WO2009010724A1 - Antennas - Google Patents

Antennas Download PDF

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Publication number
WO2009010724A1
WO2009010724A1 PCT/GB2008/002386 GB2008002386W WO2009010724A1 WO 2009010724 A1 WO2009010724 A1 WO 2009010724A1 GB 2008002386 W GB2008002386 W GB 2008002386W WO 2009010724 A1 WO2009010724 A1 WO 2009010724A1
Authority
WO
WIPO (PCT)
Prior art keywords
antenna
dielectric structure
end portion
central portion
feed element
Prior art date
Application number
PCT/GB2008/002386
Other languages
French (fr)
Inventor
William Giles Scanlon
Gareth Anthony John Conway
Original Assignee
The Queen's University Of Belfast
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by The Queen's University Of Belfast filed Critical The Queen's University Of Belfast
Publication of WO2009010724A1 publication Critical patent/WO2009010724A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/273—Adaptation for carrying or wearing by persons or animals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/40—Radiating elements coated with or embedded in protective material
    • 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
    • H01Q1/526—Electromagnetic shields
    • 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
    • H01Q19/06—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 refracting or diffracting devices, e.g. lens
    • H01Q19/09—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 refracting or diffracting devices, e.g. lens wherein the primary active element is coated with or embedded in a dielectric or magnetic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems
    • 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
    • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
    • H01Q9/32—Vertical arrangement of element
    • H01Q9/38—Vertical arrangement of element with counterpoise

Definitions

  • the invention relates to antennas and particularly, but not exclusively, to wearable antennas.
  • the body may be a human body, and the antennas used for example on clothing, armour, wireless medical sensors, or the body may be that of a vehicle, e.g. a car, aircraft or spacecraft.
  • monopole-antenna structures mounted over a groundplane are used, and, in some applications, may be realised using conductive fabric or micro-strip substrate materials.
  • conductive fabric or micro-strip substrate materials there are limitations on the performance and durability of such antennas.
  • an antenna comprising an antenna feed element, a dielectric structure comprising a first end portion, a second end portion and a central portion extending between the first and second end portions which at least partially surrounds the antenna feed element, and a groundplane provided on the first end portion of the dielectric structure, wherein the central portion of the dielectric structure tapers from at least one of the first and second end portions of the dielectric structure towards an other of the first and second end portions of the dielectric structure.
  • the tapered central portion of the dielectric structure may provide increased electromagnetic signal emission from the antenna feed element through the central portion in comparison to electromagnetic signal emission from the antenna feed element through the first and second end portions.
  • the tapered central portion of the dielectric structure may promote propagation of electromagnetic signals along a surface of the body.
  • the tapered central portion of the dielectric structure may promote coupling of the electromagnetic signals along a dielectric interface formed between the surface of the body and free space around the body.
  • the tapered central portion of the dielectric structure may taper from the first end portion of the dielectric structure to the second end portion of the dielectric structure.
  • the tapered central portion of the dielectric structure may taper from the second end portion of the dielectric structure to the first end portion of the dielectric structure.
  • the dielectric structure may be substantially frustoconical in shape.
  • the tapered central portion of the dielectric structure may taper from the first end portion of the dielectric structure towards the second end portion of the dielectric structure, and from the second end portion of the dielectric structure towards the first end portion of the dielectric structure.
  • the dielectric structure may be substantially shaped as an hour glass.
  • the dielectric structure may comprise a material having a dielectric constant of approximately 10.
  • the second end portion of the dielectric structure may form a base of the antenna. When used with a body, the second end portion may be placed in close proximity to the body.
  • the antenna feed element may be elongate and may extend substantially from the first end portion of the dielectric structure to substantially the second end portion of the dielectric structure.
  • the antenna feed element may be substantially surrounded by the central portion of the dielectric structure.
  • the antenna feed element may comprise a rod-like structure.
  • the antenna feed element may receive and/or transmit electromagnetic signals.
  • the antenna feed element may be substantially perpendicular to the groundplane.
  • the antenna feed element may comprise a plate.
  • the plate may be attached to an end of the antenna feed element closest to the second end of the dielectric structure.
  • the plate may comprise a metallic disk.
  • the plate may promote decreasing the height of the antenna, providing a low profile or very low profile antenna.
  • the plate may promote an increase in the bandwidth of the antenna.
  • the groundplane may comprise a conductive material, e.g. a metallic material.
