Classifications

• • 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
• • 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
  • H01Q19/28—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 a secondary device in the form of two or more substantially straight conductive elements
  • H01Q19/30—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 a secondary device in the form of two or more substantially straight conductive elements the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
• • 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
  • H01Q9/26—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength

Definitions

• the present invention generally relates to antennas adapted to transmit and receive UHF signals of the TNT (Digital Terrestrial Television) or analog type, in a frequency band more particularly between 471 and 783 MHz.
• TNT Digital Terrestrial Television
• the rake antennas comprise a plurality of rods mounted on a support arm, including a rear rod called reflector, an intermediate rod said radiating and a front rod called director. These different rods are tuned according to the wavelengths of the signals to be received.
• the radiating rod constitutes the active element of this antenna, since it transmits the UHF signals to the television set via a coaxial cable. It forms a loop around the support arm, with two strands respectively connected to the inner and outer electrical conductors of the coaxial cable. This radiating stem is commonly called a paper clip.
• Document FR 2 841 688 discloses, however, a plane antenna comprising a rectangular radiating plate open by two parallel main slots connected to one another by a slot of small width. Thanks to these slots, this antenna has a broad frequency band for transmitting and receiving signals. This antenna is in particular adapted to receive all the frequencies of UHF signals TNT type.
• the main disadvantage of this antenna is that the slots, which are cut into the radiating plate at a distance from its peripheral edge and which are sized to match the frequencies of the UHF type signals TNT, require the use of a large radiating plate, to the detriment of the size of the antenna.
• Document WO2005 / 041355 also discloses an antenna of the "folded doublet" type, which comprises, on the one hand, a flat plate in which are provided three T-shaped slots which delimit two wings, and, on the other hand, a cable a conductor is connected to one of these two wings and another driver is connected to the other of these two wings.
• the connection of the electrical conductors is here carried out on tabs which extend in extension of the wings.
• the present invention proposes an antenna having dimensions reduced by approximately 40% compared with the antenna disclosed in document FR 2 841 688, for a substantially identical gain on the entire frequency band of the UHF signals of the TNT type, and which has optimum impedance.
• an antenna comprising:
• a planar radiating plate in which are arranged three T-slots, a first slot and a second slot forming the base of the T and a third slot of which forms the foot of the T, said third slot being the only one opening onto the peripheral edge; the radiating plate and said three slots delimiting two wings located on either side of the third slot, and
• an electrical conduction element such as a coaxial cable, comprising a first electrical conductor connected to the end edge of a first of said wings and a second electrical conductor connected to a second of said wings by at least two distinct contact points or by a continuous line of contact.
• the radiating plate forms a doublet folded in the manner of a staple, the two ends of which delimit the third slot. Thanks to this folded staple form, the radiating plate of the antenna has a small footprint. It is further adapted to radiate over a sufficiently wide frequency band to capture all the UHF signals of the TNT type.
• the connection of the electrical conduction element to the wings finally allows the antenna to be perfectly tuned impedance, so that it has a significant gain for capturing signals of reduced power.
• the second electrical conductor is connected at a distance from said edge of the second wing which is between the fifth and the half of the width of the second wing ;
• the radiating plate has, in unfolded form, a width equal, within 20%, to 200 millimeters;
• the radiating plate has, in unfolded form, a height equal to 20%, to 100 millimeters;
• said electrical conduction element is a coaxial cable having an impedance of 75 Ohm;
• each wing extends along an axis of symmetry
• said first and second electrical conductors are respectively connected to the first and second wings at a distance from said axis of symmetry;
• each wing has an edge opposite to said first and second slots which is equipped with a shutter;
• each flap is located in the plane of the radiant plate
• each flap is folded in a plane inclined with respect to the plane of the radiating plate
• said first and second slots extend in length up to a distance from the peripheral edge of the radiating plate which is between 5 and 65 millimeters;
• a reflector which comprises a flat base positioned parallel to the plane of the radiating plate, the height and width of which are greater than or equal to the height and width of the radiating plate;
• the flat base of the reflector is flanked by two flanges extending in the direction of the radiating plate, over a distance less than or equal to half the distance separating the radiating plate from the flat base of the reflector;
• the radiating plate extending on one of the faces of a substrate of a printed circuit, at least one of the electrical conductors is formed by a track of this printed circuit, extending on the other side of this substrate.
