Triangular slotted antenna

Abstract

The present invention relates to a method for manufacturing a slotted antenna comprising the step of: forming by additive manufacturing a waveguide 1 comprising a radiating wall 10 provided with radiation slots 100 for radiating a portion of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide 1, characterized in that the radiating wall 10 is supported against a support platform 11 on which the waveguide is manufactured, and in that a cross-section of the waveguide 1 lacks a side parallel to the side of the cross-section supported by the radiating wall 10. The present invention also relates to an antenna obtained by the above method. Figure for the abstract: Fig. 1

Description

Title of the invention: Triangular slotted antenna technical field

[0001] The present invention relates to a method of manufacturing such a slotted antenna and an antenna obtained by such a process. State of the art

[0002] Slotted antennas constitute a particular type of antenna, generally comprising a waveguide, one of whose walls has one or more holes or slots. When a radio frequency (RF) signal is introduced into the waveguide, all or part of the signal's electromagnetic energy is radiated outward through the holes or slots. The size, shape, and arrangement of the holes or slots in the waveguide determine the antenna's radiation pattern. Several such waveguides can be arranged in parallel to form a slotted antenna array.

[0003] The additive manufacturing of passive RF components, and in particular slot antennas, is known in the prior art. By way of example, application FR3118538 discloses a slot antenna array that can be obtained by additive manufacturing.

[0004] This type of manufacturing offers significant advantages over more traditional manufacturing methods. Additive manufacturing requires little to no assembly of RF components, which drastically reduces not only manufacturing time but also assembly errors. This results in increased reproducibility. Furthermore, additive manufacturing also reduces the weight of RF components, for example by limiting the need for flanges used to connect elements or by sharing certain walls. Finally, additive manufacturing makes it possible to obtain complex geometries that are not achievable through traditional machining and assembly.

[0005] One of the main difficulties in additive manufacturing lies in producing cantilevered sections that tend to sag during printing. Using printing supports is not optimal because these supports must then be manually removed, thus negating some of the advantages of additive manufacturing. The angle of the cantilevered sections relative to the printing direction (generally vertical) therefore plays an important role in the design of the devices to be printed.

[0006] Waveguides are generally printed in the direction corresponding to the longitudinal direction of the waveguide channel. This orientation prevents the waveguide walls from being cantilevered during printing.

[0007] In the case of additive manufacturing of slotted antennas, an additional difficulty lies in the formation of the slots themselves. Indeed, the sides of the slots constitute portions that can be cantilevered during manufacturing. The cross-section of the slots must therefore be adapted accordingly to allow for their printing, which limits the choice of available cross-sections and thus affects the radiation pattern of the antenna. Brief summary of the invention

[0008] An object of the present invention is to propose a method of manufacturing a slotted antenna free from the limitations present in the prior art.

[0009] Another object of the present invention is to propose a method for manufacturing a slotted antenna allowing the creation of slots of arbitrary cross-sections.

[0010] According to the invention, these objectives are achieved in particular by means of a method for manufacturing a slotted antenna comprising the step of:

[0011] forming by additive manufacturing a waveguide comprising a radiating wall provided with radiation slots allowing to radiate a part of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide,

[0012] characterized in that the radiating wall is supported against a support platform on which the waveguide is manufactured,

[0013] and in that a cross-section of the waveguide is devoid of a side parallel to a side of the cross-section of the waveguide supported by the radiating wall.

[0014] Printing the waveguide by placing the radiating wall directly against the support platform, i.e. by starting by printing the radiating wall against the support platform, prevents certain portions of the radiation slots from being cantilevered during printing.

[0015] The fact that a cross-section of the waveguide is devoid of a side parallel to the side of the cross-section supported by the radiating wall makes it possible to limit the number of other cantilevered sections, in particular at the level of the side walls of the waveguide.

[0016] A first and a second side of the cross-section can each form an angle with the side of the cross-section supported by the radiating wall of between 40° and 70°.