  • the groundplane may comprise a plate-like structure.
  • the groundplane may be provided with a dielectric layer.
  • the dielectric layer may be provided on the groundplane, between the groundplane and the first end portion of the dielectric structure.
  • the dielectric layer may be provided on an opposite side of the groundplane from the first end portion of the dielectric structure.
  • the antenna may comprise electronic circuitry, for use with the antenna feed element for emission of electromagnetic signals or receiving of electromagnetic signals or both.
  • the electronic circuitry may be provided on the groundplane.
  • the electronic circuitry may be provided on a first side of the groundplane, and the groundplane may be provided on the dielectric structure by a second, opposite, side of the groundplane.
  • the presence of the groundplane provides separation of the electronic circuitry and the antenna feed element. This will reduce interference between electromagnetic signals emitted by the antenna feed element and any electromagnetic signals which may be emitted by the electronic circuitry. This will also reduce the effect of changes in the electronic circuitry and construction on the antenna performance.
  • the antenna may comprise a shield structure.
  • the shield structure may be provided on the second end portion of the dielectric structure.
  • the shield structure may substantially cover the second end portion.
  • the shield structure may comprise a meta-material.
  • the shield structure may be patterned. In use of the antenna with a body, the shield structure may be positioned adjacent the body.
  • the shield structure may act to shield the body from electromagnetic signals emitted by the antenna feed element.
  • the shield structure may act to reduce electromagnetic signal losses to the body, which will improve efficiency of the antenna.
  • the antenna may have a bandwidth of approximately 24% at approximately 2.45 GHz.
  • the antenna may have a bandwidth much greater than 500 MHz in the 3 to 10 GHz region, for example approximately 1.2 GHz or more at 6 GHz.
  • an antenna system comprising a plurality of antennas according to the first aspect of the invention, wherein each antenna emits electromagnetic signals to at least one other antenna.
  • the antenna system may be used in conjunction with a body, and the plurality of antennas may be positioned adjacent the body at spaced locations of the body.
  • the body may comprise a human body and the antennas may be attached to the body or to a covering on the body e.g. clothing.
  • the antenna system may then comprise a wearable antenna system.
  • Figure 1 is a schematic representation of a first embodiment of an antenna according to the invention
  • Figure 2 is a schematic representation of a second embodiment of an antenna according to the invention
  • Figure 3 is a schematic representation of a body provided with three antennas according to the invention.
  • FIG. 1 shows an antenna 1 , according to a first embodiment of the invention.
  • This comprises a groundplane 3, an antenna feed element 5 in the form of a rod, a tapered dielectric structure 7, and electronic circuitry 9, for use with the antenna feed element 5 for generating and detecting electromagnetic (EM) signals.
  • EM electromagnetic
  • the groundplane 3 comprises a metallic material.
  • the antenna feed element 5 comprises a highly conductive material.
  • the dielectric structure 7 comprises a dielectric material which has a dielectric constant of approximately 10 in this embodiment. It will be understood that other dielectric materials may be used.
  • the dielectric structure 7 has a frustoconical shape, and comprises a first end portion 11 , a central portion 13, and a second end portion 15. In this embodiment, the central portion 13 tapers from the second end portion 15 to the first end portion 11 , as shown.
  • the groundplane 3 (and the electronic circuitry 9) is provided on the first end portion 11 of the dielectric structure 7.
  • the electronic circuitry 9 is positioned on a first side of the groundplane 3, and the antenna feed element 5 positioned on a second, opposite side of the groundplane 3 forming a coaxial feed. This is advantageous in that any EM signals produced by the electronic circuitry 9 will be less likely to interfere with EM signals produced by the antenna feed element 5.
  • the antenna 1 further comprises a shield structure 17, which is attached to the second end portion 15 of the dielectric structure 7, such that it substantially covers the second end portion 15.
  • the shield structure 17 comprises a meta-material, and provides a shield for EM signals produced by the antenna feed element 5.
  • the dimensions of the antenna 1 are diameter approximately equal to 30mm and height approximately equal to 13mm.
  • the dimensions of the antenna are chosen with regard to the frequency of EM signals that it is desired that the antenna feed element 5 should emit and receive. Provision of the dielectric structure 7 around the antenna feed element 5 allows the length of the antenna feed element 5 to be reduced, and hence the height of the antenna to be reduced. This is advantageous when the antenna 1 is used on a body, as there is less chance of damage to the antenna 1 as protrusion of the antenna 1 from the body is reduced.
