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WO1996019846A1 - Antenne helicoidale reglable - Google Patents

Antenne helicoidale reglable Download PDF

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Publication number
WO1996019846A1
WO1996019846A1 PCT/NZ1995/000136 NZ9500136W WO9619846A1 WO 1996019846 A1 WO1996019846 A1 WO 1996019846A1 NZ 9500136 W NZ9500136 W NZ 9500136W WO 9619846 A1 WO9619846 A1 WO 9619846A1
Authority
WO
WIPO (PCT)
Prior art keywords
antenna
wire
carriages
wires
substantially constant
Prior art date
Application number
PCT/NZ1995/000136
Other languages
English (en)
Inventor
Peter Eric Chadwick
Peter Bruce Graham
Cornelis Frederick Du Toit
Original Assignee
Deltec New Zealand Limited
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 Deltec New Zealand Limited filed Critical Deltec New Zealand Limited
Priority to AU43188/96A priority Critical patent/AU703819B2/en
Priority to NZ297911A priority patent/NZ297911A/xx
Publication of WO1996019846A1 publication Critical patent/WO1996019846A1/fr

Links

Classifications

    • 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

  • the present invention relates to an adjustable helical antenna. More particularly, but not exclusively, the present invention relates to a helical antenna, the wires of which may be adjusted to steer the beam of the antenna.
  • a helical antenna can be used to generate substantially circularly polarised electromagnetic radiation.
  • the radius of the helix is chosen to be much smaller than the pitch length, radiation is directed away from the helical axis, opposite to the direction of propagation of the wave giving rise to the radiation.
  • Helical antennas are often used in mobile satellite communication systems. This type of antenna is particularly suitable in this application as such antennas can be constructed in the form of a relatively thin rod and mounted vertically on a vehicle or other mobile structure. To direct the beam of an antenna of a desired satellite some form of beam steering is required to allow for azimuth variations in the transmission/ reception direction.
  • the helix geometry may be twisted. Such mechanical adjustment may result in the desired beam steering depending on the reproducibility and degree of control available.
  • Antenna geometry may be altered by keeping the pitch or length constant. If the pitch remains constant the change in radius must be large. If the length is constant, the change in radius is smaller. It is difficult to support the wires of the antenna while the radius changes.
  • the present invention is concerned with a practical means of adjusting the geometry of a helical antenna which obviates the abovementioned difficulties.
  • a helical antenna including a means for varying the length and pitch of the antenna whilst keeping the antenna radius substantially constant.
  • the antenna includes means for rotating one end of the wire or wires of the antenna relative to the other end as the length of the antenna is varied so as to maintain the radius substantially constant.
  • the wire or wires at the one end are attached to a first carriage and the wire or wires at the other end are attached to a second carriage and arranged so that variation of carriage separation causes relative rotation of the carriages in such a manner as to keep the antenna radius substantially constant.
  • the means for rotating includes a central member having threaded portions at each end, each threaded portions cooperating with a treated bore in each movable carriage to cause relative rotation of the carriages.
  • the antenna is fed at centrally located voltage maxima and the ratio the distance from the feed point to each end of the antenna remains substantially constant.
  • the antenna is a multifilar antenna, preferably having three or more wires.
  • a method of adjusting a helical antenna comprising moving one end of a wire of a helical antenna towards or away from the other end of the wire to vary the length and pitch of the wire whilst relatively rotating the one end relative to the other end to maintain the radius of the antenna substantially constant.
  • the antenna is a multifilar antenna and each wire is simultaneously adjusted in the same manner.
  • Figure 1 illustrates a cross-sectional view through a quadrifilar antenna incorporating the adjustment device.
  • Figure 2 illustrates a perspective detail of the construction indicated by "A” .
  • the adjustment device described herein is not restricted to such an antenna and the novel adjustment means may be adapted to other helical antenna constructions and topologies.
  • Beam steering of an antenna array such as that found in a multifilar helical antenna, viewed as a continuous array of circularly polarized antenna elements, may be achieved by changing the array pattern factor. This is accomplished most simply by changing the relative phases of the element excitations.
  • phase of a circularly polarised antenna element can be changed by simply rotating the element, the phase change being equal to the rotation angle.
  • beam steering in an array of infinitesimal quadrifilar helical sections can be accomplished by rotating each infinitesimal section around the central axis with respect to the previous section.
  • a radome 14 has threaded couplers 11a and lib attached at each end.
  • First and second moveable carriages 15a and 15b are threaded into the bore of the adaptors 11a and lib. If the carriages are rotated about the axis of the bore 24a and 24b, they will move along the axis of the radome. Therefore, if the radome is rotated about its axis relative to the carriages, the carriages will move axially along the bores 24a and
  • the thread connecting coupler 11a and carriage 15a is left handed and that connecting carriage 15b and coupler lib is right handed. Therefore, as the radome/coupler assembly is rotated with respect to the carriages, the carriages 15a and 15b move towards or away from each other depending on the direction of rotation of the radome.
  • a central core member comprises a core tube 19, upper threaded rod 12a and lower threaded rod 12b.
  • the core member is fixed in relation to the mounting member 16.
  • the upper and lower rods 12a and 12b have a coarse thread formed by twisting two rigid tubes together which are inserted through corresponding threaded bores 24a and 24b of carriages 15a and 15b respectively.
