EP0876688B1 - Antenne pour frequences superieures a 200 mhz - Google Patents

Antenne pour frequences superieures a 200 mhz Download PDF

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Publication number
EP0876688B1
EP0876688B1 EP97900334A EP97900334A EP0876688B1 EP 0876688 B1 EP0876688 B1 EP 0876688B1 EP 97900334 A EP97900334 A EP 97900334A EP 97900334 A EP97900334 A EP 97900334A EP 0876688 B1 EP0876688 B1 EP 0876688B1
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EP
European Patent Office
Prior art keywords
antenna
core
unit according
elements
antenna elements
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
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EP97900334A
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German (de)
English (en)
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EP0876688A1 (fr
Inventor
Oliver Paul Leisten
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Sarantel Ltd
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Sarantel Ltd
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Priority claimed from GBGB9601250.5A external-priority patent/GB9601250D0/en
Application filed by Sarantel Ltd filed Critical Sarantel Ltd
Publication of EP0876688A1 publication Critical patent/EP0876688A1/fr
Application granted granted Critical
Publication of EP0876688B1 publication Critical patent/EP0876688B1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q11/00—Electrically-long antennas having dimensions more than twice the shortest operating wavelength and consisting of conductive active radiating elements
    • H01Q11/02—Non-resonant antennas, e.g. travelling-wave antenna
    • H01Q11/08—Helical antennas