  • the antenna 1 is placed adjacent a body, such that the shield structure 17 attached to the dielectric structure 7 is closest to the body and the dielectric structure 7 and the antenna feed element 5 project from the body.
  • EM signals will be emitted by the antenna feed element 5 in substantially all directions.
  • EM signals emitted by the antenna feed element 5 towards the body will be at least partially shielded from coupling with the body by the shield structure 17.
  • Patterning may be applied to the shield structure 17 to enhance its shielding function.
  • the tapering of the central portion 13 of the dielectric structure 7 increases EM signal emission through the central portion 13 in comparison to EM signal emission through the end portions 11 , 15 of the dielectric structure 7 and the groundplane 3 and the shield structure 17.
  • EM signals which are emitted substantially perpendicular to the length of the antenna feed element 5 will propagate along a surface of the body to which the shield structure 17 is adjacent, i.e. will propagate along a dielectric interface between the body and free space around the body. Propagation of EM signals along this interface is enhanced in comparison to propagation of EM signals away from the body, due to the tapered central portion 13 of the dielectric structure 7 which surrounds the antenna feed element 5.
  • the tapering of this portion enhances coupling of EM signals along the interface, and, subject to careful design, can reduce dielectric losses increasing antenna efficiency.
  • the degree of tapering of the central portion 13 may be varied, along with other properties of the antenna 1 , e.g.
  • the bandwidth of the antenna 1 is of the order of 1OdB, which is much greater than state-of-the-art microstrip patch antennas or similar antennas.
  • Such a broadband antenna 1 is more robust than previous antennas, in the sense that the antenna 1 of the invention is able to function well even if the distance between the antenna 1 and the body changes, e.g. due to movement of the antenna 1 on the body.
  • FIG. 2 shows an antenna 21 according to a second embodiment of the invention, which offers an alternative arrangement to the first embodiment of the invention shown in Figure 1.
  • the antenna 21 comprises a groundplane 23, an antenna feed element 25 in the form of a rod, a tapered dielectric structure 27, and electronic circuitry 29, for use with the antenna feed element 25 for generating and detecting EM signals.
  • the dielectric structure 27 has a frustoconical shape, and comprises a first end portion 31 , a central portion 33, and a second end portion 35.
  • the central portion 33 tapers from the first end portion 31 to the second end portion 35, as shown.
  • the antenna 21 further comprises a shield structure 37, which is attached to the second end portion 35 of the dielectric structure 27, such that it substantially covers the second end portion 35.
  • the shield structure 37 comprises a meta-material, and provides a shield for EM signals produced by the antenna feed element 25.
  • the dimensions of the antenna 21 are diameter approximately equal to 30mm and height approximately equal to 13mm.
  • the dimensions of the antenna 21 are again chosen with regard to the frequency of EM signals that it is desired that the antenna feed element 25 should emit. Provision of the dielectric structure 27 around the antenna feed element 25 allows the length of the antenna feed element 25 to be reduced, and hence the height of the antenna to be reduced. This is again advantageous when the antenna 21 is used on a body, as there is less chance of damage to the antenna 21 as protrusion of the antenna 21 from the body is reduced.
  • the antenna 21 is again placed adjacent a body, such that the shield structure 37 provided on the second end portion 35 is closest to the body and the dielectric structure 27 and the antenna feed element 25 project from the body.
  • EM signals will be emitted by the antenna feed element 25 in substantially all directions.
  • EM signals emitted by the antenna feed element 25 towards the body will be at least partially shielded from coupling with the body by the shield structure 37.
  • Patterning may be applied to the shield structure 37 to enhance its shielding function.
  • the tapering of the central portion 33 of the dielectric structure 27 also increases EM signal emission through the central portion 33 in comparison to EM signal emission through the end portions 31 , 35 of the dielectric structure 27 and the groundplane 23 and the shield structure 37.
  • EM signals which are emitted substantially perpendicular to the length of the antenna feed element 25, will propagate along a surface of the body to which the shield structure 37 is adjacent, i.e. will propagate along a dielectric interface between the body and free space around the body. Propagation of EM signals along this interface is enhanced in comparison to propagation of EM signals away from the body, due to the tapered central portion 33 of the dielectric structure 27 which surrounds the antenna feed element 25. The tapering of this portion enhances coupling of EM signals along the interface.
