FR2738674A1 - WIRED ANTENNA FOR MACHINE - Google Patents

Abstract

The wire antenna comprises a hull (2S) in the form of an airplane wing mounted in free rotation around an antenna strand (1S). The rotational freedom of the hull brings a considerable gain on the drag of a machine carrying the antenna. In order not to increase the thrust during takeoff of the machine, a strand holder (3S) rotates in the machine to deploy the strand only after takeoff from a folded position substantially against the machine, to a position (PD) forming an acute angle with a longitudinal axis of the machine. The antenna may include two symmetrical strands developed perpendicular to the plane of support of the machine.

Description

The present invention relates to an antenna

  wired intended in particular to be carried on a machine such as an aircraft. In particular, the aircraft may be an aircraft or a reconnaissance drone in which the antenna is used for jamming radio waves. Such an antenna is generally of the type

  dipole with a large span of a few meters.

  The two antenna strands are respectively fixed laterally in front of the fuselage of the aircraft, in front of the wings of the aircraft, and symmetrically by

  relative to the longitudinal axis of the machine.

  During takeoff or catapulting of the craft, the strands are in a first position at which they are arranged along the fuselage of the craft. In cruising mode of the machine, the strands are deployed suddenly to a second position at which they extend perpendicular to the axial horizontal plane of the aircraft. One of the strands extends laterally to the fuselage upwards, and the other

  strand extends laterally down the fuselage.

  This antenna considerably increases the drag of the aircraft up to approximately 50%, and requires a significantly higher engine power of the aircraft than that necessary for propelling the aircraft without an antenna. As a corollary, the arrangement of the antenna strands and their drag disturb the effectiveness of the control surfaces of the craft, particularly that of the rudder

also called yaw control.

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  The present invention aims to remedy the aforementioned drawbacks, and more specifically to provide an antenna whose drag increases only by a few percent, that is to say negligibly, the drag of the mobile machine. To this end, the wire antenna comprises a strand and is characterized in that it comprises a hull

  free rotation mounted around the antenna strand.

  Thanks to this free rotation assembly, the hull is always positioned at zero incidence. The presence of this free rotating hull brings a considerable gain on the drag of a vehicle carrying the faired antenna, compared to the drag of this vehicle with a non-faired antenna. The gain can

reach around 50 to 80%.

  The hull includes rigid transverse plates and spacers between the plates. The antenna strand slidly crosses the plates and freely the spacers in order to reduce the friction of the hull on the strand. The inserts and spacers are extremely

  light to reduce the inertia of the hull.

  The spacers may consist of two symmetrical molded half-spacers having faces glued against one another in a plane

longitudinal to the strand.

  Preferably, the hull is translatable with clearance along the antenna strand between a stop fixed to one free end of the antenna strand and another stop to which is fixed the antenna strand which forms the root of the hull relative to the fuselage

of a mobile machine.

  The aerodynamics of the hull is chosen in such a way that it has an airplane wing profile transversely to the strand. The profile preferably has a cord substantially between a quarter and a fifth of the thickness of the profile. The axis of the antenna strand may be located between a leading edge of the hull and an aerodynamic focus of the hull. As already said, the invention is particularly directed towards an antenna on board a mobile vehicle such as an aircraft. In this case, the strand has one end fixed in the machine and extends in a plane substantially longitudinal to the machine. In particular, the antenna may comprise two strands symmetrical with respect to a longitudinal axis of the vehicle and developed perpendicular to the plane of lift formed by the wings of the vehicle. In other words, each strand extends substantially in a longitudinal plane of the rudder of the vehicle. In order to reduce the effect of the antenna on the control surfaces of the machine, particularly when the root of the strands is located at the front of the aircraft, each strand forms an arrow, preferably between approximately 15 and 45 , with a

  plane perpendicular to the longitudinal axis of the machine.

  The aerodynamic focus of the hull is preferably

  located near the center of gravity of the craft.

