Ballistic radome shell, ballistic radome and corresponding radome assembly

Abstract

Ballistic radome shell, ballistic radome and corresponding radome assembly. This ballistic radome shell (2) comprises: a ballistic wall (6) extending around a central axis (AA'), having an axial length (LP) and an upper end, the ballistic wall being in the form of a tube with a circular cross-section, and a ballistic cover (10) sealing the upper end of the ballistic wall. The ballistic wall includes a ballistic protection layer (20) comprising thermoplastic fibers, and two frequency-matching layers (22, 24), the ballistic protection layer of the wall being sandwiched between the frequency-matching layers of the wall. The ballistic protection layer (20) extends in a single block around the central axis and over the entire axial length (LP), and the frequency adaptation layers (22, 24) extend in a single block around the central axis and preferably also over the entire axial length (LP).Application to radomes of radio antennas. Figure for the abstract: Figure 1.

Description

Title of the invention: Ballistic radome shell, ballistic radome and corresponding radome assembly

[0001] The present invention relates to a ballistic radome shell, of the type comprising: a ballistic wall extending around a central axis, having an axial length and an upper end, the ballistic wall being in the form of a tube of circular cross-section, a ballistic cover sealing the upper end of the ballistic wall, the ballistic wall comprising a ballistic protection layer which includes wires of thermoplastic material, and two frequency matching layers, the ballistic protection layer of the wall being sandwiched between the frequency matching layers of the wall.

[0002] Satellite telecommunications antennas can be mounted on vehicles to provide mobile communication links. This equipment must be protected against external threats. In particular, such antennas can be mounted on military vehicles, which adds a compactness requirement to any protective element for said antennas. External threats can then be related to environmental conditions or originate from gunfire. Such protection can be achieved by designing a radome incorporating internal ballistic protection.

[0003] Numerous radome designs are known, with ballistic shields generally made of thermoplastic material, which satisfies both the requirements for frequency transparency and those relating to ballistic protection. The radomes can then be made up of an assembly of protective segments, or be made of a single block.

[0004] Ballistic radomes are known for example from documents WO2012076549A1; WO2020131150A1 and CN106058459B.

[0005] However, these solutions do not give complete satisfaction and existing radomes provide satisfactory performance according to one or more criteria but generally at the expense of at least one of the other validation criteria of such a radome.

[0006] One of the aims of the present invention is to propose a ballistic radome shell whose design is compact, while ensuring good frequency transparency, and preferably best satisfying the other aforementioned requirements.

[0007] To this end, the invention relates to a ballistic radome shell of the type indicated above, characterized in that

[0008] - the ballistic protection layer extends in a single block around the central axis and along its entire axial length, and in that

[0009] - the frequency adaptation layers extend in a single block around the axis central and preferably also along the entire axial length.

[0010] According to other advantageous aspects of the invention, the ballistic radome shell comprises one or more of the following features, taken individually or in any technically feasible combinations:

[0011] - the ballistic cover includes a ballistic protection layer, which includes thermoplastic wires, and two frequency matching layers, and the ballistic protection layer of the cover is sandwiched between the frequency matching layers of the ballistic cover;

[0012] - the ballistic protection layer of the wall and the ballistic protection layer of the lid are together as a single unit, and preferably, each of the two frequency matching layers of the wall and one of the two frequency matching layers of the lid are together as a single unit;

[0013] - the ballistic protection layer of the wall, and where applicable the layer of ballistic protection of the lid, is composed of threads, including braided polyethylene, and preferably the frequency matching layers of the wall, and where applicable the frequency matching layers of the lid, are made of polyurethane foam;

[0014] - the ballistic cover has an outer cover surface which, at every point is has a slope having a component directed radially outwards with respect to the central axis and directed in a direction extending from the ballistic cover, or is perpendicular with respect to the central axis,

[0015] the outer surface of the cover which includes:

[0016] - a transition portion which is of revolution around the central axis and which is in partial torus shape or partial sphere shape, and

[0017] - a closure portion in the shape of a flat disc or in the shape of a truncated cone or of a cone having an opening angle such that water located on the closing portion is evacuated towards the ballistic wall under the effect of gravity; and

[0018] - the ballistic radome shell meets the STANAG 4569 standard at least of level 1.