• FIGS. 1 to 3 are diagrammatic front, bottom and side plan views of a planar antenna according to the invention.
• FIG. 4 is a diagrammatic plan view of the radiating plate of the planar antenna shown in FIGS. 1 to 3, and
• FIG. 5 is a schematic perspective view of an alternative embodiment of the radiating plate of the plane antenna of FIG. 1.
• the planar antenna 1 is designed to pick up UHF signals. It is also designed to have a significant gain, so as to capture low power signals.
• This flat antenna 1 is thus particularly adapted to the reception of digital terrestrial television (DTT) type digital radio signals whose power is often inferior to that of the radio analogue signals.
• DTT digital terrestrial television
• This flat antenna 1 is directive. It is therefore designed to be placed in an optimal position of receiving signals, facing the main direction of propagation of the signals. In this position, the height and the width of the plane antenna are respectively defined as the two vertical and horizontal dimensions of this plane antenna 1, which are perpendicular to said main direction of propagation of the signals.
• This plane antenna 1 comprises two essential elements, namely a radiating plate 100 and an electric cable 400 connected to this radiating plate 100.
• the radiating plate 100 constitutes the active element of this plane antenna 1, since it transmits the signals to the television set via the electric cable 400.
• the radiating plate 100 is substantially rectangular and flat. It is cut so as to delimit three slots 161, 162, 163 in T, of which only one of the slots 163 opens on the rectangular peripheral edge 101 of this radiating plate 100.
• the two slots 161, 162 which form the base of the T then delimit, with the lower side of the peripheral edge 101 of the radiating plate 100, a so-called support portion 1 10.
• the third slot 163 which forms the foot of the T defines, in turn, with the upper side of the peripheral edge 101 of the radiating plate 100 and with the two slots 161, 162, two wings 120, 130.
• the electrical conductors 401, 402 of the electrical cable 400 are respectively connected to these two wings 120, 130.
• this plane antenna 1 also comprises, on either side of the radiating plate 100, a reflector 200 and a director 300. These two elements 200, 300 are tuned in frequency with the radiant plate 100 to optimize the performance of the radiant plate 100.
• planar antenna 1 is devoid of one and / or the other of these two elements 200, 300, in which case it would however have reduced performance.
• the radiating plate 100 forms a folded and flat doublet, which can be related to the trombone rod of a rakes antenna.
• This radiating plate 100 here has a vertical axis of symmetry A1.
• the radiating plate 100 has a reduced footprint of the order of 40% compared to a standard flat antenna, and therefore a lower wind resistance.
• the total width L6 of the radiating plate 100 is chosen as a function of the low frequency of the plane antenna 1.
• the radiating plate 100 has a total width L6 equal, within 20%, to 200 millimeters.
• the total height H6 of the radiating plate 100 is chosen according to the high frequency of the plane antenna 1. It is not chosen to be higher, so as not to reduce the gain of the plane antenna 1.
• the radiating plate 100 has a total height H6 equal, within 20%, to 100 millimeters.
• the thickness of the radiating plate 100 is here particularly small, of the order of 0.3 millimeters, so as to reduce the cost of the raw materials necessary for the manufacture of the plane antenna 1.
• the support portion 1 10 of the radiating plate 100 has a shape of elongated rectangle along the width of the antenna. It therefore comprises a lower edge 1 1 1 and an upper edge 1 12 parallel to each other, and two end edges 1 13, 1 14 also parallel to each other.
• Each wing 120, 130 has a rectangular flat plate shape elongated along the width of the antenna, and has a horizontal axis of symmetry A2.
• Each wing 120, 130 therefore has a lower edge 121, 131 and an upper edge 122, 132 parallel to each other, and an outer edge 123, 133 and a free end edge 124, 134 also parallel to each other.
• the free end edges 124, 134 of the two wings are rotated towards each other to define between them the third slot 163.
• Each wing 120, 130 has a height H2, H3 at least twice the height H8 of the support portion 1 10.
• the two corners of the free end edge 124, 134 of each wing 120, 130 are here and preferentially bevelled at 45 degrees.
