WO1994021004A1 - Very low frequency compact radio antenna - Google Patents

Very low frequency compact radio antenna Download PDF

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Publication number
WO1994021004A1
WO1994021004A1 PCT/FR1994/000250 FR9400250W WO9421004A1 WO 1994021004 A1 WO1994021004 A1 WO 1994021004A1 FR 9400250 W FR9400250 W FR 9400250W WO 9421004 A1 WO9421004 A1 WO 9421004A1
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WO
WIPO (PCT)
Prior art keywords
antenna
antenna according
monopoly
conductive
arms
Prior art date
Application number
PCT/FR1994/000250
Other languages
French (fr)
Inventor
Jean Bourdier
Original Assignee
Rayan
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 Rayan filed Critical Rayan
Priority to AU62106/94A priority Critical patent/AU6210694A/en
Publication of WO1994021004A1 publication Critical patent/WO1994021004A1/en

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Classifications

    • 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
    • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
    • H01Q9/32—Vertical arrangement of element
    • H01Q9/36—Vertical arrangement of element with top loading

Definitions

  • the invention relates to a compact radio antenna for very low frequencies, comprising a vertical monopoly.
  • the height of an antenna is inversely proportional to the frequency at which it must transmit or receive a signal.
  • the frequencies at which the antenna of the invention must transmit or receive a signal are situated approximately between 100 kHz and 3 MHz.
  • a monopole antenna radiating in quarter wave should have a height between 750 m and 25 m.
  • R r + Pp where R r is the radiation resistance and Rp is the energy lost by the Joule effect.
  • the loss resistance becomes preponderant and the antenna dissipates most of the RF energy it receives, in calories.
  • the complementary tuning element, a choke or another circuit adds its own loss resistance to the own loss resistances of the conducting elements of the antenna. This obviously again decreases the ratio ⁇ and the radiation efficiency.
  • the section of the antenna conductive elements could be enlarged. This would, on the other hand, lead to a consequent increase in the masses and the cost of the antenna. The increase in the mass of the antenna is particularly felt when the antenna of reduced height must be used for the establishment of mobile or temporary links.
  • the object of the invention is to provide a compact antenna for very low frequencies, comprising a vertical monopoly, which overcomes the aforementioned drawbacks.
  • the object of the invention is also to propose a compact antenna whose height for a given transmission or reception frequency is at most equal to a quarter of the height of a quarter-wave monopoly of the same radiation efficiency. .
  • the subject of the invention is a compact antenna for very low frequencies, comprising a vertical monopoly having an upper end defining a top of the antenna, and at least two conductive arms each connected by one of its ends to the top of the antenna and forming a top layer.
  • each conductive arm of this antenna comprises a inductive element arranged in series at about a third of the length of the conductive arm, measured from the top of the antenna.
  • the free end of any radiating element, situated opposite the excitation, requires the distribution of the antenna currents.
  • the currents are practically zero at the free ends and increase as a function of the position of the point considered according to a sinusoidal law towards the excitation point of the antenna.
  • the inductive element is placed in a portion of the antenna where the partial current is low.
  • the invention also relates to the following characteristics, considered in isolation or in all their technically possible combinations: -
  • the crown ply has a plane geometry.
  • This arrangement corresponds to the type of antenna commonly called a "T-shaped antenna", the number of conductive arms which form the crown ply generally being between four and eight.
  • the use of a flat top ply obviously implies the need for fixing points for the free ends of the conductive arms. Generally, the fixing points are presented by support masts.
  • the top layer has the shape of an inverted cone.
  • This arrangement corresponds to an antenna commonly called “umbrella antenna”. It has the advantage that the free ends of the conductive arms can be fixed to the ground. In Consequently, this type of antenna only needs a single fixing point above the ground, this fixing point can be constituted by the top of a mast or by any other point raised above the ground. . -
  • the vertical monopoly is made up of a wire element.
  • This arrangement is preferably used in the case of a T-shaped or L-shaped antenna.
  • the center of the crown ply at the same time constitutes the point of suspension of the wire element.
  • the antenna includes at least two support masts.
  • the antenna comprises as many support masts as conductive arms forming the crown ply.
  • the vertical monopoly consists of a conductive mast.
  • the antenna comprises a base intended to be connected to ground radians forming an artificial earth plane or counterweight.
  • the number of radians of soil can be equal to the number of conductive arms of the crown ply.
  • the antenna includes an articulation connecting the base to the vertical monopoly.
  • This provision preferably applies to mobile or temporary installations. This provision is intended to facilitate the assembly and disassembly of the antenna and in particular to make it possible carry out these operations by only one or two people.
  • the vertical monopoly is made up of a plurality of nestable elements. This arrangement makes it possible to present
  • the support masts are each composed of a plurality of nestable elements.
  • This arrangement has the advantage of being able to present the antenna in a version which, by the size of the various elements constituting it, facilitates its transport. Furthermore, such an antenna can be adapted to different situations depending on the location provided. More particularly, this arrangement makes it possible to vary the height of each of the support masts independently of the other in order to obtain, for example, despite the unevenness of the terrain where the antenna is to be installed, a substantially flat top ply and horizontal.
  • FIG. 1 shows the principle of a compact T-shaped antenna, in accordance with the invention.
  • Figure 2 shows, schematically, a top view of the antenna of Figure 1.
  • Figure 3 shows the principle of a parasol antenna, according to the invention.
  • FIG. 4 shows a preferred example of the compact antenna according to the invention
  • FIG. 1 shows the principle of a compact T-antenna for very low frequencies, according to the invention.
  • the antenna is referenced in its together at 100. It comprises a vertical monopoly 1 having an upper end 2 forming an apex S of the antenna and a lower end 3.
  • the antenna 100 includes a plurality of conductive arms each connected by one of its ends to the top of the antenna.
  • the total number of conductive arms is generally four or six; but it can also be eight, twelve or sixteen.
  • the antenna 100 comprises as many support masts as conductive arms.
