US3747112A - Wide band dipole antenna with capacitive reactance added to arms - Google Patents

Wide band dipole antenna with capacitive reactance added to arms Download PDF

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Publication number
US3747112A
US3747112A US00146412A US3747112DA US3747112A US 3747112 A US3747112 A US 3747112A US 00146412 A US00146412 A US 00146412A US 3747112D A US3747112D A US 3747112DA US 3747112 A US3747112 A US 3747112A
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United States
Prior art keywords
antenna
capacitor
arms
end portions
conductor
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Expired - Lifetime
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US00146412A
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English (en)
Inventor
K Hidaka
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/28—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements
    • H01Q19/30—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • 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
    • H01Q19/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/10—Resonant antennas
    • H01Q5/15—Resonant antennas for operation of centre-fed antennas comprising one or more collinear, substantially straight or elongated active elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/30—Arrangements for providing operation on different wavebands
    • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
    • H01Q5/314—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors
    • H01Q5/321—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors within a radiating element or between connected radiating elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole

Definitions

  • a wide-band antenna comprising a dipole antenna mainly consisting of a pair of linearly arranged antenna arms and a capacitor disposed at a prescribed one point on each of said paired arms equally spaced from the center of a feeding portion.
  • This invention relates to a wide frequency band antenna and more particularly to a wide frequency band antenna having a capacitor disposed at those points on an antenna element which is equally spaced from the center of the feeding portion of said antenna element.
  • a wide variety of antennas for reception of broadcast television signals are used.
  • the Yagi antenna in particular is widely accepted in receiving especially VHF and UHF television signals.
  • the Yagi antenna is generally only capable of receiving as narrow frequency bands as lass than 150 MHz, failing to cover the entire range of 470 to 770 MHz bands of UHF television signals used, for example, in Japan.
  • T. S. M. Maclean states in the Proceed ings of I.E.E., Vol. 115, No. 10, October, 1968 that if there is provided a capacitor at a plularity of, for example, fouror six points on a dipole antenna-element which'are equally spaced from the center of its feeding portion, then the antenna can receive much broader frequency bands.
  • VSWR voltage standing wave ratio
  • Another object of this invention is to provide a wide frequency band antenna constructed by disposing a capacitor of, for example, 0.5 to 5 PF at two points on the radiator of a Yagi antenna equally spaced from the center of its feeding portion in linear, as well as electrically serial arrangement, thereby receiving all frequency bands of UHF television signals adopted all over the world.
  • FIG. 1 is a perspective view of a wide frequency band antenna according to an embodiment of this invention
  • FIG. 2 is a substantially equivalent representation of the wide frequency band antenna of FIG. 1;
  • FIG. 3 to 5 are concrete sectional views of that portion of an antenna element where there is formed the capacitor of FIG. 1;
  • FIG. 6 is another concrete sectional view of the capacitor portion of FIG. 1;
  • FIG. 7 shows the arrangement of antenna arms as viewed from the top of FIG. 6;
  • FIGS. 8 to 10 are Smith charts showing the properties of a wide frequency band antenna according to an embodiment of the invention.
  • FIG. 11 is a perspective view of a Yagi antenna to the radiator of which there is applied this invention.
  • FIG. 12 is a plan view of another antenna arm using the invention.
  • FIG. 13 is a curvediagram showing the properties of the Yagi antenna of FIG. 11.
  • FIG. I presents a dipole antenna according to the invention.
  • an electrically insulated antenna arm holder.3 provided with feeder terminals 1 and 2 are fitted a pair of antenna arms 4 and 5 to constitute an antenna element or dipole antenna.
  • the feeder terminals I and 2 are connected to a feeder (not shown).
  • the inner ends of the antenna arms 4 and 5 are electrically connected to the feeder terminals 1 and 2 in the antenna arm holder 3.
  • FIG. 2 The arrangement of the dipole antenna of FIG. 1 is equivalently presented in FIG. 2, in which the capacitors 6 and 7 are both designated as C
  • the distance between the capacitors C is indicated by 21,, the total length of the antenna by 21 the radius of that portion of the antenna arms 4 and 5 which extends from the central point of the feeding portion to each capaciter C, by p, (in FIG. 2 the diame ter of said portion is taken and indicated by 2p,), and the radius of that portion of the antenna arms 4 and 5 which extends from the outer end thereof to each capacitor C, by p (in FIG. 2 the diameter of said portion is taken and indicated by 2p).
  • the present inventor has found the conditions required for an antenna to display desired wide frequency band properties simply by disposing, as mentioned by reference to FIGS. 1 and 2, a capacitor on each of a pair of antenna arms constituting a dipole antenna at such an equal distance as meeting the later described conditions from the center of the feeding portion of said dipole antenna.