[0017] The cross-section can be triangular or pentagonal.

[0018] According to one embodiment, at least two sides of the cross-section are connected by a curved portion. This curved portion can, for example, connect two flat sides, so as to obtain a triangular or pentagonal section with some rounded angles.

[0019] According to one embodiment, at least one side of the cross-section comprises a curved portion.

[0020] Advantageously the radiation slits have a cross-section whose shape is selected from: a circle, an ellipse, a triangle, a square, a rectangle, a pentagon, a hexagon, an octagon and a cross.

[0021] According to one embodiment, the radiating slits are arranged such that a larger dimension of the slits extends in a direction transverse to a direction of propagation of electromagnetic waves in the waveguide.

[0022] According to one embodiment, the antenna includes an electromagnetic wave introduction port disposed at one of the longitudinal ends of the waveguide.

[0023] Alternatively, the antenna may include an electromagnetic wave introduction port disposed on a wall of the waveguide opposite said radiating wall.

[0024] According to one embodiment, the manufacturing process also includes the fabrication of several slotted waveguides to form a slotted array antenna. In this case, the waveguide is a first waveguide, and the process further includes the step of:

[0025] formed by additive manufacturing, at least a second waveguide comprising a radiating wall provided with radiation slots allowing to radiate a part of the electromagnetic energy of an electromagnetic wave propagating inside the at least a second waveguide,

[0026] the waveguides being formed parallel to each other,

[0027] characterized in that the radiating wall of each waveguide is supported against the support platform on which the waveguides are manufactured,

[0028] and in that a cross-section of each waveguide is devoid of a side parallel to a side of the cross-section supported by the corresponding radiating wall.

[0029] Advantageously, the antenna is made monolithically without an assembly step.

[0030] According to one embodiment, the process further comprises the step of:

[0031] form by additive manufacturing a coupling waveguide allowing each waveguide to be fed individually, the coupling waveguide being devoid of a wall parallel to the radiating walls.

[0032] The aforementioned goals are also achieved by means of a slotted antenna obtained by the process described above. Brief description of the figures

[0033] Examples of implementation of the invention are given in the description illustrated by the accompanying figures in which:

[0034] [Fig-1]: schematically illustrates a cross-sectional view of a waveguide with triangular section slots on a printing platform.

[0035] [Fig.2]: schematically illustrates a perspective view of a slotted waveguide of triangular section.

[0036] [Fig.3]: schematically illustrates a perspective view of a slotted waveguide of pentagonal cross-section.

[0037] [Fig.4]: schematically illustrates a perspective view of a guide network of slit waves.

[0038] [Fig. 5]: illustrates several possible geometries for the slits of a waveguide according to the invention. Example(s) of an embodiment of the invention

[0039] The present invention relates to an additive manufacturing method for a slotted antenna that allows the production of slots whose geometry is not restricted by the constraints related to additive manufacturing.

[0040] For the purposes of this disclosure, the term "additive manufacturing" includes, but is not limited to, manufacturing techniques such as • Selective Laser Melting (SLM); • stereolithography (SLA); • powder binding (Binder Jetting); • the deposition of molten material (Directed Energy Deposition, DED); • sheet lamination of metal sheets; • Metal inkjet printing. Furthermore, the expressions "additive manufacturing" and "3D printing" are used interchangeably and are therefore considered synonymous.

[0041] One of the major constraints related to the additive manufacturing of waveguides, and in particular slotted waveguides, lies in minimizing overhanging portions during printing. During their fabrication, such portions are susceptible to sagging and often require adjustment of their orientation and / or the presence of support structures that must then be removed by machining or polishing. To overcome this drawback, waveguides are usually arranged so that their longitudinal axis, i.e., the direction of wave propagation in the waveguide, essentially coincides with the printing direction. However, printing along the propagation direction of a slotted waveguide remains problematic because, since the slots are located on a side wall of the waveguide, some portions of the slots are then cantilevered during manufacturing.The result is that the geometry and / or orientation. Slots must be adapted (and therefore limited) in order to limit the risks of sagging of the cantilevered portions.