  • Each of the support masts 7 and 8 can be made in one piece. It is however more advantageous to manufacture it, from a certain height, in two or more elements. When mounting the antenna, these elements can be assembled, either by fitting one element into another, or by superimposing the elements around the longitudinal axis of the mast and attaching one element to the other by means fastening provided for this purpose and known per se (not shown) or by any other means available to those skilled in the art to superimpose a variable quantity of elements which can form a support mast of variable height.
  • Figure 1 shows the antenna 100 installed on a flat and horizontal ground.
  • Each of the support masts of the antenna 100 is made of a non-conductive material or is at least insulated with respect to the conductive arms of the crown ply 6.
  • each of the support masts is retained, in a manner known per se , by guy lines of which Figure 1 shows only the guy lines 9 and 10.
  • the guy lines 9 and 10 are fixed to the ground at anchor points 18 and 19.
  • FIG. 2 The arrangement of a vertical monopoly 1 - of conducting arms forming the top ply 6, of support masts and guy lines, together forming the antenna 100, is shown, in plan view schematically in FIG. 2.
  • the antenna 100 is connected, at its lower end 3, to a transmitter / receiver equipment (not shown).
  • this connection corresponds to the connection of an excitation device to an input B of the antenna.
  • the excitation is connected to the antenna between the lower end 3 of the monopoly 1 and a ground network 15 disposed at ground level and constituting an artificial earth plane, also called the mass or counterweight of the 'antenna.
  • the free end located opposite the excitation, requires the distribution of the antenna current.
  • the antenna current is distributed over all of the conductive arms of the crown ply.
  • the partial currents of the various conducting arms which result therefrom are practically zero at the free ends of the arms, referenced at E and E '. They increase as a function of the position of the point considered, according to a sinusoidal law of point E, or respectively of the point E ', towards the excitation point B, passing the vertex S of the antenna.
  • the inductive elements, referenced in 13 and 14, are arranged in each of the conducting arms of the crown ply 6 at a location, referenced in L.
  • the point L is chosen so that LS is equal to one third of ES.
  • the inductive element 13, or respectively 14 is arranged in series at about a third of the length of the conductive arm 4, respectively 5, measured from the top 2 of the antenna 100.
  • the distance LS can take a value between 30 and 40% of the length ES of the conductive arm, measured from the apex 2 of the antenna.
  • FIG 3 shows the principle of a parasol antenna according to the invention.
  • the antenna referenced as a whole in 200, comprises elements which have identical functions to the corresponding elements of antenna 100 of Figure 1 and which, for this reason, have the same reference numbers.
  • the antenna 200 comprises a vertical monopoly 1 having an upper end 2, representing the top of the antenna, and a lower end 3.
  • Conducting arms 4 and 5 are stretched from the upper end 2 towards the ground on which they are fixed by means of insulating fixing elements 11 and 12.
  • the lower end 3 of the antenna and a ground network 15, representing the mass of the antenna, are connected to a transmitter / receiver equipment.
  • the lower end 3 of the vertical monopoly 1 represents the excitation point B of the antenna.
  • inductive elements 13 and 14 are arranged in series respectively in the conducting arms 4 and 5.
  • the place where these inductive elements are introduced is located at 30 to 40% the length of the conductive arm 4 or 5, measured from the top S of the antenna. In most cases, location L will be located approximately one third of the length of the conductive arm.
  • Figure 4 shows an embodiment of the compact antenna according to the invention.
  • This umbrella antenna which is referenced as a whole at 300, comprises elements whose function is identical to the elements shown in Figure 3 and which, for this reason, bear the same reference numbers.
  • the antenna 300 comprises a vertical monopoly 1, consisting of a plurality of nestable elements 21 forming a conductive mast.
  • Mast 1 has an upper end 2 and an end lower 3.
  • the lower end 3 is provided with a base 22, with which it is mechanically connected, but with respect to which it is electrically insulated.
  • the mast 1 is made essentially of a composite material based on an epoxy resin.
  • Each of the elements 21 of the mast 1 is in the form of a cylindrical tube of revolution, covered with a layer of projected aluminum on which a layer of paint is applied.
  • the ends of element 21 are provided with stainless steel end pieces, glued to the ends of the tube with a conductive adhesive.
  • the tips are at least partially conical to ensure a good seat, after fitting, to ensure secure electrical contact between the elements 21 fitted.
  • the mechanical connection between the mast 1 and the base 22 is produced in the form of a joint 23.
  • the lower end 3 comprises a connection device 24 making it possible to connect the antenna 300 to a transmitter / receiver equipment (not shown) and to connect an adaptation admittance 35 between the mast 1 and the earth 15 of the 'antenna.
  • the arrangement of the admittance 35 in parallel with the connection of the radio equipment corresponds to the principle of reducing, preferably even avoiding, any additional resistance, connected in series with the monopoly 1 at a level of the antenna where the current antenna has great values.
  • the compact antenna 300 also includes four conductive arms 4, 4 ', 5 and 5'. These four conductive arms are attached by one of their ends to the upper end 2 of the antenna, and by the other end, by means of fixing elements. insulators 11, 11 ', 12 and 12', at fixing points 16, 16 ", 17 and 17 'on the ground.
  • shrouds 25 to 28 are stretched between the fixing points 16, 16 ', 17 and 17', on the one hand, and a point 29 located approximately halfway up mast 1, on the other hand.
  • the guys 25 to 28 are electrically insulated from the mast 1.
  • each of the guys 25 to 28 is provided with a tensioner 30.
  • the tensioner 30 can be a ball tensioner.
  • the antenna 300 also includes four ground radians 31, 32, 33 and 34 constituting an artificial earth plane representing the mass of the antenna.
  • the four ground radians 31 to 34 are electrically and mechanically connected to the base 22.
  • inductors 13, 13 ', 14 and 14' are arranged in series in the corresponding conductive arms 4, 4 ', 5 and 5 ".
  • the antenna 300 finds its application for example as an antenna of a transceiver station temporarily installed. Two people, possibly even one person, are able to mount and dismantle this antenna. This is in particular possible thanks to the arrangement of the articulation 23 at the foot of the monopoly 1.
  • the antenna must work at a frequency of 2 MHz.
  • the height of the monopoly 1 is only about 9 meters, and the mast constituting the vertical monopoly 1, is composed of nine interlocking elements.
  • the chokes 13, 13 ', 14 and 14' have an inductivity of 44 ⁇ H and they are placed respectively about 3.5 meters from the top of the antenna.
  • the reference signs inserted after the technical characteristics mentioned in the claims, have the sole purpose of facilitating the understanding of the latter, and in no way limit their scope.

