 2d, and containing the common diagonal 3 to the said plates.
• the pair of plates 2b, 2d forms a symmetrical dipole radiating a polarized electric field, and this in a plane perpendicular to that of the plates 2a, 2b, 2c, 2d, and containing the common diagonal 4 to the said plates.
• the two orthogonal pairs of plates thus generate two electric fields orthogonal to one another.
• the polarization planes make an angle of +/- 45 ° with respect to the vertical axis W of FIG. 1, which passes in the interval between the plates 2a, 2b on the one hand, and 2c, 2d d ' somewhere else.
• the plane of the four plates is arranged parallel to a plane reflector 5.
• Each of the plates 2a, 2b, 2c, 2d can be mounted and supported on the reflector 5 by means of conductive tubes referenced respectively 6a, 6b, 6c, 6d.
• Each tube is fixed at one of its ends to the plane reflector 5, and oriented in a general direction perpendicular to the plane of the plates and to the plane of the reflector 5.
• the reflector 5 allows the back radiation from the plates to be reflected by reflection. It is positioned so that the overall resulting radiation corresponds to a unidirectional diagram, directed towards the half-space which contains the radiating plates (relative to the reflector).
• the pair of tubes 6a, 6c forms the balun of the pair of diagonally opposite plates 2a, 2c.
• the pair of tubes 6b, 6d forms the balun of the pair of diagonally opposite plates 2b, 2d.
• Each balun can be seen as a two-wire line, the upper ends of which are electrically connected to the plates respectively and the lower ends of which are electrically connected to the reflector 5, as well as to a hot supply point.
• one of the tubes 6b or 6c of a balun can be traversed by a central conductor 7b or 7c, one end of which is connected to the diagonally opposite plate 2d or 2a, and the other end of which is connected to the conductor central of a power connector 8 or possibly to the central conductor of a coaxial cable not shown, the sheath of which would be welded to the reflector 5.
• the tube 6b or 6c thus forms, with its central conductor 7b or 7c, a transforming coaxial line impedance for the dipole formed by the pair of plates connected to the balun, in each case.
• each central conductor 7b or 7c passing through a tube 6b or 6c can be of circular, square, rectangular or other section.
• the section of the tubes 6a, 6b, 6c, 6d of the baluns can be circular, square, rectangular, trapezoidal, almost triangular or of another shape, preferably substantially regular.
• the section of the tubes may also not be closed, for example by being open on one side.
• the main thing is that the tubes can receive the central conductor, which can possibly have the shape of a conductive strip (strip) to allow the supply of the hot spot and the impedance transformation.
• the tubes can also be filled with a dielectric to facilitate the mechanical resistance of the central conductor or to achieve the necessary length of the central conductor for the adaptation of impedance.
• the tubes not receiving a central conductor can be hollow or solid.
• the transverse dimension of this section is chosen to produce a suitable excitation of the plate concerned (that which receives the end of the central conductor concerned, 7b or 7c), and, by symmetry of the opposite plate on the same diagonal 3 or 4.
• the plates 2a, 2b, 2c, 2d can be hollowed out, and each have a hole 9, substantially of the same shape, for example a circular hole centered at the point of intersection of the diagonals of the square defined by each plate. This makes it possible to lighten their weight; and it has been observed that this does not appreciably modify the radioelectric properties of the radiating elements.
• FIG 4 A variant applicable to the previous embodiments is shown in Figure 4, where the elements homologous to those of Figure 1 retain the same references.
• the four outer corners of the plates 2a, 2b, 2c, 2d situated at the ends of the two alignment axes 3 and 4 can also be cut along cutting planes perpendicular to the alignment axes; this section is substantially identical on the four corners to maintain the geometric symmetry of the two polarization paths.
• Another variant consists in folding the corner of each plate more or less down or up relative to the horizontal plane of the plates at a certain angle " ⁇ ". In this way the folded corner forms an isosceles triangle with side "w” inclined by " ⁇ " relative to the plane of the plates ( ⁇ is between -90 ° and + 90 °).
• ⁇ is between -90 ° and + 90 °.