[0019] The invention further relates to a ballistic radome, of the type comprising a ballistic radome shell and a ring-shaped annular support, provided with an annular groove that is complementary to a free edge of the ballistic wall, characterized in that the ballistic radome shell is a ballistic radome shell as defined above, and in that the ballistic radome shell is fixed to the annular support, in particular by fastening elements, and preferably in that the annular support includes attachment elements for the ballistic radome to an antenna base.

[0020] According to advantageous aspects of the invention, the ballistic radome comprises one or more of the following features, taken individually or in any technically feasible combination:

[0021] - the ring support comprises at least one handle, and in particular at least two handles, each handle extending radially outside the ballistic wall; and

[0022] - the ballistic radome includes a sealing gasket disposed on the support annular on the side opposite the ballistic radome shell.

[0023] The invention further relates to a radome assembly comprising a ballistic radome as defined above and a tarpaulin adapted to cover the ballistic radome.

[0024] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0025] [Fig-1] [Fig.1] is a perspective view of a ballistic radome according to the invention,

[0026] [Fig.2] [Fig.2] is a perspective view of the annular support of the radome ballistics of the [Fig.1],

[0027] [Fig.3] [Fig.3] is a schematic cross-sectional view of the ballistic radome of [Fig.1] along a plane containing the central axis of said radome,

[0028] [Fig.4] [Fig.4] is an enlarged view of a detail of [Fig.3],

[0029] [Fig. 5] [Fig. 5] is an exploded view of the ballistic radome of [Fig. 1], and

[0030] [Fig.6] [Fig.6] is a schematic profile view of a radome assembly according to the invention and its antenna base,

[0031] Figure 1 shows a ballistic radome 1 extending mainly along a central axis AA'. The central axis AA' acts as both the axis of revolution and the axis of elevation. The terms "axially", "radially", and "circumferentially" will be used hereafter, unless otherwise indicated, with respect to this central axis.

[0032] The ballistic radome 1 comprises a ballistic radome shell 2 and an annular support 4.

[0033] The ballistic radome shell 2 comprises a ballistic wall 6 extending around the central axis AA' and having an axial length LP. The ballistic wall 6 is tube-shaped with a substantially circular cross-section and has a radial thickness EP (see [Fig. 4]). The ballistic radome shell 2 defines an upper end 8, which forms an end opening. The upper end 8 is the axial end opposite the annular support.

[0034] The ballistic radome shell 2 includes a ballistic cover 10 completely sealing the upper end 8 or the end opening. In this case, the ballistic radome shell 2 is made up of the ballistic wall 6 and the ballistic cover 10.

[0035] The ballistic wall 6 is composed of a ballistic protection layer 20, also called the wall ballistic protection layer, and two frequency-matching layers 22 and 24, also called wall frequency-matching layers. The ballistic protection layer 20 is sandwiched between the frequency-matching layers 22 and 24. In other words, the ballistic wall 6 consists of the ballistic protection layer 20 and the two frequency-matching layers 22 and 24. The ballistic wall forms a free edge 26.

[0036] The ballistic protection layer 20 is composed of a composite material made up of fibers in the form of yarns, particularly braided yarns, and a thermoplastic material. In particular, these yarns, particularly braided yarns, are for example made of polyethylene. The polyethylene is advantageously a very high molecular weight polyethylene (UHMWPE), such as polyethylene marketed under the trade names "Spectra"® or "Dyneema"®.

[0037] According to the invention, the ballistic protection layer 20 extends in one piece around the central axis AA' and over the entire axial length LP and in one piece around the axis AA'.

[0038] Advantageously, the thickness and density of this ballistic protection layer 20 are dimensioned so as to ensure satisfactory resistance to projectiles, in particular so as to meet the STANAG standard, with a level of protection adapted to the threat, for example level 1. The thickness and density are also determined so as to ensure sufficient transparency of radio waves which would come from an antenna located under the radome, for suitable radio frequencies, in particular for the X and Ka bands.

[0039] The frequency-matching layers 22 and 24 can, for example, be made of plastic, such as polyurethane foam. Their thickness is determined to optimize the reflection and transmission of radio waves at the interface of the protective wall. The frequency-matching layers 22 and 24 extend in a single block around the central axis AA', in particular continuously and uninterruptedly around this central axis AA'. Advantageously, the frequency-matching layers 22 and 24 also extend along the entire axial length LP of the ballistic wall 6.