Abstract

Very low frequency compact radio antenna comprising a vertical single pole (1) with an upper end (2) defining the apex (S) of the antenna (100), and at least two conducting arms (4, 5), each connected by one of its ends (E, E') to the antenna's apex (5). The antenna is characterized in that each conducting arm (4, 5) comprises an inductive element (13, 14) disposed in series at approximately one third of the length of the conducting arm (4, 5) measured from the antenna's apex (3).

Description

Antenne radioélectrique compacte pour très basses fréquences. Compact radio antenna for very low frequencies.
L'invention concerne une antenne radioélectrique compacte pour très basses fréquences, comprenant un monopole vertical.The invention relates to a compact radio antenna for very low frequencies, comprising a vertical monopoly.
La hauteur d'une antenne est inversement proportionnelle à la fréquence à laquelle elle doit émettre ou recevoir un signal. Les fréquences auxquelles l'antenne de l'invention doit émettre ou recevoir un signal sont situées environ entre 100 kHz et 3 MHz. Il en résulte, qu'une antenne monopole rayonnant en quart d'onde devrait avoir une hauteur entre 750 m et 25 m.The height of an antenna is inversely proportional to the frequency at which it must transmit or receive a signal. The frequencies at which the antenna of the invention must transmit or receive a signal are situated approximately between 100 kHz and 3 MHz. As a result, a monopole antenna radiating in quarter wave should have a height between 750 m and 25 m.
Des antennes d'une telle hauteur sont difficiles, voir impossibles à réaliser. Surtout, leur application est limitée à des stations fixes. Des réalisations pratiques, de coût limité et facilement anipulables peuvent être obtenues en mettant en oeuvre un schéma électrique permettant la réduction de la hauteur physique de l'antenne.Antennas of such a height are difficult, even impossible to achieve. Above all, their application is limited to fixed stations. Practical realizations, of limited cost and easily anipulable can be obtained by implementing an electrical diagram allowing the reduction of the physical height of the antenna.
Parmi les dispositions utilisées à ce jour pour réduire la hauteur d'une antenne émettant à une fréquence donnée, on trouve notamment l'introduction d'une charge capacitive. Plus particulièrement, cette charge capacitive est réalisée sous forme d'une nappe de sommet en T ou en V. L'accord d'une telle antenne à la fréquence de travail est effectué par l'intermédiaire d'une self localisée ou répartie, introduite en série dans la partie rayonnante verticale basse ou haute de 1'antenne. Le fait de réduire la hauteur d'un élément rayonnant entraîne une diminution de sa résistance de rayonnement. En conséquence, la réduction de la hauteur d'une antenne est limitée, car le rapport 7] de l'énergie utile rayonnée à l'énergie perdue par effet Joule décroît très vite: Rr η =Among the arrangements used to date to reduce the height of an antenna transmitting at a given frequency, there is in particular the introduction of a capacitive load. More particularly, this capacitive load is produced in the form of a T or V top layer. The tuning of such an antenna at the working frequency is carried out by means of a localized or distributed self, introduced in series in the low or high vertical radiating part of the antenna. Reducing the height of a radiating element reduces its radiation resistance. Consequently, the reduction in the height of an antenna is limited, because the ratio 7] of the useful energy radiated to the energy lost by the Joule effect decreases very quickly: Rr η =
Rr + Pp où Rr est la résistance de rayonnement et Rp est l'énergie perdue par effet Joule.R r + Pp where R r is the radiation resistance and Rp is the energy lost by the Joule effect.
Pour des hauteurs très réduites, la résistance de perte devient prépondérante et l'antenne dissipe la plus grande partie de l'énergie RF qu'elle reçoit, en calories. De plus, l'élément complémentaire d'accord, une self ou un autre circuit, ajoute sa propre résistance de perte aux résistances de perte propres des éléments conducteurs de l'antenne. Ceci diminue évidemment à nouveau le rapport η et l'efficacité de rayonnement. Pour diminuer les pertes globales, on pourrait grossir la section des éléments conducteurs de l'antenne. Ceci entraînerait, par contre, une augmentation conséquente des masses et du coût de l'antenne. L'augmentation de la masse de l'antenne est particulièrement ressentie lorsque l'antenne de hauteur réduite doit être utilisée pour l'établissement de liaisons mobiles ou provisoires.For very reduced heights, the loss resistance becomes preponderant and the antenna dissipates most of the RF energy it receives, in calories. In addition, the complementary tuning element, a choke or another circuit, adds its own loss resistance to the own loss resistances of the conducting elements of the antenna. This obviously again decreases the ratio η and the radiation efficiency. To reduce the overall losses, the section of the antenna conductive elements could be enlarged. This would, on the other hand, lead to a consequent increase in the masses and the cost of the antenna. The increase in the mass of the antenna is particularly felt when the antenna of reduced height must be used for the establishment of mobile or temporary links.
Le but de l'invention est de proposer une antenne compacte pour très basses fréquences, comprenant un monopole vertical, qui remédie aux inconvénients précités.The object of the invention is to provide a compact antenna for very low frequencies, comprising a vertical monopoly, which overcomes the aforementioned drawbacks.
Le but de l'invention est également de proposer une antenne compacte dont la hauteur pour une fréquence d'émission ou de réception donnée est au plus égale à un quart de la hauteur d'un monopole de quart d'onde de même efficacité de rayonnement.The object of the invention is also to propose a compact antenna whose height for a given transmission or reception frequency is at most equal to a quarter of the height of a quarter-wave monopoly of the same radiation efficiency. .
L'invention a pour objet une antenne compacte pour très basses fréquences, comprenant un monopole vertical ayant une extrémité supérieure définissant un sommet de l'antenne, et au moins deux bras conducteurs reliés chacun par une de ses extrémités au sommet de l'antenne et formant une nappe de sommet. Conformément à l'invention, chaque bras conducteur de cette antenne comporte un élément selfique disposé en série à un tiers environ de la longueur du bras conducteur, mesuré à partir du sommet de l'antenne.The subject of the invention is a compact antenna for very low frequencies, comprising a vertical monopoly having an upper end defining a top of the antenna, and at least two conductive arms each connected by one of its ends to the top of the antenna and forming a top layer. According to the invention, each conductive arm of this antenna comprises a inductive element arranged in series at about a third of the length of the conductive arm, measured from the top of the antenna.