• the depth w of the section shown in FIG. 4 or of the fold of the variant embodiment described above, measured along a side of length "c" of the square of a plate from its angle at the top, can in these configurations be at most equal to the length of the side "c" of the square, reducing the latter to the shape of a triangle, without the proper functioning of the radiating element being significantly altered.
• FIG. 5 it is also possible to combine the embodiments of the plates 2a, 2b, 2c, 2d of FIGS. 3 and 4 to produce a radiating element in the form of a "Maltese cross.
• the plates 2a, 2b, 2c, 2d are pierced with a circular hole 9 and the outer corners located on the alignment axes are truncated.
• the weight of the radiating element is reduced, without the characteristics of the radiating element being significantly degraded.
• FIG. 6 several radiating elements of one of the types described with reference to FIGS. 1 to 4 are aligned above a common reflector 5, to form an array of antennas.
• the alignment axes 3 and 4 of the radiating plates of the dipoles are inclined at an angle equal to ⁇ 45 ° relative to the longitudinal axis w 'of the reflector 5.
• Other alignments are possible, depending on the needs.
• the field of variation of the main dimensions "a” and "h” can be as follows: 0.35 ⁇ ⁇ a ⁇ 0.6 ⁇
• ⁇ is the wavelength corresponding to the operating frequency of the radiating element.
• the spacing between the plates "b" is typically a few millimeters or a few hundredths of the dimension "a".
• the radiating element is particularly well suited to the production of base station antennas for cellular radiocommunication networks such as GSM900 (870 to 960 MHz), GSM1800 (1710 to 1880 MHz) or the new UMTS system (1920 to 2170 MHz) for which the links with the mobiles must be made according to two orthogonal polarizations inclined by ⁇ 45 ° with respect to the vertical.
• GSM900 870 to 960 MHz
• GSM1800 (1710 to 1880 MHz
• the new UMTS system (1920 to 2170 MHz) for which the links with the mobiles must be made according to two orthogonal polarizations inclined by ⁇ 45 ° with respect to the vertical.
• the radiating element according to the invention can be used for other applications and other frequency bands requiring for example to transmit and receive electromagnetic waves with right or left circular polarization by combining the two polarization channels. orthogonal in phase quadrature.
• a planar network that is to say a bi-directional network
• the radiating elements are aligned horizontally with a determined step and vertically with another determined step.
• a sub-network of two horizontal elements associated in parallel with equal supply allows an opening at -3dB of approximately 29 ° in the horizontal plane for a step of 0.9 ⁇ , where ⁇ is the wavelength functionally.
• a uniform vertical alignment of 8 of such sub-networks allows an opening of approximately 7 ° in the vertical plane with the same pitch of 0.9 ⁇ ; the global network thus formed has a theoretical gain of approximately 22.5 dBi.
• the radiating plates by etching on a thin dielectric support, for example of the "Nerre-Teflon” or “Duro ⁇ d” type.
• This printed technology will find its application in particular at high frequencies ranging from 5 Ghz to 24 GHz.
• FIG. 7a is a diagram of a radiating element according to the invention in which the pair of plates 2b and 2d inclined at -45 ° relative to the axis W is supplied by an RF source of potential -N and + N respectively in points 6b and 6d.
• FIG. 7b is a diagram of a radiating element according to the invention in which the pair of plates 2a and 2c inclined at + 45 ° relative to the axis W is supplied by an RF source of potential -N and + N respectively in points 6a and 6c.
• the slits seem to behave like dipoles of magnetic current, and are, consequently, at the origin of a radiation.
• the width (b) and length (a) of the orthogonal slits would then define the radiation impedance of the equivalent magnetic dipoles, just as the diameter and length of a cylindrical electric dipole determine its radiation impedance.

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• Aerials With Secondary Devices (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)

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• 2002
  • 2002-06-04 FR FR0206852A patent/FR2840455B1/fr not_active Expired - Fee Related
• 2003
  • 2003-05-28 AU AU2003263233A patent/AU2003263233A1/en not_active Abandoned
  • 2003-05-28 CN CN038129353A patent/CN1659743B/zh not_active Expired - Fee Related
  • 2003-05-28 EP EP03756019A patent/EP1550183A2/de not_active Ceased
  • 2003-05-28 WO PCT/FR2003/001620 patent/WO2003103086A2/fr not_active Application Discontinuation

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