US3626418A - Broadband, omnidirectional, horizontally polarized, loop antenna - Google Patents

Broadband, omnidirectional, horizontally polarized, loop antenna Download PDF

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Publication number
US3626418A
US3626418A US22946A US3626418DA US3626418A US 3626418 A US3626418 A US 3626418A US 22946 A US22946 A US 22946A US 3626418D A US3626418D A US 3626418DA US 3626418 A US3626418 A US 3626418A
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antenna
feedlines
loop
broadband
horizontally polarized
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US22946A
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Walter Clayton Berryman Jr
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Bendix Corp
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Bendix Corp
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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
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
    • H01Q9/28—Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines

Definitions

  • This invention relates to antennas. More particularly, it relates to antennas useful in the reception of horizontally polarized signal energy from a plurality of directions over a wide band of frequencies.
  • VHF entertainment transmissions are typically transmitted by the broadcasters with horizontal polarization which requires that the receiving antenna be horizontally polarized in order to couple the transmitted energy to the receiver with maximum efi'lciency.
  • the most common type of receiving antenna now employed for these signals is the Yagi-type array which comprises a horizontally polarized parasitic linear array of dipole elements. This type of antenna is directive and can not efficiently receive energy over the entire two-octave range of the VHF entertainment bands. Because of the restricted bandwidth, it is common for users of such Yagi receiving antennas to use several of them to cover the desired frequency range; typically, three such antennas are used: one for television channels 2 through 6, one for the FM broadcast band, and one for television channels 7 through 13.
  • each antenna In order to provide proper impedance matching, separate transmission lines should be used between each antenna and the receiver associated therewith. 1f the user is interested in receiving signals from one direction only, he need only aim his array in that direction. If, on the other hand, he desires to receive signals from transmitters located at differing azimuths from his location, he must either employ an antenna rotor, which is expensive and typically requires maintenance more frequently than the antenna does, or he must accept severely degraded performance of his receiving system. The problem occasioned by directivity of the antenna is especially severe when the receiving installation is mobile, for instance on a boat or the like.
  • log periodic arrays in order to overcome the bandwidth limitations of Yagi antennas, the use of log periodic arrays has become increasingly popular for VHF entertainment reception in recent years.
  • Log periodic antennas for VHF entertainment use are broadband, directional and horizontally polarized. The user of a log periodic antenna, therefore, may cover the desired frequency range with a single antenna and transmission line, but still requires a rotor just as the Yagi user does.
  • Marconi antennas which are end-fed quarter-wave vertical antennas. Marconi antennas are omnidirectional, but are not broadband or horizontally polarized.
  • Dipole antennas which are center-fed half-wave antennas which are oriented either vertically or horizontally.
  • a dipole antenna When horizontally oriented, a dipole antenna is horizontally polarized, but is not broadband or omnidirectional; when vertically oriented it is omnidirectional, but not broadband or horizontally polarized.
  • Discone antennas which are broadband and omnidirectional, but are not horizontally polarized.
  • the principal object of the present invention is to provide a broadband, horizontally polarized, omnidirectional antenna.
  • Another object is to provide such an antenna which is light in weight, and simple and inexpensive to manufacture.
  • the invention is embodied in an antenna comprising a plurality of closed loop radiating elements which are parallel-fed by a tapered pair feedline.
  • Each loop element consists of a single turn of conductive material whose dimensions are uniform over the entire loop. This results in each loop being electrically uniform and continuous.
  • the loops are fed in parallel by a pair of uniformly tapered feedlines comprising two congruent strips of conductive material which diverge at a small angle.