Comme il sera expliqué plus en détail en référence aux figures, l'extrémité libre de tout élément rayonnant, située à l'opposé de l'excitation, impose la distribution des courants de l'antenne. Les courants sont pratiquement nuls aux extrémités libres et croissent en fonction de la position du point considéré selon une loi sinusoïdale vers le point d'excitation de l'antenne. Selon l'invention, l'élément selfique est placé dans une portion de l'antenne où le courant partiel est faible.As will be explained in more detail with reference to the figures, the free end of any radiating element, situated opposite the excitation, requires the distribution of the antenna currents. The currents are practically zero at the free ends and increase as a function of the position of the point considered according to a sinusoidal law towards the excitation point of the antenna. According to the invention, the inductive element is placed in a portion of the antenna where the partial current is low.
L'invention concerne également les caractéristiques ci-après, considérées isolément ou selon toutes leurs combinaisons techniquement possibles: - La nappe de sommet a une géométrie plane.The invention also relates to the following characteristics, considered in isolation or in all their technically possible combinations: - The crown ply has a plane geometry.
Cette disposition correspond au type d'antenne communément appelée "antenne en T", le nombre de bras conducteurs qui forment la nappe de sommet étant compris en général entre quatre et huit. L'utilisation d'une nappe de sommet plane implique bien évidemment la nécessité de points de fixation pour les extrémités libres des bras conducteurs. Généralement, les points de fixation sont présentés par des mâts de support. - La nappe de sommet a la forme d'un cône renversé.This arrangement corresponds to the type of antenna commonly called a "T-shaped antenna", the number of conductive arms which form the crown ply generally being between four and eight. The use of a flat top ply obviously implies the need for fixing points for the free ends of the conductive arms. Generally, the fixing points are presented by support masts. - The top layer has the shape of an inverted cone.
Cette disposition correspond à une antenne communément appelée "antenne ombrelle". Elle a pour avantage que les extrémités libres des bras conducteurs peuvent être fixées au sol. En conséquence, ce type d'antenne n'a besoin que d'un seul point de fixation au-dessus du sol, ce point de fixation pouvant être constitué par le sommet d'un mât ou par tout autre point élevé au-dessus du sol. - Le monopole vertical est constitué par un élément filaire.This arrangement corresponds to an antenna commonly called "umbrella antenna". It has the advantage that the free ends of the conductive arms can be fixed to the ground. In Consequently, this type of antenna only needs a single fixing point above the ground, this fixing point can be constituted by the top of a mast or by any other point raised above the ground. . - The vertical monopoly is made up of a wire element.
Cette disposition est utilisée de préférence dans le cas d'une antenne en T ou en L. Le centre de la nappe de sommet constitue en même temps le point de suspension de l'élément filaire.This arrangement is preferably used in the case of a T-shaped or L-shaped antenna. The center of the crown ply at the same time constitutes the point of suspension of the wire element.
- L'antenne comprend au moins deux mâts de support.- The antenna includes at least two support masts.
- L'antenne comprend autant de mâts de support que de bras conducteurs formant la nappe de sommet. - Le monopole vertical est constitué par un mât conducteur.- The antenna comprises as many support masts as conductive arms forming the crown ply. - The vertical monopoly consists of a conductive mast.
Cette disposition concerne principalement des antennes pour des liaisons mobiles ou provisoires.This provision mainly concerns antennas for mobile or temporary links.
Elle se prête à la réalisation d'antennes de faible hauteur, par exemple d'une dizaine de mètres. Et plus particulièrement, elle se prête à la réalisation d'antennes qui peuvent être montées et démontées par une ou deux personnes.It lends itself to the realization of antennas of low height, for example of ten meters. And more particularly, it lends itself to the production of antennas which can be mounted and dismantled by one or two people.
- L'antenne comprend une embase destinée à être reliée à des radians de sol formant un plan de terre artificiel ou contrepoids. Le nombre de radians de sol peut être égal au nombre de bras conducteurs de la nappe de sommet.- The antenna comprises a base intended to be connected to ground radians forming an artificial earth plane or counterweight. The number of radians of soil can be equal to the number of conductive arms of the crown ply.
- L'antenne comprend une articulation reliant l'embase au monopole vertical.- The antenna includes an articulation connecting the base to the vertical monopoly.
Cette disposition s'applique, de préférence, aux installations mobiles ou provisoires. Cette disposition est destinée à faciliter le montage et le démontage de l'antenne et notamment à rendre possible d'effectuer ces opérations par une ou deux personnes seulement.This provision preferably applies to mobile or temporary installations. This provision is intended to facilitate the assembly and disassembly of the antenna and in particular to make it possible carry out these operations by only one or two people.
Le monopole vertical est composé d'une pluralité d'éléments emboîtables. Cette disposition permet de présenterThe vertical monopoly is made up of a plurality of nestable elements. This arrangement makes it possible to present
1 'antenne dans une forme peu encombrante pour le transport.1 antenna in a space-saving form for transport.
- Les mâts de support sont composés chacun d'une pluralité d'éléments emboîtables. Cette disposition a pour avantage de pouvoir présenter l'antenne dans une version qui, par la dimension des différents éléments la constituant, facilite son transport. Par ailleurs, une telle antenne peut être adaptée à différentes situations en fonction de l'emplacement prévu. Plus particulièrement, cette disposition permet de varier la hauteur de chacun des mâts de support indépendamment de l'autre afin d'obtenir, par exemple, en dépit des dénivellements du terrain où l'antenne doit être installée, une nappe de sommet sensiblement plane et horizontale.- The support masts are each composed of a plurality of nestable elements. This arrangement has the advantage of being able to present the antenna in a version which, by the size of the various elements constituting it, facilitates its transport. Furthermore, such an antenna can be adapted to different situations depending on the location provided. More particularly, this arrangement makes it possible to vary the height of each of the support masts independently of the other in order to obtain, for example, despite the unevenness of the terrain where the antenna is to be installed, a substantially flat top ply and horizontal.
