EP0142233A2 - Antenne losange - Google Patents

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Publication number
EP0142233A2
EP0142233A2 EP84306021A EP84306021A EP0142233A2 EP 0142233 A2 EP0142233 A2 EP 0142233A2 EP 84306021 A EP84306021 A EP 84306021A EP 84306021 A EP84306021 A EP 84306021A EP 0142233 A2 EP0142233 A2 EP 0142233A2
Authority
EP
European Patent Office
Prior art keywords
extensions
aerial
arms
arm
extension
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84306021A
Other languages
German (de)
English (en)
Other versions
EP0142233A3 (fr
Inventor
Eric John Patrick May
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Exeter
Original Assignee
University of Exeter
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Exeter filed Critical University of Exeter
Publication of EP0142233A2 publication Critical patent/EP0142233A2/fr
Publication of EP0142233A3 publication Critical patent/EP0142233A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q11/00—Electrically-long antennas having dimensions more than twice the shortest operating wavelength and consisting of conductive active radiating elements
    • H01Q11/02—Non-resonant antennas, e.g. travelling-wave antenna
    • H01Q11/06—Rhombic antennas; V-antennas

Definitions

  • This invention relates to aerials suitable for radio reception and transmission, and more particularly to rhombic aerials. Amongst many other applications, these aerials can be used for T.V. reception and transmission.
  • the signal is fed to the two wires at one end of the rhombus, and to ensure correct termination it is necessary to connect a suitable resistor between the other ends of the two wires.
  • the angle formed by each wire in the side corners of the rhombus is also important for the performance of the aerial, and its value depends on the wavelength and the aerial dimensions. The value of this angle can be calculated in a known way.
  • the present invention arises out of work to adapt the known rhombic aerials for use at higher frequencies, e.g. VHF and higher.
  • One use of such an aerial would be for television reception, though of course the invention is not limited to such use, or to aerials for any particular frequency band.
  • the usual receiving aerial system used at present is the Yagi array. Yagi arrays can only be designed for specific television group bands. This means that three models are required to cover the whole range in the United Kingdom. This presents stocking problems.
  • the present invention seeks to overcome this problem so that the aerial may be used at higher frequencies. It does this by providing extensions on each arm of the rhombus, usually from one pair of adjacent ends of the arms, the extensions being electrically conductive and forming a transmission line in or close to the zero potential plane. The two extensions are electrically connected together and so form a balun. This permits the reactance of the aerial to be tuned so as to match that of a feed cable to the aerial.
  • connection It the position of the connection is fixed, then it is possible to match the aerial to the cable only at a particular band of frequencies. Therefore it is desirable that the position of the connection is adjustable, e.g. by providing a slide on the extensions.
  • the extensions may extend outwardly of the rhombus (normally in the plane of a rhombus), in which case it is possible for the cable to extend along one extension or, if the extension is hollow, to extend within it. Normally the extension will be at the ends of the arms of the rhombus to which electrical connection is made to the cable. It is also possible to provide the extension at the other or both ends, and this permits the cable to extend through or along one of the arms as discussed in our European Patent Application No. 84.305136.8.
  • each extension may extend inwardly of the rhombus.
  • One convenient arrangement is then to have each extension extending from one end of a arm to the other so that the arms and extensions from two triangles. The triangles are arranged with the extensions parallel and fastened together. It the extensions are tubular, the cable may then enter the aerial through a mid point of one of the extensions.
  • the aerials described below are manufactured from circular section tube. It is believed that all known rhombic aerials use relatively thin wires. However, the use of arms in the form of tubes has a number of advantages and some of these are discussed in our European Application No. 84.305136.8. As mentioned in that application, however, elliptical or pseudo- elliptical tube can be used, or elements of U, L, I or any other cross-section.
  • the material used can be copper, brass, aluminium, various alloys or any other material which can be made to conduct electricity.
  • One further possibility also discussed in our European Application No. 84.305736.8 is for the arms to be made of conductive plastics material.
  • Fig. 1 The aerial shown.in Fig. 1 comprises two arms 10, 12 formed by lengths of tube.
  • the tube of arm 10 is bent into two legs 10a, lOb with a 130° bend between them.
  • An optional reinforcing sleeve 14 is provided at the bend.
  • the tube of arm 12 is similarly constructed of two legs 12a, 12b and a sleeve 14.
  • the two arms are arranged in the same plane in the form of a rhombus. At the front end of the rhombus, they are held together by a nut 16, and a bolt 18 of plastics or other insulating material, with insulating spacers 20.
  • the ends of the tube may be connected by a resistor or other impedence R across the spacer, of a value to terminate the line correctly, but it has been found that this is often unnecessary, particularly when the aerial is a receiving aerial. It is also possible for the spacer 20 to be resistive, in which case it is unnecessary to provide a separate impedance R. The thickness of the tubular conductors forming the arms may be the reason for this.
  • the 130 0 bends in the tubes are spaced and supported by a plastics boom 22, by means of which the aerial may be affixed to a mast or other supporting structure.
  • the aerial has a plane of symmetry, 24, which is the earth plane or zero potential plane of the aerial.
  • the tube of each arm 10, 12 is bent at 25 to provide an extension 10c, 12c, extending rearwardly, parallel to each other and to the earth plane. These form a short transmission line in or close to the earth plane.
  • the ends of the extensions 10c, 12c are held mechanically and short-circuited by an end piece 26 brazed to them.
  • a co-axial signal feed cable 28 is led into the tube of arm 12 at the rear end and passes within the tube along the extension 12c to a hole 30 at the bend 25.
  • the outer conductor of the cable is soldered to the edges of the hole 30.
  • the inner conductor of the cable 32 is taken across the gap between the bends 25 and soldered to the bend 25 of the tube of arm 10. In this manner, the signal feed connection from the unbalanced co-axial cable 28 is made without disturbing the balance of the aerial.