[0040] The ballistic cover 10 is composed of different layers and advantageously has a layer structure identical to that of the ballistic wall 6. The ballistic cover 10 is therefore composed of a ballistic protection layer 30, also called the cover's ballistic protection layer, and two frequency-matching layers 32 and 34, also called frequency-matching layers. of the cover. In other words, the ballistic cover 10 consists of the ballistic protection layer 30 and the two frequency matching layers 32 and 34. The ballistic protection layer 30 of the cover is sandwiched between the frequency matching layers 32 and 34 of the cover.

[0041] The ballistic protection layer 30 advantageously meets the same requirements in terms of wave transmission and ballistic protection as the wall ballistic protection layer 20. The ballistic protection layer 30 therefore advantageously comprises yarns, in particular braided yarns, made of thermoplastic material. This thermoplastic material is, in particular, polyethylene. Advantageously, the thermoplastic material of the yarns in the wall ballistic protection layer 20 and the thermoplastic material of the yarns in the lid ballistic protection layer 30 are identical.

[0042] Similarly, the frequency matching layers 32 and 44 of the lid can, for example, be made of plastic, advantageously polyurethane foam. Advantageously, the material of the frequency matching layers 32 and 34 of the lid and the material of the frequency matching layers 22 and 24 of the wall are identical.

[0043] According to the particular embodiment shown in the figures, the ballistic cover 10 and the ballistic wall 6 are formed from a single piece. In this case, the ballistic protection layer 20 of the wall and the ballistic protection layer 30 of the cover are a single block and form a single continuous ballistic protection layer. In other words, the ballistic protection layer 20 of the wall and the ballistic protection layer 30 of the cover are integral and form a single piece and are, in particular, obtained during the same manufacturing steps.

[0044] Similarly, the frequency matching layer 22 of the wall and the associated frequency matching layer of the lid 32 are a single unit and form a single continuous frequency matching layer. Likewise, the frequency matching layer 24 of the wall and the associated frequency matching layer of the lid 34 are a single unit and form a single continuous frequency matching layer. In other words, the frequency matching layer 22 and 24 of the wall and the frequency matching layer of the lid 32 and 34 of the lid are integral and a single unit and are notably produced during the same manufacturing steps. The frequency matching layers are essentially continuous along the central axis AA', and advantageously over essentially the entire height of the ballistic shell.

[0045] The ballistic radome shell 2 comprises an outer surface 40 (see in particular [Fig. 5]). The outer surface 40 consists of an outer surface of wall 42, which is the outer surface of the ballistic wall 6 and of an outer surface of lid 44, which is the outer surface of the ballistic lid 10.

[0046] The outer surface of wall 42 has a hollow cylindrical shape with central axis AA'.

[0047] The outer surface of the cover 44 at any point on this surface has a slope having a component directed radially outwards with respect to the central axis AA' and directed in a direction extending from the ballistic cover 10 towards the ballistic wall 6, or is perpendicular with respect to the central axis AA'. Thus, the outer surface of cover 44 is entirely devoid of any open cavity in a direction directed from the ballistic wall 6 towards the ballistic cover 10, i.e. upwards in the installed state of the ballistic radome 2.

[0048] In this case, the outer surface of the cover 44 comprises, and in particular is made up of, a transition portion 46 which is of revolution around the central axis AA' and a closing portion 48.

[0049] The transition portion 46 is in this case in the form of a partially open torus. According to an unrepresented variant, the transition portion 46 is in the form of a partial sphere or spherical zone.

[0050] Advantageously, the transition portion 46 and the outer wall surface 42 join without a crease. This is achieved, for example, by the fact that the sum of the minor torus radius and the major torus radius of the partial torus is identical to the radius of the cylinder of the outer wall surface 42. Alternatively, this is achieved by the fact that the radius of the partial sphere or spherical zone of the transition portion 46 is identical to the radius of the cylinder of the outer wall surface 42.

[0051] The closure portion 48 is in this case cone-shaped. Alternatively, the closure portion is truncated cone-shaped. The cone or truncated cone preferably has an opening angle α greater than 80° and less than 89°. The opening angle α is advantageously chosen so that water on the closure portion 48 is discharged towards and to the ballistic wall 6 under the effect of gravity. Alternatively, the closure portion is flat, i.e., perpendicular to the axis A-A'.

[0052] Advantageously, the transition portion 46 and the closing portion 48 join without a crease. This is achieved because the angle of inclination of the transition portion 46 at the point of junction between the transition portion 46 and the closing portion 48 is identical to the inclination of the cone, truncated cone, or flat disk of the closing portion.

[0053] The opening angle a ([Fig.3]) is advantageously chosen to reduce or avoid the stagnation of a liquid on the upper part, which would lead to a loss of radio frequency transmission quality.