D'autres caractéristiques et avantages de l'invention ressortiront de la description d'un exemple de réalisation faite en référence aux figures: La Figure 1 montre le principe d'une antenne compacte en T, conforme à l'invention.Other characteristics and advantages of the invention will emerge from the description of an exemplary embodiment made with reference to the figures: FIG. 1 shows the principle of a compact T-shaped antenna, in accordance with the invention.
La Figure 2 montre, de façon schématisée, une vue de dessus de l'antenne de la Figure 1.Figure 2 shows, schematically, a top view of the antenna of Figure 1.
La Figure 3 montre le principe d'une antenne ombrelle, conforme à l'invention.Figure 3 shows the principle of a parasol antenna, according to the invention.
La Figure 4 montre un exemple préféré de l'antenne compacte selon l'invention, etFIG. 4 shows a preferred example of the compact antenna according to the invention, and
La Figure 1 montre le principe d'une antenne compacte en T pour très basses fréquences, conforme à l'invention. L'antenne est référencée dans son ensemble en 100. Elle comprend un monopole vertical 1 ayant une extrémité supérieure 2 formant un sommet S de l'antenne et une extrémité inférieure 3.Figure 1 shows the principle of a compact T-antenna for very low frequencies, according to the invention. The antenna is referenced in its together at 100. It comprises a vertical monopoly 1 having an upper end 2 forming an apex S of the antenna and a lower end 3.
De plus, l'antenne 100 comprend une pluralité de bras conducteurs reliés chacun par une de ses extrémités au sommet de l'antenne. Le nombre total de bras conducteurs est en général quatre ou six; mais il peut également être huit, douze ou seize. Ces bras conducteurs dont ne sont représentés que les bras conducteurs 4 et 5, constituent une nappe de sommet 6, également appelée "toit capacitif".In addition, the antenna 100 includes a plurality of conductive arms each connected by one of its ends to the top of the antenna. The total number of conductive arms is generally four or six; but it can also be eight, twelve or sixteen. These conductive arms, of which only the conductive arms 4 and 5 are represented, constitute a crown ply 6, also called "capacitive roof".
Les extrémités libres des bras conducteurs 4 et 5 sont attachées chacune à un mât de support correspondant, référencé sur la Figure 1 en 7 et 8. Habituellement, l'antenne 100 comprend autant de mâts de support que de bras conducteurs. Chacun des mâts de support 7 et 8 peut être réalisé en une seule pièce. Il est cependant plus avantageux de le fabriquer, à partir d'une certaine hauteur, en deux ou plusieurs éléments. Lors du montage de l'antenne, ces éléments peuvent être assemblés, soit par emboîtement d'un élément dans un autre, soit par superposition des éléments autour de l'axe longitudinal du mât et attachement d'un élément à l'autre au moyen de fixation prévu à cet effet et connu en soi (non représenté) ou par tout autre moyen dont l'homme du métier dispose pour superposer une quantité variable d'éléments pouvant former un mât de support de hauteur variable. La Figure 1 montre l'antenne 100 installée sur un terrain plan et horizontal. Il est cependant concevable, notamment au vu des dimensions d'une antenne opérant à quelques dizaines de kHz, que les mâts de support 7 et 8 ne se trouvent pas au même niveau. Par ajustement de la hauteur respective de chacun des mâts 7 et 8, on peut obtenir que la nappe de sommet 6 soit sensiblement plane et horizontale.The free ends of the conductive arms 4 and 5 are each attached to a corresponding support mast, referenced in Figure 1 at 7 and 8. Usually, the antenna 100 comprises as many support masts as conductive arms. Each of the support masts 7 and 8 can be made in one piece. It is however more advantageous to manufacture it, from a certain height, in two or more elements. When mounting the antenna, these elements can be assembled, either by fitting one element into another, or by superimposing the elements around the longitudinal axis of the mast and attaching one element to the other by means fastening provided for this purpose and known per se (not shown) or by any other means available to those skilled in the art to superimpose a variable quantity of elements which can form a support mast of variable height. Figure 1 shows the antenna 100 installed on a flat and horizontal ground. It is however conceivable, in particular in view of the dimensions of an antenna operating at a few tens of kHz, that the support masts 7 and 8 are not at the same level. By adjusting the respective height of each of the masts 7 and 8, it is possible to obtain that the crown ply 6 is substantially flat and horizontal.
Chacun des mâts de support de l'antenne 100 est réalisé en un matériau non conducteur ou est au moins isolé par rapport aux bras conducteurs de la nappe de sommet 6. En outre, chacun des mâts de support est retenu, de manière connue en soi, par des haubans dont la Figure 1 ne montre que les haubans 9 et 10. Les haubans 9 et 10 sont fixés au sol à des points d'ancrage 18 et 19.Each of the support masts of the antenna 100 is made of a non-conductive material or is at least insulated with respect to the conductive arms of the crown ply 6. In addition, each of the support masts is retained, in a manner known per se , by guy lines of which Figure 1 shows only the guy lines 9 and 10. The guy lines 9 and 10 are fixed to the ground at anchor points 18 and 19.
La disposition d'un monopole vertical 1 - de bras conducteurs formant la nappe de sommet 6, de mâts de support et de haubans, formant ensemble l'antenne 100, est montrée, en vue de dessus schématisée sur la Figure 2.The arrangement of a vertical monopoly 1 - of conducting arms forming the top ply 6, of support masts and guy lines, together forming the antenna 100, is shown, in plan view schematically in FIG. 2.
L'antenne 100 est reliée, à son extrémité inférieure 3, à un équipement émetteur/récepteur (non représenté) . Pour la fonction émetteur, ce branchement correspond au branchement d'un dispositif d'excitation à une entrée B de l'antenne. En l'occurrence, l'excitation est reliée à l'antenne entre l'extrémité inférieure 3 du monopole 1 et un réseau de sol 15 disposé au niveau du sol et constituant un plan de terre artificiel, appelé aussi la masse ou contrepoids de l'antenne.The antenna 100 is connected, at its lower end 3, to a transmitter / receiver equipment (not shown). For the transmitter function, this connection corresponds to the connection of an excitation device to an input B of the antenna. In this case, the excitation is connected to the antenna between the lower end 3 of the monopoly 1 and a ground network 15 disposed at ground level and constituting an artificial earth plane, also called the mass or counterweight of the 'antenna.