Definitions

  • This invention relates to a handheld radio communication unit including an antenna coupled to a transceiver in the unit.
  • the antenna requirements of a cellular or cordless telephone handset are primarily that it should be compact and omnidirectional.
  • the antenna is typically an extendable rod having a length approximately equivalent to the a quarter wavelength when extended, or a helical wire having several turns.
  • the antenna is usually mounted partially within the handset unit and partly projecting from the end of the unit adjacent the earphone.
  • One difficulty with radio telephone handsets is the perceived health hazard associated with prolonged irradiation of the user's head by the intense electric and magnetic fields generated close to the antenna.
  • 90 per cent of the radiated power is absorbed by the head, particularly by the blood-rich parts such as the ears and lips. Absorption of radiation by the head can also lead to radiation inefficiency and consequent reduction of the operating range of the handset, depending on the orientation of the handset and user with respect to the nearest base station.
  • antennas for operation within the frequency range (800 MHz to 2 GHz) employed by cellular telephones include the so-called Inverted-F antenna. This has two resonant patches, one spaced above the other. However, the antenna is mechanically bulky.
  • a miniature satellite navigation antenna having elements formed by four helical conductive tracks on the outer surface of a ceramic rod made of a material with a relative dielectric constant of 36.
  • the helical elements are arranged primarily for receiving circularly polarised signals.
  • WO-A-9421001 discloses a radio telephone handset with a radio transceiver, an integral earphone and a helical antenna located in the region of the earphone.
  • EP-A-0521511 discloses various backfire helical antennas for use in a navigation system such as GPS.
  • the antennas are each air-cored, and include at least one antenna in which pairs of co-extensive and opposing helical antenna elements are formed on a flexible substrate and connected to a coaxial feeder passing through the core.
  • US-A-4442438 discloses a composite antenna consisting of a centre-fed half-wave dipole formed by a pair of coaxial multi-turn helical elements supported on an insulative rod and extending in opposite directions from the feed point, and an elongate wire element extending axially from the feed point through one of the helical elements and projecting beyond the end of one of helical elements.
  • One of the objects of the present invention to provide an improved radio telephone handset antenna which results in reduced radiation into the user's head.
  • a radio communication unit having an antenna which comprises an antenna element structure including a pair of antenna elements disposed co-extensively in an opposing configuration and connected together to form a loop, the antenna including an electrically insulative core, characterised in that the unit is a handheld unit having a radio transceiver and an integral earphone for directing sound energy from an inner face of the unit which, in use, is placed against the user's ear, the antenna is coupled to the transceiver and located in the region of the earphone; the core of the antenna is of a solid material having a relative dielectric constant greater than 5, the antenna elements being disposed on or adjacent the outer surface of the core; the antenna element structure has a radiation pattern which has a null in direction transverse to the antenna elements; and the antenna is so mounted in the unit that the null is directed generally perpendicularly to the said inner face of the unit to reduce the level of radiation from the unit in the direction of the user's head.
  • the core of the antenna is cylindrical, having a central axis, and the antenna elements are co-extensive, each element extending between axially spaced-apart positions on the outer cylindrical surface of the core.
  • the elements are preferably metallised tracks deposited or bonded onto the core and arranged such that at each of the spaced-apart positions the respective spaced-apart portions of the elements are substantially diametrically opposed.
  • the spaced-apart portions all lie substantially in a single plane containing the central axis of the core, and the portions at one of the spaced-apart positions are connected together by a link conductor to form the loop, by cross elements extending generally radially on an end face of the core.
  • the feed connections may be connected to a coaxial feeder structure.
  • the radiation pattern of the preferred antenna has a pair of nulls directed perpendicularly on each side of the plane. With the exception of the two nulls, the radiation pattern is omnidirectional.
  • the antenna can be constructed so as to be particularly compact.
  • the antenna core being in the form of a cylinder, which may be drum- or rod-shaped, and with a pair of co-extensive antenna elements the ends of which lie in the plane containing the central axis of the core, the plane is preferably parallel to the inner face of the unit Providing the antenna with a trap or balun in the form of a metallised sleeve not only allows the antenna loop to be fed in a substantially balanced condition, but also reduces the effect of the comparatively small ground mass represented by the unit and provides a useful surface area for secure mounting of the antenna, e.g. by soldering or clamping.
  • the material of the core may be ceramic, e.g. a microwave ceramic material such as a zirconium-titanate-based material, magnesium calcium titanate, barium zirconium tantalate, and barium neodymium titanate, or a combination of these.
  • the preferred relative dielectric constant ( ⁇ r ) is upwards of 10 or, indeed, 20, with a figure of 36 being attainable using zirconium-titanate-based material.
