Electromagnetic field stirrer for an EMC test enclosure

Description

[0001] The present invention relates to the field of electromagnetic compatibility (EMC) test chambers for electronic equipment in aerospace, automotive, and civil aviation applications. These test chambers are also known as Faraday cages. More particularly, the invention relates to a device for mechanically mixing electromagnetic waves within such a test chamber.

[0002] An electromagnetic compatibility (EMC) test chamber is used to measure the electromagnetic compatibility of a device or its electronic components. It is a Faraday cage (or Faraday tent), which is an enclosed space delimited by walls with high electrical conductivity, or covered with a metallic or metallized enclosure with high electrical conductivity.

[0003] The various electronic components of a car, airplane, or satellite interact electromagnetically with each other and with their environment, as they are affected by the environment and, in turn, can also affect it. Therefore, it is necessary to verify their electromagnetic compatibility to ensure their proper functioning both with each other and within a given, often hostile, electromagnetic environment. Immunity and emission tests are thus performed in response to applicable regulatory and normative requirements in the relevant field, within an EMC test chamber.

[0004] More specifically, during these tests, the electronic equipment being tested is subjected to strong, pulsed electromagnetic fields across very wide frequency bands. These tests can be carried out in an EMC test chamber equipped with mechanical mixing devices, thus forming a reverberation chamber. Indeed, strong electromagnetic fields (hundreds or thousands of volts) are generated within the chamber, and the incident waves are subjected to multiple reflections by a rotating mechanical mixer against the chamber walls. The mechanical mixer consists of metal blades fixed to a rotating shaft. The electromagnetic environment thus created by the rotation of the mixer is statistically isotropic and homogeneous.

[0005] A reverberating EMC test chamber comprising a mechanical stirring device and a rotating transmitting antenna is known from document CN203643474U. The mechanical stirring device consists of an assembly of zigzag-folded metal panels supported by the shaft of a metal structure, a first motor for rotating the shaft, and a motor control device. In operation, a uniform electromagnetic field is obtained in the reverberating chamber due to the simultaneous rotation of the mechanical stirring device and the antenna. The need for a more efficient stirring device remains.

[0006] Another type of mechanical electromagnetic wave agitator is also known, consisting of a metal structure with a central shaft and several arms extending radially outwards. Each arm supports a blade made of a reflective material. The blades are flat panels folded at a specific angle to each other. Such a metal structure is very heavy and difficult to move, especially when large (several meters) to accommodate rooms with significant volume. These devices are heavy, inflexible, and bulky.

[0007] One objective of the invention is to remedy the disadvantages of the aforementioned devices and to provide an original solution for a device for mechanically stirring or mixing electromagnetic waves inside an EMC test chamber which is very light, which can be easily transported or moved, whose structure allows it to adapt to test chambers of different volumes, at a lower cost.

[0008] This objective is achieved with a mechanical electromagnetic field stirrer for an electromagnetic compatibility test chamber comprising: a chassis forming a support for a rotating platform intended to be coupled to means for driving its rotation; a mast arranged at the center of the rotating platform; and at least one blade of the field stirrer fixed on the mast and having a reflective face, characterized in that said blade comprises a frame comprising at least one element comprising at least one fabric-based envelope and at least one inflatable tube arranged inside said at least one envelope.

[0009] In other words, the invention proposes a device for mechanically agitating or mixing electromagnetic waves used to test a device or equipment inside an EMC test chamber. This device comprises a mast mounted on a rotating platform and fixed to it for rotation, designed to be driven in rotation about its longitudinal axis. The mast includes at least one blade with a face that reflects electromagnetic waves. The blade comprises a frame made of one or more elements, each element including at least one inflatable bladder arranged inside a fabric envelope. The various elements form independent air chambers. Preferably, an element includes a closed envelope made by assembling several pieces of fabric together. This envelope has an opening for inserting an inflatable bladder. The elements thus formed become rigid when the bladders are inflated.This results in a fabric blade that maintains its shape and can rotate with the mast when it is driven into rotation, which allows the electromagnetic waves emitted by a test device located in the enclosure to be mixed by sending them towards the reflective walls of the enclosure and thus creating a uniform field.

[0010] The term "frame" refers to a set of rigid elements that support other components of the blade and also allow for its assembly with the mast. The frame of a blade of the invention comprises first peripheral rigid elements that define the outline of the blade and may also include second reinforcing elements located inside the outline formed by the first elements and connected to them. For example, the frame of a polygonal blade comprises first peripheral elements defining the outline of the polygon, each element containing an inflatable tube, and second elements containing inflatable tubes that may be located inside the polygon, particularly to ensure the rigidity of the frame of larger blades.

