US2339234A - Directional antenna system - Google Patents

Directional antenna system Download PDF

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Publication number
US2339234A
US2339234A US384525A US38452541A US2339234A US 2339234 A US2339234 A US 2339234A US 384525 A US384525 A US 384525A US 38452541 A US38452541 A US 38452541A US 2339234 A US2339234 A US 2339234A
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coil
core
loop
directional
antenna
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US384525A
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Wladimir J Polydoroff
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
    • H01Q7/06—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop with core of ferromagnetic material

Definitions

  • the present invention relates to frame or loop antennae for high frequency reception and/or transmission of electromagnetic Waves.
  • antennae employed an appropriate number of turns wound on a frame of insulated material and may be termed air cored antennae, as distinguished from iron cored coil antennae as described in United States Letters Patent 2266262 of Dec. 16, 1941, to Polydoroff.
  • the present invention has for its object, new constructions and new uses of this type of coil antennae which employ high frequency comminuted magnetic materials in the form of magnet cores associated with the coils.
  • such antennae are usually arranged to act substantially as collectors or radiators of the electromagnetic energy.
  • FIG. 2 shows construction of a loop antenna, in accordance with the invention and Figs. 2a and 2b constructonal details of Fig. 2.
  • Fig. 3 shows a modification of the invention.
  • Figs. 4 and 5 diagrammatically show the directional functions of the devices of the invention and Flgs. 6 and 7 show an apparatus in which the invention is also applicable.
  • the presence of a ferromagnetic mass in the field of a coil may substantially improve the electrical quality (Q) of the coil which improvement by itself increases pick-up and directional properties of the coil, provided that both coil and the core are proportioned in the way of choice of particle size, Litz wire and the spacings between the wires and the core.
  • the effective height of the antenna is increased in direct proportion to the effective permeability of the core in the given coil; which phenomena may be explained by the increase, either by induction or by attraction, of magnetic lines threading through the core with the result that greater voltage is generated in the coil.
  • the core need not be an integral part of the antenna.
  • the magnetic mass may be now regarded as an inducer or final source of the electromagnetic energy and 'the coil merely as the collector from this source, if it happens in the vicinity of the mass.
  • the core produces another function if it is close enough to the coil, vz. it
  • the core may be made stationary and the loop 'tenna.
  • Fig. 1 represents a plot of field intensities of a coil antenna (dotted lines on the left half of the coil) and a resultant line pattern of the fields plainly shows a directional vconclensation of the lines in such coil an-
  • the removal of the core will result in spreading' of the lines in all directions and greater number of stray fie1ds, of which three lines are shown in the figure when iron core I is inserted in the coil 2.
  • This diagram explains the improvement in directional properties of a radio Compass equipped with iron core antenna, where it is known to seek the direction by the null point or zero signal occurring when the plane of the coil is perpendicular to the source of radiation. This improvement of directional properties is apart from and additional to the improvement due to the increase of pick-up properties through increase of Q and effective height.
  • an asymmetrical mass in the coil may displace the main directional axis of the coil towards the mass so that direction readings will be somewhat displaced with relation to the physical axis of the coil. If therefore a coil is arranged to rotate about an asymmetrical mass, at some positions where magnetic and physical axis coincide the reading will be correct, while at other positions a certain deviation may occur.
  • radio directional compass placed on board a ship or an aircraft may produce some errors of observation which are due to the deflection of the true direction of the wave front because of interferng metal parts in close vicinity of the compass.
  • core pieces which are asymmetrical with respect to the coil, and which come closer to or further from the windings when the loop is rotated thus causing a defiection in direction finding of exact- ⁇ ly opposite sense.
  • FIG. 1 Further examination of the coil antennae shown in Fig. 1 establishes the fact that better directioning of lines of field results from an elongated core.
  • a core of this type represents considerable added weight, particularly if the whole antenna is made rotatable. It is possible, however, to so re-distribute the mass of the core that substantially the same results are obtainable with less core material if the core is made with relatively thin walls adjoining the winding only and the core mass extended lengthwise so that the same or higher permeabilities will result, with improved directional properties.
  • Fig. 2 and Fig. 3 Both figures show symmetrical type of cores, i. e. such that coil can be rotated around the core without any change in inductance, provided of course that the magnetic mass distribution is uniform throughout the magnetic structures.
  • the coil comprises a rectangular frame, preferably the square 3, of good insulating material, having four diagonally placed spacers 4 with slots to provide for laying the Wire in several sections.
  • the wire may also be laid so as to form a loose basket weave of several layers.
  • a cross-section through one of the spacers 4 is shown in Fig. 2a.
  • a hollow shaft 5 is secured to the frame 3 to control rotation of the frame from a remote point.