  • Such materials have negligible dielectric loss to the extent that the Q of the antenna is governed more by the electrical resistance of the antenna elements than core loss.
  • the antenna has a cylindrical core of solid material with an axial extent at least as great as its outer diameter, and with the diametrical extent of the solid material being at least 50 per cent of the outer diameter.
  • the core may be in the form of a tube having a comparatively narrow axial passage of a diameter at most half the overall diameter of the core.
  • the antenna elements are helical, with each element executing a half-turn around the core, it is also possible to form the elements such that they are parallel to the central axis and still achieve a radiation pattern having a null which is directed transversely to the axis, as in the case of the above-described antenna with helical elements.
  • the antenna elements are fed from a distal end, the core having a central passage housing a coaxial feeder structure extending from a proximal or mounting end of the core and opening out at the distal end where radial elements couple the antenna elements on the cylindrical outer surface of the core respectively to the inner and outer conductors of the feeder structure.
  • the link conductor may then be annular, and advantageously is constituted by a cylindrical sleeve on the outer surface of the proximal part of the core.
  • the choice of antenna element configuration affects the bandwidth of the antenna, insofar as the use of helical elements tends to increase bandwidth compared with antenna elements parallel to the central axis of the core.
  • an antenna 10 for use in a handheld radio communication unit in accordance with the invention has an antenna element structure with two longitudinally extending antenna elements 10A, 10B formed as metallic conductor tracks on the cylindrical outer surface of a ceramic core 12.
  • the core 12 has an axial passage 14 with an inner metallic lining 16, and the passage houses an axial inner feeder conductor 18.
  • the inner conductor 18 and the lining 16 in this case form a feeder structure for coupling a feed line to the antenna elements 10A, 10B at a feed position on the distal end face 12D of the core.
  • the antenna element structure also includes corresponding radial antenna elements 10AR, 10BR formed as metallic tracks on the distal end face 12D connecting diametrically opposed ends 10AE, 10BE of the respective longitudinally extending elements 10A, 10D to the feeder structure.
  • the other ends 10AF, 10BF of the antenna elements 10A, 10B are also diametrically opposed and are linked by an annular common virtual ground conductor 20 in the form of a plated sleeve surrounding a proximal end portion of the core 12. This sleeve 20 is in turn connected to the lining 16 of the axial passage 14 by plating 22 on the proximal end face 12P of the core 12.
  • the conductive sleeve 20 covers a proximal portion of the antenna core 12, thereby surrounding the feeder structure 16, 18, the material of the core 12 filling the whole of the space between the sleeve 20 and the metallic lining 16 of the axial passage 14.
  • the sleeve 20 forms a cylinder connected to the lining 16 by the plating 22 of the proximal end face 12P of the core 12, the combination of the sleeve 20 and plating 22 forming a balun so that signals in the transmission line formed by the feeder structure 16, 18 are converted between an unbalanced state at the proximal end of the antenna and a balanced state at an axial position approximately in the plane of the upper edge 20U of the sleeve 20.
  • the axial length of the sleeve 20 is such that in the presence of an underlying core material of relatively high dielectric constant, the balun has an electrical length of about ⁇ /4 at the operating frequency of the antenna. Since the core material of the antenna has a foreshortening effect, the annular space surrounding the inner conductor 18 is filled with an insulating dielectric material 17 having a relatively small dielectric constant, and the feeder structure distally of the sleeve 20 has a short electric length. As a result, signals at the distal end of the feeder structure 16, 18 are at least approximately balanced.
  • a further effect of the sleeve 20 is that for signals in the region of the operating frequency of the antenna, the rim 20U of the sleeve 20 is effectively isolated from the ground represented by the outer conductor 16 of the feeder structure. This means that currents circulating between the antenna elements 10A, 10B, are confined to the rim 20U and the loop formed by the antenna element structure is isolated. The sleeve 20 thus acts as an isolating trap.
  • the longitudinally extending elements 10A, 10B are of equal length, each being in the form of a simple helix executing a half turn around the axis 12A of the core 12.
  • the antenna elements 10A, 10B are connected respectively to the inner conductor 18 and outer lining 16 of the feeder structure by their respective radial elements 10AR, 10BR. It will be seen, then, that the helical elements 10A, 10B, the radial elements 10AR, 10BR, and the sleeve 20 together form a conductive loop on the outer surface of the core 12, the loop being fed at the distal end of the core by a feeder structure which extends through the core from the proximal end and lies between the antenna elements 10A, 10B.
  • the antenna consequently has an end-fed bifilar helical structure.
  • the four ends 10AE, 10AF, 10BE, 10BF of the antenna elements 10A, 10B all lie in a common plane containing the axis 12A of the core 12. This common plane is indicated by the chain lines 24 in Figure 1.
  • the feed connection to the antenna element structure also lies in the common plane 24.
  • the antenna element structure is so configured that the integral of currents induced in elemental segments of this structure by a wave incident on the antenna from a direction 28 normal to the plane 24 and having a planar wavefront sums to zero at the feed position, i.e. where the feeder structure 16, 18 is connected to the antenna element structure.