  The means set out below relating to one strand are identical to means relating to the other strand and arranged symmetrically with respect to the axis

longitudinal of the machine.

  In order not to increase the thrust during takeoff or catapulting of the craft, a means linked to the craft deploys the antenna strand only after takeoff from a first position in which the antenna strand is substantially folded back against the machine, towards a second position at which the strand

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  antenna forms an acute angle with an axis

longitudinal of the machine.

  According to a particular embodiment, the strand comprises a free and bendable portion between a point of attachment of the strand linked to the machine and a carrier to which the antenna strand is fixed and forming the root of the hull. The free portion of the strand is bent at said first position and substantially linear at said second position. In order to avoid any breakage of the strand, the strand holder rotates around a center located in an obtuse sector in front of the strand and delimited by the strand in the second position.

and the longitudinal axis of the machine.

  The means for deploying may comprise a guide in the form of an obtuse circular segment, preferably of the order of 120, fixed to the body of the machine. The mobile strand holder then substantially forms a circular sector covering substantially half of the guide and is slidably mounted in the guide to rotate from a front position corresponding to the first position of the antenna strand to a rear position corresponding to the second. position of the antenna strand. Motor means may be provided to activate the means for deploying in order to move the antenna strand from the first position to the second position after takeoff of the craft. This motor means can also be provided for moving the antenna strand from the second position to the first

  position before landing of the machine.

  According to a first embodiment, the antenna comprises a strand holder to which the antenna strand is fixed and sliding in a circular slide, and a traction strap having one end fixed to a strand holder and another end linked to a means reel, preferably through a return means located substantially along the slide, by

  example at the rear end of the slide.

  According to a second embodiment, the antenna comprises a strand holder to which the antenna strand is fixed and sliding in a circular slide, and a threaded rod having one end cooperating with a toothing along a circular edge of said strand holder and another end driven in

rotation by motor means.

  According to a third embodiment, the antenna comprises a strand holder to which the antenna strand is fixed and sliding in a circular slide, and a threaded rod having a first end cooperating with a nut linked to said strand holder and another driven end by a drive means preferably through a bevel gear located

  substantially along the slide.

  Other characteristics and advantages of the present invention will appear more clearly on

  reading the following description of several

  preferred embodiments of the invention with reference to the corresponding accompanying drawings in which: - Figures 1 and 2 are schematic front and vertical side views of an aircraft supporting two antenna strands according to the invention in the folded position; - Figures 3 and 4 are schematic front views and vertical side of an aircraft supporting two antenna strands according to the invention in the deployed position; Figure 5 is a schematic top view of the aircraft;

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  - Figure 6 is a top view of a hull of a strand of the antenna; Figure 7 is a side view of a hull reinforcement plate; Figure 8 is a sectional view of the hull along the longitudinal axis of the strand; - Figure 9 is an exploded cross-sectional view of a mold for the hull spacer; - Figure 10 is a perspective view of a guide of the strand holder of a strand of the antenna in the folded position; - Figure 11 is a perspective view of the guide of the strand holder of Figure 10 in the deployed position; - Figure 12 is a schematic cross-sectional diagram through the slot of the guide showing the passage from a straight position to a bent position of a portion of antenna strand located between the strand holder and a cable connector in the structure of the aircraft; - Figure 13 is a vertical longitudinal schematic view, partially in section at the top, of the deployment means in the folded antenna position according to a first embodiment; - Figure 14 is a vertical longitudinal schematic view, partially in section at the top, of the deployment means in the folded antenna position according to a second embodiment; and - Figure 14 is a vertical longitudinal schematic view, partially in section at the top, deployment means in

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  folded antenna position according to a third embodiment. The embodiments described below relate to a wired antenna of the dipole type mounted on a mobile machine, such as an aircraft A of the drone type to be boarded on a shuttle plane and to

catapult from this one.

