INFLATABLE ANTENNA STRUCTURE
The subject of the invention is an inflatable antenna structure in which the radiating elements or dipoles are connected to an inflatable support, the antenna being easy to fold up.
It applies, for example, in the field of tactical antennae.
It is also used for radio direction-finding antennae.
Most of the antennae known in the prior art have rigid structures which have certain disadvantages, for example:
• deployment and folding of the structure taking some time,
• considerable weight and volume of footprint.
The prior art describes various structures using inflatable elements.
For example, patent application WO 2004/036690 describes an antenna which comprises a torus-based inflatable reflector.
Patent application EP1 596 464 discloses a portable and inflatable antenna structure. It relates to a Ku satellite antenna which comprises a parabolic antenna the structure of which is inflatable and which comprises a telescopic antenna element, the antenna body being attached in a casing. The parabolic surface of the antenna is covered with a layer of conductive material.
The invention relates to at least one inflatable antenna structure, characterized in that it comprises a supporting mast comprising hooking means, one or more inflatable supports of radiating elements, the inflatable support(s) being attached to the mast, a system for the inflation of the inflatable support; said radiating elements are dipoles supported by the inflatable supports.
Compared with conventional antenna structures according to the prior art, the inflatable antenna structure according to the invention notably offers the following advantages:
• performance which involves particular dimensions, for example, a
pentagon of approximately 1.5 meters in diameter,
• rapid folding/deployment in less than 5 minutes,
• able to be carried on a man's back in the folded position, low weight and footprint which allows a man to carry it on his back,
• the possibility of housing it in a carrying quiver, for example, the quiver being able to be fitted with positioning means.
Other features and advantages of the present invention will better appear on reading the following description given as an illustration and in no way limiting, with the appended figures which represent:
• figure 1, an example of an antenna structure according to the invention,
• figures 2A, 2B and 2C, details of an example of a mast according to the invention, of the inflation system and of the parts for adaptation of the inflatable arms of the antenna structure,
• figures 3A, 3B and 3C, exemplary embodiments for the ends of the inflatable arms which are connected to the mast,
• figures 4A and 4B, the position of the inflation system relative to the mast and details of this inflation system,
• figure 5, an example of a quiver being used for stowage and of a supporting mast for the structure of figure 1.
Figure 1 shows an example of an antenna structure according to the invention comprising inflatable elements or inflatable arms used as a support for the dipoles.
The "inflatable" antenna structure comprises, for example, a mast 1 on which hooking means 2 are placed, for example slotted or else slides, straps, clips or saddle adapted to the shape of the inflatable elements. Several inflatable supports 3, for example inflatable arms, support radiating elements 4 or dipoles. These inflatable supports 3 are secured to the mast 1 thanks to the handing or hooking means 2 and to sleeves 22 detailed in figures 2A to 2C. The dipoles 4 are held in place on an inflatable arm 3 by means of attaching straps, such as Velcro elements 11. An inflation system placed, for example, at the foot of the mast consists of an inlet via a valve 5, another inlet 6 with nonreturn element and tapping for gas cartridges for example (the details are given in figures 4A, 4B), a distributor 7 for distributing gas to the inflatable
elements and a pressure gauge 8 (figures 4A, 4B). The mast 1 also comprises a second series of hanging points 9 or holes for securing stays having the function of securing retaining cords 10'. The function of the retaining cords 10', with the aid of cords 10, 10a, 10b connecting various dipoles together, is notably to keep in place and in a given geometry the assembly formed by an inflatable support and a radiating element relative to the mast and also all the assemblies forming the final structure of the antenna.
The foot of the mast is fitted, for example, with positioning means, such as a positioning level 13, a compass 12.
Figures 2A, 2B and 2C represent an exemplary constitution of a mast and of the sleeves for attaching the inflatable arms.
In figures 2A, 2B and 2C, the mast 1 comprises a cover 20, a mast foot 21. A sleeve 22 for attaching the inflatable arms is attached by means of screws and nuts 23 and holes 24 situated on the sleeve and a zone of the mast. A locking ring 25 is placed on the upper portion of the sleeve.