  • a first loop of said plurality of loops has a circumference equal to one half wavelength at the lowest desired frequency.
  • a second loop has a circumference equal to one half wavelength at the highest desired frequency.
  • the remaining loops are of intermediate size between said first and second loops.
  • Said first loop is connected to said feedlines at the point of maximum separation of said feedlines and the remaining loops are connected to said feedlines to form a conical structure whose height is,equal to the diameter of said first loop.
  • Nonconductive structural support members are employed to mechanically support the antenna structure. Means are provided at the end of the pair of feedlines near the apex of the cone whereby said feedlines are connected to a transmission line.
  • FIG. 1 is a perspective view of the inventive antenna.
  • the circumference of loop 11 is equal to one-half wavelength at the lowest desired frequency.
  • the circumference of loop 12 is equal to one-half wavelength of the highest desired frequency.
  • Loops 13 are of intermediate size between loops 1! and 12 and are disposed between them to define a conical surface.
  • the loops are connected in parallel through a uniformly tapered feedline comprising metal strips 14 and 15. At the apex end of the feedline, strip 14 has terminal 16 and strip 15 has terminal 17 attached thereto. Terminals l6 and 17 are connected respectively to terminals 18 and 19 of connection box 20.
  • Connection box 20 also contains coaxial connector 21.
  • Terminals 18 and 19 are connected within connection box 20 to coaxial connector 21 either directly, or, for improved performance, through an appropriate balun transformer which will be more fully described below. Interconnection of the antenna is thus provided with a coaxial transmission line 23 by means of coaxial connector 21 and cable mounted coaxial connector 22.
  • the antenna also includes a base member 35 which supports nonconductive structural support members 31, 32 and 33. Feedline strips 14 and 15 and the ends of loops 11 through 13 are attached to support members 32 and 33 by means of a plurality of fasteners illustrated as a nut and bolt fastener at 37. Electrical connection of the loops to the feedline is accomplished by direct connection at the fasteners.
  • the loops are also mechanically supported by support member 31 which is disposed on the opposite side of the conical surface from members 32 and 33.
  • the loop members are attached to support member 31 by mechanical fasteners illustrated as nut and bolt fasteners at 36.
  • Nonconductive spacer 34 is disposed between support members 32 and 33 at the upper ends thereof, and cooperatively with base member 35 maintains the desired taper of the feedline.
  • the antenna illustrated was designed for 50 ohm feedpoint impedance.
  • the dimensions discussed below are particular to this design.
  • Other impedances may be provided by design by changing the dimensions.
  • the diameter of loop 11 is D and is equal to H211 at the lowest desired operating frequency.
  • the spacing between successive loop elements is uniform and is equal to 0/5. This spacing is optimum to insure a continuous impedance characteristic with frequency.
  • the spacing between facing edges of feedline members 14 and 15 is 0/12 at the point of connection to loop 11 and is D/48 at the facing edges opposite terminals 16 and 17. This provides the taper of the feedline which determines the antenna characteristic impedance.
  • Loops 11 through 13 are not less than D/24 nor more than 0/12 wide. A width of at least D/24 is required to ensure a continuous impedance characteristic with frequency and a width of less than D/l2 is required to maintain an omnidirectional antenna pattern.
  • connection within connection box 20 between tenninals 18 and 19 and coaxial connector 21 may be by way of a balun transformer of one to one impedance ratio. It has been found, however, that very acceptable results will also be obtained under these conditions with a direct connection within connection box 20 between terminals 18 and 19 and coaxial connector 21. If it is desired to use a coaxial cable 23 of impedance other than 50 ohms. the feedline taper may be changed or, alternatively, a balun transformer of appropriate means for connecting said feedlines to a transmission line.
  • a first loop of said plurality of loops has. a circumference equal to one-half wavelength at the lowest desired antenna operating frequency, and a second loop of said plurality of loops has a circumference equal to one-half wavelength at the highest desired antenna operating frequency.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