  • the function of the transmission line formed by the extensions 10c, 12c is to form a balun for tuning out the reactance (the imaginary part of the impedance) of the aerial so as to match the feed cable.
  • a non- adjustable balun could be formed simply by the extensions 10c, 12c and the end piece 26, the length of the extensions being chosen (in relation to the size of a quarter-wavelength) to give the desired effect.
  • an adjustable slide 34 is provided on the extensions lOc, 12c. This slide can be moved to any desired position along the extensions 10c, 12c and secured there (e.g.
  • the effect length of the transmission line can be adjusted to tune the reactance of the aerial precisely for a given frequency band, giving optimum matching over the range of frequency bands at which the aerial is capable of operating.
  • Fig. 1 also shows another option.
  • the tube extension 12c may be provided with not just one hole 30 but also with a series of spaced holes 30a.
  • the cable outer can be soldered at any one of these, with the cable inner 32 being soldered at an opposing point on the extension 10c.
  • the cable then "sees" not a resistance R O (the real part of the impedance of the aerial) but n 2 R 0 , where n is the turns ratio of the (ideal) transformer formed by the transmission line from the selected hole to the bend 25.
  • R O the real part of the impedance of the aerial
  • n 2 R 0 the turns ratio of the (ideal) transformer formed by the transmission line from the selected hole to the bend 25.
  • the slide 34 is then adjusted to counter (tune out)the reactance of the aerial and transformer combination thus formed.
  • the extension 12c may have a longitudinal slot, and the cable can be positioned at any desired position along the slot.
  • suitable dimensions for the aerial are:
  • Fig. 2 The embodiment of Fig. 2 is in many respects similar to that of Fig. 1, and where appropriate the same reference numerals have been used, and description of corresponding parts will not be repeated.
  • the difference lies at the front end of the aerial.
  • the front ends of the tubular legs 10a, 12a are bent at 25a, and have forwardly extending extensions 10d, 12d.
  • These are provided with an end piece 26a and a movable slide 34a, forming a transmission line essentially identical to that at the rear end of the aerial. This enables the reactance at the forward end of the aerial to be turned out, to optimise the termination and improve the aerial etticiency.
  • Fig. 3 shows a preferred form of this aerial. Again, the same reference numerals have been used as previously where appropriate. In this aerial, however, the transmission line extensions have been provided inwardly instead of outwardly, and the resulting construction is mechanically advantageous.
  • the aerial essentially comprises two simple triangles made of tube. In this example, as a matter of rhombic aerial design with which a skilled man will be familiar, the bends between the legs 10a and 10b and between the legs 12a and 12b are 90° rather than the previous 130°, and the long sides 10e, 12e of the two triangles lie side by side (at a suitable spacing for the transmission lines which they form). Movable slides 34, 34a have the same function as previously.
  • tubular sides 10e, 12e effectively provide a mechanical supporting boom for this aerial, which can be fixed to a mast, so that there is no need for a separate plastics boom 22, or for other insulators.
  • Expense of manufacture is further reduced by the fact that the two triangles can be identical, so that the aerial can be made up of two identical modules.
  • the signal cable 28 can feed to the interior of the tubular side 12e via a central hole 38 (which is convenient for the likely position of a supporting mast).
  • the aerial of Fig. 3 can be modified by dispensing with the slides 34 and 34a. Instead, pairs of pre-drilled holes are provided at various positions along the sides 10e, 12e, at predetermined positions corresponding to the positions of the slides for given frequency bands.
  • the bolts 36 are then used to fulfil the function of the slides 34, 34a as well as for securing the triangles; the aerial will be supplied with instructions as to which fixing holes should be used for which frequency bands.
  • This system is particularly well suited for T.V. reception aerials, since it can be manufactured cheaply, erected easily, and only one model will cover all the frequency bands in use.
  • Figs. 4 and 5 show slight modifications of the aerial of Fig. 3.
  • the rear, feed end is provided with a double balun, by reason of the provision of a rearward extension 10f, 12f, giving another transmission line, and including more holes 30a for connection of the feed cable, and a further slide 34b.
  • Fig. 5 shows a simpler version, with no extra slide 34b, in which the co-axial feed cable is simply connected at the rear end of the transmission line projection 10f, 12f.
  • a predetermined ratio is . provided for matching the real part of the impedance and the imaginary part is tuned out as usual with the slide 34.
  • Figs. 6 and 7 illustrate how the geometry of the legs 10a, 10b, 12a, 12b can be modified to increase aerial efficiency.
  • metal strips 40 whose width increases from the ends of the aerial towards the middle.
  • Figs. 8 and 9 illustrate an aerial with two elements, one above another, each substantially as described above, having two tubular triangles 10, 12 and conducting supporting spacers 42 which are used for tuning the reactance.
  • At the front end of the aerial there is a resistive support spacer 44 vertically between the two elements, and the feed cable 28 enters the lower arm 12 through the space 44.
  • the concept of passing the co-axial cable through one of the arms is discussed in detail in our European Patent Application No. 84.305136.8 This concept is applicable not only to the embodiment of Figs. 8 and 9 but also could be used in the embodiments of Fig. 1 or Fig. 2, although in the latter case the cable would enter the arms 12 through extension 12d.
  • each tube 10, 12 has a supporting link member 48 leading to a Y-piece 46, where the cable 28 is connected in a similar manner to that described above.
  • Extending rearwardly from the Y-pieces 46 is another tubular extension transmission line 50, having an end-piece (or if desired, a slider) 52, the position of which is important to tune out the reactance and provide the necessary spacing.
  • the length of the link members 48 is also important, since they effectively provide transmission lines close to the earth plane taking the signal to the upper and lower elements, and thus affect the impedance at the feed point of the co-axial cable. As previously, several holes 30 may be provided at the feed point to adjust this impedance "seen" by the cable.

