US3611390A - Wide band rod antenna with impedance matching - Google Patents

Wide band rod antenna with impedance matching Download PDF

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Publication number
US3611390A
US3611390A US867044A US3611390DA US3611390A US 3611390 A US3611390 A US 3611390A US 867044 A US867044 A US 867044A US 3611390D A US3611390D A US 3611390DA US 3611390 A US3611390 A US 3611390A
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United States
Prior art keywords
wire
length
antenna
band
wide band
Prior art date
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Expired - Lifetime
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US867044A
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English (en)
Inventor
Bernard Chiron
Louis Duffau
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Lignes Telegraphiques et Telephoniques LTT SA
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Lignes Telegraphiques et Telephoniques LTT SA
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    • 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

Definitions

  • L is the unitary inductance per unit of length of the wire surrounded by the ferromagnetic material.
  • C. is the corresponding unitary capacitance.
  • L is the geometrical length of the antenna.
  • f is the operating frequency which varies within the operating bandwidth.
  • the ferromagnetic material is to be chosen so as to meet equation I. As will be explained in further details, some ferromagnetic materials suitable for this use are commercially available. Available magnetic materials which do not comply with law l may be forced to comply through automatic control.
  • the present invention relates to an improvement in wide band antenna design and more particularly to mobile equipment antennas.
  • Wide band means a bandwidth which covers several octaves.
  • an antenna consisting of a plain wire mechanically and electrically connected at one of its ends.
  • the length of the wire has to be related to the wavelength in order to obtain maximum gain.
  • the gain decreases rapidly.
  • Wire antennas are therefore small bandwidth designs. It has been proposed to widen the operating bandwidth through the addition of a matching unit. Such matching units are difficult to design to cover a bandwidth as large as mentioned above. They always introduce a loss in the circuit which reduces maximum gain.
  • the present invention concerns an antenna design which does not spoil the mechanical simplicity and robustness of the wire antenna and allows a several octave coverage.
  • a fraction of the antenna wire is coupled with a ferromagnetic material, the electrical parameters of which meet the following condition:
  • L,C, l/l6L -l/ f (l) where L is the unitary inductance per unit of length of the wire surrounded by the ferromagnetic material.
  • C is the corresponding unitary capacitance.
  • L is the geometrical length of the antenna.
  • f is the operating frequency which varies within the operating bandwidth.
  • the ferromagnetic material is to be chosen so as to meet equation I. As will be explained in further details, some ferromagnetic materials suitable for this use are commercially available. Available magnetic materials which do not comply with law l may be forced to comply through automatic control.
  • the ferrite need not be located on the whole length of the antenna wire. It may be localized around a section less than one-tenth of said length so that it will practically not spoil the mechanical characteristics (flexibility-weight, etc. of the design.
  • condition (I) is met through biasing of the ferromagnetic material by means of an auxiliary DC magnetic field either constant or automatically varied.
  • an auxiliary DC magnetic field either constant or automatically varied.
  • condition (I) can be met by three classes of magnetic materials:
  • ferromagnetic materials with constant permeability in the operating frequency band permittivity varies according to condition l
  • the biasing field, when required, is easily applied through a coil at the base of the antenna.
  • the class of materials b) above should be located at the point of the antenna where voltage is maximum, that is at the top of the antenna for maximum efiiciency.
  • FIG. 1 is a first embodiment of the invention.
  • FIG. 2 is a plotted curve showing the variation of permeability of the ferromagnetic material used in the antenna of FIG. I.
  • FIGS. 3 and 4 show the reflection coefficient of the antenna versus the frequency and the transmission losses between two identical antennas in the same frequency band.
  • FIGS. 5 and 6 show two automatic control devices for the DC biasing magnetic field.
  • FIG. 7 is an another embodiment of the invention.
  • FIG. I shows the base of a wire antenna I connected to an equipment 2 (either a receiver or a transmitter).
  • the base of wire 1 is surrounded with a ring of ferromagnetic material 3 the upper extremity of which is tapered as shown at 3' so as to provide for a progressive matching of impedance between the base of the antenna and its free end.
  • the cylindrical lower part of ring 3 is surrounded with a ring 4 made of a dielectric material provided to match the impedance of the loaded part of the antenna with that of the surrounding space.
  • the base of the antenna is entirely packaged in an insulating resin 5 such as a very low density polyurethan resin which reproduces the cylindro-conical shape of ring 3.
  • Potting 5 is necessary to secure the antenna mechanically and to protect the rings 3 and 4. It should preferably consist of a low permittivity insulating material in order not to disturb the impedance matching provided by ring 4.
  • magnetic material of ring 3 meets equation I in the operating frequency.
  • the ferrite material sold by the assignee of this application under the trade number meets the requirement in the 0 to 30 MHz band as shown in FIG. 2 and table 1.
  • Ring 4 is made of a dielectric material.
  • the permittivity of which is chosen in order to match the permittivity of the ferrite material of ring 3 to that of the air.
  • the permittivity of ring 4 is preferably about 4.
  • the material which is commercially sold by the assignee of this application as trade number D 6226 meets the requirement. It is a mixture of polythene and titanium dioxide. Of course, any other available dielectric material with a permittivity of 4 can be used for ring 4.