  • the degree of tapering of the central portion 33 may be varied, along with other properties of the antenna 21 , e.g. dimensions and choice of material for the components of the antenna, to maximise the propagation of EM signals along the body/free space interface.
  • the bandwidth of the antenna 21 is again of the order of 1OdB, and again is much greater than state-of-the-art microstrip patch antennas or similar antennas.
  • Such a broadband antenna 21 is more robust than previous antennas, in the sense that the antenna 21 of the invention is able to function well even if the distance between the antenna 21 and the body changes, e.g. due to movement of the antenna 21 on the body.
  • FIG 3 shows three antennas 40, as described in Figure 1 and or Figure 2, placed adjacent a body 42.
  • the body 42 may comprise a human torso, in which case the antennas 40 may be placed over clothing on the body.
  • the body may comprise a vehicle, in which case the antennas 40 may be attached to the body.
  • the antennas 40 work on a basis of propagating EM signals emitted by the antennas 40 along a dielectric interface between the body 42 and free space around the body 42. Due to the tapered central portion of the dielectric structure of the antennas 40, coupling of the EM signals along the interface is enhanced. The EM signals will therefore propagate at angles allowing them to contour along the surface of the body 42.
  • the antennas 40 may then communicate with each other, despite being located on different parts of the body, with, in some cases, no direct line of sight between them.
  • the antennas 40 may thus form a wearable antenna system.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Details Of Aerials (AREA)
  • Waveguide Aerials (AREA)

Abstract

An antenna comprising an antenna feed element, a dielectric structure comprising a first end portion, a second end portion and a central portion extending between the first and second end portions which at least partially surrounds the antenna feed element, and a groundplane provided on the first end portion of the dielectric structure, wherein the central portion of the dielectric structure tapers from at least one of the first and second end portions of the dielectric structure towards an other of the first and second end portions of the dielectric structure. An antenna system comprising a plurality of antennas of the invention, wherein each antenna emits electromagnetic signals to at least one other antenna, and when used in conjunction with a body, the plurality of antennas may be positioned adjacent the body at spaced locations of the body. The body may comprise a human body and the antennas may be attached to the body or to a covering on the body. The antenna system may then comprise a wearable antenna system.

Description

Antennas
The invention relates to antennas and particularly, but not exclusively, to wearable antennas.
Recently there has been renewed interest in antennas for application to a body for transmission of waves along or around the body. The body may be a human body, and the antennas used for example on clothing, armour, wireless medical sensors, or the body may be that of a vehicle, e.g. a car, aircraft or spacecraft. Currently, monopole-antenna structures mounted over a groundplane are used, and, in some applications, may be realised using conductive fabric or micro-strip substrate materials. However, there are limitations on the performance and durability of such antennas.
According to a first aspect of the invention there is provided an antenna comprising an antenna feed element, a dielectric structure comprising a first end portion, a second end portion and a central portion extending between the first and second end portions which at least partially surrounds the antenna feed element, and a groundplane provided on the first end portion of the dielectric structure, wherein the central portion of the dielectric structure tapers from at least one of the first and second end portions of the dielectric structure towards an other of the first and second end portions of the dielectric structure.
The tapered central portion of the dielectric structure may provide increased electromagnetic signal emission from the antenna feed element through the central portion in comparison to electromagnetic signal emission from the antenna feed element through the first and second end portions. In use of the antenna with a body, the tapered central portion of the dielectric structure may promote propagation of electromagnetic signals along a surface of the body. The tapered central portion of the dielectric structure may promote coupling of the electromagnetic signals along a dielectric interface formed between the surface of the body and free space around the body. The tapered central portion of the dielectric structure may taper from the first end portion of the dielectric structure to the second end portion of the dielectric structure. The tapered central portion of the dielectric structure may taper from the second end portion of the dielectric structure to the first end portion of the dielectric structure. The dielectric structure may be substantially frustoconical in shape. The tapered central portion of the dielectric structure may taper from the first end portion of the dielectric structure towards the second end portion of the dielectric structure, and from the second end portion of the dielectric structure towards the first end portion of the dielectric structure. The dielectric structure may be substantially shaped as an hour glass. The dielectric structure may comprise a material having a dielectric constant of approximately 10.
The second end portion of the dielectric structure may form a base of the antenna. When used with a body, the second end portion may be placed in close proximity to the body.