  As shown schematically in Figures 1 to 5, the antenna is composed of two fine cylindrical metal strands 1S and lI which project at the level of the nose

  NE of aircraft A in front of wings AI thereof.

  The strands are always arranged in a longitudinal axial plane of the aircraft, preferably vertical, that is to say in a plane perpendicular to the aircraft wings AI according to the embodiments illustrated, and symmetrically with respect to the longitudinal axis XX of the aircraft. At rest, and during catapulting of the aircraft, the strands 1S and II are in a first position, called the folded position PR, and are arranged along the fuselage FU of the aircraft, as shown in FIGS. 1 and 2. Des free ends 10S and 0lI of the strands are arranged towards the rear of the machine. Ends 11S and 11I of the strands mounted to "flexably pivot" in the structure of the aircraft are disposed towards the front of the aircraft. One strand 1S is arranged above the aircraft and the other strand hI

is located below the aircraft.

  After catapulting, the strands are deployed in a second position, called the deployed position PD, by deployment means 4S and 4I which will be described later. In this deployed position, the strands 1S and hI are perpendicular to the longitudinal axis XX of the aircraft, or according to the embodiments described

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  below, form an arrow FL of the order of 15 to with a transverse plane of the aircraft, as

shown in Figures 3 and 4.

  With reference to FIGS. 6 to 8, the portion of each of the strands of the antenna external to the aircraft comprises a very light aerodynamic hull in the shape of an airplane wing so as to reduce the drag of the antenna strands. Knowing that the strands are

  identical, we will refer in the following to the strand.

higher 1S for example.

  As shown particularly in FIG. 7, the transverse profile of the hull 2S of the strand iS comprises a substantially ogival leading edge 20, a body 21 tapering in the form of a bevel from the leading edge 20 towards a trailing edge 22 at

the back of the hull.

  According to the embodiment illustrated in Figures 6 to 8, the structure of the hull is composed of several plastic plates 23 distributed almost regularly along the antenna strand iS and having the transverse profile described above and shown in Figure 7. The plates form wing reinforcement ribs and have circular holes 231 traversed by sliding by the antenna strand IS. Between these plates, sections of foam, for example of rigid or semi-rigid polyurethane foam reinforced, form light spacers 24 also having the profile

  transverse external shown in figure 7.

  As shown in Figure 9, each foam spacer 24 is obtained by means of a mold for molding one of two half-spacers - identical which are glued against each other along a mediator longitudinal plane 21P of the hull 2S. The mold includes a punch and a die. The punch 241 has a planar internal surface 242 which corresponds to the hull mediating plane 21P. A semi-cylindrical protuberance 243 projects on the surface 242 and is complementary to half of the longitudinal cylindrical conduit 244 in a spacer crossed by the strand 1S. The matrix 245 has an internal face 246 which reproduces the transverse external half-profile of the hull. In order to limit as much as possible the friction of the hull 2S on the strand 1S and consequently any risk of blocking in rotation of the hull which would make the aircraft ungovernable, the strand 1S freely crosses the cylindrical conduits 244 formed in front of the spacers foam 24, wider than the plate holes 231. In addition, the metal friction on plastic of the strand 35 in the pads 23 can be further reduced by wrapping the strand in a plastic sheath such as Teflon. Under these conditions, the hull 24 can rotate freely around the antenna strand 1S carrying the hull 2S, almost without friction, and thus position itself freely at zero incidence in order to remain in the wind bed as well during the deployment of the strands antenna only during the cruising speed of the aircraft with the antenna strands deployed. As shown in detail in FIG. 8, the hull 2S is also mounted in free translation over a short distance, that is to say with a large clearance, along the carrying strand 1S. At the free end 10S of the strand 1S is screwed a plug 12 which forms a first stop limiting the sliding of the hull 25 outwards. On the side of the other end they of the strand 1S penetrating into the fuselage FU of the aircraft, o 2738674 the translation of the hull 25 is limited by a second stop formed by a movable profiled strand holder 3S constituting a root of the hull independent of the displacement of the hull in rotation and translation. As will be seen below, the 3S strand holder is mounted at perpendicular rotation

  to strand 1S in the structure of the aircraft.

