US2748386A - Antenna systems - Google Patents

Antenna systems Download PDF

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Publication number
US2748386A
US2748386A US259770A US25977051A US2748386A US 2748386 A US2748386 A US 2748386A US 259770 A US259770 A US 259770A US 25977051 A US25977051 A US 25977051A US 2748386 A US2748386 A US 2748386A
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United States
Prior art keywords
antenna
permeability
length
dipole
frequency
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Expired - Lifetime
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US259770A
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English (en)
Inventor
Wladimir J Polydoroff
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Individual
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Individual
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Publication date
Priority to BE507544D priority Critical patent/BE507544A/xx
Priority to FR1060816D priority patent/FR1060816A/fr
Application filed by Individual filed Critical Individual
Priority to US259770A priority patent/US2748386A/en
Application granted granted Critical
Publication of US2748386A publication Critical patent/US2748386A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/24—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave constituted by a dielectric or ferromagnetic rod or pipe
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • H01Q1/362—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith for broadside radiating helical antennas

Definitions

  • This invention relates to antennas for radio apparatus either for radiating or for receiving electromagnetic energy.
  • the invention is principally directed to antennas having dimensions related to the frequency of the energy to be transmitted or received.
  • An object of the invention is to provide improved antennas and a principal object is to decrease the size of antennas without reduction in its performance.
  • the invention is based on the fact that wavelength of electromagnetic energy of a given frequency is reduced in the vicinity of ferromagnetic material from the wavelength in vacuo. According to Maxwells equation, the velocity of propagation of the energy,
  • a and k are respectively the permeability and permittivity of the medium in which the energy is travelling.
  • f is the frequency
  • the wavelength of energy of a given frequency is decreased, owing to decreased velocity, when it strikes a medium of higher permeability.
  • a radio antenna according to the invention is made in part of ferromagnetic material to shorten in the vicinity of receiving or transmitting conducting element or elements, the wavelength of the radio waves to be received or transmitted.
  • the dimensions of an antenna can be reduced since the wavelength in the vicinity of the antenna is reduced.
  • the arms of a dipole antenna are covered in ferromagnetic material, the length of the antenna can be almost halved from the value normally required since the wavelength in the vicinity of the dipole is reduced proportionally.
  • the invention is applicable both to open and closed types of antennas particularly when the antennas of the latter type are considerably elongated.
  • Figure l is a side view of a magnetically loaded dipole antenna
  • Figure 2 is a side View, partly in section, of a magnetically loaded closed type antenna
  • Figure 3 is a sectional view of a modified form of the antenna of Figure 2 adapted for tuning.
  • Figure l illustrates a so called Hertzian Dipole of the linear type commonly employed for the reception and transmission of horizontally or vertically polarised high frequency radiation.
  • a dipole operates most elliciently when its length is equal to an odd multiple of half wavelength of the radiations received or transmitted.
  • two arms each a quarter wavelength long are used, slightly spaced apart at their inner ends.
  • the dipole is usually oriented in accordance with the polarization of the radiated energy; thus placed in a horizontal plane it is particularly suited for reception of horizontally polarized waves.
  • the theoretical optimum dimension of the dipole can United States Patent O 2,748,386 Patented May 29, 1956 ICC be easily verified by actual experiments; if the length of the dipole is varied the maximum signal occurs when the total length of the dipole is equal to the half wavelength ofthe incoming signal. Thus for a frequency of megacycles per second the required total length will be 7.7 feet to produce a maximum signal.
  • the theoretical resistance of such a dipole is 73.2 ohms and this resistance sometimes referred to as the radiation resistance, is a measure of the efficiency of an antenna both as a radiator and as' a collector. With suitable high frequency bridge type instruments it can be measured fairly accurately.
  • the effective length of an antenna is reduced by the location on or about the conductors of the dipole a magnetic material.
  • the material is a ferromagnetic material having such high frequency characteristics that the magnetic losses introduced can be tolerated.
  • a large number of beads 1 of high frequency ferromagnetic material are threaded onto the arms 2 of the dipole so that the arms are substantially covered.
  • Each bead is in the form of a cylindrical tube about in diameter and has an axial bore 3 slightly larger than the diameter of the conducting arms 2 of the dipole preferably made of compressed carbonyl iron powder.
  • the total length of the dipole is reduced to approximately half; to tune the antenna for maximum efficiency the branches are approximately 25 inches long. Further reduction in length results if the diameter of the beads 1 is increased so that the ferromagnetic material is better utilized. In this latter case it is possible to increase considerably the thickness of the arms 2 thus reducing the magnetic material by making the beads 1 thin-walled.
  • the effective permeability nerf is related to the permeability ,u of the material in the following manner:
  • d is demagnetization coefficient depending on the length-to-diameter-ratio (L/D) of the cylindrical core.
  • the effective D may be calculated from the area of the circle which is equivalent to the cross-sectional area of said other shaped cores.
  • aeff 45 and 420 respectively. Therefore in elongated closed type antennas employing high permeability ferrites the ratio of length to diameter must be as great as possible and in any case not less than 8 in order to utilize the benefits of the high effective permeability.
  • Figure 2 shows a new construction of such an elongated antenna in which a plurality of elongated beads 1 are strung together on a supporting conducting rod 4 to form a cylinder ⁇ of great length around which an insulated wire 5 forms a Vcoil which substantially covers the entire length of the core beads 1.
  • the coil of insulated wire is characterized by the turns thereof being spaced one from the other.
  • an antenna of this form possesses an extremely high ability to pick up the signal or effective height, which ability depends on nerf, the number of turns which is made as large as possible, and on the axial length of the antenna; by increasing the number of turns and the axial length of volume of space from which to pick up the radiations is increased.
  • Such an antenna may be termed a coil antenna.
  • This vterm is used to distinguish the structures of the present invention from the usual loop antenna. In the latter the electromotive force is usually derived from the center of the loop, while with the antenna of the present invention the entire space occupied by the coil antenna contributes to the sensitivity thereof.
  • such an antenna may have its diameter from 1/2" to 2' and even 4" with the length correspondingr to from 8 to l0() diameters.
  • the hollowing of the core-beads saves a considerable amount of magnetic material without materially affecting the performance. It is evident that in very small size antennas the hollow cores may be produced as single pieces which can be made by extrusion of ferrites during their pre-fabrication.
  • a thin-walled tubing 6 made from ferrite of lower-permeability is wound with a number of turns 5a of insulated wire to correspond to an inductance which with its own so-called distributed capacity or with an external capacitor is made resonant to a high frequency of a certain band of frequencies.
  • a cylindrical core 7 of higher permeability magnetic material is slidably arranged inside the tubing to increase thereby the effective permeability and to lower the frequency at which the circuit will resonate.
  • the extreme in ⁇ position of the slidable core 7 thus corresponds to the lowest frequency of the band of frequency and by varying the position of the core 7 the coil-antenna may be directly tuned.
  • the movement of the core 7 may be synchronized with the movement of other tuning members in a radio apparatus, as well as with the tuning indicator by coupling the core 7 to the other tuning members by means of the coupling 8, for example.
  • the total possible inductance variation of the tuned antenna must be the square of that ratio or 9:1.
  • the above described magnetically loaded antenna possesses high sensitivity in spite of the greatly reduced dimensions.
  • the tunable antenna of Figure 3 exhibits the advantage in that when receiving low frequency (longer wavelength) signals the eiciency does not drop but is amply compensated by the increase of eftective permeability.
  • a coil antenna comprising an elongated ferromagnetic element having its length to effective diameter ratio not less than about 8 and not more than about 100 and said element having an effective permeability of not less than about 4 and not more than about 420, an axially associated conductive member, and a conductive winding surrounding but insulated from said ferromagnetic element the turns of said winding being spaced between themselves and spread over substantially the entire length of said element thereby materially to increase the electromagnetic radiation pick-up properties of said antenna in the space occupied by said antenna.