  • the two elements 10A, 10B are equally disposed and equally weighted on either side of the plane 24, yielding vectorial symmetry about the plane.
  • Each element 10A, 10B may be regarded as being made up of a plurality of increments, each one of which lies diametrically opposite a corresponding complementary increment of the other of the elements 10A, 10B at an equal distance from the central axis 12A.
  • the antenna element structure with half-turn helical elements 10A, 10B performs in a manner similar to a simple planar loop, having a null in its radiation pattern in a direction transverse to the axis 12A and perpendicular to the plane 24.
  • the radiation pattern is, therefore, approximately of a figure-of-eight form in both the vertical and horizontal planes transverse to the axis 12A, as shown by Figure 2.
  • Orientation of the radiation pattern with respect to the perspective view of Figure 1 is shown by the axis system comprising axes X, Y, Z shown in both Figure 1 and Figure 2.
  • the radiation pattern has two nulls or notches, one on each side of the antenna, and each centred on the line 28 shown in Figure 1.
  • the antenna has particular application at frequencies between 200 MHz and 5 GHz.
  • the radiation pattern is such that the antenna lends itself especially to use in a handheld communication unit such as a cellular or cordless telephone handset, as shown in Figure 3.
  • the antenna is mounted such that its central axis 12A (see Figure 3) and the plane 24 (see Figure 1) are parallel to the inner face 30I of the handset 30, and specifically the inner face 30I in the region of the earphone 32.
  • the axis 12A also runs longitudinally in the handset 30, as shown. Again, the relative orientations of the antenna, its radiation pattern, and the handset 30 are evident by comparing the axis system X, Y, Z as it is shown in Figure 3 with the representations of the axis system in Figures 1 and 2.
  • the preferred material for the core 12 of the antenna is a zirconium-titanate-based material. This material has a relative dielectric constant of 36 and is noted also for its dimensional and electrical stability with varying temperature. Dielectric loss is negligible.
  • the core may be produced by extrusion or pressing.
  • the antenna elements 10A, 10B, 10AR, 10BR are metallic conductor tracks bonded to the outer cylindrical and distal end surfaces of the core 12, each track being of a width of at least four times its thickness over its operative length.
  • the tracks may be formed by initially plating the surfaces of the core 12 with a metallic layer and then selectively etching away the layer to expose the core according to a pattern applied in a photosensitive layer similar to that used for etching printed circuit boards.
  • the metallic material may be applied by selective deposition or by printing techniques. In all cases, the formation of the tracks as an integral layer on the outside of a dimensionally stable core leads to an antenna having dimensionally stable antenna elements.
  • an antenna as described above for the DECT band in the region of 1880 MHz to 1900 MHz typically has a core diameter of about 5mm and the longitudinally extending elements 10A, 10B have a longitudinal extent (i.e. parallel to the central axis 12A) of about 12.7mm.
  • the width of the elements 10A, 10B is about 0.3mm.
  • the length of the balun sleeve 20 is typically in the region of 7.5mm or less.
  • these dimensions are, for the longitudinal (axial) extent of the elements 10A, 10B: 0.08 ⁇ , for the core diameter: 0.0315 ⁇ , for the balun sleeve: 0.047 ⁇ or less, and for the track width: 0.00189 ⁇ .
  • Precise dimensions of the antenna elements 10A, 10B can be determined in the design stage on a trial and error basis by undertaking eigenvalue delay measurements.
  • Adjustments in the dimensions of the plated elements during manufacture of the antenna may be performed in the manner described in the afore mentioned US-A-5,854,608, with reference to Figures 3 to 6 thereof.
  • the small size of the antenna renders it particularly suitable in handheld devices such as a mobile telephone handset and other personal communication devices.
  • the plated balun sleeve 20 and/or the plated layer 22 on the proximal end face 12P of the core 12 allow the antenna to be directly mounted on a printed circuit board or other ground structure in a particularly secure manner.
  • the proximal end face 12P can be soldered to a ground plane on the upper face of a printed circuit board with the inner feed conductor 18 passing directly through a plated hole in the board for soldering to a conductor track on the lower surface.
  • sleeve 20 may be clamped or soldered to a printed circuit board ground plane extending parallel to the axis 12A, with the distal part of the antenna, bearing antenna elements 10A, 10B, extending beyond an edge of the ground plane. It is possible to mount the antenna 10 either wholly within the handset unit, or partially projecting as shown in Figure 3.
  • the antenna elements 10A, 10B plated on the cylindrical surface of core 12 are, in this case, parallel to the central axis 12A on opposite sides of the latter.
  • the antenna elements 10A, 10B are connected respectively to the inner and outer conductors 18, 16 of the feeder structure via radial elements 10AR, 10BR on the distal end face 12D of the core 12.
  • radial elements 10AR, 10BR on the distal end face 12D of the core 12.
  • sleeve 20 forms an isolating trap so that its upper rim forms part of a loop extending around the core from one feeder conductor 16 to the other 18.
  • the antenna of Figure 4 is similar to that of Figure 1. It has a similar radiation pattern, with nulls directed transversely of the central axis and perpendicular to the plane containing elements 10A, 10B, and the feeder structure 16, 18.