  • Both the upper and lower coarse threaded rods 12a, 12b have a right-handed pitch for an antenna with left-handed helical wires; or a left- handed pitch for an antenna with right-handed helical wires.
  • the pitch of treaded rod 12a is preferably the same as that of threaded rod 12b.
  • the radome assembly is secured to the mount by means of bearing 20, thereby allowing the radome to rotate about its axis with respect to the mount 16.
  • the inner core tube 19 and threaded rod construction held fixed with respect to the mount 16 it can be seen that, depending on the direction of the rotation of the radome 14, carriages 15a and 15b move together or apart under the action of the upper and lower fine threads while simultaneously rotating axially along the coarse threaded rods.
  • the antenna undergoes length variation via linear movement of the carriages simultaneously with pitch variation via carriage rotation about the axis (i.e resulting in twisting the helix).
  • the degree of pitch change and length variation are related such that the helical radius is kept constant.
  • Helical radiating wires (filaments) 22a, 22b, 22c and 22d extend between carriages 15a and 15b. Only two wires 22a and 22b are shown for clarity. Segments 22c and 22d of the remaining two wires are indicated as the two dotted elements in figure 1.
  • the filaments form a helix with a radius defined generally by the inner diameter of the radome 14 and is therefore supported by the radome.
  • the radius may be smaller than this diameter, down to the smallest which can be accommodated by the central core 19.
  • additional support means (not shown) is needed running along the length of the core tube 19 which maintain the filament spacing and relative orientation as the length and pitch are varied.
  • the filaments are shorted at each end and the antenna operates in a resonant mode.
  • the antenna is fed at the centre by feedlines 23a, 23b, 23c and 23d.
  • the feedlines 23a, 23b, 23c and 23d are routed to the centre of the antenna by means of a threaded rod 12b.
  • Figure 2 illustrates the detail of the core tube segment where the feeder wires 23a-d exit.
  • the upper and lower sections are coupled producing a tube with feeder lines 23a-d protruding from it.
  • the feeder network may be constructed in a number of ways and adapted to the mechanical constraints of the novel adjustment mechanism.
  • the threaded rods 12a and 12b may be in the form of a continuous rod running the entire length of the antenna threaded over part or all of its length, and serve only to rotate the upper and lower carriages 15a and 15b upon rotation of the radome.
  • the feeder lines 23a, 23b, 23c and 23d may be connected to the centre of the antenna via wires internal to the rod and exit the base of the carriage 15b where it is connected to the base 16, via some mechanical means as is known in the art.
  • a power splitter 24 provides an equal two way power split to coaxial lines 17a and 17b.
  • the signal supplied via coaxial conductor 17a is phase delayed by 90° with respect to that supplied via coaxial line 17b due to the greater length of line 17a.
  • the antenna is an odd number of half wave lengths long so that it operates in a resonant mode with a voltage maxima at the centre of each copper wire. For clarity only two complete radiating wires 22a and 22b are shown. Segments 22c and 22d of the remaining two wires are shown by the dotted elements in figure 1.
  • Co-axial lines 17a and 17b are threaded along the axis of the helical antenna by way of the threaded rod 12b.
  • Wire 22d is fed at its central voltage maxima directly from coaxial line 17b and has a 0° delay.
  • Wire 22b is fed at its central voltage maxima directly from coaxial cable 17a and has a 90° delay (i.e. the delay produced by the greater length of cable 17a than 17b) .
  • Wire 22c is fed at its central voltage maxima via a balun 18b from coaxial cable 17b. This balun introduces a 180° phase shift and so the feed signal supplied to the wire 22c is 180° delayed with respect to that supplied to wire 22b.
  • Wire 22a is fed at its central voltage maxima via a balun 18a from coaxial cable 17a.
  • the balun introduces a 180° phase shift on top of the 90° phase delay produced by cable 17a. Accordingly, the feed signal to the wire 22a is 270° phase delayed with respect to the signal supplied to wire 22d.
  • feedline arrangement described in the above particular embodiment is adapted for a quadrifilar helical antenna construction.
  • similar feedline arrangements may be constructed for other multifilar antennas operating in resonant or non resonant modes. Such variations are described in PCT/NZ95/00128.
  • the method of attaching the radome to the mount 16 is shown in figure 1.
  • Other constructions may be implemented wherein such constructions are within the scope of one skilled in the art.
  • the bearings 20 may be located inside the radome wherein they are connected to the mount 16.
  • transmit and receive feedlines may be connected at different points along each wire to improve alignment of the transmit and receive beams, and/or to provide some isolation between the transmitter and receiver.
  • the number of filaments provided in the antenna may be selected for a particular application.
  • the filaments may be formed of a variety of conductive materials such as copper, silver plated brass or steel.
  • the radome 14 may be constructed from a non conducting rigid material and, while shown in the present embodiment as a cylindrical tube, other cross-sectional shapes are envisaged. Such shapes would require a more complicated construction as well as modification to ensure that the helical filaments retain a constant radius along the length of the antenna. Such modifications are herein incorporated where they constitute such variations that would be within the scope of one skilled in the art .
  • carriage rotation could be effected using stepper motors controlled electronically.
  • Such a technique could provide for independent control of the carriages position and rotation and hence allow tapered helix topologies.
  • Such a method may employ microprocessor techniques to control the stepper motors.
  • the antenna of the invention may find application in mobile satellite communications.