The antenna feed element may be elongate and may extend substantially from the first end portion of the dielectric structure to substantially the second end portion of the dielectric structure. The antenna feed element may be substantially surrounded by the central portion of the dielectric structure. The antenna feed element may comprise a rod-like structure. The antenna feed element may receive and/or transmit electromagnetic signals. The antenna feed element may be substantially perpendicular to the groundplane. The antenna feed element may comprise a plate. The plate may be attached to an end of the antenna feed element closest to the second end of the dielectric structure. The plate may comprise a metallic disk. The plate may promote decreasing the height of the antenna, providing a low profile or very low profile antenna. The plate may promote an increase in the bandwidth of the antenna.
The groundplane may comprise a conductive material, e.g. a metallic material. The groundplane may comprise a plate-like structure. The groundplane may be provided with a dielectric layer. The dielectric layer may be provided on the groundplane, between the groundplane and the first end portion of the dielectric structure. The dielectric layer may be provided on an opposite side of the groundplane from the first end portion of the dielectric structure.
The antenna may comprise electronic circuitry, for use with the antenna feed element for emission of electromagnetic signals or receiving of electromagnetic signals or both. The electronic circuitry may be provided on the groundplane. The electronic circuitry may be provided on a first side of the groundplane, and the groundplane may be provided on the dielectric structure by a second, opposite, side of the groundplane. The presence of the groundplane provides separation of the electronic circuitry and the antenna feed element. This will reduce interference between electromagnetic signals emitted by the antenna feed element and any electromagnetic signals which may be emitted by the electronic circuitry. This will also reduce the effect of changes in the electronic circuitry and construction on the antenna performance.
The antenna may comprise a shield structure. The shield structure may be provided on the second end portion of the dielectric structure. The shield structure may substantially cover the second end portion. The shield structure may comprise a meta-material. The shield structure may be patterned. In use of the antenna with a body, the shield structure may be positioned adjacent the body. The shield structure may act to shield the body from electromagnetic signals emitted by the antenna feed element. The shield structure may act to reduce electromagnetic signal losses to the body, which will improve efficiency of the antenna.
The antenna may have a bandwidth of approximately 24% at approximately 2.45 GHz. The antenna may have a bandwidth much greater than 500 MHz in the 3 to 10 GHz region, for example approximately 1.2 GHz or more at 6 GHz.
According to a second aspect of the invention there is provided an antenna system comprising a plurality of antennas according to the first aspect of the invention, wherein each antenna emits electromagnetic signals to at least one other antenna.
The antenna system may be used in conjunction with a body, and the plurality of antennas may be positioned adjacent the body at spaced locations of the body. The body may comprise a human body and the antennas may be attached to the body or to a covering on the body e.g. clothing. The antenna system may then comprise a wearable antenna system.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a schematic representation of a first embodiment of an antenna according to the invention; Figure 2 is a schematic representation of a second embodiment of an antenna according to the invention, and
Figure 3 is a schematic representation of a body provided with three antennas according to the invention.
Figure 1 shows an antenna 1 , according to a first embodiment of the invention. This comprises a groundplane 3, an antenna feed element 5 in the form of a rod, a tapered dielectric structure 7, and electronic circuitry 9, for use with the antenna feed element 5 for generating and detecting electromagnetic (EM) signals.
The groundplane 3 comprises a metallic material. The antenna feed element 5 comprises a highly conductive material. The dielectric structure 7 comprises a dielectric material which has a dielectric constant of approximately 10 in this embodiment. It will be understood that other dielectric materials may be used.
The dielectric structure 7 has a frustoconical shape, and comprises a first end portion 11 , a central portion 13, and a second end portion 15. In this embodiment, the central portion 13 tapers from the second end portion 15 to the first end portion 11 , as shown. The groundplane 3 (and the electronic circuitry 9) is provided on the first end portion 11 of the dielectric structure 7. The electronic circuitry 9 is positioned on a first side of the groundplane 3, and the antenna feed element 5 positioned on a second, opposite side of the groundplane 3 forming a coaxial feed. This is advantageous in that any EM signals produced by the electronic circuitry 9 will be less likely to interfere with EM signals produced by the antenna feed element 5. The antenna 1 further comprises a shield structure 17, which is attached to the second end portion 15 of the dielectric structure 7, such that it substantially covers the second end portion 15. The shield structure 17 comprises a meta-material, and provides a shield for EM signals produced by the antenna feed element 5.