A broadband, horizontally polarized, omnidirectional antenna comprising a plurality of parallel-fed loop radiating elements is disclosed. This antenna has particular utility for reception of VHF entertainment broadcasts (Television channels 2-13 and the FM broadcast band).

Description

United States Patent Inventor Walter Clayton Berryman, Jr. Westminster, Md.
Mar. 26, 1970 Dec. 7, 1971 The Bendix Corporation Appl. No. Filed Patented Assignee BROADBAND, OMNIDIRECTIONAL, HORIZONTALLY POLARIZED, LOOP ANTENNA 3 Claims, 1 Drawing Fig.
US. Cl 343/742,
343/863, 343/884 lnt.Cl H0111 11/12 Field 01 Search 343/742,
[56] References Cited UNITED STATES PATENTS 2,751,590 6/1956 Troutman 343/742 2,622,196 12/1952 Alford 343/742 3,448,454 6/1969 Lane 343/742 Primary Examiner Eli Lieberman Altorneys- Plante, Arens, Hartz, Smith & Thompson, Bruce L. Lamb and William G. Christoforo ABSTRACT: A broadband, horizontally polarized, omnidirectional antenna comprising a plurality of parallel-led loop radiating elements is disclosed. This antenna has particular utility for reception of VHF entertainment broadcasts (Television channels 2-13 and the FM broadcast band).
BROADBAND, OMNIDIRECTIONAL, HORIZONTALLY POLARIZED, LOOP ANTENNA This invention relates to antennas. More particularly, it relates to antennas useful in the reception of horizontally polarized signal energy from a plurality of directions over a wide band of frequencies.
VHF entertainment transmissions are typically transmitted by the broadcasters with horizontal polarization which requires that the receiving antenna be horizontally polarized in order to couple the transmitted energy to the receiver with maximum efi'lciency. The most common type of receiving antenna now employed for these signals is the Yagi-type array which comprises a horizontally polarized parasitic linear array of dipole elements. This type of antenna is directive and can not efficiently receive energy over the entire two-octave range of the VHF entertainment bands. Because of the restricted bandwidth, it is common for users of such Yagi receiving antennas to use several of them to cover the desired frequency range; typically, three such antennas are used: one for television channels 2 through 6, one for the FM broadcast band, and one for television channels 7 through 13. In order to provide proper impedance matching, separate transmission lines should be used between each antenna and the receiver associated therewith. 1f the user is interested in receiving signals from one direction only, he need only aim his array in that direction. If, on the other hand, he desires to receive signals from transmitters located at differing azimuths from his location, he must either employ an antenna rotor, which is expensive and typically requires maintenance more frequently than the antenna does, or he must accept severely degraded performance of his receiving system. The problem occasioned by directivity of the antenna is especially severe when the receiving installation is mobile, for instance on a boat or the like.
in order to overcome the bandwidth limitations of Yagi antennas, the use of log periodic arrays has become increasingly popular for VHF entertainment reception in recent years. Log periodic antennas for VHF entertainment use are broadband, directional and horizontally polarized. The user of a log periodic antenna, therefore, may cover the desired frequency range with a single antenna and transmission line, but still requires a rotor just as the Yagi user does.
Other types of antenna which are known in the art but which have not achieved wide use in VHF entertainment reception include:
Marconi antennas which are end-fed quarter-wave vertical antennas. Marconi antennas are omnidirectional, but are not broadband or horizontally polarized.
Dipole antennas which are center-fed half-wave antennas which are oriented either vertically or horizontally. When horizontally oriented, a dipole antenna is horizontally polarized, but is not broadband or omnidirectional; when vertically oriented it is omnidirectional, but not broadband or horizontally polarized.
Discone antennas which are broadband and omnidirectional, but are not horizontally polarized.
Turnstile antennas which are horizontally polarized and omnidirectional, but are not broadband.
The principal object of the present invention is to provide a broadband, horizontally polarized, omnidirectional antenna.
Another object is to provide such an antenna which is light in weight, and simple and inexpensive to manufacture.