  • FIG. 2 shows the measured variation of the permeability of L'IT-type I401 ferrite versus frequency.
  • the permittivity of this material is constant in the frequency band considered (10-30 MHz) as is shown on table I which gives the value of the capacity of the complete antenna structure at different frequencies within the operating band.
  • the electromagnetic energy stored within the elementary volume of magnetic material at r from the axis and of unitary length is:
  • the increase in inductance AL, per unit oflength is:
  • FIG. 2 shows as a plain line the measured values of pt, with respect to frequency.
  • FIGS. 3 and 4 show the operating characteristics of an antenna design according to the invention (full-line curves) with respect to a prior art wire antenna of the same geometrical length (interrupted line curves).
  • FIG. 3 shows the reflection coefficient of the antenna between and 35 MHz.
  • FIG. 4 shows the transmission losses between two identical wire antennas connected respectively to a transmitter and to a receiver.
  • the transmission loss is the ratio between the transmitted energy and the received energy. Obviously, the value of the losses depends of the length of the transmission path. The variation of the losses with respect to frequency, however, is independent of the path length. As can be seen, the loss of the prior art wire antenna varies much in the 10 to 30 MHz band (from 40 db. up to almost 0) in the same frequency band. The loss in the transmission established with antennas according to the invention remains practically constant and equal to 12 db.
  • FIGS. 3 and 4 correspond to an embodiment of the invention according to FIG. I with the following geometrical dimensions:
  • FIG. 5 shows schematically such a design.
  • the antenna wire shown at I is surrounded at its lower extremity by the magnetic ring 3.
  • An external magnetic DC field is established in ring 3 by means of coil 6.
  • Coil 6 is fed through an electronic device controlled by the signal picked-up by loop 8 located in the field radiated by the antenna.
  • Electronic device 7 is designed in order to maintain the impedance of the antenna constant that is to say to maintain the radiated field picked-up by loop 8 constant.
  • the variation of the feed current to coil 6 is thereby automatically matched to the permeability variation of the magnetic material so as to meet relation 1.
  • Device 7 is essentially constituted by a linear wide band amplifier.
  • the bandwidth of the amplifier is 2-30 MHz.
  • the amplifier is fed with the pickup loop 8 signal and feeds an automatic gain control circuit which feeds the magnetizing coil 6 through a DC rectifier.
  • an automatic gain control circuit which feeds the magnetizing coil 6 through a DC rectifier.
  • the wire antenna is designed for maximum gain at the upper limit of the frequency band, a linear automatic control is sufficient for practical purposes.
  • the theoretical study of the circuit is rather complex since two independent phenomena are to be considered: the first one is the variation of the permeability versus frequency and the second the variation of permeability with applied field (the current in coil 6 varies). The second phenomenon is out of reach of the designer.
  • the first may be adjusted through a correct selection of parameters r and d, as shown in FIG. 2.
  • FIG. 6 is another embodiment of the electronic control device associated with the magnetic material.
  • the antenna is constituted of wire 1 the base of which is surrounded with the ferrite ring 3 as previously described.
  • Wire I is serially connected with an additional inductor made of a coil 9 surrounding a ferromagnetic rod I0. This inductor is mechanically independent of radiating wire I.
  • the control device varies inductance of the 9l0 unit through an auxiliary DC magnetic field applied to the ferromagnetic rod I0 by means of coil II.
  • the current fed into 11 is delivered by an electronic regulator 7' controlled by the signal picked-up by loop 8' which is representative of the value of the current flowing in conductor 1.
  • Electronic regulator 7' is set so as to control the current through coil 11 so as to modify the value of inductance 9-10 to maintain constant the current flowing through I.
  • FIG. 7 shows another embodiment of the invention using a ferromagnetic material with a constant permeability in the operating frequency band.
  • the mathematical relation between the permittivity and the frequency for condition l can be established as has been described above with reference to the permeability. The calculations are more complex and will therefor be omitted here.
  • the permittivity of the material may be controlled so as to meet condition (1) through the use of an adjustable capacitance connected serially or in parallel with the loaded part of the antenna. For instance. a varactor-type diode is used to match the variation law of the permittivity versus the frequency with condition (1 In FIG.
  • Fernalite 1008 One example of a ferromagnetic material which would be useful in connection with the structure for FIG. 7 and which is manufactured by the assignee of this application is known as "Ferrnalite 1008.” This is a manganese ferrite material, the permeability of which is about 150 and is substantially constant in the l to [0 MHz band.
  • L is the wire length
  • I is the operating frequency within the band.
  • a wide band wire antenna consisting of a conductive nonmagnetic wire partially surrounded with a magnetic material sleeve serially connected with an adjustable lump impedance so that:
  • L,c,
  • L is the wire length
  • f is the operating frequency within the band.
  • L is the wire length
  • f is the operating frequency within the band.
  • L is the wire length
  • f is the operating frequency within the band.
  • a wide band wire antenna consisting of a conductive nonmagnetic wire the feed end of which is surrounded with a sleeve of magnetic material having a constant permittivity in the frequency band and a permeability which varies so that:
  • L C, l/l6L"l/f
  • C. is the capacitance of the same
  • L is the wire length
  • f is the operating frequency within the band.