  • the hollow shaft 5 may carry inside lead-in-wires connected at the bottom to slip ring '5a which are in contact with the brushes 5b to which a cable could be attached, as shown in Fig. 2b from the coil.
  • the magnetic core 6 is moulded in toroldal Sections which in the present case are 4 inches external diameter, 3 inches internal diameter and 1 inch long so that four rings form a cylinder 4 x 4 with a wall thickness of 1/2.
  • the core Sections are cemented to a Bakelite drum 1, preferably moulded in one piece, having an inner tube to house shaft 5 and a fiange 8 for permanent installation on a ship or aircraft. If the magnetic mass is uniform, or is made uniform by rotating the individual core sections before they are cemented, the frame coil 3, 4, can be rotated 360 degrees without altering the inductance. Experiments prove that such arrangement provides a very Satisfactory rotatable loop for a radio compass.
  • the Vertical wires contribute to directional quality, the balancing of the frame to zero signal resulting in two signals of equal strength 'but opposite phase in the Vertical branches. Since the improvement in directional qualities as already explained is due to the iron in the immediate vicinity of the acting conductors, the distribution of the iron also appears to be a factor producing optimum conditions.
  • the magnification factor or Q of the frame antenna with the thin walled iron core is about 400 when measured at 0300 kc. A slight improvement in Q Will 'result with a solid core.
  • Fig. 3 shows another form of rotatable loop with a fixed core.
  • the core in this case is composed of two sections which when cemented and clamped together form a, hollow sphere 9. Both. lhemi-spheres may be moulded and are held together by a hollow bolt IO with a foot I.
  • a control shaft 12 passing through the bolt rotates the loop [3, which in this case is wo-und on a ring of polystyrene, the wire being laid so as to form a loose basket weave of severa1 layers resembling so-called universal coils.
  • a small number of turns is employed to form so-called low impedance loops which are usually coupled through a low impedence cable to the primary of a transformer, the secondary of which is tunable.
  • the signal generated by such system is again proportional to Q"hen; which aifects the pick-up properties of the loop, as well as its directional properties in accordanoe with the diagram of Fig. 5.
  • the inductance of aperiodic loops is usually kept small consistent with ability to tune the system to a shortest wavelength and it is usual in the directional finding systems to 'connect such a low impedance loop to a series of transformers each covering a certain range of wavelength (frequency), by means of suitable switching mechanism.
  • Such system While producing a sufiicient pick-up for the higher frequency range is detrimental for the lowest frequencies.
  • the existing system employs a loop in which it is possible to improve the loop performance by providing a loop of an increased number of turns suitable for the lowest frequency ranges. When the same loop is switched to the higher frequency ranges the outer terminals of the loop are connected .together thus forming a single loop which has two sections paralleled. This expedient enables to increase the efiiciency of the system at all frequencies. Such arrangement is illustrated on Fig. 2b.
  • Figs. 2 and 3 may be advantageously applied to the Bellini Tosi system.
  • Two vertically elongated loops are placed with their planes at right angles as shown in Fig. 6 and both loops are loosely coupled by auxiliary coils to a rotatable coil.
  • the coupling must b'e weak and the. efficiency poor to avoid reaction between two antennae, as such reaction will result in poor directional properties.
  • 5 feed independently through screened grid type tubes 16 and
  • the third winding 22 constitutes a secondary of tunable type and is therefore capable of high gain and is made rotatable around the iron core cylinder, such as in the case of the coil 3, 4 of Fig. 2.
  • the whole construction may be made considerably smaller, consistent with high Q of the rotatable coil in the small space.
  • a high degree of directional selectivity by maximum observation is obtainable due to the preamplification of the signals, additional high Q of the rotatable oircuit and exact location of the fields at right angle without scattering of strays.
  • a directional system for the reception of electroma-gnetic radiations including a rotatable coil antenna a stationary ferromagnetic core in the field of said coil and composed of comminuted magnetic particles, said core being of such shape relative to the coil that at any angular position of rotation of said coil the magnetic reluctance remains substantially Constant.
  • a directional system for the reception of electromagnetic radiations including a rotatable coil antenna of a rectangular shape a stationary ferromagnetic core of cylindrical shape the axis of the cylinder and the axis of rotation of the coil being identical.
  • a directional antenna for the reception of electromagnetic radiated energy comprising a stationary ferromagnetic mass in the field of said radiations in the form of a body of rotation, pickup coil antenna rotatable around said mass the axis of the body and of the coil being identical.
  • a directional system for wireless communication comprising a stationary ferromagnetic mass in the form of a hollow body of rotation a coil antenna arranged to rotate around said mass, the axis of rotation of the coil being identical with the axis of said body.
  • a directional system for the reception of electromatic radiations comprising a rotatable coil antenna, a ferromagnetic core disposed in the field of said coil symmetrically to the axis of rotation of said coil, additional ferromagnetic core means placed asymmetrically to said axis to thereby cause a devation of bearings of said directional system in the desired position of said antenna.
  • Directional system as per claim 5 characterized in that said additional ferromagnetic core means are adjustable.