[0011] The frame, made from fabric elements containing inflatable tubes, offers the advantage of being very lightweight, requiring relatively low inflation pressure (less than 0.4 bar), and thus quickly taking its shape through inflation. This also facilitates the repair or replacement of damaged tubes, thereby improving the lifespan of the aerator. The blade frame can then be covered or wrapped in reflective fabric, making the entire blade very lightweight and allowing the aerator to be easily transported for use. Thus, a folded blade is lightweight and easily transported manually by an operator, requiring only a few minutes to inflate. The aerator can therefore be quickly installed in an EMC test chamber, while requiring minimal storage space.Furthermore, a lighter structure of the mast and blade assembly allows the use of a less powerful motor for its rotation drive, thus saving electrical energy.

[0012] Such a blade with an inflatable frame can therefore easily pass from the inflated state in which it has a large wingspan, for example of a few meters, to the uninflated state in which it occupies a very small volume.

[0013] The mast can consist of a fabric mast sleeve and an inflatable tube arranged inside the sleeve. The sleeve can be made of electrically conductive fabric or covered with it. This allows for an inflatable structure for the entire mast and blade assembly, resulting in even lower weight and easier transport. Such an inflatable mast and blade assembly is extremely compact when deflated; it can be carried in a backpack, and inflation, given the low inflation pressure, takes approximately 15 minutes, even for a wingspan of just a few meters.

[0014] The fabric of the frame components may include synthetic textile fibers, for example "DACRON"®, and the inflatable tube may contain polyurethane. This allows for a lightweight frame with good mechanical strength.

[0015] The frame of the blade may have an arched shape comprising at least two parallel arched elements, each containing at least one inflatable bladder, connected by at least two cross members, each containing at least one inflatable bladder. This design ensures good rigidity of the arched frame after the bladders are inflated.

[0016] The mixing device may consist of at least two blades extending radially from the central axis of the mast and arranged at approximately equal angular intervals from each other. Arranged at approximately equal angular intervals from each other, it is understood that the blades form an angle with each other equal to 360° divided by the number of blades, with a tolerance of + / - 20°. Thus, several blades uniformly distributed around the circumference of the mast allow for improved mixing of the electromagnetic field within the EMC enclosure.

[0017] The stirrer can include at least two blades of different shapes and / or sizes. This further improves the mixing of the electromagnetic field within the EMC enclosure.

[0018] The mast can be cylindrical, and the blade(s) can be attached to the mast's generatrix by a structural element. The mast may be equipped with fasteners that work in conjunction with complementary attachments on the blades. This allows the blades to be attached to, or even, when the fasteners are removable, detached from the mast, while also enabling a large overall span for optimized wave mixing within the EMC enclosure.

[0019] The mast attachments and the additional blade attachments may include one or more zippers. Such a zipper, ratchet, or zip closure allows the blades to be easily attached and detached from the mast, while ensuring precise positioning of the assembled components.

[0020] The blade frame can be covered with an electrically conductive material. The frame can be wrapped with such an electrically conductive material capable of reflecting electromagnetic waves, or it can be attached to the frame, for example by stitching permanently or detachably, in particular by means of a hook and loop fastener or "VELCRO" ® type fastener.

[0021] The mast casing can be attached to a rigid plate designed to be removable and fixed to the rotating platform. This allows the same platform to be used with different masts, while also making the mast easily transportable. The rigid plate fixed to the base of the mast contributes to the stability of the mast and the blades it supports.

[0022] The frame can be supported by feet that are radially offset outwards from the support plate. This solution ensures good stability for the entire brewer, despite its considerable size when inflated.

[0023] These feet can be fitted with casters at their ends. This allows the entire brewer to be moved within the EMC test chamber.

[0024] The object of the invention is also achieved with a method of assembling a mechanical electromagnetic field stirrer for an electromagnetic compatibility test chamber comprising: a frame forming a support for a rotating platform intended to be coupled to means for driving the rotation thereof; a mast mounted on the rotating platform; and at least one blade of the field stirrer fixed on the mast and having a reflective face, in which said blade comprises a frame comprising at least one element comprising at least one fabric-based envelope and at least one inflatable tube arranged inside said envelope and where the method comprises a step of inflating the inflatable tube(s) inside the frame of said blade after assembling said blade with the mast.