  In order to fix the ideas, an antenna according to the invention for jamming electromagnetic waves in the metric and decimetric ranges is composed of strands 1S and lI each having a length of between a quarter wave and a half-wave approximately. To obtain a stream of the streamlined antenna of the order of 5% of the trail of the aircraft without the antenna and therefore a low lift of the streamlined strands, the thickness E of the streamers 2S and 2I is between a quarter and a fifth of the cord C of the hulls, that is to say the width of the hulls. For example, the length L of the hull 2S, 2I of each strand is approximately 1.5 m, the cord C of the hull is 74 mm, the thickness E of the hull is 18 mm, the diameter of the strand 1S, lI and holes 231 in the plates 23 is 17 mm, and the axis of the plate holes 231 and spacer holes 244

  is located 14 mm from the front of the leading edge 20.

  Thanks to wind tunnel measurements, it has been shown that the influence of the antenna on the control surfaces of the aircraft is linked to the distance between the aerodynamic focus FA of the hull and the center of gravity G of the aircraft. So that the antenna does not destabilize the aircraft, and in particular does not intervene in a preponderant manner on the effects of the control surfaces of the aircraft, in particular of the rudder GD of the aircraft, the aerodynamic focus FA of hull 2 is provided in front, from the center of

  aircraft gravity G, as shown in Figure 5.

  Preferably, the aerodynamic focus FA is located in the vicinity of the center of gravity G of the aircraft. It is indeed imperative to have hull roots 3S, 3I as far back as possible on the FU fuselage so that the streamlined strands do not disturb the effects of the control surfaces both during the deployment of the antenna and in cruising speed of the aircraft. When the bases 3S and 3I of the faired strands 1S and 1I are relatively in front of the center of gravity of the aircraft due to the implantation of other elements, notably of lift on the rear of the fuselage FU, the deployed strands have an arrow FL can be chosen between and 45, preferably approximately 30 according to the illustrated embodiment, for drawing back the foci FA of the hulls. To obtain the stability of each of the hulls 2S and 2I when the aircraft is at cruising speed, the axis of rotation constituted by the antenna strand 1S, lI is located in front of the focus FA of the hull, it is that is to say between the focal point FA and the leading edge 20 of the hull, as shown in FIG. 7. Typically, the distance, called "static margin", between the axis of the strand 1S, hI and the aerodynamic focal point FA of the hull is around 5% of the cord C

of the hull 2S, 2I.

  The deployment means for simultaneously deploying the streamlined strands 1S and hI are identical and symmetrical with respect to the longitudinal axis XX of the aircraft. Consequently, one of them relating to the upper strand 1S is described in

  detail with reference to Figures 10 to 12.

  The 4S deployment means of the upper strand iS

  includes a guide 40 for the respective strand holder 3S.

  The guide 40 has a circular segment shape and extends perpendicular to the fuselage FU, in a vertical axial plane of the aircraft A. It is fixed to the structure of the aircraft by two consoles 4C. The guide has a transverse slot 41 in a circular segment which is substantially 120 according to the illustrated embodiment. The rope of the slit segment opens out substantially at the surface of the fuselage and can be protected at the front by an aerodynamic cover fixed to the FU fuselage. The circular edge 42 of the guide through which the slot 41 opens inside the aircraft is surrounded by two circular rails 43 with an L-profile concentric with the

  segment and fixed to the structure of the aircraft.