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US259770A 1951-12-04 1951-12-04 Antenna systems Expired - Lifetime US2748386A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE507544D BE507544A (fr) 1951-12-04
FR1060816D FR1060816A (fr) 1951-12-04 1951-12-03 Perfectionnements dans la réalisation d'antennes radioélectriques
US259770A US2748386A (en) 1951-12-04 1951-12-04 Antenna systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US259770A US2748386A (en) 1951-12-04 1951-12-04 Antenna systems

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US2748386A true US2748386A (en) 1956-05-29

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US259770A Expired - Lifetime US2748386A (en) 1951-12-04 1951-12-04 Antenna systems

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US (1) US2748386A (fr)
BE (1) BE507544A (fr)
FR (1) FR1060816A (fr)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3017567A (en) * 1957-12-03 1962-01-16 Selco Exploration Company Ltd Reconnaissance electromagnetic survey pack
US3100893A (en) * 1960-11-30 1963-08-13 Helmut Brueckmann Broad band vertical antenna with adjustable impedance matching network
US3295137A (en) * 1964-09-08 1966-12-27 Collins Radio Co Shortened folded monopole with radiation efficiency increased by ferrite loading
US3302208A (en) * 1964-03-20 1967-01-31 Hendrickson Alice Dipole antenna including ferrite sleeves about the medial portions of its radiating elements
US3372395A (en) * 1963-11-13 1968-03-05 Gen Electric Vlf antenna
US3717877A (en) * 1970-02-27 1973-02-20 Sanders Associates Inc Cavity backed spiral antenna
US3774221A (en) * 1972-06-20 1973-11-20 R Francis Multielement radio-frequency antenna structure having linear and helical conductive elements
US3845417A (en) * 1958-02-21 1974-10-29 Singer Co Gyromagnetic circuit element
US3922684A (en) * 1973-08-30 1975-11-25 Plessey Handel Investment Ag Radio antennae encased in dielectric to reduce size
US3924238A (en) * 1974-06-12 1975-12-02 Plessey Co Ltd Dipole antenna with dielectric casing
US3936834A (en) * 1972-06-21 1976-02-03 The United States Of America As Represented By The Secretary Of The Navy High powered ferrite loaded helicopter antenna
US4167011A (en) * 1976-12-22 1979-09-04 Hustler, Inc. Radio antenna construction
US4290070A (en) * 1979-05-09 1981-09-15 Osamu Tanaka Magnetic loop antenna with diamagnetic properties
WO1984004426A1 (fr) * 1983-05-05 1984-11-08 Commw Of Australia Lignes de transmission
US4978966A (en) * 1988-06-24 1990-12-18 Nippon Antenna Co., Ltd. Carborne antenna
EP0480064A1 (fr) * 1990-04-27 1992-04-15 Creatic Japan, Inc. Element d'antenne
US6657601B2 (en) * 2001-12-21 2003-12-02 Tdk Rf Solutions Metrology antenna system utilizing two-port, sleeve dipole and non-radiating balancing network