[0042] The terms "slit", "radiating slit" and "radiation slit" here refer to an opening made in a side wall of a waveguide and intended to radiate a part of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide.

[0043] Such waveguides are particularly suited to the satellite domain because of their low profile and wide bandwidth, but also in radar, navigation and surveillance applications.

[0044] Thus, the present invention can be implemented in antennas intended for frequency bands between 6GHz and 40GHz.

[0045] The process of the present invention allows the production of slotted waveguides whose geometry does not require any adaptation or limitation.

[0046] The one-step additive manufacturing process of forming a waveguide 1 comprising a radiating wall 10 provided with radiation slits 100 allowing to radiate a part of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide 1.

[0047] As illustrated in [Fig. 1], the radiating wall 10 is advantageously supported against the support platform 11 on which the waveguide 1 is manufactured. In this way, none of the portions of the slots 100 are cantilevered during the printing of the waveguide since the radiating wall 10 is entirely supported by the support platform 11.

[0048] Since this orientation of the waveguide during printing implies that the direction of propagation x of the waves in the waveguide is parallel to the support platform 11, it is necessary that the cross-section of the waveguide 1 be devoid of a side parallel to the side of the cross-section supported by the radiating wall 10 in order to limit, or even eliminate, the portions of this cross-section which may be cantilevered during manufacturing and at risk of sagging.

[0049] During manufacturing, the radiating wall 10 is thus typically made first on the support platform 11 and then the rest of the waveguide is printed on top of it.

[0050] According to an embodiment illustrated in [Fig. 1], the cross-section of the waveguide comprises a first side forming a first angle α with the side of the cross-section belonging to the radiating wall 10, and a second side forming a second angle [3] with the side of the cross-section belonging to the radiating wall 10. These first and second angles α and [3] are between 40° and 70°. Such an inclination with respect to the side of the cross-section belonging to the wall Radiant heating helps to limit the risks of wall collapse, including on the first and second sides.

[0051] In order to avoid overhanging portions of the cross-section, the cross-section of the waveguide is advantageously triangular or pentagonal.

[0052] According to an embodiment illustrated in [Fig. 2], the waveguide 1 comprises two side walls in addition to the radiating wall 10, such that its cross-section is triangular. The triangle may be equilateral, isosceles, or any other shape depending on the application and the intended geometric constraints. In order to minimize the risk of sagging, the angles between the side walls and the radiating wall 10 are typically greater than 40°, preferably greater than or equal to 45°.

[0053] According to an embodiment illustrated in [Fig. 3], the waveguide 1 comprises four side walls in addition to the radiating wall 10, such that its cross-section is pentagonal. In order to minimize the risk of sagging, the angles between the side walls and the radiating wall 10 are typically greater than 40°, preferably greater than or equal to 45°.

[0054] In the particular embodiment illustrated in [Fig.3], the angles between the side walls and the radiating wall 10 are essentially equal to 90°. Two other side walls opposite the radiating wall 10 are joined together so as to form an angle typically less than or equal to 100°.

[0055] To further limit the risk of sagging during printing, certain portions of the waveguide can be curved. Indeed, curved, or arched, portions generally require less support during printing and are thus well suited to joining cantilevered sections.

[0056] Thus, in an embodiment not shown, the junction between the side walls and the radiating wall may include a curved portion. Similarly, the junctions between the different side walls, depending on their number, may include curved portions.

[0057] In addition to the junctions between different side and / or radiating walls, certain portions of the side walls can also be curved according to the geometry of the waveguide in order to limit the risks of sagging.

[0058] Due to the orientation of the waveguide during printing, the radiation slots 100 arranged on the radiating wall 10 have virtually no geometric constraints. Indeed, since the support platform 11 is in contact with the radiating wall 10 during printing, all sections of the radiation slots are fully supported by the platform during additive manufacturing.