[0054] The ballistic radome shell 2 thus formed advantageously meets the STANAG 4569 standard, with a level of protection adapted to the threat, for example at least level 1.

[0055] A method for manufacturing the ballistic radome shell 2 according to the invention may comprise the following successive steps:

[0056] - Installation of a preliminary ballistic protection layer for the wall, the preliminary of a ballistic protection layer of the wall extending continuously around a central rough axis,

[0057] - Installation of a preliminary ballistic protective layer for the lid, rough draft of the lid ballistic protection layer being linked to the rough draft of the wall ballistic protection layer;

[0058] - simultaneous hardening of the rough wall ballistic protection layer and the rough ballistic protection layer of the lid, thus simultaneously obtaining in one piece the ballistic protection layer 20 of the wall and the ballistic protection layer 30 of the lid, forming a rough ballistic radome shell.

[0059] The aforementioned setup steps may include shaping the layer blank(s) in a mold to the final external shape of the ballistic protection layer(s) 20 and / or 30 by draping pre-impregnated plies. The curing step may include autoclaving under a suitable pressure / temperature cycle to polymerize the material.

[0060] Next, the frequency matching layer 22 of the wall and the frequency matching layer 32 of the lid are applied in one piece to the ballistic radome shell blank. Then, the frequency matching layer 24 of the wall and the frequency matching layer 34 of the lid are applied in one piece to the ballistic radome shell blank, obtaining the ballistic radome shell 2

[0061] The hardening step can for example be carried out under vacuum in an autoclave, for example by pressing or polymerization.

[0062] The manufacture of the frequency matching layers may contain a machining step, in particular of the free edge 26 of the ballistic wall 6.

[0063] Figure 5 shows an exploded view of the radome according to the invention of Figure 1. The annular support 4, which is crown-shaped and has an annular groove 50 complementary to the free edge 26 of the ballistic wall 6, is visible. The annular groove 50 is also clearly visible in Figure 2. The annular groove 50 is adapted to accommodate the free edge 26. The ballistic radome 1 also includes fastening elements 52 for attaching the annular support 4 to the ballistic radome shell 2. In this case, the fastening elements 52 are screws.

[0064] Advantageously, the connection between the ballistic shell 2 and the annular support 4 is watertight, this watertightness being achieved by the presence of a sealing gasket, not shown, interposed between the annular groove 50 and the free edge 26. In addition, the holding in position can be achieved in particular by means of an adhesive, between the surface of the annular groove and the lower surface of the ballistic radome shell.

[0065] The annular support 4 further includes attachment elements 54 for the ballistic radome to an antenna base (see, e.g., [Fig. 2]). The attachment elements 54 may include openings and fasteners, such as screws, which engage in the openings. The attachment elements may be carried, for example, by a flange of the annular support 4, this flange projecting radially outwards.

[0066] The ballistic radome advantageously also includes a sealing gasket 56, disposed on the annular support 4 on the side opposite the ballistic wall shell 2, and adapted to be interposed between the annular support 4 and a base 60 of the antenna, making the connection between the annular support 4 and the base 60 watertight and / or dustproof. This gasket can be housed in the annular support, which has a groove on its underside.

[0067] In the present embodiment, the annular support 4 comprises at least one handle 58, and in this case four handles 58. Each handle 58 is advantageously oriented outwards from the central elevation axis AA', to facilitate the transport of the ballistic radome for installation on an antenna base (see [Fig. 6]). Each handle 56 extends radially outwards from the ballistic wall 6.

[0068] The invention also relates to a radome assembly 70 shown schematically in [Fig. 6] and the antenna base 60. The radome assembly 70 comprises the ballistic radome 1 and a removable cover 72, used to camouflage the ballistic radome optically. This cover 72 can be a color similar to the vehicle transporting the ballistic radome. The cover 72 also provides protection against solar radiation, reducing the cooling requirements of the antenna system housed within the ballistic radome.

[0069] In a preferred embodiment, this tarpaulin 72 is made of coated PVC.

[0070] Furthermore, the cover 72 includes suitable fastening means for securing the cover 72 to the ballistic radome and for pressing and tensioning the cover 72 against the outer surface of the ballistic radome. These fastening means advantageously include straps and / or tensioners. In this way, wind resistance and / or excessive degradation of the RF transparency performance of the radome assembly 70 is / are prevented.