  The strand holder 3S forming the root of the hull has a circular edge on which is fixed a rigid U-shaped section 31 which is slidably mounted between the edge 42 of the guide 40 and the rails 43, which form a circular slide 42-43 for guide the 3S strand holder with slot 41. As shown by comparing Figures 10 and 11 and as shown schematically in Figure 12, the strand holder 3S has the substantial shape of a circular sector relative to an angle PB substantially equal to half that FE relating to the circular segment defining the slot 41 in the guide 40. Under these conditions, in the folded position PR shown in FIG. 10, the strand holder 3S occupies substantially the half-segment relating to the guide slot 41 and situated towards the front of the aircraft, and in the deployed position PD shown in FIG. 11, the strand holder 3S occupies substantially the other half-segment relating to the guide slot 41

  and located towards the rear of the aircraft.

  As shown diagrammatically in FIG. 12, after having crossed the hull 2S, the strand 1S is fixed, for example by gluing, in a short internal conduit formed in the top 32 of the strand holder substantially in extension of the leading edge 20 of the 2S hull. Then a portion 13 of the strand 1S freely crosses a front slot 33 of the strand holder 3S, particularly in the folded position PR (FIG. 10), and the slot 41 of the guide 40 up to a connector 14 fixed to the structure of the aircraft . The connector connects the strand 1S to a coaxial power cable 15S coming out of a power amplifier 16S from a jamming source installed in the NE nose of the aircraft. The amplifier 16S is separated by a central cooling plate 17 from another amplifier 16I supplying by a coaxial cable 15I

the other antenna strand 1I.

  In the deployed position PD, the point of attachment of the strand 1S materialized by the connector 14 is substantially on the axis of the strand and the strand is substantially rectilinear. In the folded position PR, the portion 13 of the strand 1S is bent with a curvature whose radius is large enough to avoid any bending or breakage of the strand, particularly at the outlet

  from the duct to the top 32 of the strand holder.

  To satisfy this condition, the fictitious center of rotation CR corresponding to the circular slide composed by the edge of the portbrin 42 and

  by the rails 43 and the circular edge 31 of the holder

  strand sliding in the slide is located in an obtuse front angular sector formed between the fuselage body FU of the aircraft, and therefore the longitudinal axis XX, and the strand 1S in the deployed position PD. As shown in Figure 12, the portion of the strand 1S fixed in the apex 32 of the strand holder 3S does not pass

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  by the CR center of rotation in order to avoid any

strand crack.

  In the three embodiments of the drive part of the means for deploying the antenna strands described below, the arrangement of the elements making up the deployment means is symmetrical with respect to the longitudinal axis XX of the aircraft, as are the antenna strands 1S and III and the strand guides 3S and 3I, and a central motor means for deploying the antenna strands is common to the two deployment means 4S and 4I. In these three embodiments, when the strands 1S, I must be deployed, the activation of the motor means is simultaneous with the unlocking of latching devices ES and EI keeping the free ends 1OS and 1OI of the hulls against the fuselage FU

  of the aircraft, as shown in Figure 2.

  According to the first embodiment shown in Figure 13, each deployment means 4Sa, 4Ia comprises a traction strap 5Sa, 5Ia. The front end of the strap is fixed to the rear end of the circular edge 31 of the respective mobile strand holder 3S

  by means of a captive nut 51Sa, 51Ia.

  The rear end of the strap is connected to a motor means constituted by a compression spring strap reel 6a. The strap is applied against the small co-circular wings of the slide rails 43 from the captive nut 51Sa, 51Ia to a deflection pulley 52Sa, 52Ia mounted mad

  at the rear end of the respective guide 40.

  In the folded position PR, the compression spring is compressed, i.e. the reel

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  is armed before takeoff or catapult of the aircraft,

  and the traction straps 5Sa and 5Ia are unwound.

  A mechanical or electromechanical timer means or such a remote-controlled timer means controls, after takeoff or catapulting of the aircraft, the release of the compressed spring in the reel 6a so as to wind

  the 5Sa and 5Ia straps which then pull the holders

  strand 3S and 3I backwards. The strand carriers slide in the respective guides 40 in opposite directions

  until reaching the deployed position PD.