Dans tout élément rayonnant, l'extrémité libre, située à l'opposé de l'excitation, impose la distribution du courant d'antenne. Dans le cas de l'antenne 100, le courant d'antenne est réparti sur l'ensemble des bras conducteurs de la nappe de sommet. Les courants partiels des différents bras conducteurs qui en résultent sont pratiquement nuls aux extrémités libres des bras, référencées en E et E' . Ils croissent en fonction de la position du point considéré, selon une loi sinusoïdale du point E, ou respectivement du point E', vers le point d'excitation B, en passant le sommet S de l'antenne.In any radiating element, the free end, located opposite the excitation, requires the distribution of the antenna current. In the case of antenna 100, the antenna current is distributed over all of the conductive arms of the crown ply. The partial currents of the various conducting arms which result therefrom are practically zero at the free ends of the arms, referenced at E and E '. They increase as a function of the position of the point considered, according to a sinusoidal law of point E, or respectively of the point E ', towards the excitation point B, passing the vertex S of the antenna.
Si la longueur ESB de l'antenne est nettement inférieure au quart d'onde, on peut observer qu'au point d'excitation B, l'amplitude du courant passant par le monopole vertical est encore loin d'un maximum, puisque le premier maximum ne peut se produire qu'après un trajet ESB égal à λ/4. Pour une antenne ayant une longueur d'environ λ/16, ceci veut dire que l'amplitude du courant a atteint, au point B, environ 75% de sa valeur maximale.If the length BSE of the antenna is clearly less than the quarter wave, it can be observed that at the point of excitation B, the amplitude of the current passing through the vertical monopoly is still far from a maximum, since the first maximum can only occur after an ESB path equal to λ / 4. For an antenna having a length of approximately λ / 16, this means that the amplitude of the current has reached, at point B, approximately 75% of its maximum value.
Si l'on introduit maintenant dans l'antenne, conformément à l'invention, des éléments selfiques en série, on obtient une antenne électriquement plus longue. Plus grande est la longueur SE, ou respectivement SE', et plus les courants circulant dans les bras conducteurs sont influents et bénéfiques pour l'efficacité de l'antenne.If we now introduce into the antenna, in accordance with the invention, inductive elements in series, we obtain an electrically longer antenna. The greater the length SE, or respectively SE ′, the more the currents flowing in the conducting arms are influential and beneficial for the efficiency of the antenna.
Les éléments selfiques, référencés en 13 et 14, sont disposés dans chacun des bras conducteurs de la nappe de sommet 6 à un endroit, référencé en L. Le point L est choisi de façon que LS soit égal à un tiers d'ES. En d'autres termes, l'élément selfique 13, ou respectivement 14, est disposé en série à un tiers environ de la longueur du bras conducteur 4, respectivement 5, mesuré à partir du sommet 2 de l'antenne 100. En fonction des caractéristiques spécifiques de l'antenne réalisée, la distance LS peut prendre une valeur comprise entre 30 et 40% de la longueur ES du bras conducteur, mesuré à partir du sommet 2 de l'antenne.The inductive elements, referenced in 13 and 14, are arranged in each of the conducting arms of the crown ply 6 at a location, referenced in L. The point L is chosen so that LS is equal to one third of ES. In other words, the inductive element 13, or respectively 14, is arranged in series at about a third of the length of the conductive arm 4, respectively 5, measured from the top 2 of the antenna 100. Depending on the specific characteristics of the antenna produced, the distance LS can take a value between 30 and 40% of the length ES of the conductive arm, measured from the apex 2 of the antenna.
La Figure 3 montre le principe d'une antenne ombrelle selon l'invention. L'antenne, référencée dans son ensemble en 200, comprend des éléments qui ont des fonctions identiques aux éléments correspondants de l'antenne 100 de la Figure 1 et qui portent, pour cette raison, les mêmes numéros de référence.Figure 3 shows the principle of a parasol antenna according to the invention. The antenna, referenced as a whole in 200, comprises elements which have identical functions to the corresponding elements of antenna 100 of Figure 1 and which, for this reason, have the same reference numbers.
Ainsi, l'antenne 200 comprend un monopole vertical 1 ayant une extrémité supérieure 2, représentant le sommet de l'antenne, et une extrémité inférieure 3. Des bras conducteurs 4 et 5 sont tendus à partir de l'extrémité supérieure 2 vers le sol sur lequel ils sont fixés au moyen d'éléments de fixation isolants 11 et 12. L'extrémité inférieure 3 de l'antenne et un réseau de sol 15, représentant la masse de l'antenne, sont reliés à un équipement émetteur/récepteur.Thus, the antenna 200 comprises a vertical monopoly 1 having an upper end 2, representing the top of the antenna, and a lower end 3. Conducting arms 4 and 5 are stretched from the upper end 2 towards the ground on which they are fixed by means of insulating fixing elements 11 and 12. The lower end 3 of the antenna and a ground network 15, representing the mass of the antenna, are connected to a transmitter / receiver equipment.
Pour la fonction émission de l'équipement, l'extrémité inférieure 3 du monopole vertical 1 représente le point d'excitation B de l'antenne.For the transmission function of the equipment, the lower end 3 of the vertical monopoly 1 represents the excitation point B of the antenna.
Conformément à l'invention, des éléments selfiques 13 et 14 sont disposés en série respectivement dans les bras conducteurs 4 et 5. L'endroit où ces éléments selfiques sont introduits, référencé en L et en L', est situé à 30 à 40% de la longueur du bras conducteur 4 ou 5, mesuré à partir du sommet S de l'antenne. Dans la plupart des cas, l'endroit L sera situé à environ un tiers de la longueur du bras conducteur. La Figure 4 montre un exemple de réalisation de l'antenne compacte selon l'invention. Cette antenne ombrelle, qui est référencée dans son ensemble en 300, comprend des éléments dont la fonction est identique aux éléments représentés sur la Figure 3 et qui, pour cette raison, portent les mêmes numéros de référence.According to the invention, inductive elements 13 and 14 are arranged in series respectively in the conducting arms 4 and 5. The place where these inductive elements are introduced, referenced in L and in L ', is located at 30 to 40% the length of the conductive arm 4 or 5, measured from the top S of the antenna. In most cases, location L will be located approximately one third of the length of the conductive arm. Figure 4 shows an embodiment of the compact antenna according to the invention. This umbrella antenna, which is referenced as a whole at 300, comprises elements whose function is identical to the elements shown in Figure 3 and which, for this reason, bear the same reference numbers.