Briefly, the invention is embodied in an antenna comprising a plurality of closed loop radiating elements which are parallel-fed by a tapered pair feedline. Each loop element consists of a single turn of conductive material whose dimensions are uniform over the entire loop. This results in each loop being electrically uniform and continuous. The loops are fed in parallel by a pair of uniformly tapered feedlines comprising two congruent strips of conductive material which diverge at a small angle. A first loop of said plurality of loops has a circumference equal to one half wavelength at the lowest desired frequency. A second loop has a circumference equal to one half wavelength at the highest desired frequency. The remaining loops are of intermediate size between said first and second loops. Said first loop is connected to said feedlines at the point of maximum separation of said feedlines and the remaining loops are connected to said feedlines to form a conical structure whose height is,equal to the diameter of said first loop. Nonconductive structural support members are employed to mechanically support the antenna structure. Means are provided at the end of the pair of feedlines near the apex of the cone whereby said feedlines are connected to a transmission line.
In the drawing the single FIGURE is a perspective view of the inventive antenna. The circumference of loop 11 is equal to one-half wavelength at the lowest desired frequency. The circumference of loop 12 is equal to one-half wavelength of the highest desired frequency. Loops 13 are of intermediate size between loops 1! and 12 and are disposed between them to define a conical surface. The loops are connected in parallel through a uniformly tapered feedline comprising metal strips 14 and 15. At the apex end of the feedline, strip 14 has terminal 16 and strip 15 has terminal 17 attached thereto. Terminals l6 and 17 are connected respectively to terminals 18 and 19 of connection box 20. Connection box 20 also contains coaxial connector 21. Terminals 18 and 19 are connected within connection box 20 to coaxial connector 21 either directly, or, for improved performance, through an appropriate balun transformer which will be more fully described below. Interconnection of the antenna is thus provided with a coaxial transmission line 23 by means of coaxial connector 21 and cable mounted coaxial connector 22. Structurally, the antenna also includes a base member 35 which supports nonconductive structural support members 31, 32 and 33. Feedline strips 14 and 15 and the ends of loops 11 through 13 are attached to support members 32 and 33 by means of a plurality of fasteners illustrated as a nut and bolt fastener at 37. Electrical connection of the loops to the feedline is accomplished by direct connection at the fasteners. The loops are also mechanically supported by support member 31 which is disposed on the opposite side of the conical surface from members 32 and 33. The loop members are attached to support member 31 by mechanical fasteners illustrated as nut and bolt fasteners at 36. Nonconductive spacer 34 is disposed between support members 32 and 33 at the upper ends thereof, and cooperatively with base member 35 maintains the desired taper of the feedline.
The antenna illustrated was designed for 50 ohm feedpoint impedance. The dimensions discussed below are particular to this design. Other impedances may be provided by design by changing the dimensions. The diameter of loop 11 is D and is equal to H211 at the lowest desired operating frequency. The spacing between successive loop elements is uniform and is equal to 0/5. This spacing is optimum to insure a continuous impedance characteristic with frequency. The spacing between facing edges of feedline members 14 and 15 is 0/12 at the point of connection to loop 11 and is D/48 at the facing edges opposite terminals 16 and 17. This provides the taper of the feedline which determines the antenna characteristic impedance. Loops 11 through 13 are not less than D/24 nor more than 0/12 wide. A width of at least D/24 is required to ensure a continuous impedance characteristic with frequency and a width of less than D/l2 is required to maintain an omnidirectional antenna pattern.
Since the antenna illustrated was designed to provide a 50 ohm characteristic impedance at terminals 16 and 17, and since coaxial cable 23 has a 50 ohm characteristic impedance, the connection within connection box 20 between tenninals 18 and 19 and coaxial connector 21 may be by way of a balun transformer of one to one impedance ratio. It has been found, however, that very acceptable results will also be obtained under these conditions with a direct connection within connection box 20 between terminals 18 and 19 and coaxial connector 21. If it is desired to use a coaxial cable 23 of impedance other than 50 ohms. the feedline taper may be changed or, alternatively, a balun transformer of appropriate means for connecting said feedlines to a transmission line.
2. The antenna of claim 1 wherein a first loop of said plurality of loops has. a circumference equal to one-half wavelength at the lowest desired antenna operating frequency, and a second loop of said plurality of loops has a circumference equal to one-half wavelength at the highest desired antenna operating frequency.
3. The antenna of claim 2 wherein said feedlines are disposed along said conical surface in conically parallel relationship whereby said conical surface determines said taper of said feedlines.
l i l l