[0025] The method of the invention may include an additional step of inflating the inflatable tube located inside the mast casing before attaching it to the rotating platform.

[0026] The aerator of the invention may comprise at least first and second blades, and these first and second blades are inflated after the mast has been inflated. This allows for very rapid assembly and shaping of the inflatable parts of the aerator. Thus, a mast supporting several wings with a wingspan of approximately 4 meters can be inflated in less than 15 minutes.

[0027] One can cover at least one face of the inflatable structure of said at least one blade with metallic fabric after inflation thereof.

[0028] The mast may include an inflatable structure and the process may include a step of inflating the inflatable structure of the mast and a step of attaching the mast to the rotating platform.

[0029] The invention will be better understood from the following description, which is based on the following figures: there figure 1 is a perspective of a brewer's assembly according to the invention; the figure 2 is a perspective view of a support frame for the structure of the brewer of the invention; the figure 3 is a perspective view of a stabilizer arm of the chassis of the figure 2 ; there figure 4 is a perspective view of a brewery set from the figure 1 in which the outer casing of the blades has been removed to reveal their frame; the figure 5 is a view similar to that of the figure 4 shot from another angle; the figure 6 is a perspective view of the framework of a first blade of the brewer of the figure 1 and the figure 7 is a front view of the blade of the figure 6 ; there figure 8 is a perspective view of the framework of a second blade of the brewer of the figure 1 , there figure 9 is a view from below of the same pale and the figure 10 is a front view of the blade of the figures 8 et 9 ; there figure 11 is a perspective view of the framework of a third blade of the brewer's figure 1 and the figure 12 is a front view of the blade of the figure 11 ; there figure 13 is a perspective view of the framework of a fourth blade of the brewer of the figure 1 , there figure 14 is a view from below of the same pale and the figure 15 is a front view of the blade of the figures 13 et 14 .

[0030] In the various figures, identical or similar elements bear the same reference. Their description is therefore not systematically repeated.

[0031] There figure 1 Figure 1 illustrates a mechanical electromagnetic wave mixer of the invention. It is intended to be installed in an EMC test chamber. All the walls, as well as the floor and ceiling of such a test chamber, are made of or covered with a metallic or metallized material. Such a chamber can be made from an inflatable structure covered with a metallized fabric, also called Faraday cloth. Inside the EMC chamber, the device to be tested and means for performing the tests are installed, such as a transmitting antenna connected to a field generator, which is installed outside the chamber. A mechanical mixer of the electromagnetic field produced is positioned near the transmitting antenna so that, during its rotation, it can intercept and direct the waves against the walls of the chamber in order to mix them and thus homogenize the electromagnetic field within the test chamber, forming a reverberation chamber.

[0032] As seen at the figure 1 The brewer 1 comprises a chassis 2 having a support plate 61 for a rotating plate 62 intended to be coupled to means for driving its rotation (not shown in the figure) around a central axis XX' of the plate, perpendicular to its plane. In the variant of the figure 2 The support plate 61 comprises three support rods 63, of adjustable height, for example by means of a threaded rod that moves inside a threaded shaft which is fixedly mounted on the underside of the plate 61. In a preferred embodiment of the invention, several feet 64 are added to the support plate 61, designed to be offset radially from the periphery of the support plate 61. Each foot 64 comprises a horizontal arm 64' connected, at one of its ends, to the plate 61 and, at the opposite end, to a vertical rod 64" which bears against the ground by means of a wheel 65. By radially offset foot, it is understood that the end of the foot carrying the vertical rod protrudes radially from the periphery of the plate 61.In a preferred embodiment, the foot 4 is offset radially by a distance at least equal to the radius of the plate 61, with five feet 64 thus arranged at equal distances around the perimeter of the plate 61. These feet 64 serve to stabilize the entire stirrer assembly. The vertical rod 64" can also be height-adjustable by being constructed in the same manner as the rod 63. The caster 65 rotates freely, allowing for easy movement of the frame 2, and therefore of the entire stirrer assembly, within the test chamber.

[0033] The rotating plate 62 is supported by the support plate 61 via bearings (not shown) and includes, in its lower part (understood to be the part opposite the upper part receiving the brewer's mast), a coupling element for the output shaft of a rotating electric drive motor. Such a motor is preferably a stepper motor, powered by a battery, and remotely controlled via electronic control. The motor, the battery, and the electronic control unit are contained in a metal housing and located beneath the support plate 61 of the frame 2.