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US867044A 1968-10-23 1969-10-16 Wide band rod antenna with impedance matching Expired - Lifetime US3611390A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR170945 1968-10-23

Publications (1)

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US3611390A true US3611390A (en) 1971-10-05

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ID=8655986

Family Applications (1)

Application Number Title Priority Date Filing Date
US867044A Expired - Lifetime US3611390A (en) 1968-10-23 1969-10-16 Wide band rod antenna with impedance matching

Country Status (4)

Country Link
US (1) US3611390A (enrdf_load_stackoverflow)
DE (1) DE1953038C3 (enrdf_load_stackoverflow)
FR (1) FR1588021A (enrdf_load_stackoverflow)
GB (1) GB1282293A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4958163A (en) * 1988-02-01 1990-09-18 Peter F. Leonard Means for tuning an antenna
US5710567A (en) * 1995-10-25 1998-01-20 Allgon Ab Antenna locking device using magnetic attractive elements when antenna is extended
US5880696A (en) * 1995-11-08 1999-03-09 Nokia Mobile Phones Ltd. Retractable antenna for a radio transmitting and receiving device
CN1332477C (zh) * 2004-03-25 2007-08-15 电子科技大学 一种宽带全向锥形套筒单极子天线
US20100134367A1 (en) * 2008-12-02 2010-06-03 Bae Systems Information & Electronic Systems Integration, Inc. X, Ku, K BAND OMNI-DIRECTIONAL ANTENNA WITH DIELECTRIC LOADING
US20120228563A1 (en) * 2008-08-28 2012-09-13 Alliant Techsystems Inc. Composites for antennas and other applications

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4246586A (en) 1977-12-20 1981-01-20 National Research Development Corporation Radio antennae
DE3312638A1 (de) * 1983-04-08 1984-10-18 Rohde & Schwarz GmbH & Co KG, 8000 München Antenne mit elektrisch verkuerztem linearstrahler
DE19900740A1 (de) 1999-01-12 2000-07-13 Bosch Gmbh Robert Verfahren und Vorrichtung zum Betreiben einer Brennkraftmaschine

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4958163A (en) * 1988-02-01 1990-09-18 Peter F. Leonard Means for tuning an antenna
US5710567A (en) * 1995-10-25 1998-01-20 Allgon Ab Antenna locking device using magnetic attractive elements when antenna is extended
US5880696A (en) * 1995-11-08 1999-03-09 Nokia Mobile Phones Ltd. Retractable antenna for a radio transmitting and receiving device
CN1332477C (zh) * 2004-03-25 2007-08-15 电子科技大学 一种宽带全向锥形套筒单极子天线
US20120228563A1 (en) * 2008-08-28 2012-09-13 Alliant Techsystems Inc. Composites for antennas and other applications
US8723722B2 (en) * 2008-08-28 2014-05-13 Alliant Techsystems Inc. Composites for antennas and other applications
US9263804B2 (en) 2008-08-28 2016-02-16 Orbital Atk, Inc. Composites for antennas and other applications
US20100134367A1 (en) * 2008-12-02 2010-06-03 Bae Systems Information & Electronic Systems Integration, Inc. X, Ku, K BAND OMNI-DIRECTIONAL ANTENNA WITH DIELECTRIC LOADING
US8063848B2 (en) 2008-12-02 2011-11-22 Bae Systems Information And Electronic Systems Integration Inc. X, Ku, K band omni-directional antenna with dielectric loading

Also Published As

Publication number Publication date
GB1282293A (en) 1972-07-19
DE1953038A1 (de) 1970-04-30
DE1953038B2 (de) 1974-05-02
FR1588021A (enrdf_load_stackoverflow) 1970-04-03
DE1953038C3 (de) 1975-01-09

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