Ballistic radome shell, corresponding ballistic radome and radome assembly

Abstract

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 piece around the central axis and over the entire axial length (LP), and the frequency-matching layers (22, 24) extend in a single piece around the central axis and preferably also over the entire axial length (LP). Application to radio antenna radomes.

Description

[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 elements for these antennas. External threats can then be related to environmental conditions or originate from gunfire. Such protection can be achieved by designing a radome that includes internal ballistic protection.

[0003] Numerous radome designs are known, with ballistic shields generally made of thermoplastic materials that meet both frequency transparency and ballistic protection requirements. Radomes can then be composed of an assembly of protective segments or made from a single block.

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

[0005] However, these solutions do not provide 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 for 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 the ballistic protection layer extends in a single block around the central axis and over the entire axial length, and in that the frequency adaptation layers extend in a single block around the central axis and preferably also over the entire axial length.

[0008] 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: The ballistic cover comprises a ballistic protection layer, which includes thermoplastic yarns, and two frequency-matching layers, and the ballistic protection layer of the cover is sandwiched between the frequency-matching layers of the ballistic cover; the ballistic protection layer of the wall and the ballistic protection layer of the cover are together in one piece, and preferably, each of the two frequency-matching layers of the wall and one of the two frequency-matching layers of the cover are together in one piece; the ballistic protection layer of the wall, and where applicable the ballistic protection layer of the cover, is composed of yarns, in particular braided yarns, of polyethylene, and preferably the frequency-matching layers of the wall, and where applicable the frequency-matching layers of the cover, are made of polyurethane foam;the ballistic cover has an outer cover surface which, at every point, either has a slope having a component directed radially outwards from the central axis and directed in a direction extending from the ballistic cover, or is perpendicular to the central axis; the outer surface of the lid which includes: a transition portion which is of revolution around the central axis and which is in the form of a partial torus or in the form of a partial sphere, and a closure portion in the form of a flat disc or in the form of a truncated cone or a cone having an opening angle such that water on the closure portion is evacuated towards the ballistic wall under the effect of gravity; and the ballistic radome shell meets the STANAG 4569 standard at least level 1.

[0009] The invention further relates to a ballistic radome, of the type comprising a ballistic radome shell and a ring-shaped support, provided with an annular groove which 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 ring support, in particular by fastening elements, and preferably in that the ring support comprises fastening elements for the ballistic radome to an antenna base.

[0010] 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: the annular support includes at least one handle, and in particular at least two handles, each handle extending radially outside the ballistic wall; and the ballistic radome includes a sealing gasket disposed on the annular support on the side opposite the ballistic radome shell.

[0011] The invention further relates to a radome assembly comprising a ballistic radome as defined above and a tarpaulin adapted to cover the ballistic radome.

[0012] 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: [ Fig. 1 ] there figure 1 is a perspective view of a ballistic radome according to the invention, [ Fig. 2 ] there figure 2 is a perspective view of the annular support of the ballistic radome of the Figure 1 , [ Fig. 3 ] there figure 3 is a schematic cross-sectional view of the ballistic radome of the Figure 1 according to a plan containing the central axis of said radome, [ Fig. 4 ] there figure 4 is an enlarged view of a detail of the figure 3 , [ Fig. 5 ] there figure 5 is an exploded view of the ballistic radome of the Figure 1 , And [ Fig. 6 ] there figure 6 is a schematic profile view of a radome assembly according to the invention and its antenna base,

[0013] There figure 1 Figure 1 shows a ballistic radome extending primarily 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.

[0014] The ballistic radome 1 comprises a ballistic radome shell 2 and an annular support 4.

[0015] 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 Figure 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.

[0016] 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 formed by the ballistic wall 6 and the ballistic cover 10.

[0017] 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.

[0018] The ballistic protection layer 20 is composed of a composite material made up of fibers in the form of yarns, including braided yarns, and a thermoplastic material. In particular, these yarns, including braided yarns, are 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"®.

[0019] According to the invention, the ballistic protection layer 20 extends in a single block around the central axis AA' and over the entire axial length LP and in one piece around the axis AA'.

[0020] Advantageously, the thickness and density of this ballistic protection layer 20 are dimensioned to ensure satisfactory resistance to projectiles, in particular to meet the STANAG standard, with a level of protection appropriate to the threat, for example level 1. The thickness and density are also determined to ensure sufficient transparency of radio waves that would come from an antenna located under the radome, for suitable radio frequencies, in particular for the X and Ka bands.

[0021] 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.

[0022] The ballistic cover 10 is composed of several 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 the cover's frequency-matching layers. In other words, the ballistic cover 10 consists of the ballistic protection layer 30 and the two frequency-matching layers 32 and 34. The cover's ballistic protection layer 30 is sandwiched between the cover's frequency-matching layers 32 and 34.

[0023] Ballistic protection layer 30 advantageously meets the same requirements in terms of wave transmission and ballistic protection as ballistic protection layer 20 of the wall. Ballistic protection layer 30 therefore advantageously comprises yarns, particularly braided yarns, made of thermoplastic material. This thermoplastic material is, in particular, polyethylene. Advantageously, the thermoplastic material of the yarns in ballistic protection layer 20 of the wall and the thermoplastic material of the yarns in ballistic protection layer 30 of the lid are identical.

[0024] 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.

[0025] According to the specific 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 integral 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 bonded and form a single unit and are obtained, in particular, during the same manufacturing steps.

[0026] 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 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 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 produced during the same manufacturing steps. The frequency matching layers are continuous essentially along the entire length of the central axis AA', and advantageously over essentially the entire height of the ballistic shell.