Ainsi, l'antenne 300 comprend un monopole vertical 1, constitué d'une pluralité d'éléments emboîtables 21 formant un mât conducteur. Le mât 1 a une extrémité supérieure 2 et une extrémité inférieure 3. L'extrémité inférieure 3 est munie d'une embase 22, avec laquelle elle est reliée mécaniquement, mais par rapport à laquelle elle est isolée électriquement. Le mât 1 est réalisé essentiellement en un matériau composite à base d'une résine époxy. Chacun des éléments 21 du mât 1 se présente sous forme d'un tube cylindrique de révolution, couvert d'une couche d'aluminium projetée sur laquelle est appliquée une couche de peinture. Les extrémités de l'élément 21 sont munies d'embouts en inox, collés sur les extrémités du tube avec une colle conductrice.Thus, the antenna 300 comprises a vertical monopoly 1, consisting of a plurality of nestable elements 21 forming a conductive mast. Mast 1 has an upper end 2 and an end lower 3. The lower end 3 is provided with a base 22, with which it is mechanically connected, but with respect to which it is electrically insulated. The mast 1 is made essentially of a composite material based on an epoxy resin. Each of the elements 21 of the mast 1 is in the form of a cylindrical tube of revolution, covered with a layer of projected aluminum on which a layer of paint is applied. The ends of element 21 are provided with stainless steel end pieces, glued to the ends of the tube with a conductive adhesive.
Les embouts sont au moins partiellement coniques pour assurer une bonne assise, après emboîtement, pour assurer un contact électrique sûr entre les éléments 21 emboîtés.The tips are at least partially conical to ensure a good seat, after fitting, to ensure secure electrical contact between the elements 21 fitted.
La liaison mécanique entre le mât 1 et l'embase 22 est réalisée sous forme d'une articulation 23.The mechanical connection between the mast 1 and the base 22 is produced in the form of a joint 23.
Par ailleurs, l'extrémité inférieure 3 comporte un dispositif de branchement 24 permettant de relier l'antenne 300 à un équipement émetteur/récepteur (non représenté) et de connecter une admittance d'adaptation 35 entre le mât 1 et la masse 15 de l'antenne. La disposition de l'admittance 35 en parallèle au branchement de l'équipement radio correspond au principe de réduire, de préférence même d'éviter, toute résistance supplémentaire, montée en série avec le monopole 1 à un niveau de l'antenne où le courant d'antenne a de grandes valeurs. L'antenne compacte 300 comprend également quatre bras conducteurs 4, 4', 5 et 5'. Ces quatre bras conducteurs sont attachés par l'une de leurs extrémités à l'extrémité supérieure 2 de l'antenne, et par l'autre extrémité, au moyen d'éléments de fixation isolants 11, 11', 12 et 12', à des points de fixation 16, 16", 17 et 17' au sol.Furthermore, the lower end 3 comprises a connection device 24 making it possible to connect the antenna 300 to a transmitter / receiver equipment (not shown) and to connect an adaptation admittance 35 between the mast 1 and the earth 15 of the 'antenna. The arrangement of the admittance 35 in parallel with the connection of the radio equipment corresponds to the principle of reducing, preferably even avoiding, any additional resistance, connected in series with the monopoly 1 at a level of the antenna where the current antenna has great values. The compact antenna 300 also includes four conductive arms 4, 4 ', 5 and 5'. These four conductive arms are attached by one of their ends to the upper end 2 of the antenna, and by the other end, by means of fixing elements. insulators 11, 11 ', 12 and 12', at fixing points 16, 16 ", 17 and 17 'on the ground.
Pour donner plus de stabilité au mât conducteur 1 qui constitue le monopole vertical, des haubans 25 à 28 sont tendus entre les points de fixation 16, 16', 17 et 17', d'une part, et un point 29 situé à peu près à mi-hauteur du mât 1, d'autre part. Les haubans 25 à 28 sont isolés électriquement par rapport au mât 1. Et chacun des haubans 25 à 28 est muni d'un tendeur 30. Le tendeur 30 peut être un tendeur à bille.To give more stability to the conductive mast 1 which constitutes the vertical monopoly, shrouds 25 to 28 are stretched between the fixing points 16, 16 ', 17 and 17', on the one hand, and a point 29 located approximately halfway up mast 1, on the other hand. The guys 25 to 28 are electrically insulated from the mast 1. And each of the guys 25 to 28 is provided with a tensioner 30. The tensioner 30 can be a ball tensioner.
L'antenne 300 comprend également quatre radians de sol 31, 32, 33 et 34 constituant un plan de terre artificielle représentant la masse de l'antenne. Les quatre radians de sol 31 à 34 sont reliés électriquement et mécaniquement à l'embase 22.The antenna 300 also includes four ground radians 31, 32, 33 and 34 constituting an artificial earth plane representing the mass of the antenna. The four ground radians 31 to 34 are electrically and mechanically connected to the base 22.
Conformément à l'invention, des selfs 13, 13', 14 et 14' sont disposées en série dans les bras conducteurs correspondants 4, 4', 5 et 5".According to the invention, inductors 13, 13 ', 14 and 14' are arranged in series in the corresponding conductive arms 4, 4 ', 5 and 5 ".
L'antenne 300, telle que représentée sur la Figure 4, trouve son application par exemple en tant qu'antenne d'une station d'émission/réception installée temporairement. Deux personnes, éventuellement même une seule personne, sont capables de monter et de démonter cette antenne. Ceci est notamment possible grâce à la disposition de l'articulation 23 au pied du monopole 1.The antenna 300, as shown in Figure 4, finds its application for example as an antenna of a transceiver station temporarily installed. Two people, possibly even one person, are able to mount and dismantle this antenna. This is in particular possible thanks to the arrangement of the articulation 23 at the foot of the monopoly 1.
A titre d'exemple dimensionnel, on peut concevoir que l'antenne doit travailler à une fréquence de 2 MHz. La hauteur du monopole 1 n'est que de 9 mètres environ, et le mât constituant le monopole vertical 1, est composé de neuf éléments emboîtables. Les selfs 13, 13', 14 et 14' ont une inductivité de 44 μH et elles sont placées respectivement à environ 3,5 mètres du sommet de l'antenne. Les signes de référence insérés après les caractéristiques techniques mentionnées dans les revendications, ont pour seul but de faciliter la compréhension de ces dernières, et n'en limitent aucunement la portée. As a dimensional example, it can be imagined that the antenna must work at a frequency of 2 MHz. The height of the monopoly 1 is only about 9 meters, and the mast constituting the vertical monopoly 1, is composed of nine interlocking elements. The chokes 13, 13 ', 14 and 14' have an inductivity of 44 μH and they are placed respectively about 3.5 meters from the top of the antenna. The reference signs inserted after the technical characteristics mentioned in the claims, have the sole purpose of facilitating the understanding of the latter, and in no way limit their scope.