• the third slot 163 has a desired length, tuned to the frequency band of TNT type digital radio signals.
• Each wing 120, 130 here has a height H2, H3 equal to 70 millimeters, to 20%.
• the wings 120, 130 also have widths L2, L3 such that the third slot 163 located between their free end edges 124, 134 has a reduced width L8, less than 5 millimeters. Due to this small width, the third slot 163 allows the plane antenna 1 to radiate over the entire frequency band of TNT type digital radio signals.
• Each wing 120, 130 here has a width L2, L3 equal to 98 millimeters, to 20%.
• the wings 120, 130 and the support portion 110 extend edge to edge.
• the lower edge 121, 31 of each wing 120, 130 is attached to the upper edge 1 12 of the support portion 1 10 only part of its length.
• the lower edge 121, 131 of each wing 120, 130 is for the rest remote from the upper edge 1 12 of the support portion 1 10 to define the first or second slot 161, 162.
• the first and second slots 161, 162 extend in length from the third slot 163 towards the outer edges 123, 133 of the wings 120, 130, to a distance L4, L5 of these edges between 5 and 65 millimeters, and preferably equal to 50 millimeters, to 20%.
• the first and second slots 162, 163 thus have reduced lengths, in favor of the gain of the plane antenna 1.
• each wing 120, 130 is extended on its upper edge 122, 132 by a flap 140, 150 which widens the width of the frequency band at which the plane antenna 1 radiates.
• Each shutter 140, 150 here has a trapezoidal shape, with a lower edge 141, 151 which is attached to the upper edge 122, 132 of the corresponding wing 120, 130, an outer edge 143, 153 which extends the outer edge 123, 133 of the wing 120 130, corresponding, and an inner edge 144, 154 which extends the bevel of the free end edge 124, 134 of the wing 120, 130 corresponding.
• Each shutter 140, 150 here has a height H9, H10 of between 5 and 20 millimeters.
• the radiating plate 100 comes here from forming by cutting a metal strip.
• the material of this metal is chosen to be not only very conductive but also inexpensive.
• the radiating plate 100 is made of a single piece of copper. It could alternatively be cut from a different material, such as for example aluminum or brass.
• the antenna could provide to manufacture the antenna from an integrated circuit comprising a rigid substrate covered on one side by a metal sheet forming said radiating plate.
• This antenna would be less easily recyclable than the antenna described above.
• the electrical cable 400 is designed for transmitting to the demodulator of the television set the signals collected by the radiating plate 100.
• This electrical cable 400 is preferably a coaxial cable comprising a central core 401 surrounded by an insulating dielectric material 403, itself surrounded by a braided conductive sheath, called the shield 402, covered with an insulating envelope (not shown).
• This coaxial cable 400 here has a standard impedance of 75 Ohm, optimized for the transmission of video signals. It is also chosen to present reduced losses.
• the central core 401 of the coaxial cable 400 is connected to the free end edge 124 of the flange 120, while the shield 402 is connected at a distance from the free end edge 134 of the flange 130 so as not to be in direct electrical contact with this free end edge.
• the end of the shield 402 is for this purpose cut away from the end of the central core 401, so that only the insulating dielectric material 403 comes into contact with the free end edge 134 of the flange 130.
• This asymmetry of connection of the coaxial cable 400 on the two wings 120, 130 optimizes the impedance matching of the plane antenna 1, so that it best captures the TNT type digital radio signals.
• the shielding 402 is more precisely here connected to a distance D1 from the free end edge 134 of the wing 130 which is between one fifth and one half of the width L3 of this wing 130.
• the central core 401 is connected to the free end edge 124 of the wing 120 by a single weld spot.
• the shield 402 is connected to the flange 130 by four separate welding points 431 - 434 distributed at regular intervals along the cable. It is also connected to the support part 110 by three other soldering points 435 - 437.
• This plurality of soldering points located at a distance from the free end edge 134 of the wing 130, makes it possible to reduce the impedance of the antenna at 75 Ohm without the aid of electronic components (resistors, ...) while this impedance would be about 300 Ohm if the shielding 402 was connected by a single point of contact at the free end edge 134 of the wing 130. It thus improves the impedance matching of the plane antenna 1.