Claims (3)

1. A broadband, horizontally polarized, omnidirectional antenna comprising: a plurality of electrically and mechanically uniform and continuous loop radiating elements but having diverse diameters, said elements positioned in vertically spaced substantially horizontal planes to thereby define a right conical surface, a pair of uniformly tapered feedlines, said feedlines interconnecting said radiating elements electrically in parallel, and means for connecting said feedlines to a transmission line.
2. The antenna of claim 1 wherein a first loop of said plurality of loops has a circumference equal to one-half wavelength at the lowest desired antenna operating frequency, and a second loop of said plurality of loops has a circumference equal to one-half wavelength at the highest desired antenna operating frequency.
3. The antenna of claim 2 wherein said feedlines are disposed along said conical surface in conically parallel relationship whereby said conical surface determines said taper of said feedlines.
US22946A 1970-03-26 1970-03-26 Broadband, omnidirectional, horizontally polarized, loop antenna Expired - Lifetime US3626418A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3754269A (en) * 1972-03-07 1973-08-21 Vorta Systems Inc Omni-directional antenna mounted in circular radome
US4117491A (en) * 1975-08-20 1978-09-26 C & S Antennas Limited Logarithmically periodic loop antenna array with spaced filters in the coupling network
US4600926A (en) * 1983-07-28 1986-07-15 Powell Stanley L Television antenna
US4635069A (en) * 1984-04-02 1987-01-06 Irt, Inc. Mutual-coupling multi-element FM antenna
US6870508B1 (en) 2003-06-16 2005-03-22 The United States Of America As Represented By The Secretary Of The Navy Antenna for deployment from underwater location
GB2455653A (en) * 2007-12-19 2009-06-24 Mark Rhodes Multiple loop antenna with broadband performance
US8604997B1 (en) 2010-06-02 2013-12-10 Lockheed Martin Corporation Vertical array antenna
US20150123868A1 (en) * 2013-11-06 2015-05-07 Motorola Solutions, Inc. Compact, multi-port, mimo antenna with high port isolation and low pattern correlation and method of making same
US9735822B1 (en) * 2014-09-16 2017-08-15 Amazon Technologies, Inc. Low specific absorption rate dual-band antenna structure
US10158178B2 (en) 2013-11-06 2018-12-18 Symbol Technologies, Llc Low profile, antenna array for an RFID reader and method of making same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622196A (en) * 1949-01-13 1952-12-16 Alford Andrew Antenna
US2751590A (en) * 1952-11-25 1956-06-19 Troutman Wilbur Earl Outdoor circular band antenna
US3448454A (en) * 1966-09-29 1969-06-03 Oscar L Lane Ominidirectional circular dipole antenna

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622196A (en) * 1949-01-13 1952-12-16 Alford Andrew Antenna
US2751590A (en) * 1952-11-25 1956-06-19 Troutman Wilbur Earl Outdoor circular band antenna
US3448454A (en) * 1966-09-29 1969-06-03 Oscar L Lane Ominidirectional circular dipole antenna

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3754269A (en) * 1972-03-07 1973-08-21 Vorta Systems Inc Omni-directional antenna mounted in circular radome
US4117491A (en) * 1975-08-20 1978-09-26 C & S Antennas Limited Logarithmically periodic loop antenna array with spaced filters in the coupling network
US4600926A (en) * 1983-07-28 1986-07-15 Powell Stanley L Television antenna
US4635069A (en) * 1984-04-02 1987-01-06 Irt, Inc. Mutual-coupling multi-element FM antenna
US6870508B1 (en) 2003-06-16 2005-03-22 The United States Of America As Represented By The Secretary Of The Navy Antenna for deployment from underwater location
US20090160723A1 (en) * 2007-12-19 2009-06-25 Mark Rhodes Antenna formed of multiple resonant loops
GB2455653A (en) * 2007-12-19 2009-06-24 Mark Rhodes Multiple loop antenna with broadband performance
GB2455653B (en) * 2007-12-19 2010-03-03 Mark Rhodes Antenna formed of multiple resonant loops
US8164530B2 (en) 2007-12-19 2012-04-24 Wfs Technologies Ltd. Antenna formed of multiple resonant loops
US8604997B1 (en) 2010-06-02 2013-12-10 Lockheed Martin Corporation Vertical array antenna
US20150123868A1 (en) * 2013-11-06 2015-05-07 Motorola Solutions, Inc. Compact, multi-port, mimo antenna with high port isolation and low pattern correlation and method of making same
US9847571B2 (en) * 2013-11-06 2017-12-19 Symbol Technologies, Llc Compact, multi-port, MIMO antenna with high port isolation and low pattern correlation and method of making same
US10158178B2 (en) 2013-11-06 2018-12-18 Symbol Technologies, Llc Low profile, antenna array for an RFID reader and method of making same
US9735822B1 (en) * 2014-09-16 2017-08-15 Amazon Technologies, Inc. Low specific absorption rate dual-band antenna structure

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