Claims

REVENDICATIONS
1. Antenne radioélectrique compacte pour très basses fréquences, comprenant un monopole vertical (1) ayant une extrémité supérieure (2) définissant un sommet (S) de l'antenne (100; 200; 300), et au moins deux bras conducteurs (4, 5) reliés chacun par une de ses extrémités (E, E') au sommet (S) de l'antenne et formant une nappe de sommet (6), caractérisée en ce que chaque bras conducteur (4, 5) comporte un élément selfique (13, 14) disposé en série à un tiers environ de la longueur du bras conducteur (4, 5) mesurée à partir du sommet (5) de l'antenne.1. Compact radio antenna for very low frequencies, comprising a vertical monopoly (1) having an upper end (2) defining an apex (S) of the antenna (100; 200; 300), and at least two conducting arms (4 , 5) each connected by one of its ends (E, E ') to the top (S) of the antenna and forming a top ply (6), characterized in that each conductive arm (4, 5) comprises an element inductive (13, 14) arranged in series to about a third of the length of the conductive arm (4, 5) measured from the top (5) of the antenna.
2. Antenne selon la revendication 1, caractérisée en ce la nappe de sommet (6) a une géométrie plane.2. Antenna according to claim 1, characterized in that the crown ply (6) has a plane geometry.
3. Antenne selon la revendication 1, caractérisée en ce que la nappe de sommet (6) a la forme d'un cône renversé.3. Antenna according to claim 1, characterized in that the crown ply (6) has the shape of an inverted cone.
4. Antenne selon la revendication 1 ou 2, caractérisée en ce que le monopole vertical (1) est constitué par un élément filaire.4. Antenna according to claim 1 or 2, characterized in that the vertical monopoly (1) is constituted by a wire element.
5. Antenne selon la revendication 4, caractérisée en ce que l'antenne comprend au moins deux mâts de support (7, 8). 5. Antenna according to claim 4, characterized in that the antenna comprises at least two support masts (7, 8).
6. Antenne selon la revendication 5, caractérisée en ce que l'antenne comprend autant de mâts de support (7, 8) que de bras conducteurs (4, 5) formant la nappe de sommet (6).6. Antenna according to claim 5, characterized in that the antenna comprises as many support masts (7, 8) as there are conductive arms (4, 5) forming the crown ply (6).
7. Antenne selon l'une quelconque des revendications 1 à 3, caractérisée en ce que le monopole vertical (1) est constitué par un mât conducteur.7. Antenna according to any one of claims 1 to 3, characterized in that the vertical monopoly (1) consists of a conductive mast.
8. Antenne selon l'une quelconque des revendications 1 à 7, caractérisée en ce que l'antenne comprend une embase (22) destinée à être reliée, à des radians de sol (15) formant une masse de l'antenne, le nombre de radians de sol (15) étant égal au nombre de bras conducteurs (4, 5) de la nappe de sommet (6), et, mécaniquement seulement, au monopole vertical (1). 8. Antenna according to any one of claims 1 to 7, characterized in that the antenna comprises a base (22) intended to be connected, to ground radians (15) forming a mass of the antenna, the number of ground radians (15) being equal to the number of conducting arms (4, 5) of the crown ply (6), and, mechanically only, at vertical monopoly (1).
9. Antenne selon la revendication 8, caractérisée en ce que l'antenne comprend une articulation (23) reliant l'embase (22) au monopole vertical ( 1) .9. Antenna according to claim 8, characterized in that the antenna comprises an articulation (23) connecting the base (22) to the vertical monopoly (1).
10. Antenne selon la revendication 8 ou 9, caractérisée en ce que le monopole vertical (1) est composé d'une pluralité d'éléments emboîtables (21).10. Antenna according to claim 8 or 9, characterized in that the vertical monopoly (1) is composed of a plurality of nestable elements (21).
11. Antenne selon l'une quelconque des revendications 6 à 8, caractérisée en ce que les mâts de support (7, 8) sont composés chacun d'une pluralité d'éléments emboîtables. 11. Antenna according to any one of claims 6 to 8, characterized in that the support masts (7, 8) are each composed of a plurality of interlocking elements.
PCT/FR1994/000250 1993-03-12 1994-03-07 Very low frequency compact radio antenna WO1994021004A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU62106/94A AU6210694A (en) 1993-03-12 1994-03-07 Very low frequency compact radio antenna

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR93/02906 1993-03-12
FR9302906A FR2702597B1 (en) 1993-03-12 1993-03-12 COMPACT RADIO ANTENNA FOR VERY LOW FREQUENCIES.

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WO1994021004A1 true WO1994021004A1 (en) 1994-09-15

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2048726A (en) * 1933-07-24 1936-07-28 Telefunken Gmbh Transmitting antenna for obtaining reduced high angle radiation
US3967276A (en) * 1975-01-09 1976-06-29 Beam Guidance Inc. Antenna structures having reactance at free end
US4047178A (en) * 1976-09-22 1977-09-06 The United States Of America As Represented By The Secretary Of The Army Low loss top termination for short monopoles

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2048726A (en) * 1933-07-24 1936-07-28 Telefunken Gmbh Transmitting antenna for obtaining reduced high angle radiation
US3967276A (en) * 1975-01-09 1976-06-29 Beam Guidance Inc. Antenna structures having reactance at free end
US4047178A (en) * 1976-09-22 1977-09-06 The United States Of America As Represented By The Secretary Of The Army Low loss top termination for short monopoles

Non-Patent Citations (2)

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Title
DAVIES: "Improved low-height antifading medium-wave antenna", PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS, vol. 124, no. 8, August 1977 (1977-08-01), STEVENAGE GB, pages 673 - 680 *
NIKOLAI: "Lang,länger,am längsten", FUNKSCHAU., no. 20, September 1984 (1984-09-01), MUNCHEN DE, pages 55 - 58 *

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FR2702597B1 (en) 1995-06-09
FR2702597A1 (en) 1994-09-16

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