In this embodiment, the dimensions of the antenna 1 are diameter approximately equal to 30mm and height approximately equal to 13mm. The dimensions of the antenna are chosen with regard to the frequency of EM signals that it is desired that the antenna feed element 5 should emit and receive. Provision of the dielectric structure 7 around the antenna feed element 5 allows the length of the antenna feed element 5 to be reduced, and hence the height of the antenna to be reduced. This is advantageous when the antenna 1 is used on a body, as there is less chance of damage to the antenna 1 as protrusion of the antenna 1 from the body is reduced.
In use, the antenna 1 is placed adjacent a body, such that the shield structure 17 attached to the dielectric structure 7 is closest to the body and the dielectric structure 7 and the antenna feed element 5 project from the body. EM signals will be emitted by the antenna feed element 5 in substantially all directions. EM signals emitted by the antenna feed element 5 towards the body will be at least partially shielded from coupling with the body by the shield structure 17. Patterning may be applied to the shield structure 17 to enhance its shielding function. The tapering of the central portion 13 of the dielectric structure 7 increases EM signal emission through the central portion 13 in comparison to EM signal emission through the end portions 11 , 15 of the dielectric structure 7 and the groundplane 3 and the shield structure 17. EM signals which are emitted substantially perpendicular to the length of the antenna feed element 5, will propagate along a surface of the body to which the shield structure 17 is adjacent, i.e. will propagate along a dielectric interface between the body and free space around the body. Propagation of EM signals along this interface is enhanced in comparison to propagation of EM signals away from the body, due to the tapered central portion 13 of the dielectric structure 7 which surrounds the antenna feed element 5. The tapering of this portion enhances coupling of EM signals along the interface, and, subject to careful design, can reduce dielectric losses increasing antenna efficiency. The degree of tapering of the central portion 13 may be varied, along with other properties of the antenna 1 , e.g. dimensions and choice of material for the components of the antenna 1 , to maximise the propagation of EM signals along the body/free space interface. The bandwidth of the antenna 1 is of the order of 1OdB, which is much greater than state-of-the-art microstrip patch antennas or similar antennas. Such a broadband antenna 1 is more robust than previous antennas, in the sense that the antenna 1 of the invention is able to function well even if the distance between the antenna 1 and the body changes, e.g. due to movement of the antenna 1 on the body.
Figure 2 shows an antenna 21 according to a second embodiment of the invention, which offers an alternative arrangement to the first embodiment of the invention shown in Figure 1. Like Figure 1 , the antenna 21 comprises a groundplane 23, an antenna feed element 25 in the form of a rod, a tapered dielectric structure 27, and electronic circuitry 29, for use with the antenna feed element 25 for generating and detecting EM signals. Again, the dielectric structure 27 has a frustoconical shape, and comprises a first end portion 31 , a central portion 33, and a second end portion 35. In this embodiment, the central portion 33 tapers from the first end portion 31 to the second end portion 35, as shown. The antenna 21 further comprises a shield structure 37, which is attached to the second end portion 35 of the dielectric structure 27, such that it substantially covers the second end portion 35. The shield structure 37 comprises a meta-material, and provides a shield for EM signals produced by the antenna feed element 25.
In this embodiment, the dimensions of the antenna 21 are diameter approximately equal to 30mm and height approximately equal to 13mm. The dimensions of the antenna 21 are again chosen with regard to the frequency of EM signals that it is desired that the antenna feed element 25 should emit. Provision of the dielectric structure 27 around the antenna feed element 25 allows the length of the antenna feed element 25 to be reduced, and hence the height of the antenna to be reduced. This is again advantageous when the antenna 21 is used on a body, as there is less chance of damage to the antenna 21 as protrusion of the antenna 21 from the body is reduced.