[0034] As seen at the figure 1 The mechanical stirrer 1 comprises a mast 11 supporting at least one blade 20 having a face reflective of electromagnetic waves, preferably both the intrados 20' and extrados 20" being reflective. The mast is arranged at the center of the rotating plate 62 and is fixed to it for rotation. More particularly, according to the invention, said at least one blade 20 comprises a frame 21 made of fabric elements, each containing at least one inflatable tube. In a preferred embodiment of the invention, illustrated in the figures, the stirrer 1 comprises several blades, including two identical blades 20, one blade 30, one blade 40, and one blade 50 having different dimensions and shapes, as will be explained later.

[0035] In the example illustrated in the figures, the mast 11 also has an inflatable frame. It comprises an inflatable cylindrical mast envelope 16 made of a flexible material, the envelope being closed at both ends. One of the ends, which forms the base of the mast, comprises a rigid circular plate 12 ( fig. 2 ) intended to be fixed to the rotating plate 62, for example using screws. The figure 2 shows the rigid plate 2 fixed to the rotating plate 62 by means of several screws 14, the mast casing 16 (not shown in the fig. 2 The mast sheath 16 is made of electrically conductive fabric, or of a synthetic fabric such as DACRON® covered with electrically conductive fabric. The mast sheath 16 contains an inflatable polyurethane tube, the tube being equipped with a valve for inflation and deflation. When inflated, the tube inside the mast sheath extends between the upper end of the mast and the rigid plate 12, thus shaping the mast 11. For example, the diameter of the mast Dm is approximately 0.7 m with a height Hm of approximately 4.2 m.

[0036] Each blade 20, 30, 40, 50 of the stirrer 1 of the invention comprises an inflatable frame having at least two parallel arches connected to each other by several crossbars. The frame of the stirrer blades is more clearly visible in figures 4 et 5 in which the outer casing of the blades has been removed. Thus, the brewer 1 comprises three groups of blades distributed around the circumference of the mast 11. A first group consists of two arch-shaped blades 20 arranged one in line with the other on the same first generatrix of the mast 11. A second group consists of two other arch-shaped blades 30 and 50 arranged substantially concentrically on either side of a second generatrix forming a 120° angle with the first generatrix. A third group comprises a single blade 40 arranged on a third generatrix of the mast 11 located at 120° to the second and first generatrices of the mast.

[0037] THE figures 6 et 7 Figures 21 illustrate different views of the frame of a blade 20. The frame 21 is formed of two peripheral arches 22, an intermediate arch 23, two sides 24 connecting the base of the arches, and three cross members 25 connecting the arches 22 and 23 to each other at different levels from their bases. The peripheral arch 22 and the intermediate arch 23 are each formed from several pieces of fabric sewn together (the seams being visible as transverse lines in the figures) to form a fabric arch into which an inflatable tube with an inflation valve is inserted. Similarly, the sides 24, as well as the cross members 25, are each obtained by sewing pieces of fabric together to form a cylindrical side into which an inflatable tube with an inflation valve is inserted.The various inflatable tubes are then advantageously connected (for example, using external, airtight connecting hoses) to facilitate the inflation of the entire frame 21 from a single inflation valve. An inflatable tube is a closed cylindrical tube made of polyurethane, whose dimensions are approximately those of the envelope into which it is inserted. The resulting frame is defined by its outside diameter D, its width L, and the diameter d of the arch 23. As an example, the frame 21 has a diameter D of approximately 2 m, a width L of approximately 2 m, and an outside diameter d of the arch of approximately 0.2 m. The external diameter of the sides 24 is approximately equal to the external diameter d of the peripheral arch 22. The external diameters of the crossbeams 25 and the intermediate arches 23 are, however, smaller than the external diameter of the peripheral arch 22. Similar to the framework of the . figure 9 which will be described below, the main arch 23 is flattened at the point where it is attached to the mast generatrix over part of the arch length between the last two crossbeams 25, the length H1 of the side 24 being about 1.4m and the length H2 of the flattened part being about 1.2m.