[0071] Figure 6 also schematically shows the enveloping area EA of the antenna arranged on the antenna base. The enveloping area EA is defined by the swept volume by the antenna during its use. It can be seen that the shape of the ballistic radome 1 results in a relatively large distance between the enclosing shield EA and the ballistic radome shell for given external dimensions of the radome shell. The distance between the ballistic radome and the enclosing shield EA is defined such that the level of protection conferred by the ballistic radome is maintained. In other words, the distance is large enough that, under the effect of a given impact, the ballistic radome 1 does not deform in such a way as to enter the enclosing shield EA. Thus, this distance guarantees that the antenna remains protected against gunfire.

[0072] One advantage of the ballistic radome according to the invention is that it provides satisfactory sealing and ballistic resistance thanks to the small number of joints and the one-piece components. Furthermore, the shape of the ballistic radome results in relatively high radio frequency transparency. In addition, the shape of the ballistic radome's shell is ergonomic, making it particularly suitable for use on a vehicle.

Claims

Demands

1. Ballistic radome shell (2), of the type comprising: - a ballistic wall (6) extending around a central axis (AA'), having an axial length (LP) and an upper end, the ballistic wall being in the form of a tube with a circular cross-section, - a ballistic cover (10) sealing the upper end of the ballistic wall, the ballistic wall comprising a ballistic protection layer (20) which includes wires of thermoplastic material, and two frequency matching layers (22,24), the ballistic protection layer of the wall being sandwiched between the frequency matching layers of the wall, characterized in that;- the ballistic protection layer (20) extends in a single block around the central axis and over the entire axial length (LP), and in that - the frequency adaptation layers (22, 24) extend in a single block around the central axis and preferably also over the entire axial length (LP).;

2. Ballistic radome shell according to claim 1, wherein the ballistic cover (10) comprises a ballistic protection layer (30), which comprises thermoplastic yarns, and two frequency matching layers (32, 34), and wherein the ballistic protection layer (30) of the cover is sandwiched between the frequency matching layers (32, 34) of the ballistic cover.

3. Ballistic radome shell according to claim 2, wherein the ballistic protection layer (20) of the wall and the ballistic protection layer (30) of the cover are together as a single block, and preferably, each of the two frequency matching layers (22, 24) of the wall and one of the two frequency matching layers (32, 34) of the cover are together as a single block.

4. Ballistic radome shell according to any one of the preceding claims, wherein the ballistic protection layer (20) of the wall, and optionally the protection layer

5.

6.

7.

8. ballistic of the cover (30), is composed of yarns, in particular braided, of polyethylene, and preferably in which the frequency matching layers (22, 24) of the wall, and where appropriate the frequency matching layers (32, 34) of the cover, are of polyurethane foam. Ballistic radome shell (2) according to any one of the preceding claims, in which the ballistic cover (10) has an outer cover surface (44) which, at every point, either has a slope having a component directed radially outwards with respect to the central axis AA' and directed in a direction extending from the ballistic cover, or is perpendicular with respect to the central axis AA', wherein the outer cover surface (44) comprises: - a transition portion (46) which is of revolution about the central axis (AA') and which is in the form of a partial torus or a partial sphere, and - a closure portion (48) in the shape of a flat disc or in the shape of a truncated cone or of a cone having an opening angle such that water on the closure portion is evacuated towards the ballistic wall (6) under the effect of gravity. Ballistic radome shell (2) according to any one of the preceding claims, wherein the ballistic radome shell (2) meets STANAG 4569 at least level 1. Ballistic radome (1), of the type comprising - a ballistic radome shell (2) and - an annular support (4) in the shape of a crown, provided with an annular groove (50) which is complementary to a free edge (26) of the ballistic wall, characterized in that the ballistic radome shell is a ballistic radome shell (2) according to any one of the preceding claims, and in that the ballistic radome shell (2) is attached to the annular support, in particular by fastening elements (52), preferably in that the annular support (4) comprises fastening elements (54) for attaching the ballistic radome to an antenna base. Ballistic radome (1), according to claim 7, wherein the annular support (4) comprises at least one handle (58), and including at least two handles (58), each handle extending radially outside the ballistic wall (6).

9. Ballistic radome (1), according to claim 7 or 8, wherein the ballistic radome includes a sealing gasket (56) disposed on the annular support (4) on the side opposite the ballistic radome shell (2).

10. Radome assembly (70) comprising a ballistic radome (1) according to any one of claims 7 to 9 and a cover (72) adapted to cover the ballistic radome.

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