In use, the antenna 21 is again placed adjacent a body, such that the shield structure 37 provided on the second end portion 35 is closest to the body and the dielectric structure 27 and the antenna feed element 25 project from the body. EM signals will be emitted by the antenna feed element 25 in substantially all directions. EM signals emitted by the antenna feed element 25 towards the body will be at least partially shielded from coupling with the body by the shield structure 37. Patterning may be applied to the shield structure 37 to enhance its shielding function. The tapering of the central portion 33 of the dielectric structure 27 also increases EM signal emission through the central portion 33 in comparison to EM signal emission through the end portions 31 , 35 of the dielectric structure 27 and the groundplane 23 and the shield structure 37. EM signals which are emitted substantially perpendicular to the length of the antenna feed element 25, will propagate along a surface of the body to which the shield structure 37 is adjacent, i.e. will propagate along a dielectric interface between the body and free space around the body. Propagation of EM signals along this interface is enhanced in comparison to propagation of EM signals away from the body, due to the tapered central portion 33 of the dielectric structure 27 which surrounds the antenna feed element 25. The tapering of this portion enhances coupling of EM signals along the interface. The degree of tapering of the central portion 33 may be varied, along with other properties of the antenna 21 , e.g. dimensions and choice of material for the components of the antenna, to maximise the propagation of EM signals along the body/free space interface. The bandwidth of the antenna 21 is again of the order of 1OdB, and again is much greater than state-of-the-art microstrip patch antennas or similar antennas. Such a broadband antenna 21 is more robust than previous antennas, in the sense that the antenna 21 of the invention is able to function well even if the distance between the antenna 21 and the body changes, e.g. due to movement of the antenna 21 on the body.
Figure 3 shows three antennas 40, as described in Figure 1 and or Figure 2, placed adjacent a body 42. The body 42 may comprise a human torso, in which case the antennas 40 may be placed over clothing on the body. Alternatively, the body may comprise a vehicle, in which case the antennas 40 may be attached to the body. As described above, the antennas 40 work on a basis of propagating EM signals emitted by the antennas 40 along a dielectric interface between the body 42 and free space around the body 42. Due to the tapered central portion of the dielectric structure of the antennas 40, coupling of the EM signals along the interface is enhanced. The EM signals will therefore propagate at angles allowing them to contour along the surface of the body 42. The antennas 40 may then communicate with each other, despite being located on different parts of the body, with, in some cases, no direct line of sight between them. The antennas 40 may thus form a wearable antenna system.

Claims

1. An antenna comprising an antenna feed element, a dielectric structure comprising a first end portion, a second end portion and a central portion extending between the first and second end portions which at least partially surrounds the antenna feed element, and a groundplane provided on the first end portion of the dielectric structure, wherein the central portion of the dielectric structure tapers from at least one of the first and second end portions of the dielectric structure towards an other of the first and second end portions of the dielectric structure.
2. An antenna according to claim 1 , in which the tapered central portion of the dielectric structure provides increased electromagnetic signal emission from the antenna feed element through the central portion in comparison to electromagnetic signal emission from the antenna feed element through the first and second end portions.
3. An antenna according to claim 1 or claim 2, in which, in use of the antenna with a body, the tapered central portion of the dielectric structure promotes propagation of electromagnetic signals along a surface of the body.
4. An antenna according to claim 3, in which the tapered central portion of the dielectric structure promotes coupling of the electromagnetic signals along a dielectric interface formed between the surface of the body and free space around the body.
5. An antenna according to any preceding claim, in which the tapered central portion of the dielectric structure tapers from the first end portion of the dielectric structure to the second end portion of the dielectric structure.
6. An antenna according to any of claims 1 to 4, in which the tapered central portion of the dielectric structure tapers from the second end portion of the dielectric structure to the first end portion of the dielectric structure.
7. An antenna according to claim 5 or claim 6, in which the dielectric structure is substantially frustoconical in shape.
8. An antenna according to any of claim 1 to 4, in which the tapered central portion of the dielectric structure tapers from the first end portion of the dielectric structure towards the second end portion of the dielectric structure, and from the second end portion of the dielectric structure towards the first end portion of the dielectric structure.
9. An antenna according to claim 8, in which the dielectric structure is substantially shaped as an hour glass.
10. An antenna according to any preceding claim, in which, when used with a body, the second end portion of the dielectric structure is placed in close proximity to the body.
11. An antenna according to any preceding claim, in which the antenna feed element is elongate and extends substantially from the first end portion of the dielectric structure to substantially the second end portion of the dielectric structure, and is substantially surrounded by the central portion of the dielectric structure.
12. An antenna according to any preceding claim, which comprises a shield structure.
13. An antenna according to claim 12, in which, in use of the antenna with a body, the shield structure is positioned adjacent the body, and acts to shield the body from electromagnetic signals emitted by the antenna feed element.
14. An antenna system comprising a plurality of antennas according to any of claims 1 to 13, wherein each antenna emits electromagnetic signals to at least one other antenna.
15. An antenna system according to claim 14, which is used in conjunction with a body, and the plurality of antennas are positioned adjacent the body at spaced locations of the body.
16. An antenna system according to claim 15, in which the body comprises a human body and the antennas are attached to the body or to a covering on the body, and the antenna system comprises a wearable antenna system.