The nuts 23 make it possible, for example, to screw a rail for clamping bonded or stitched straps to inflatable arms. They also make it possible to attach slides receiving the straps of the inflatable arms furnished with rods sliding in these slides.
The holes are, for example, holes with a flat in order to sink the head of the screw and the nut in order to allow attachment to the mast by through-bolts.
Figure 2C shows the presence of rectangular drill holes or openings 26 which allow the passage of the bonded or stitched straps of the inflatable arms.
Figures 3A, 3B and 3C schematize three examples of the end of the fitted arms. In figure 3A, the end 3a of the inflatable arms comprises stitches or bonding 27 allowing the passage of a rod for a slide 28 used as a coupling means. The slides are attached to the mast where the straps fitted with rods dimensioned to the slides are housed.
Figure 3B represents the end 3a of an arm comprising a saddle with attachment holes 29 and a portion of the top strap 30 allowing retention relative to the mast. The arm is then bonded in the saddle secured to the mast.
Figure 3C schematizes a variant embodiment in which the attachment means is a Velcro fastener strap 31. The straps are stitched or bonded to the inflatable arms and end in a loop or coupling zone of the Velcro type.
The inflatable supports are, for example, in the form of boards 3 of inflatable material made of a material giving rigidity to the structure. The board has given thickness, length and width according to the dipole 4 to be supported, the application, and the final structure of the antenna. The air intake occurs at each inflatable arm through a valve 35 (figure 1) to which a flexible pipe 32 (figure 4A) is closely fitted and bonded which is connected to the air distributor.
The dipoles 4 are represented in this example by a dipolar element 4 one end 4a of which is kept in place relative to the end 4'a of an adjacent dipole 4' by means of a cord 10a and a second end 4b which is also kept in place relative to the end 4'b of the dipole 4' by means of a cord 10b. The middle of the dipole 4m is attached to one end of the inflatable board by means of an attachment strap, for example. Cords 10' to prevent bending and to maintain the structure may also be used.
Figures 4A and 4B represent the position of the inflation system relative to the mast and details of this inflation system. The inflation system consists of an inlet via an inlet valve 5 for inflation by pump and for deflation of the inflatable structure, an inlet with nonreturn element 6 for inflation by cartridges, a distributor 7 for distributing the gas to the inflatable elements by means of several pipes 32, each pipe being connected to the valve 35 situated on an inflatable arm and a pressure gauge 8 to notify the operator of the pressure of the inflatable structure. A C02 cartridge, 33, is connected to the inlet with nonreturn element 6. A pump 36 allowing the inflation of the elements is connected to the inlet 5.
In the example of figure 1, the antenna structure consists of five antenna elements forming a pentagonal system for 5 dipoles. Each inflatable board 3 is attached to the mast at the anchoring point 2 bearing the same index number and comprises a radiating element 4 at its end opposite to the end attached to the mast.
The inflatable boards are, for example, made of hair fabrics giving rigidity to the structure. Any type of element making it possible to obtain an inflatable support of radiating elements may be used. Therefore, it is possible to use tori, panels, inflatable fenders in order to support the radiating elements.
The cords or stays allowing the retention of a radiating element and the positioning of the radiating elements relative to one another are made of any type of material.
The mast is formed in an insulating material.
The dipoles may be chosen from the dipoles known to those skilled in the art. They are attached by coupling means.
It is possible to inflate each inflatable arm separately with an adapted endpiece, but the deployment time will be longer. This can be used for repairs (bursts).
Figure 5 represents an example of a quiver 40 making it possible to house the antenna structure, transport it, for example on a man's back and to position it for use.
The carrying bag (quiver) 40 comprises various housings 41, 42, 43 making it possible to carry the antenna structure, the inflation system, the pump, etc.
It comprises adjustable feet 44 for operational positioning in a tripod manner in order to adapt to the majority of terrains. Locking slings 45 make it possible to hold the tripod feet in a given position.