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Claims (31)

  1. Appareil de communication radio (30) comprenant une antenne (10) qui comprend une structure d'antenne élémentaire comprenant une paire d'antennes élémentaires disposées de façon coextensive dans une configuration en opposition et qui sont reliées ensemble de façon à former une boucle, l'antenne comprenant un coeur isolant électrique, caractérisé en ce que :
    l'appareil est un appareil susceptible d'être tenu à la main comprenant un émetteur-récepteur radio et un écouteur miniature intégral (32) pour diriger l'énergie sonore depuis une face interne (30I) de l'appareil qui, lorsqu'il est utilisé, est placé contre l'oreille de l'utilisateur ;
    l'antenne (10) est couplée à l'émetteur-récepteur et est située dans la région de l'écouteur miniature (32) ;
    le coeur de l'antenne est un matériau plein présentant une constante diélectrique relative supérieure à 5, les antennes élémentaires (10A, 10B) étant disposées sur la surface extérieure du coeur (12) ou adjacentes à lui ;
    la structure d'antenne élémentaire présente un motif de rayonnement qui présente un zéro dans une direction transversale aux antennes élémentaires ; et
    l'antenne est ainsi montée dans l'appareil (30) que le zéro est dirigé généralement perpendiculairement à ladite face interne (30I) de l'appareil de façon à réduire le niveau de rayonnement en provenance de l'appareil dans la direction de la tête de l'utilisateur.
  2. Appareil selon la revendication 1, caractérisé en ce que le coeur (12) de l'antenne se présente sous la forme d'un cylindre dont l'axe central (12A) est sensiblement parallèle à ladite face interne (30I) dans la région de l'écouteur miniature (32).
  3. Appareil selon la revendication 2, caractérisé en ce que les antennes élémentaires (10A, 10B) s'étendent entre une paire de positions espacées axialement sur le cylindre, avec les extrémités des antennes élémentaires (10AE, 10BE, 10AF, 10BF) chacune à une position telle qu'elles se trouvent diamétralement opposées les unes les autres et qu'elles se situent dans un plan (24) qui contient l'axe central (12A) et qui est généralement parallèle à la face interne (30I) de l'appareil (30) dans la région de l'écouteur miniature (32).
  4. Appareil selon la revendication 3, caractérisé en ce que la structure d'antenne élémentaire comprend en outre un conducteur de liaison (20) qui relie les extrémités des antennes élémentaires (10AF, 10BF) à l'une des positions espacées.
  5. Appareil selon l'une quelconque des revendications 2 à 4, caractérisé en ce que les antennes élémentaires (10A, 10B) sont hélicoïdales et sont axialement co-extensives.
  6. Appareil selon la revendication 5, caractérisé en ce que les antennes élémentaires (10A, 10B) exécutent chacune un demi tour autour de l'axe central.
  7. Appareil selon la revendication 4 ou la revendication 5, caractérisé en ce que le conducteur de liaison est formé par un manchon conducteur (20) encerclant le cylindre pour former un piège isolant, et les antennes élémentaires (10A, 10B) aux autres positions espacées sont couplées à une structure de ligne d'alimentation axiale (16-18) qui traverse le coeur (12).
  8. Appareil selon l'une quelconque des revendications précédentes, caractérisé en ce que le coeur d'antenne (12) est formé en un matériau plein occupant la partie principale du volume défini par la surface extérieure du coeur, et en ce que les antennes élémentaires (10A, 10B) s'étendent entre des positions espacées dans la direction d'un axe central (12A) de l'antenne, tandis que lesdits éléments sont reliés à leurs extrémités respectives pour former une boucle conductrice autour du coeur, les autres extrémités des antennes élémentaires constituant une connexion d'alimentation.
  9. Appareil selon la revendication 8, caractérisé en ce que le coeur (12) définit l'axe central (12A), et en ce que les antennes élémentaires (10A, 10B) sont essentiellement coextensives dans la direction axiale, chaque élément s'étendant entre des positions espacées axialement sur la surface extérieure du coeur ou adjacent à lui de telle sorte qu'à chacune des positions espacées les parties respectives espacées (10AE, 10BE, 10AF, 10BF) des antennes élémentaires se situent sensiblement dans un plan unique (24) contenant l'axe central du coeur.
  10. Appareil selon la revendication 9, caractérisé en ce que le coeur (12) est cylindrique et les antennes élémentaires (10A,10B) sont de même longueur et sont hélicoïdales, chacune exécutant un demi tour autour du coeur (12) entre lesdites positions espacées (10AE, 10BE, 10AF, 10BF).
  11. Appareil selon l'une quelconque des revendications 8 à 10, caractérisé par un piège intégral (20) disposé de façon à favoriser une condition sensiblement équilibrée au niveau de la connexion d'alimentation.
  12. Appareil selon l'une quelconque des revendications 8 à 11, comprenant une structure de ligne d'alimentation (16-18) passant à travers le coeur et qui est reliée auxdites autres extrémités des antennes élémentaires.