• the shield 402 is connected to the wing 130 by a different number of welding spots, or by a continuous weld line.
• the weld points of the central core 401 and the shield 402 on the wings 120, 130 are located at a distance from the horizontal axis of symmetry A2 of the wings 120, 130.
• this plane antenna 1 it is not possible to indeed not necessary to connect the coaxial cable 400 along the horizontal axis of symmetry A2 of each wing 120, 130, which facilitates the manufacturing operations of the plane antenna 1.
• these points are located below the axis of horizontal symmetry A2 wings 120, 130. Alternatively, they could be located above this axis.
• the plane antenna 1 comprises here, in addition to the two essential elements that are the radiating plate 100 and the coaxial cable 400, a reflector 200.
• This reflector 200 makes it possible, on the one hand, to concentrate the digital radio signals on the radiating plate 100, and, on the other hand, to reduce the echo phenomena. With this reflector 200, the directivity of the plane antenna 1 is substantially increased, so that it has a gain of about 3 dB higher than a planar antenna that would be devoid of this reflector.
• the reflector 200 comprises a rectangular plane base 210, which is positioned parallel and at a distance from the radiating plate 100.
• This flat base 210 is thus positioned at the rear of the radiating plate. 100 to form a ground plane favoring the front-to-back ratio of the plane antenna 1.
• the flat base 210 of the reflector 200 is preferably positioned at a distance D2 from the radiating plate 100 which is between 50 and 100 millimeters and which is here equal to 70 millimeters.
• This flat base 210 of the reflector has a height H7 and a width L7 greater than or equal to the total height H6 and total width L6 of the radiating plate 100.
• the dimensions of the base 210 are more precisely from a compromise between the size of the planar antenna 1 and the performance of the reflector 200.
• the widths L7 and height H7 of the planar base 210 are chosen to be 10 mm greater than the total height H6 and total width L6 of the radiating plate 100, so that as seen from the front as shown in FIG. plane 210 of the reflector 200 is greater than one-half centimeter on each side of the radiating plate 100.
• the flat base 210 of the reflector 200 has two rectangular flanges 220, 230 which extend from the two small opposite sides of the flat base 210, perpendicularly thereto, towards the radiating plate 100.
• These two edges 220, 230 thus extend orthogonally to the plane of polarization of the radiating plate 100. They optimize the performance of the reflector without increasing the size of the antenna.
• these two edges 220, 230 extend in length over the entire height H7 of the flat base 210 of the reflector 200. They also extend towards the radiating plate 100 over a distance D3, D4 lower or equal to half the distance D2 separating the radiating plate 100 from the plane base 210 of the reflector 200, so as not to degrade the impedance of the plane antenna 1.
• this distance D3, D4 is equal to 30 millimeters.
• the reflector 200 is derived from a cutting and folding operation of a copper or aluminum metal strip, so that its manufacturing cost is reduced.
• the plane antenna 1 comprises at least one director 300 positioned parallel to the radiating plate 100, in front of the latter.
• Such a director 300 makes it possible to increase the gain of the plane antenna 1 in the high frequencies to which it radiates.
• the plane antenna 1 here comprises a single director 300 positioned at a distance D5 from the radiating plate 100.
• This distance D5 is greater than 20 millimeters for the antenna to remain in a transmission and reception frequency band which covers the TNT type signals.
• the plane antenna 1 comprises a greater number of directors, for example two or three, superimposed parallel and at a distance from each other.
• This director 300 here has the form of a rectangular plate of height and width less than the height and width of the support portion 1 10 of the radiating plate 100. It more particularly has a height H1 1 of between 2 and 10 millimeters, here equal to 8 millimeters, and a width L1 1 of between 100 and 200 millimeters, here equal to 150 millimeters.
• This director 300 is, like the radiating plate 100 and the reflector 200, obtained by cutting a metal strip of copper or aluminum, so that the total manufacturing cost of the planar antenna 1 is limited.
• the director has a different shape, for example a tubular shape with a diameter of between 2 and 10 millimeters.
• the radiating plate 100 and the reflector 200 are held in a fixed position and parallel to one another.