[0059] Various examples of radiation slit cross-sections 100 are illustrated in a non-limiting manner in [Fig. 5]. In particular, the radiation slits may be circular, elliptical, triangular, square, rectangular, pentagonal, Hexagonal, octagonal, cross-shaped, etc. The polygons mentioned can be regular or irregular.

[0060] The number of radiation slots 100 arranged on the radiating wall 10 can depend on the specific applications for which the antenna is intended. This number can vary from a few units to several tens, or even more.

[0061] The dimensions of the radiation slit cross-sections 100 can also vary depending on the specific applications for which the antenna is intended. In particular, the dimensions of the radiation slits of the same waveguide can be identical or vary relative to each other.

[0062] The orientation of the radiation slits 100 can be identical over the entire radiating wall 10 or alternatively vary over all or part of the radiating wall.

[0063] Figures 2 and 3 illustrate embodiments in which the radiating wall 10 is provided with a plurality of radiating slots 100. These slots have a rectangular section and the orientation of the slots is identical over the entire radiating wall 10.

[0064] Figure 4 illustrates an embodiment in which the radiating wall 10 is provided with a plurality of radiating slots 100. These slots have a rectangular cross-section and are inclined with respect to the longitudinal direction of the waveguide. Moreover, the angle of inclination varies between two successive radiating slots.

[0065] The present method advantageously enables the additive manufacturing of waveguides in which the largest dimension of the radiation slit cross-sections extends transversely to the direction of wave propagation in the waveguide. Indeed, such cross-sections are difficult to produce without special support in conventional additive manufacturing processes, particularly when the largest dimension of the slits forms a significant angle (for example, more than 45°) with the propagation direction (usually corresponding to the printing direction), and therefore must be printed in cantilever mode.

[0066] In one embodiment, the waveguide 1 is manufactured such that it includes an electromagnetic wave introduction port at one of its longitudinal ends. This introduction port allows a signal to be introduced into the waveguide so that it can radiate outwards from the antenna when it is operating in transmit mode and transmit a signal from the outside to the electronic components of the antenna when it is operating in receive mode.

[0067] One, the other or both ends of the waveguide may include a signal introduction port.

[0068] Alternatively, the waveguide 1 is manufactured so that it includes an electromagnetic wave introduction port disposed on a wall of the waveguide opposite the radiating wall 10. This introduction port allows a signal to be introduced in the waveguide so that it can radiate outwards from the antenna when it is operating in transmit mode and transmit a signal from the outside to the electronic components of the antenna when it is operating in receive mode.

[0069] As illustrated in [Fig.4], the present invention also relates to an additive manufacturing method for a slotted array antenna formed by the addition of several slotted waveguides as described above.

[0070] Thus, the process further comprises an additive manufacturing step of at least one second waveguide 1, which also includes a radiating wall 10 provided with radiation slots 100 for radiating a portion of the electromagnetic energy of an electromagnetic wave propagating inside at least one second waveguide. The second waveguide (as well as any additional waveguides) are formed parallel to each other, i.e., the wave propagation directions of the waveguides are all parallel. The radiating wall 10 of each waveguide is advantageously supported against the support platform 11 on which the waveguides are printed, and the cross-section of each waveguide has no side parallel to the side of the cross-section supported by the corresponding radiating wall 10.

[0071] In other words, the array antenna 2 is manufactured additively, starting with the radiating walls of the waveguides, which are thus all supported against the support platform. The advantages are identical to those mentioned above, namely that this process makes it possible to obtain arbitrary radiation slot geometries 100 since there is no constraint related to the risk of sagging of certain portions of these slots 100 due to orientation.

[0072] This process thus makes it possible to obtain monolithic array slot antennas 2, requiring very little or no assembly after printing. This results in cost and production time savings. Furthermore, the radiation slots can be created during printing, eliminating the need for post-fabrication machining.