  Referring to Figure 14, a deployment means 4Sb, 4Ib according to the second embodiment comprises a wheel and worm system. The worm is a rigid nylon 5Sb, 5Ib threaded rod extending longitudinally in the aircraft. At a screw bearing 51Sb, 51Ib under the middle of the respective slide 42-43, a front end of the rod meshes with a corresponding toothing provided on the circular edge 31 of the respective strand holder 3S, 3I. A rear end of the rod meshes with a bevel gear 52Sb, 52Ib linked to a respective end of the shaft of a

electric motor 6b.

  Under the control of an armed timer before takeoff or catapult, or remote-controlled, the electric motor is activated to turn the threaded rods 5Sb and 5Ib in opposite directions so that the strand carriers 3S and 3I turn towards

  the rear by sliding in the respective guides 40.

  At least one deployment limit switch 7Db is disposed at the rear end of one of the guide rails 42-43 to be

  actuated by a stop at the rear end of the holder

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  respective strand 35 in order to cut the supply of the

motor 6b.

  Deployment means 4Ss, 4Ic according to the third embodiment shown in FIG. 15 comprises

  also a wheel and worm system.

  However, the worm is a flexible threaded rod 5Sc, 5Ic which is developed substantially parallel to the rear circular half-edge of the respective slide 42-43. The front end of the 5Sc, 5Ic rod meshes with a 51Sc, 51Ic nut fixed to

  the rear end of the circular edge 31 of the holder

  respective strand 3S, 3I. A bevel gear 52Sc, 52Ic connects the rear end of the respective slide to a respective end of a motor

electric 6c.

  When the motor 6c is activated, the rotation of the rod 5Sc, 5Ic is screwed into the nut 51Sc, 51Ic, which passes between the respective rails 43 in the direction of the respective angular gear 52Sc, 52Ic. A 7Dc deployment limit switch is also provided at the end

  rear of one of the guide rails 42-43.

  Preferably, in the second and third embodiments, the electric motor 6b, 6c can control the rotation of the threaded rods in opposite directions so that the strand holders pass from the deployed antenna position PD to the folded antenna position PR, before the landing of the aircraft, and the free ends 10S and lOI of the hulls fit into the snap-on devices ES and EI. In this case, at least one folding limit switch 7Rb, 7Rc is provided at the front end of one of the slides

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  guide 41-42 to be actuated by a stop at the front end of the respective strand holder for cutting

the power supply to the motor 6b, 6c.

  According to other embodiments, and depending on the type of aircraft and particularly its wings, the strands with their means of deployment are positioned in a horizontal plane, that is to say are parallel to the wings and elevators

of the aircraft.

Claims (13)