  • the arm 4 formed of a hollow conductor is divided substantially at the center into two sections 8 and 9. The facing ends of these divisions 8 and 9 are separated at a prescribed space.
  • a central conductor 10 of prescribed length which intersects at right angles a plane including the end face of each division and extends well thereinto.
  • the interior of the hollow arm divisions 8 and 9 including a space between the facing ends thereof is packed with a dielectric material 11 such as phenol resin or acrylonitrile-butadiene-styrene terpolymer in a manner to surround the central conductor 10 and also fill up the space between the facing ends of the arm divisions 8 and 9.
  • a dielectric material 11 such as phenol resin or acrylonitrile-butadiene-styrene terpolymer
  • On the outer peripheral surface of that part of the antenna arm 44 which is filled with said dielectric material 11 is deposited another insulating material 12 of the same kind as or a different kind from said interior dielectric material 11 so as to cause both arm divisions 8 and 9 to be integrally fixed in place.
  • This construction enables a capacitor C, to be formed between the hollow antenna arm 4 and the central conductor 10 as well as between the facing ends of the arm divisions 8 and 9.
  • These capacitors have a tatal capacitance equal to C, shown in FIG. 2.
  • the space defined by the inserted portion of the rod conductor 14 with the inner walls of the hollow conductor 13 is filled with a dielectric material 11.
  • an insulating material 12 On the outer peripheral surface of that part of the hollow conductor 13 where the rod conductor 14 is coupled therewith is deposited an insulating material 12 so as to integrally fix both conductors l3 and 14.
  • This construction causes a capacitor to be formed between both conductors 13 and 14 with a capacitance corresponding to the volume of a space defined therebetween plus the prescribed areas of the facing surfaces thereof.
  • the aforesaid rod conductor 14 may be substituted by a hollow conductor having a prescribed smaller diameter than the outer hollow'conductor 14.
  • columnar or plate conductors 15 and 16 with the prescribed surfaces thereof disposed to face each other and a specified gap allowed therebetween in order to form a capacitor C, having a desired capacitance.
  • the interspace between both conductors l5 and 16 is filled with a dielectric material 11.
  • the capacitor C is formed mainly between the interfaces of both conductors 15 and 16.
  • the capacitor C may be formed otherwise as shown in FIGS. 6 and 7.
  • conductors 17 and 18 formed of, for example, hollow aluminum tubes to constitute antenna arm 4 or 5 have the facing ends compressed flat and inclined in opposite directions with respect to the axis of said conductors 17 and'l8 to constitute flat end portions 19 and 20.
  • the conductors l7 and 18 are so arranged as to cause said inclined flat end portions 19 and 20 to face each other at a prescribed space.
  • a dielectric material of, for example, phenol resin or acrylonitrile-butadiene-styrene terpolymer to cause both conductors 17 and 18 to be integrally fixed, and also a capacitor C, to be formed essentially between said facing flat end portions 19 and 20.
  • Said conductors l7 and 18 may consist of hollow cylindrical types having different diameters.
  • the aforementioned construction enables the flat end portions 19 and 20 to act as a stopper with respect to the dielectric material 11 thereby preventing the conductors l7 and 18 from being displaced in the axial directionor rotating around the axis, when subjected to an external force.
  • the inventor has theoretically calculated input admittance Yin as viewed from the feeding portion of a dipole antenna shown in FIGS. 1 and 2 and indicated said admittance by the following equation:
  • the equation (1) above has been converted as follow by substituting input impedance Zin for the aforesaid input admittance Yin.
  • a wave length l,, natural logarithm
  • the factors l,, 1 p, and p denote the measurements of the various parts of the antenna shown in FIG. 2.
  • I may be expressed as follows:
  • FIGS. 8, 9 and 10 are Smith charts in which the input impedance Zin is indicated in combinations of these variables. It will be noted that said Smith charts used in the following description represent a normalized impedance of 300 0.
  • FIGS. 8, 9 and 10 indicate Zin varying in proportion to the value of Kl, with C,/l a and I), taken as variables.
  • the inventor has also found that as seen from said charts, Zin can be defined within the range of VSWR of less than 2.5 by setting the variables of C,/l a and Q, at a proper value. His experimental results also satisfactorily proved this fact.
  • FIG. 8 represents the case where the normalized impedance was set at 300 0., a at 0.5, and (I, at 8.65, showing Zin curves obtained by choosing the variable C,/l, to be 0.0417, 0.0625 and 0.0834. As described above, I), is a particularly important factor in defining the ratio which the radius of the antenna arm bears to its length.
  • 2.2 to 4.0 denote the values of K1,
  • the capacitance of a capacitor C, included in the variable C,/l is indicated in pico-farads, and l, in centimeters.
  • the value of Kl can be so defined as to cause VSWR to fall within the fully satisfactory range of less than 2.5.
  • the capacitance of the capacitor C may be calculated as 0.0834 X22 1.8 PF.
  • FIG. 8 further shows that as C,/l has increasing values, the associated curve is successively shifted to the adjacent outer curves, namely,