It also comprises means of attachment by way of 'fasteners or overcenter latches' onto which the antenna structure is placed and fixed.
The structure of the quiver is, for example, made of resin or of the canvas rucksack type.
The antenna structure is put in place, for example, in the following manner.
For deployment:
The operator arrives in the installation location carrying the antenna on his back.
He deploys the antenna in 5 phases:
Phase 1: He places the antenna quiver on the ground. He adjusts the tripod to set the height and levelness of the quiver with the aid of a spirit level built into the top of the quiver.
Phase 2: He unlocks the cover of the quiver (overcenter latches), and takes out the inflatable structure of the antenna in the folded position.
Phase 3: He turns over the structure in high position and latches it into the cover housing with the aid of the aforementioned overcenter latches.
Phase 4: He detaches the strap to release the dipoles and the inflatable panels. He then screws an air cartridge into the housing provided for this purpose and pulls on the percussion cord (like a lifejacket). The released air inflates the panels and positions the dipoles according to the dimensioning lines (which becomes a pentagon for 5 dipoles). The inflation time is about ten seconds. He then withdraws the cartridge and returns it to the storage tray. The pressure gauge tells him if the pressure is correct.
Phase 5: He takes and connects the coaxial cable to the receiving and interception hardware and then he transfers the compass indication to the operating system.
The antenna is operational.
For folding:
The operator also carries out 5 phases:
Phase 1: He disconnects the antenna link connector. He coils it into its reserved location at the base of the central mast.
Phase 2: He turns the pump air lever to empty the inflatable panels (the period of emptying is about ten seconds). He stores each dipole in its housing close to the central mast while expelling the remaining air from the associated panel. Then, he folds around the mast the panels emptied of air while immobilizing them with the central strap which will be closed by a Velcro-type system.
Phase 3: He unlocks the cover immobilizing the inflatable structure in the high position (overcenter latches, etc.), and then lifts the folded antenna structure.
Phase 4: He turns over and inserts the structure in the low position in the quiver and then latches the cover with the aid of the overcenter latches.
Phase 5: He releases, slides and locks the feet into the reservations of the quiver.
He departs while putting the quiver on his back. Phases 2 and 3 can be mechanized to limit the manual operations during deployment or folding of the antenna.

Claims
1. An inflatable antenna structure, characterized in that it comprises a supporting mast (1) comprising hooking means (2, 5), one or more inflatable supports (3) of radiating elements (4), the support(s) (3) being attached to the mast (1), a system suitable for the inflation of the inflatable support (3); said radiating elements (4) are dipoles supported by the inflatable supports (3).
2. The inflatable antenna structure as claimed in claim 1, characterized in that an inflatable antenna support is an inflatable board.
3. The inflatable antenna structure as claimed in claim 2, characterized in that the board is made of hair fabric.
4. The inflatable antenna structure as claimed in claim 1, characterized in that it comprises an attachment sleeve (22) that is attached to the mast (1) by means of holes (24) and attachment means (23).
5. The inflatable antenna structure as claimed in claim 1, characterized in that it comprises 5 radiating elements, each being secured to a board, and in that the 5 boards and the 5 radiating elements are held by means of cords in a pentagonal structure.
6. The inflatable antenna structure as claimed in claim 1, characterized in that one end (3a) of an inflatable support (3) comprises means (27) allowing the passage of a rod for a slide (28).
7. The inflatable antenna structure as claimed in claim 1, characterized in that one end (3a) of an inflatable support (3) comprises a shoe with attachment holes (29).
8. The inflatable antenna structure as claimed in one of claims 1 to 7, characterized in that the inflation system comprises a valve (5), an inlet with nonreturn element (6), a gas distributor (7), several pipes (32), one pipe
being connected to a saddle (35) situated on an inflatable support, a pressure gauge (8).
9. The inflatable antenna structure as claimed in claim 1, characterized in that the inflation system is secured to the mast at the foot.