  1 - Wire antenna comprising a strand (iS), characterized in that it comprises a hull (2S) mounted with free rotation around the antenna strand ('S). 2 - Antenna according to claim 1, characterized in that the hull comprises rigid transverse plates (23) and spacers (24) between the plates, the antenna strand (iS) slidingly passing through the plates   (23) and freely the spacers (24).   3 - Antenna according to claim 2, characterized in that the spacers (24) consist of two symmetrical molded half-spacers having faces (21F) glued one   against the other in a longitudinal plane to the strand.   4 - Antenna conforms to any of the   claims 1 to 3, characterized in that the   hull is translatable with clearance along the antenna strand between a stop (12) fixed to a free end of the antenna strand (1S) and another stop (3S) to which the antenna strand is fixed, preferably forming the root of the hull.   - Antenna conforms to any of the   claims 1 to 4, characterized in that the   hull (2S) has an airplane wing profile transversely to the strand (1S), the profile preferably having a cord (C) substantially between a quarter and a fifth of the thickness (E) of the profile.   6 - Antenna according to claim 5, characterized in that the axis of the antenna strand is located between a leading edge (20) of the hull and an aerodynamic focus (FA) of the hull. 7 - Antenna conforming to any of the   claims 1 to 6, characterized in that said   strand (1S) has one end (14) fixed in a machine (A) and extends in a substantially longitudinal plane to the craft.   8 - Antenna according to claim 7, characterized in that the strand (3S) extends substantially in a longitudinal plane of the control surface direction (GD) of the machine (A).   9 - Antenna according to claim 7 or 8, characterized in that the strand forms an arrow (FL), preferably between 15 and 45 approximately, with a plane perpendicular to the longitudinal axis (XX) of the craft (A).   - Antenna conforms to any of the   Claims 7 to 9, characterized in that a hearth   aerodynamics (FA) of the hull (1S) is located   near the center of gravity (G) of the machine (A).   11 - Antenna conforming to any of the   claims 7 to 10, comprising means (4S) related to   the machine (A) for deploying the antenna strand (1S) from a first position (PR) at which the antenna strand is folded substantially against the machine, towards a second position (PD) at which the strand d antenna forms an acute angle with an axis longitudinal (XX) of the machine.   12 - Antenna according to claim 11, characterized in that the strand (1S) has a free and bendable portion (13) between a point of   fixing (14) of the strand linked to the machine (A) and a holder   strand (3S) to which the antenna strand (1S) is fixed and forming the root of the hull (2S), said free portion of said strand being bent at said first position (PR) and substantially linear at said second position (PD).   13 - Antenna according to claim 12, characterized in that the strand holder (3S) rotates around a center (CR) located in an obtuse sector in front of the strand (1S) and delimited by the strand in the second position ( PD) and the longitudinal axis (XX) of the machine. 14 - Antenna according to claim 12 or 13, characterized in that the means for deploying comprises a guide (40) in the form of an obtuse circular segment, preferably of the order of 120, fixed to the body of the machine, said movable strand holder substantially forming a circular sector covering substantially half of the guide (40) and being slidably mounted in the guide to rotate from a front position corresponding to said first position (PR) of the antenna strand to a rear position corresponding to said second position (PD) of the antenna strand.   - Antenna conforms to any of the   claims 11 to 14, comprising a driving means 21 2738674   (6a, 6b, 6c) to activate the means for deploying (4Sa, 4Sb, 4Sc) in order to move the antenna strand from said first position (PR) to said second position (PD) after takeoff of the craft, and preferably from said second position (PD) to said first position (PR) before landing of the craft.   16 - Antenna conforming to any of the   Claims 7 to 15, comprising a strand holder (3S)   to which the antenna strand (1S) is fixed and sliding in a circular slide (42-43), and a traction strap (5Sa) having one end (51Sa) fixed to a strand holder (3S) and another end linked to a winding means (6a), preferably through a deflection means (52Sa) located substantially along said slide (42-43).   17 - Antenna conforming to any of the   Claims 7 to 15, comprising a strand holder (3S)   to which the antenna strand (1S) is fixed and sliding in a circular slide (42-43), and a threaded rod (5Sb) having one end cooperating with a toothing along a circular edge (31) of said holder strand (3S) and another end (52Sb)   driven in rotation by a motor means (6b).   18 - Antenna conforming to any of the   Claims 7 to 15, comprising a strand holder (3S)   to which the antenna strand (1S) is fixed and sliding in a circular slide (42-43), and a threaded rod (5Sc) having a first end cooperating with a nut (51Sc) linked to said strand holder (3S) and another end driven by a motor means (6c) preferably through a bevel gear 22 2738674   (52Sc) located substantially along the slide (42-43).   19 - Antenna conforming to any of the   Claims 1 to 18, comprising another strand (III)   around which another hull (2I) is mounted to rotate freely, the strands (1S, 1I) being arranged symmetrically with respect to a longitudinal axis (XX)   a machine (A) supporting the antenna.