Landscapes

  • Aerials With Secondary Devices (AREA)
EP84306021A 1983-09-03 1984-09-03 Antenne losange Withdrawn EP0142233A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8323691 1983-09-03
GB838323691A GB8323691D0 (en) 1983-09-03 1983-09-03 Rhombic aerials

Publications (2)

Publication Number Publication Date
EP0142233A2 true EP0142233A2 (fr) 1985-05-22
EP0142233A3 EP0142233A3 (fr) 1986-08-06

Family

ID=10548314

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84306021A Withdrawn EP0142233A3 (fr) 1983-09-03 1984-09-03 Antenne losange

Country Status (2)

Country Link
EP (1) EP0142233A3 (fr)
GB (2) GB8323691D0 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2565010A1 (es) * 2015-10-05 2016-03-30 Doralte Servicios, S.L. Antena de polarización mixta

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB490192A (en) * 1936-12-21 1938-08-10 Telefunken Gmbh Improvements in or relating to aerial and associated feeder arrangements
DE1027261B (de) * 1956-04-10 1958-04-03 Siemens Ag Rhombus-Antenne

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB490192A (en) * 1936-12-21 1938-08-10 Telefunken Gmbh Improvements in or relating to aerial and associated feeder arrangements
DE1027261B (de) * 1956-04-10 1958-04-03 Siemens Ag Rhombus-Antenne

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
AUDIO, no. 1, January 1982, pages 24,26,28,29, Columbus, Ohio, US; R. KAUFMAN: "Try a rhombic FM antenna" *
R.A. SMITH: "Aerials for metre and decimetre wave-lengths", 1949, pages 130-135, Cambridge University Press, Cambridge, GB. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2565010A1 (es) * 2015-10-05 2016-03-30 Doralte Servicios, S.L. Antena de polarización mixta

Also Published As

Publication number Publication date
EP0142233A3 (fr) 1986-08-06
GB8323691D0 (en) 1983-10-05
GB8422191D0 (en) 1984-10-10

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Inventor name: MAY, ERIC JOHN PATRICK