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  • Coils Or Transformers For Communication (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
US384525A 1940-03-21 1941-03-21 Directional antenna system Expired - Lifetime US2339234A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB551546X 1940-03-21

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BE (1) BE476857A (nl)
GB (1) GB551546A (nl)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2438680A (en) * 1943-03-11 1948-03-30 Wladimir J Polydoroff Loop antenna apparatus
US2719922A (en) * 1950-12-15 1955-10-04 Zenith Radio Corp Core tuned loop
US2975421A (en) * 1956-02-28 1961-03-14 George D Chichester Magnetic antenna
DE975621C (de) * 1950-12-04 1962-03-01 Gen Aniline & Film Corp Spulenantenne zum Aussenden oder Empfangen von Rundfunkwellen
WO1998044586A1 (en) * 1997-04-03 1998-10-08 Destron Fearing Corporation Multi-phase transmitter with single receive antenna for transponder interrogator
US20090179741A1 (en) * 2008-01-11 2009-07-16 Mu-Gahat Holdings Inc. Enhancing the efficiency of energy transfer to/from passive id circuits using ferrite cores
US20090289773A1 (en) * 2008-02-25 2009-11-26 Mu-Gahat Holdings Inc. Extending the read range of passive rfid tags
US20100013602A1 (en) * 2008-04-21 2010-01-21 Mu-Gahat Holdings Inc. H-Field Shaping Using a Shorting Loop
US20100277387A1 (en) * 2004-12-21 2010-11-04 Q-Track Corporation Space Efficient Magnetic Antenna Method
US8436780B2 (en) 2010-07-12 2013-05-07 Q-Track Corporation Planar loop antenna system
US9997845B2 (en) 2004-12-21 2018-06-12 Q-Track Corporation Embedded symmetric multiple axis antenna system with isolation among the multiple axes

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2438680A (en) * 1943-03-11 1948-03-30 Wladimir J Polydoroff Loop antenna apparatus
DE975621C (de) * 1950-12-04 1962-03-01 Gen Aniline & Film Corp Spulenantenne zum Aussenden oder Empfangen von Rundfunkwellen
US2719922A (en) * 1950-12-15 1955-10-04 Zenith Radio Corp Core tuned loop
US2975421A (en) * 1956-02-28 1961-03-14 George D Chichester Magnetic antenna
GB2338835A (en) * 1997-04-03 1999-12-29 Destron Fearing Corp Multi-phase transmitter with single receive antenna for transponder interrogator
US5923300A (en) * 1997-04-03 1999-07-13 Destron-Fearing Corporation Multi-phase transmitter with single receive antenna for transponder interrogator
AU730314B2 (en) * 1997-04-03 2001-03-01 Destron Fearing Corporation Multi-phase transmitter with single receive antenna for transponder interrogator
ES2154613A1 (es) * 1997-04-03 2001-04-01 Destron Fearing Corp Transmisor de fases multiples con antena de recepcion unica para interrogador de respondedor.
GB2338835B (en) * 1997-04-03 2001-06-27 Destron Fearing Corp Multi-phase transmitter with single receive antenna for transponder interrogator
WO1998044586A1 (en) * 1997-04-03 1998-10-08 Destron Fearing Corporation Multi-phase transmitter with single receive antenna for transponder interrogator
US20100277387A1 (en) * 2004-12-21 2010-11-04 Q-Track Corporation Space Efficient Magnetic Antenna Method
US9997845B2 (en) 2004-12-21 2018-06-12 Q-Track Corporation Embedded symmetric multiple axis antenna system with isolation among the multiple axes
US8922440B2 (en) 2004-12-21 2014-12-30 Q-Track Corporation Space efficient magnetic antenna method
US20090179741A1 (en) * 2008-01-11 2009-07-16 Mu-Gahat Holdings Inc. Enhancing the efficiency of energy transfer to/from passive id circuits using ferrite cores
US8432283B2 (en) * 2008-01-11 2013-04-30 Magnet Consulting, Inc. Enhancing the efficiency of energy transfer to/from passive ID circuits using ferrite cores
US8988224B2 (en) 2008-01-11 2015-03-24 Magnet Consulting, Inc. Enhancing the efficiency of energy transfer to/from passive ID circuits using ferrite cores
US8395525B2 (en) * 2008-02-25 2013-03-12 Magnet Consulting, Inc. Extending the read range of passive RFID tags
US20090289773A1 (en) * 2008-02-25 2009-11-26 Mu-Gahat Holdings Inc. Extending the read range of passive rfid tags
US8395507B2 (en) * 2008-04-21 2013-03-12 Magnet Consulting, Inc. H-field shaping using a shorting loop
US20100013602A1 (en) * 2008-04-21 2010-01-21 Mu-Gahat Holdings Inc. H-Field Shaping Using a Shorting Loop
US8981940B2 (en) 2008-04-21 2015-03-17 Magnet Consulting, Inc. H-field shaping using a shorting loop
US8436780B2 (en) 2010-07-12 2013-05-07 Q-Track Corporation Planar loop antenna system

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Publication number Publication date
GB551546A (en) 1943-03-01
BE476857A (nl)

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