[0073] Each individual waveguide of the array antenna may possess the characteristics described above, in particular with regard to the waveguide sections, cross-sections, dimensions, orientations and number of radiation slots.

[0074] The method may also include an additional step of additive manufacturing a coupling waveguide to individually feed each waveguide of the arrayed antenna.

[0075] In an embodiment not shown, a coupling waveguide is printed transversely to the propagation directions in the waveguides.

[0076] Advantageously, this coupling waveguide is devoid of a wall parallel to the radiating walls 10 of the waveguides so as to limit the cantilevered portions during printing.

[0077] For this purpose, the section of the coupling waveguide can be, for example, triangular or pentagonal and / or include curved portions.

[0078] Finally, the present invention also relates to a waveguide with and / or a network of slotted waveguides obtained by the process described above. [Tables 1] Reference numbers used in the figures 1 Slotted waveguide 10 Radiant Wall 100 Radiation Slit 11 Support Platform 2. Slotted waveguide array x Direction of propagation z Printing direction First angle [3 Second angle

Claims

Demands

1. A method for manufacturing a slotted antenna comprising the step of: forming by additive manufacturing a waveguide (1) comprising a radiating wall (10) provided with radiation slots (100) for radiating a portion of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide (1), characterized in that the radiating wall (10) is supported against a support platform (11) on which the waveguide is manufactured, a direction of propagation of the electromagnetic waves in the waveguide being non-parallel to a manufacturing direction of the antenna, and in that a cross-section of the waveguide (1) is devoid of a side parallel to a side of the cross-section of the waveguide supported by the radiating wall (10).

2. A manufacturing method according to claim 1, characterized in that a first and a second side of the cross section each form an angle with the side of the cross section supported by the radiating wall (10) of between 40° and 70°.

3. A manufacturing method according to any one of claims 1 to 2, characterized in that the cross-section is triangular or pentagonal.

4. A manufacturing method according to any one of the preceding claims, characterized in that at least two sides of the cross-section are connected by a curved portion.

5. A manufacturing method according to any one of the preceding claims, characterized in that at least one side of the cross-section comprises a curved portion.

6. A manufacturing method according to any one of the preceding claims, characterized in that the radiation slits (100) have a cross-section whose shape is selected from: a circle, an ellipse, a triangle, a square, a rectangle, a pentagon, a hexagon, an octagon and a cross.

7. A manufacturing method according to any one of the preceding claims, characterized in that the radiating slots (100) are arranged such that a larger dimension of the slots extends along a direction transverse to the direction of propagation of electromagnetic waves in the waveguide (1).

8. A manufacturing method according to any one of claims 1 to 7, characterized in that the antenna comprises an electromagnetic wave introduction port disposed at one of the longitudinal ends of the waveguide (1).

9. A manufacturing method according to any one of claims 1 to 7, characterized in that the antenna comprises an electromagnetic wave introduction port disposed on a wall of the waveguide opposite said radiating wall (10).

10. A manufacturing method according to any one of the preceding claims, the waveguide being a first waveguide, the method further comprising the step of: forming by additive manufacturing, at least a second waveguide (1) comprising a radiating wall (10) provided with radiation slots (100) enabling the radiation of a portion of the electromagnetic energy of an electromagnetic wave propagating inside the at least a second waveguide, the waveguides being formed parallel to each other, characterized in that the radiating wall (10) of each waveguide is supported against the support platform (11) on which the waveguides are manufactured, and in that a cross-section of each waveguide (1) is devoid of a side parallel to a side of the cross-section supported by the corresponding radiating wall (10).

11. Method according to the preceding claim, characterized in that the antenna is made monolithically without an assembly step.

12. A method according to any one of claims 10 or 11, further comprising: forming by additive manufacturing a coupling waveguide enabling each waveguide to be fed individually, the coupling waveguide being devoid of a wall parallel to the radiating walls (10).

13. Slotted antenna obtained by the process of one of the preceding claims.

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