[0038] THE figures 8 à 10 illustrate different views of the frame 31 of a blade 30. The frame 31 is formed of two peripheral arches 32, an intermediate arch 33, two sides 34 connecting the base of the arches, and four cross members 35 connecting the arches 32 and 33 to each other at different levels from their bases. The elements of the frame 31, in particular the arches, sides, and cross members, are made in a similar manner to those of the blade 20, as already described. It is particularly noteworthy with reference to the figure 9 that one of the main arches 33, which is intended for attachment to the generatrix of the mast 11, is flattened over a portion of its length between the last two cross members 35, corresponding to dimension H2 on the figure 9 equal to approximately 1.2m, for a length of side H1 of the arch of approximately 1.4m. As an example, the frame 31 has a diameter D of approximately 3.1m, a width L of approximately 3.1m and a diameter d of the arch of approximately 0.2m.

[0039] THE figures 11 à 12 illustrate different views of the frame 41 of a blade 40 similar to those already described. The frame 41 is formed of two peripheral arches 42, an intermediate arch 43, two sides 44 connecting the base of the arches, and four cross members 45 connecting the arches 42 and 43 to each other at different levels from their bases. The elements of the frame 41, in particular the arches, sides, and cross members, are made in a similar manner to those of the blade 20, as already described. It is also noted, as previously described, that one of the main arches 43, which is intended for attachment to the generatrix of the mast 11, is flattened over a length of the arch between the last two cross members 45, corresponding to dimension H2 of the figure 9 equal to approximately 1.2m for a length of side H1 of the arch of approximately 1.4m. As an example, the frame 41 has a diameter D of approximately 4.1m, a width L of approximately 3.9m and a diameter d of the arch of approximately 0.2m.

[0040] THE figures 13 à 15 illustrate different views of the frame 51 of a blade 50, which is also similar to the previous ones. The frame 51 is formed of two peripheral arches 52, an intermediate arch 53, two sides 54 connecting the base of the arches, and four cross members 55 connecting the arches 52 and 53 to each other at different levels from their bases. The elements of the frame 51, in particular the arches, sides, and cross members, are made in a similar manner to those of the blade 20, as already described. It is particularly noteworthy, with reference to the figure 14 that one of the main arches 53, which is intended for attachment to the generator of the mast 11, is flattened over approximately a portion of its length between the last two crossbeams 55, corresponding to dimension H2 on the figure 14equal to approximately 1.2m, for a length of side H1 of the arch of approximately 1.4m. As an example, the frame 31 has a diameter D of approximately 5.1m, a width L of approximately 4.6m and a diameter d of the arch of approximately 0.2m.

[0041] The casing of the frame elements 21, 31, 41, 51, is made of a synthetic fabric of the "DACRON" ® type. The casing of each element is closed and made by sewing several pieces of fabric together, and an opening has been made in it to allow the insertion of an inflatable tube.

[0042] The frame of each blade is covered with an electrically conductive fabric. Advantageously, the fabric is attached using hook and loop fasteners or "VELCRO"® type strips, with some of the strips sewn onto the frame and others onto the blade covering fabric.

[0043] The resulting blades are very lightweight. They are evenly distributed around the circumference of the mast, which is already weighted by the rigid plate that attaches it to the rotating platform and thus to the frame, ensuring good stability. Therefore, adding lightweight blades, evenly distributed around the mast's circumference, results in excellent overall stability. This stability is further enhanced by the feet, which are radially offset outwards from the rotating platform, ensuring uniform rotation of the paddle around the mast's vertical axis.

[0044] According to an advantageous embodiment of the invention, the mast 11 and the blades 20, 30, 40, 50 are joined using zippers. To achieve this, one part of the zipper is sewn onto the mast's generatrix, and the corresponding part is sewn onto one of the opposite blade's arches.

[0045] The storage of the various parts containing inflatable tubes is done in the deflated state, with the blades detached from the mast to facilitate storage and transport, especially in the case of large blades.

[0046] To start up the aerator, begin by assembling the blades and the mast using the zippers. Once assembled, inflate one blade first, then the mast, and finally the remaining blades with the mast positioned and secured to its frame. The inflation pressure of the inflatable bladders inside the mast and blades is approximately 0.2 to 0.35 bar.

[0047] In operation, the rotating plate 62 receives rotational motion from a drive mechanism enclosed in a metal housing, comprising a battery-powered stepper motor and its control means. This rotates the mixer according to a predetermined control protocol, resulting, after a specified time interval, in a homogeneous and isotropic electromagnetic field throughout the internal volume of the EMC test chamber.

[0048] In one variant, the blades 20 can be arranged one in line with the other on the mast 11, but with one of the blades 20 rotated 180° relative to the other, thus obtaining an S-shaped blade. Several S-shaped blades can be arranged on the mast 11.