• This box thus makes it possible not only to protect the radiating plate 100 and the reflector 200, but also to ensure perfect parallelism between these two elements.
• the box is here made of a composite material based on wood to be less polluting than a plastic box, and therefore more easily recyclable.
• the director is arranged to emerge at the front of the box. It is for this purpose held parallel to the radiating plate 100 by a rigid foot 310, conductor or not, which extends between the front face of the portion of 'support 1 10 of the radiating plate 100 and the rear face of this director 300, through an opening provided in the box.
• the box only acts as a protective member of the planar antenna 1, in which case the radiating plate 100 and the reflector 200 will be held parallel and at a distance from each other by spacers. in the form of a rod.
• the circular section coaxial cable can be replaced by a flat-section electrical conduction element.
• the antenna comprises a printed circuit formed of an insulating substrate (for example Bakelite) and at least one conductive track (for example made of copper) extending on one of the faces of the substrate. .
• an insulating substrate for example Bakelite
• at least one conductive track for example made of copper
• the radiating plate is then formed by a thin metal layer, identical in shape to the radiating plate shown in Figure 1, extending on the other side of the substrate of the printed circuit.
• the insulating substrate carries, on one of its two faces, the radiating plate, and on the other of its two faces, the conductive track.
• the electrical conduction element is partly formed by this conductive track.
• This electrical conduction element more precisely comprises, on the one hand, an electrical wire connected to the support part of the radiating plate at a point situated on the vertical axis of symmetry A1 of the antenna, and, on the other hand , said conductive track.
• This track then extends on the substrate along a path substantially identical to that of the coaxial cable shown in FIG. 1, with a first portion extending along the support portion of the radiating plate, on the opposite side of the substrate, and a second portion extending along one of the wings of the radiating plate, on the opposite side of the substrate, along the horizontal axis of symmetry A2 of the wing.
• This track here has a width substantially equal to 3 millimeters, to 20%. It thus presents an optimal impedance adaptation.
• the end of this track extends at a distance D1 from the third slot of the radiating plate, which is between one fifth and one half of the width of the corresponding wing of the radiating plate.
• This end is extended by a wire of reduced diameter, of the order of 0.3 millimeters, which extends beyond the third slot and which is connected to the other wing of the radiating plate, via a hole made in the substrate of the printed circuit.
• the thickness and the material of the substrate are chosen here so that the electrical conductor has a characteristic impedance of 75 Ohm.
• This particularly flat antenna is preferably devoid of reflector and director, to have a particularly low thickness.
• This antenna may further comprise a protective envelope molded on the printed circuit, so as to be easily transportable.
• FIG. 5 shows another variant embodiment of the radiating plate 100.
• This radiating plate 100 has a shape close to that of the radiating plate illustrated in FIG. 1. It comes in effect from a flat plate of equal width, within 20%, to 200 millimeters and of equal height. to 20%, to 100 millimeters. It is cut in three slots 161, 162, 163 T, so as to delimit a support portion 1 10 and two wings 120, 130 which each have an axis of symmetry A2.
• the wings of the flattening 100 are extended, on their edge opposite the support part 1 10, by flaps 140 ', 150' which are folded at right angles to the plane of the wings 120, 130 .
• the directivity of the antenna is slightly reduced compared to that illustrated in FIG. 1 (the gain of this antenna is about 0.3 dB less than that of this antenna), but its overall size is much smaller than that shown in FIG. .
• it could also provide to fold its support portion 110, parallel to the flaps 140 ', 150'.

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

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• 2010
  • 2010-02-05 FR FR1000472A patent/FR2956251B1/fr not_active Expired - Fee Related
• 2011
  • 2011-02-04 PT PT117089037T patent/PT2532049E/pt unknown
  • 2011-02-04 BR BR112012018455A patent/BR112012018455A2/pt not_active IP Right Cessation
  • 2011-02-04 WO PCT/FR2011/000071 patent/WO2011095712A1/fr active Application Filing
  • 2011-02-04 ES ES11708903.7T patent/ES2523224T3/es active Active
  • 2011-02-04 US US13/576,244 patent/US20120299790A1/en not_active Abandoned
  • 2011-02-04 EP EP11708903.7A patent/EP2532049B1/de not_active Not-in-force

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