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  • Details Of Aerials (AREA)

Abstract

Antenne hélicoïdale réglable dans laquelle la longueur et le pas de l'antenne peuvent être variés tandis que le rayon est maintenu sensiblement constant. Les extrémités des fils (23a-d) peuvent être fixées aux premier et second chariots (15a-15b), lesquels peuvent être rapprochés ou éloignés par un radôme rotatif (14). Pour maintenir le rayon de l'hélice sensiblement constant, les premier et second chariots (15a-15b) sont mis en rotation l'un par rapport à l'autre par des sections filetées (12a-12b) à mesure qu'ils se rapprochent ou s'écartent. Les fils (23a-d) sont de préférence alimentés à des maxima de tension centrale et l'antenne est de préférence une antenne hélicoïdale multifilaire.
PCT/NZ1995/000136 1994-12-22 1995-12-21 Antenne helicoidale reglable WO1996019846A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU43188/96A AU703819B2 (en) 1994-12-22 1995-12-21 An adjustable helical antenna
NZ297911A NZ297911A (en) 1994-12-22 1995-12-21 Helical antenna with adjustable length and pitch

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NZ27025494 1994-12-22
NZ270254 1994-12-22

Publications (1)

Publication Number Publication Date
WO1996019846A1 true WO1996019846A1 (fr) 1996-06-27

Family

ID=19925103

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NZ1995/000136 WO1996019846A1 (fr) 1994-12-22 1995-12-21 Antenne helicoidale reglable

Country Status (2)

Country Link
AU (1) AU703819B2 (fr)
WO (1) WO1996019846A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6011525A (en) * 1997-07-04 2000-01-04 Piole; Philippe Variable helical antenna
US6232929B1 (en) 1997-11-27 2001-05-15 Nokia Mobile Phones Ltd. Multi-filar helix antennae
WO2002087017A1 (fr) * 2001-04-23 2002-10-31 M & S Smith Pty Ltd Antenne helicoidale
US6552695B1 (en) 2002-02-22 2003-04-22 Ems Technologies Canada, Ltd. Spin-scan array
AU2002248994B2 (en) * 2001-04-23 2008-01-31 Syntonic Technologies Pty Ltd Helical antenna