[0049] In another variant, the 20 blades are flat, polygonal in shape, for example rectangular.

[0050] Other variations and embodiments of the invention can be envisaged within the scope of the invention as claimed. For example, the paddles of the aerator can have the shape of a portion of a sphere or a portion of a parabola, or any other curved shape. Furthermore, the mast 11 can have the shape of a right prism, in order to provide a flat surface for attaching the paddles of the aerator. In one embodiment, the mast is rigid and preferably telescopic.

[0051] In addition, it is possible to consider making a smaller stirrer that can be inserted inside a device to make the electromagnetic field homogeneous for EMC measurements inside it.

Claims

1. Mechanical electromagnetic field stirrer (1) for an electromagnetic compatibility test enclosure comprising: a chassis (2) forming a support for a turntable (62) suitable for being coupled to means for rotating said turntable; a mast (11) mounted on the turntable (62); and at least one blade (20, 30, 40, 50) of the field stirrer fastened to the mast and comprising a reflective face, characterized in that said blade (20, 30, 40, 50) comprises a framework (21, 31, 41, 51) comprising at least one element comprising at least one fabric-based envelope and at least one inflatable tube arranged inside said at least one envelope.

2. Stirrer according to Claim 1, characterized in that said mast (11) comprises a fabric mast envelope and an inflatable tube arranged inside the mast envelope.

3. Stirrer according to one of Claims 1 and 2, characterized in that said fabric comprises synthetic textile fibres and said inflatable tube comprises polyurethane.

4. Stirrer according to one of the preceding claims, characterized in that the framework (21, 31, 41, 51) of said blade (20, 30, 40, 50) is in the shape of an arch comprising at least two parallel arch-shaped elements each containing at least one inflatable tube and connected to each other by at least two elements forming crossmembers, each containing at least one inflatable tube.

5. Stirrer according to one of the preceding claims, characterized in that it comprises at least two blades (20, 30, 40, 50) extending radially relative to the central axis of the mast (11) and arranged substantially angularly equidistant from each other.

6. Stirrer according to one of the preceding claims, characterized in that it comprises at least two blades (20, 30, 40, 50) having different shapes and / or dimensions.

7. Stirrer according to one of the preceding claims, characterized in that said mast (11) has a cylindrical shape and the blade(s) (20, 30, 40, 50) is / are fastened to the generatrix of the mast (11) by an element of their framework (21, 31, 41, 51), the mast being provided with fasteners that interact with complementary fasteners on the blades.

8. Stirrer according to the preceding claim, characterized in that the fasteners on the mast (11) and the complementary fasteners on said at least one blade (20, 30, 40, 50) comprise one or more sliding fasteners.

9. Stirrer according to one of the preceding claims, characterized in that the framework (21, 31, 41, 51) of said at least one blade (20, 30, 40, 50) is covered in an electrically conductive material.

10. Stirrer according to Claim 2 or one of Claims 3 to 9 taken in combination with Claim 2, characterized in that the envelope of the mast (11) is rigidly connected to a rigid plate (12) suitable for being removably fastened to said turntable (62).

11. Stirrer according to one of the preceding claims, characterized in that said chassis (2) is supported by feet (64) that are radially offset outwards relative to the supporting plate.

12. Stirrer according to the preceding claim, characterized in that the ends of said feet (64) are provided with casters (65).

13. Method for assembling a mechanical electromagnetic field stirrer (1) for an electromagnetic compatibility test enclosure comprising: a chassis (2) forming a support for a turntable (62) suitable for being coupled to means for rotating said turntable; a mast (11) mounted on the turntable (62); and and at least one blade (20, 30, 40, 50) of the field stirrer fastened to the mast (11) and comprising a reflective face, wherein said blade (20, 30, 40, 50) comprises a framework (21, 31, 41, 51) comprising at least one element comprising at least one fabric-based envelope and at least one inflatable tube arranged inside said at least one envelope and wherein the method comprises a step of inflating the inflatable tube(s) inside the framework of said blade after having assembled said blade on the mast.

14. Method for assembling a stirrer according to the preceding claim, wherein said mast (11) comprises a mast envelope that contains an inflatable tube, characterized in that it comprises a step of inflating the inflatable tube situated inside the envelope of the mast before it is fastened to the turntable.

15. Method according to the preceding claim, wherein the stirrer comprises at least first and second blades and said first and second blades are inflated.