  13. Appareil selon la revendication 10, caractérisé en ce que les antennes élémentaires (10A, 10B) sont couplées à des parties radiales respectives (10AR, 10BR) qui se situent sur un diamètre unique, lesdites parties d'antenne élémentaire aux autres des positions espacées étant couplées à la connexion d'alimentation.
  14. Appareil selon la revendication 13, caractérisé par une structure de ligne d'alimentation coaxiale (16-18) passant à travers le coeur et qui est reliée aux parties radiales à une extrémité distale du coeur.
  15. Appareil selon la revendication 14, caractérisé en ce que le conducteur de liaison (20) est annulaire et est relié de façon proximale aux antennes élémentaires (10A, 10B).
  16. Appareil selon la revendication 15, caractérisé en ce que le conducteur de liaison comprend un manchon conducteur cylindrique (20) sur une partie proximale de la surface extérieure du coeur (12), et en ce que l'extrémité proximale du manchon (20) est reliée à une partie écran extérieure (16) de la structure de ligne d'alimentation.
  17. Appareil selon l'une quelconque des revendications précédentes, caractérisé en ce que les antennes élémentaires forment une partie d'une boucle ayant une paire de parties latérales (10A, 10B) et des parties transversales (10AR, 10BR, 20U) qui s'étendent entre chacune des parties latérales, les extrémités (10AE, 10BE, 10AF, 10BF) des parties latérales définissant les angles d'un rectangle imaginaire, l'une des parties transversales contenant la connexion d'alimentation.
  18. Appareil selon la revendication 17, caractérisé en ce que, entre leurs extrémités, les parties latérales (10A, 10B) s'étendent sur les côtés opposés du plan du rectangle.
  19. Appareil selon la revendication 18, caractérisé en ce que chaque incrément de chaque partie latérale (10A, 10B) présente un incrément complémentaire correspondant dans l'autre partie latérale, de telles paires d'incréments complémentaires étant espacées également et en opposition à partir d'un axe central du rectangle.
  20. Appareil selon la revendication 8, caractérisé en ce que les antennes élémentaires forment une boucle autour du coeur et sont configurées de telle façon que dans la région de la connexion d'alimentation et dans une région opposée à la connexion d'alimentation, lesquelles régions sont associées à un axe central (12A) de l'antenne, les courants résultant dans la boucle se déplacent dans un plan commun (24) contenant l'axe central.
  21. Appareil selon la revendication 20, caractérisé en ce que les éléments sont configurés de telle sorte que les courants résultants dans les régions respectives voyagent dans des directions identiques et parallèles dans le plan commun (24).
  22. Appareil selon la revendication 20, caractérisé en ce que les éléments sont configurés de telle façon que les courants résultants dans les régions respectives voyagent dans des directions parallèles mais opposées dans le plan commun (24).
  23. Appareil selon l'une quelconque des revendications 20 à 22, caractérisé en ce que les antennes élémentaires comprennent, dans la région opposée à la connexion d'alimentation, des conducteurs (20U) qui s'étendent sur les côtés opposés dudit plan (24) entre des points contenus dans le plan et qui sont situés sur des côtés opposés de l'axe central (12A).
  24. Appareil selon la revendication 21, caractérisé en ce que la constante diélectrique relative du matériau du coeur est supérieure à 10.
  25. Appareil selon la revendication 21, caractérisé en ce que la constante diélectrique relative du matériau du coeur est supérieure à 20.
  26. Appareil selon l'une quelconque des revendications précédentes, configuré de façon à avoir une fréquence de fonctionnement située dans la région de 800 MHz à 900 MHz.
  27. Appareil selon l'une quelconque des revendications 1 à 25, configuré de façon à avoir une fréquence de fonctionnement située dans la région de 1800 à 2000 MHz.
  28. Appareil selon l'une quelconque des revendications 1 à 7, caractérisé en ce que l'antenne (10) a une alimentation équilibrée au niveau de la connexion d'alimentation.
  29. Appareil selon la revendication 28, caractérisé en ce que la boucle a une longueur électrique de 360° pour une fréquence de fonctionnement de l'appareil.
  30. Appareil selon l'une quelconque des revendications précédentes, caractérisé en ce que l'antenne a un motif de rayonnement généralement toroïdal.
  31. Appareil selon l'une quelconque des revendications précédentes, caractérisé en ce que la structure d'antenne élémentaire est une boucle tordue comprenant une paire d'éléments hélicoïdaux coextensifs d'un demi-tour ayant un axe commun et qui sont disposés dans une configuration en opposition, les extrémités des éléments étant situées dans un plan commun contenant l'axe commun.
EP97900334A 1996-01-23 1997-01-10 Antenne pour frequences superieures a 200 mhz Expired - Lifetime EP0876688B1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
GB9601250 1996-01-23
GBGB9601250.5A GB9601250D0 (en) 1996-01-23 1996-01-23 An antenna
GB9610581A GB2309592B (en) 1996-01-23 1996-05-21 An Antenna
GB9610581 1996-05-21
PCT/GB1997/000085 WO1997027642A1 (fr) 1996-01-23 1997-01-10 Antenne pour frequences superieures a 200 mhz