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61208904A (ja) * 1985-03-13 1986-09-17 Sharp Corp ヘリカルアンテナ装置
DE4040233A1 (de) * 1990-12-15 1992-06-17 Bilstein August Gmbh Co Kg Schwenklager an einer ausstellvorrichtung von dreh-kipp-fluegeln von fenstern, tueren oder dergleichen
WO1993006631A1 (fr) * 1991-09-23 1993-04-01 Allied-Signal, Inc. Antenne helicoidale reglable pour radio vhf
WO1993022804A1 (fr) * 1992-04-24 1993-11-11 Industrial Research Limited Antenne en helice a faisceau orientable
JPH06232620A (ja) * 1993-02-03 1994-08-19 N T T Idou Tsuushinmou Kk アンテナ装置
JPH0722839A (ja) * 1993-07-01 1995-01-24 Nec Corp ヘリカルアレイアンテナ
AU7908894A (en) * 1993-12-06 1995-06-15 Radio Frequency Systems Pty Limited Antenna assembly
JPH07176940A (ja) * 1993-12-21 1995-07-14 Nec Corp ヘリカルアンテナ

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT393762B (de) * 1989-12-18 1991-12-10 Akg Akustische Kino Geraete Als wendelantenne ausgebildete uhf-sendeund/oder empfangsantenne

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61208904A (ja) * 1985-03-13 1986-09-17 Sharp Corp ヘリカルアンテナ装置
DE4040233A1 (de) * 1990-12-15 1992-06-17 Bilstein August Gmbh Co Kg Schwenklager an einer ausstellvorrichtung von dreh-kipp-fluegeln von fenstern, tueren oder dergleichen
WO1993006631A1 (fr) * 1991-09-23 1993-04-01 Allied-Signal, Inc. Antenne helicoidale reglable pour radio vhf
WO1993022804A1 (fr) * 1992-04-24 1993-11-11 Industrial Research Limited Antenne en helice a faisceau orientable
JPH06232620A (ja) * 1993-02-03 1994-08-19 N T T Idou Tsuushinmou Kk アンテナ装置
JPH0722839A (ja) * 1993-07-01 1995-01-24 Nec Corp ヘリカルアレイアンテナ
AU7908894A (en) * 1993-12-06 1995-06-15 Radio Frequency Systems Pty Limited Antenna assembly
JPH07176940A (ja) * 1993-12-21 1995-07-14 Nec Corp ヘリカルアンテナ

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
DERWENT ABSTRACT, Accession No. 95-095784/13, Class W02; & JP,A,07 022 839, (NEC CORP), 24 January 1995. *
PATENT ABSTRACTS OF JAPAN, E-1632, page 101; & JP,A,06 232 620, (NTT IDOU TSUUSHINMOU), 19 August 1994. *
PATENT ABSTRACTS OF JAPAN, E-479, page 30; & JP,A,61 208 904, (SHARP CORP), 17 September 1986. *
PATENT ABSTRACTS OF JAPAN, Vol. 95, No. 10; & JP,A,07 176 940, (NEC CORP), 14 July 1995. *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6011525A (en) * 1997-07-04 2000-01-04 Piole; Philippe Variable helical antenna
US6232929B1 (en) 1997-11-27 2001-05-15 Nokia Mobile Phones Ltd. Multi-filar helix antennae
WO2002087017A1 (fr) * 2001-04-23 2002-10-31 M & S Smith Pty Ltd Antenne helicoidale
US6940471B2 (en) 2001-04-23 2005-09-06 Syntonic Technologies Pty Ltd Helical antenna
AU2002248994B2 (en) * 2001-04-23 2008-01-31 Syntonic Technologies Pty Ltd Helical antenna
AU2002248994B8 (en) * 2001-04-23 2008-06-12 Syntonic Technologies Pty Ltd Helical antenna
US6552695B1 (en) 2002-02-22 2003-04-22 Ems Technologies Canada, Ltd. Spin-scan array

Also Published As

Publication number Publication date
AU703819B2 (en) 1999-04-01
AU4318896A (en) 1996-07-10

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