PCT/GB2008/002386 2007-07-13 2008-07-11 Antennas WO2009010724A1 (en)

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GBGB0713644.3A GB0713644D0 (en) 2007-07-13 2007-07-13 Antenna
GB0713644.3 2007-07-13

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WO2010089564A1 (en) 2009-02-04 2010-08-12 Rebecca Lynn Pilditch Skin-safe conductive ink and method for application on the body
US20120087506A1 (en) * 2010-10-12 2012-04-12 Gn Resound A/S Antenna System for a Hearing Aid
US9237405B2 (en) 2013-11-11 2016-01-12 Gn Resound A/S Hearing aid with an antenna
US9237404B2 (en) 2012-12-28 2016-01-12 Gn Resound A/S Dipole antenna for a hearing aid
US9293814B2 (en) 2010-10-12 2016-03-22 Gn Resound A/S Hearing aid with an antenna
US9369813B2 (en) 2012-07-06 2016-06-14 Gn Resound A/S BTE hearing aid having two driven antennas
US9402141B2 (en) 2012-07-06 2016-07-26 Gn Resound A/S BTE hearing aid with an antenna partition plane
US9408003B2 (en) 2013-11-11 2016-08-02 Gn Resound A/S Hearing aid with an antenna
US9446233B2 (en) 2007-05-31 2016-09-20 Gn Resound A/S Behind-the-ear (BTE) prosthetic device with antenna
US9554219B2 (en) 2012-07-06 2017-01-24 Gn Resound A/S BTE hearing aid having a balanced antenna
US9686621B2 (en) 2013-11-11 2017-06-20 Gn Hearing A/S Hearing aid with an antenna
US9883295B2 (en) 2013-11-11 2018-01-30 Gn Hearing A/S Hearing aid with an antenna
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US11819690B2 (en) 2007-05-31 2023-11-21 Cochlear Limited Acoustic output device with antenna
US11491331B2 (en) 2007-05-31 2022-11-08 Cochlear Limited Acoustic output device with antenna
US10219084B2 (en) 2007-05-31 2019-02-26 Gn Hearing A/S Acoustic output device with antenna
US9936312B2 (en) 2007-05-31 2018-04-03 Gn Hearing A/S Acoustic output device with antenna
WO2010089564A1 (en) 2009-02-04 2010-08-12 Rebecca Lynn Pilditch Skin-safe conductive ink and method for application on the body
US20120087506A1 (en) * 2010-10-12 2012-04-12 Gn Resound A/S Antenna System for a Hearing Aid
US10390150B2 (en) 2010-10-12 2019-08-20 Gn Hearing A/S Antenna system for a hearing aid
US20190320270A1 (en) * 2010-10-12 2019-10-17 Gn Hearing A/S Antenna system for a hearing aid
US10728679B2 (en) 2010-10-12 2020-07-28 Gn Hearing A/S Antenna system for a hearing aid
US9729979B2 (en) * 2010-10-12 2017-08-08 Gn Hearing A/S Antenna system for a hearing aid
US20170303056A1 (en) * 2010-10-12 2017-10-19 Gn Hearing A/S Antenna system for a hearing aid
US9293814B2 (en) 2010-10-12 2016-03-22 Gn Resound A/S Hearing aid with an antenna
US9369813B2 (en) 2012-07-06 2016-06-14 Gn Resound A/S BTE hearing aid having two driven antennas
US9554219B2 (en) 2012-07-06 2017-01-24 Gn Resound A/S BTE hearing aid having a balanced antenna
US9402141B2 (en) 2012-07-06 2016-07-26 Gn Resound A/S BTE hearing aid with an antenna partition plane
US9237404B2 (en) 2012-12-28 2016-01-12 Gn Resound A/S Dipole antenna for a hearing aid
US9883295B2 (en) 2013-11-11 2018-01-30 Gn Hearing A/S Hearing aid with an antenna
US9686621B2 (en) 2013-11-11 2017-06-20 Gn Hearing A/S Hearing aid with an antenna
US9408003B2 (en) 2013-11-11 2016-08-02 Gn Resound A/S Hearing aid with an antenna
US9237405B2 (en) 2013-11-11 2016-01-12 Gn Resound A/S Hearing aid with an antenna
US10595138B2 (en) 2014-08-15 2020-03-17 Gn Hearing A/S Hearing aid with an antenna

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