Publications (2)

Publication Number Publication Date
EP0876688A1 EP0876688A1 (fr) 1998-11-11
EP0876688B1 true EP0876688B1 (fr) 2003-06-04

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EP97900334A Expired - Lifetime EP0876688B1 (fr) 1996-01-23 1997-01-10 Antenne pour frequences superieures a 200 mhz

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EP (1) EP0876688B1 (fr)
JP (1) JP4467642B2 (fr)
CN (1) CN1099721C (fr)
AT (1) ATE242550T1 (fr)
AU (1) AU720873B2 (fr)
CA (1) CA2245882C (fr)
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GB9813002D0 (en) * 1998-06-16 1998-08-12 Symmetricom Inc An antenna
GB9828768D0 (en) * 1998-12-29 1999-02-17 Symmetricom Inc An antenna
GB9902765D0 (en) * 1999-02-08 1999-03-31 Symmetricom Inc An antenna
DE19923524C1 (de) * 1999-05-21 2001-04-19 Siemens Ag Verfahren zur Herstellung einer Antenne für Sende-/Empfangseinrichtungen
GB9912441D0 (en) * 1999-05-27 1999-07-28 Symmetricon Inc An antenna
GB2420230B (en) * 2004-11-11 2009-06-03 Sarantel Ltd A dielectrically-loaded antenna
GB2444749B (en) * 2006-12-14 2009-11-18 Sarantel Ltd A radio communication system
KR100821981B1 (ko) * 2007-02-02 2008-04-15 이성철 무지향성 안테나
DE102013201685B4 (de) 2013-02-01 2019-04-04 Siemens Healthcare Gmbh Leiteranordnung mit dielektrischer Mantelwellensperre
CN115693106A (zh) * 2022-11-10 2023-02-03 星启空间(南通)通信设备有限公司 一种卫星及星载天线

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US4442438A (en) * 1982-03-29 1984-04-10 Motorola, Inc. Helical antenna structure capable of resonating at two different frequencies
US5346300A (en) * 1991-07-05 1994-09-13 Sharp Kabushiki Kaisha Back fire helical antenna
US5708445A (en) * 1993-01-29 1998-01-13 Motorola, Inc. Antenna assembly for radio circuit and method therefor
GB9417450D0 (en) * 1994-08-25 1994-10-19 Symmetricom Inc An antenna

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CN1099721C (zh) 2003-01-22
WO1997027642A1 (fr) 1997-07-31
AU1391997A (en) 1997-08-20
AU720873B2 (en) 2000-06-15
ATE242550T1 (de) 2003-06-15
CA2245882A1 (fr) 1997-07-31
CA2245882C (fr) 2004-11-09
JP2000506690A (ja) 2000-05-30
CN1214151A (zh) 1999-04-14
JP4467642B2 (ja) 2010-05-26
DE69722590T2 (de) 2004-05-06
DE69722590D1 (de) 2003-07-10
EP0876688A1 (fr) 1998-11-11

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