[0027] The ballistic radome shell 2 comprises an external surface area of ​​40 (see in particular Figure 5 ). The outer surface 40 consists of an outer wall surface 42, which is the outer surface of the ballistic wall 6 and an outer cover surface 44, which is the outer surface of the ballistic cover 10.

[0028] The outer surface of wall 42 has the shape of a hollow cylinder with central axis AA'.

[0029] The outer surface of the cover 44, at every point on this surface, either has a slope with a component directed radially outwards with respect to the central axis AA' and 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 the cover 44 is entirely free of any open recess 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.

[0030] In this case, the outer surface of the cover 44 includes, 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.

[0031] 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.

[0032] Advantageously, the transition portion 46 and the outer wall surface 42 join without a crease. This is achieved, for example, because 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 because 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.

[0033] 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, disc-shaped, i.e., perpendicular to the axis A-A'.

[0034] 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.

[0035] The opening angle α ( Figure 3 ) is advantageously chosen to reduce or avoid the stagnation of liquid on the upper part, which would lead to a loss of radio frequency transmission quality.

[0036] The ballistic radome shell thus formed advantageously meets the STANAG 4569 standard, with a level of protection adapted to the threat, for example at least level 1.

[0037] A method for manufacturing the ballistic radome shell 2 according to the invention may comprise the following successive steps: Placement of a rough wall ballistic protection layer, the rough wall ballistic protection layer extending continuously around a central rough axis; Placement of a rough lid ballistic protection layer, the rough lid ballistic protection layer being linked to the rough wall ballistic protection layer; simultaneous hardening of the rough wall ballistic protection layer and the rough lid ballistic protection layer, thus simultaneously and in one piece obtaining the wall ballistic protection layer 20 and the lid ballistic protection layer 30, forming a rough ballistic radome shell.

[0038] The aforementioned setup steps may include shaping the layer(s) in a mold to the final external shape of the 20 and / or 30 ballistic protection layer(s) by draping pre-impregnated plies. The curing step may include autoclaving under a suitable pressure / temperature cycle to polymerize the material.

[0039] 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

[0040] The hardening stage can, for example, be carried out under vacuum in an autoclave, for example by pressing or polymerization.

[0041] The manufacturing of frequency matching layers may include a machining step, in particular of the free edge 26 of the ballistic wall 6.

[0042] There figure 5 shows an exploded view of the radome according to the invention of the Figure 1 We see 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. The annular groove 50 is also clearly visible on the Figure 2 The annular groove 50 is adapted to accommodate the free edge 26. The ballistic radome 1 also includes fixing elements 52 for the annular support 4 to the ballistic radome shell 2. In this case, the fixing elements 52 are screws.

[0043] 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.

[0044] The annular support 4 also includes fixing elements 54 of the ballistic radome to an antenna base (see e.g. Figure 2 The fasteners 54 may include openings and fasteners, such as screws, which engage in the openings. The fasteners may be carried, for example, by a flange of the annular support 4, this flange projecting radially outwards.

[0045] The ballistic radome advantageously also includes a sealing gasket 56, located 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, thus 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.

[0046] 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 Figure 6 ). Each handle 56 extends radially outside the ballistic wall 6.

[0047] The invention also relates to a radome assembly 70 shown schematically on the Figure 6 and the antenna base 60. The radome assembly 70 consists of 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.

[0048] In a preferred embodiment, this 72 tarpaulin is made of coated PVC.

[0049] Furthermore, the cover 72 includes suitable fastening means for securing the cover 72 to the ballistic radome and for tightening and tensioning the cover 72 against the outer surface of the ballistic radome. These fastening means advantageously include straps and / or tensioners. Thus, wind resistance and / or excessive degradation of the RF transparency performance of the radome assembly 70 is / are prevented.

[0050] There Figure 6 also schematically shows the enveloping EA of the antenna mounted on the antenna base. The wraparound EA is defined by the volume swept by the antenna during its use. We see that the shape of the ballistic radome 1 leads to a relatively large distance between the enveloping EA and the ballistic radome shell for given external dimensions of the radome shell. The distance between the ballistic radome and the enclosing structure EA is defined such that the level of protection conferred by the ballistic radome is maintained. In other words, the distance is sufficiently great so that, under the effect of a given impact, the ballistic radome 1 does not deform in such a way as to enter the enclosing structure. EA Thus, this distance ensures that the antenna remains protected from gunfire.

[0051] One advantage of the ballistic radome according to the invention is that it ensures 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 ergonomic shape of the ballistic radome's casing makes it particularly suitable for vehicle-mounted applications.

Claims

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 thermoplastic yarns, 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 along the entire axial length (LP), and in that - the frequency matching 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 includes 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 where applicable the ballistic protection layer of the cover (30), is composed of yarns, in particular braided yarns, of polyethylene, and preferably wherein the frequency matching layers (22, 24) of the wall, and where applicable the frequency matching layers (32, 34) of the cover, are made of polyurethane foam.

5. Ballistic radome shell (2) according to any one of the preceding claims, wherein 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 in the form of a partial sphere, and - a closure portion (48) in the form of a flat disk or in the form of a truncated cone or 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.

6. 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.

7. Ballistic radome (1), of the type comprising - a ballistic radome shell (2) and - a ring-shaped support (4) 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 fixed to the annular support, in particular by fastening elements (52), preferably in that the annular support (4) includes attachment elements (54) for the ballistic radome to an antenna base.

8. Ballistic radome (1), according to claim 7, wherein the annular support (4) comprises at least one handle (58), and in particular 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.

Images