  • FIG. 8 relates to the case where the proportion constant a indicating the required position of the capacitor C that is, 1 /1 was chosen to be 0.5.
  • FIG. 9 presents the curves of the impedance Zin when the normalized impedance was set at 300 .Q, Q, at 8.65, C,/I at 0.0625 and the proportion constant a at 0.416, 0.5 and 0.583 respectively.
  • This figure shows that as the proportion constant has increasing values, the associated curve is successively shifted to adjacent outer curves, and conversely where a has decreasing values, Zin is represented by progressively inner curves.
  • FIG. 10 indicates the curve of the impedance Zin when the normalized impedance was set at 300 Q, C,/l at 0.0625, a at 0.5 and Q, at 7.75, 8.65 and 9.2 respectively.
  • the impedance Zin is represented by progressively outer curves. Tests show that if .0 was chosen to be 8.65 with respect to an antenna desired to receive wide frequency bands of 470 to 770 MHz, then such antenna would well serve practical purpose. It has been found that 0, should generally be choosen to be less than 12. The term (I, of the equation (6') is also taken to be less than 12.
  • a dipole antenna capable of receiving wide frequency bands which can be defined within the range of VSWR of less than 2.5. If the radiator 20 of the Yagi antenna of FIG. 11 consists of this dipole antenna, said Yagi antenna will be able to receive wide frequency bands.
  • the aforesaid dipole antenna may be formed by arranging a plurality of antenna arms 21 and 22 in parallel with each other in a horizontal plane or by bending the facing ends of said arms as indicated in broken lines for connection.
  • the modification of FIG. 12 is equivalent to a single dipole antenna whose thickness has been considerably increased.
  • the ratio of the capacitor C to the distance 1 from the outer end of the antenna arm to the center 0 of the feeding portion, that is C /l is defined to be 0.025 to 0.3 PF/cm.
  • the ratio of a distance I, from the center line of said feeding portion to the position of the capacitor which bears to a distance I, from the center 0 of the feeding portion of the antenna element to the outer end of the antenna arm, that is, l ll a is set at 0.4 to 0.6.
  • FIG. 13 illustrates the properties of the Yagi antenna of eight elements, which is constituted of director, reflector and radiator elements 213, 24 and 20, to the radiator element 20 of which there is applied this invention.
  • the curve diagram of FIG. 13 represents the case where a distance l from the center of the feeding portion of the Yagi antenna radiator of FIG.
  • a wide band dipole antenna comprising:
  • a pair of capacitors one disposed in each of said arms respectively, located at points equally spaced from the center of said feeding portion, and connected electrically in series with said arms;
  • 2ln(2I /p and 2ln(2l /p are each less than l,/I is between 0.4 and 0.6
  • C is the capacitance of said capacitor in picofarads I, is the distance between said capacitor and the center of said feeding portion 1 is the distance from the end of either arm to the center of said feeding portion 12;
  • a wide-band antenna according to claim 1 wherein said capacitor is formed of those end portions of pair of hollow conductors substantially constituting the antenna arm which face each other at a predetermined space; a central conductor of predetermined length coaxially disposed with the hollow conductors in the interspace between said facing end portions; an inner dielectric material filled in an area defined by the inner walls of the facing end portions of the hollow conductors with the outer walls of the central conductor as well as in an interspace between said facing end portions; and an outer insulation material mounted on the outer peripheral surface of said facing end portions, as well as of the fractional extensions of said end portions.
  • a wide-band antenna according to claim 1 where said capacitor is formed of the end portion of a first hollow conductor substantially constituting the antenna arm; that end portion of a second conductor having a smaller diameter than said first hollow conductor and inserted coaxially therewith at a space for predetermined distance which faces the end portion of said first hollow conductor; an inner dielectric material filled in said first hollow conductor so as to surround the aforesaid end of the second conductor; and an outer insulation material deposited on the outer peripheral surface of the end portion of the first hollow conductor as well as of the fractional extension of the end portion of the second conductor.
  • a wide-band antenna according to claim 1 wherein said capacitor consists of those portions of a pair of plate conductors substantially constituting the antenna arm which face each other at predetermined space; an inner dielectric material filled between said facing end portions; an outer insulation material deposited on the outer peripheral surface of those portions of the paired conductors between which there is filled said dielectric material as well as of the fractional extensions of said portions.
  • a wide-band antenna according to claim 1 wherein said capacitor is constituted by flattened end portions 'of a pair of hollow conductors substantially forming the antenna arms which are inclined in opposite directions with respect to the axis of said conductors so as to face each other at a predetermined space; and a dielectric material deposited between said facing flattened end portions and on the outer peripheral surface of said end portions as well as of the fractional extensions thereof.
  • a wide band yagi antenna comprising director. elements, a reflector element and a dipole element as defined by claim 1.