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR641575A (fr) * 1927-09-21 1928-08-07 Appareil capteur d'ondes hertziennes
US1710085A (en) * 1926-02-20 1929-04-23 Cooper George William Fading and static eliminating radio antenna
GB430548A (en) * 1934-06-28 1935-06-20 Baxendale And Company Ltd Improvements in wireless or radio aerials
US2311364A (en) * 1939-04-03 1943-02-16 Buschbeck Werner Broad-band antenna
US2335969A (en) * 1941-04-04 1943-12-07 Johnson Lab Inc Loop antenna system
GB592763A (en) * 1945-04-13 1947-09-29 Gen Electric Co Ltd Improvements in aerial arrangements for radio signalling systems
US2438680A (en) * 1943-03-11 1948-03-30 Wladimir J Polydoroff Loop antenna apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1710085A (en) * 1926-02-20 1929-04-23 Cooper George William Fading and static eliminating radio antenna
FR641575A (fr) * 1927-09-21 1928-08-07 Appareil capteur d'ondes hertziennes
GB430548A (en) * 1934-06-28 1935-06-20 Baxendale And Company Ltd Improvements in wireless or radio aerials
US2311364A (en) * 1939-04-03 1943-02-16 Buschbeck Werner Broad-band antenna
US2335969A (en) * 1941-04-04 1943-12-07 Johnson Lab Inc Loop antenna system
US2438680A (en) * 1943-03-11 1948-03-30 Wladimir J Polydoroff Loop antenna apparatus
GB592763A (en) * 1945-04-13 1947-09-29 Gen Electric Co Ltd Improvements in aerial arrangements for radio signalling systems

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3017567A (en) * 1957-12-03 1962-01-16 Selco Exploration Company Ltd Reconnaissance electromagnetic survey pack
US3845417A (en) * 1958-02-21 1974-10-29 Singer Co Gyromagnetic circuit element
US3100893A (en) * 1960-11-30 1963-08-13 Helmut Brueckmann Broad band vertical antenna with adjustable impedance matching network
US3372395A (en) * 1963-11-13 1968-03-05 Gen Electric Vlf antenna
US3302208A (en) * 1964-03-20 1967-01-31 Hendrickson Alice Dipole antenna including ferrite sleeves about the medial portions of its radiating elements
US3295137A (en) * 1964-09-08 1966-12-27 Collins Radio Co Shortened folded monopole with radiation efficiency increased by ferrite loading
US3717877A (en) * 1970-02-27 1973-02-20 Sanders Associates Inc Cavity backed spiral antenna
US3774221A (en) * 1972-06-20 1973-11-20 R Francis Multielement radio-frequency antenna structure having linear and helical conductive elements
US3936834A (en) * 1972-06-21 1976-02-03 The United States Of America As Represented By The Secretary Of The Navy High powered ferrite loaded helicopter antenna
US3922684A (en) * 1973-08-30 1975-11-25 Plessey Handel Investment Ag Radio antennae encased in dielectric to reduce size
US3924238A (en) * 1974-06-12 1975-12-02 Plessey Co Ltd Dipole antenna with dielectric casing
US4167011A (en) * 1976-12-22 1979-09-04 Hustler, Inc. Radio antenna construction
US4290070A (en) * 1979-05-09 1981-09-15 Osamu Tanaka Magnetic loop antenna with diamagnetic properties
WO1984004426A1 (fr) * 1983-05-05 1984-11-08 Commw Of Australia Lignes de transmission
US4638272A (en) * 1983-05-05 1987-01-20 The Commonwealth Of Australia Lossy transmission line using spaced ferrite beads
US4978966A (en) * 1988-06-24 1990-12-18 Nippon Antenna Co., Ltd. Carborne antenna
EP0480064A1 (fr) * 1990-04-27 1992-04-15 Creatic Japan, Inc. Element d'antenne
EP0480064A4 (en) * 1990-04-27 1992-06-10 Creatic Japan, Inc Antenna element
US5220338A (en) * 1990-04-27 1993-06-15 Creatic Japan, Inc. Antenna element
US6657601B2 (en) * 2001-12-21 2003-12-02 Tdk Rf Solutions Metrology antenna system utilizing two-port, sleeve dipole and non-radiating balancing network

Also Published As

Publication number Publication date
FR1060816A (fr) 1954-04-06
BE507544A (fr)

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