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US00146412A 1970-05-25 1971-05-24 Wide band dipole antenna with capacitive reactance added to arms Expired - Lifetime US3747112A (en)

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JP45043989A JPS522592B1 (ru) 1970-05-25 1970-05-25

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JP (1) JPS522592B1 (ru)
DE (1) DE2125964A1 (ru)
GB (1) GB1307496A (ru)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4568944A (en) * 1982-07-28 1986-02-04 U.S. Philips Corporation Y-Shaped dipole antenna
EP0205227A1 (en) * 1985-02-19 1986-12-17 Siemens Plessey Electronic Systems Limited Aerials
FR2609214A1 (fr) * 1986-12-30 1988-07-01 Thomson Csf Antenne a large bande, utilisable en ondes metriques
US5451968A (en) * 1992-11-19 1995-09-19 Solar Conversion Corp. Capacitively coupled high frequency, broad-band antenna
WO1998048477A1 (en) * 1997-04-24 1998-10-29 The Whitaker Corporation Multiple band whip antenna
US6091370A (en) * 1998-08-27 2000-07-18 The Whitaker Corporation Method of making a multiple band antenna and an antenna made thereby
US6498589B1 (en) * 1999-03-18 2002-12-24 Dx Antenna Company, Limited Antenna system
US20120056795A1 (en) * 2009-04-01 2012-03-08 Murata Manufacturing Co., Ltd. Antenna matching circuit, antenna device, and method of designing antenna device

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5667957U (ru) * 1979-10-24 1981-06-05
GB2112579A (en) * 1981-09-10 1983-07-20 Nat Res Dev Multiband dipoles and ground plane antennas
GB8316510D0 (en) * 1983-06-17 1983-07-20 Hately M C Antenna
GB2148605B (en) * 1983-10-18 1988-02-17 Plessey Co Plc Whip aerial
GB2148604B (en) * 1983-10-18 1988-01-06 Plessey Co Plc Monopole aerial
JP5891623B2 (ja) * 2011-07-07 2016-03-23 ソニー株式会社 通信制御装置、通信制御方法およびプログラム

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4568944A (en) * 1982-07-28 1986-02-04 U.S. Philips Corporation Y-Shaped dipole antenna
EP0205227A1 (en) * 1985-02-19 1986-12-17 Siemens Plessey Electronic Systems Limited Aerials
FR2609214A1 (fr) * 1986-12-30 1988-07-01 Thomson Csf Antenne a large bande, utilisable en ondes metriques
US5451968A (en) * 1992-11-19 1995-09-19 Solar Conversion Corp. Capacitively coupled high frequency, broad-band antenna
WO1998048477A1 (en) * 1997-04-24 1998-10-29 The Whitaker Corporation Multiple band whip antenna
US6091370A (en) * 1998-08-27 2000-07-18 The Whitaker Corporation Method of making a multiple band antenna and an antenna made thereby
US6498589B1 (en) * 1999-03-18 2002-12-24 Dx Antenna Company, Limited Antenna system
US20120056795A1 (en) * 2009-04-01 2012-03-08 Murata Manufacturing Co., Ltd. Antenna matching circuit, antenna device, and method of designing antenna device

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GB1307496A (en) 1973-02-21
JPS522592B1 (ru) 1977-01-22
DE2125964A1 (de) 1971-12-09

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