Triangular slot antenna

Abstract

The present invention relates to a method for manufacturing a slot antenna, which comprises the step of: forming, by additive manufacturing, a waveguide (1) comprising a radiating wall (10) provided with radiating slots (100) for radiating part of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide (1), characterised in that the radiating wall (10) bears against a support platform (11) on which the waveguide is manufactured, and in that a cross-section of the waveguide (1) has no 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.

Description

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 method. State of the art

[0002] Slot antennas are a special type of antenna that typically includes a waveguide with one or more holes or slots in one of its walls. When a radio frequency (RF) signal is introduced into the waveguide, all or a portion of the signal's electromagnetic energy is radiated through the holes or slots to the outside of the waveguide. 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 slot antenna array.

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

[0004] This type of manufacturing allows for significant gains compared to more traditional manufacturing methods. Indeed, additive manufacturing requires little, if any, assembly of RF components, which drastically reduces not only manufacturing time, but also assembly-related errors. This results in increased reproducibility. Furthermore, additive manufacturing also allows for a reduction in the weight of RF components, for example by limiting the need for flanges used for connecting elements or by sharing certain walls. Finally, additive manufacturing allows to obtain complex geometries that are not achievable using traditional machining and assembly.

[0005] One of the main challenges of additive manufacturing is the creation of overhanging portions that tend to sag during printing. Using printing supports is not optimal because these supports must then be removed manually, thus eliminating some of the advantages of additive manufacturing. The angle of the cantilever sections relative to the printing direction (usually vertical) thus plays an important role in the development of the devices to be printed.

[0006] Waveguides are typically printed in the direction corresponding to the longitudinal direction of the waveguide channel. This orientation prevents the waveguide walls from being overhanging 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 as many portions that can be cantilevered during manufacturing. The cross-section of the slots must therefore be adapted accordingly to allow their printing, which limits the choice of available cross-sections and therefore affects the radiation pattern of the antenna. Brief summary of the invention

[0008] An object of the present invention is to provide 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 of manufacturing a slotted antenna allowing the production of slots of arbitrary sections.

[0010] According to the invention, these aims are achieved in particular by means of a method for manufacturing a slotted antenna comprising the step of: forming by additive manufacturing a waveguide comprising a radiating wall provided with radiation slots making it possible to radiate a portion of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide, characterized in that the radiating wall bears against a support platform on which the waveguide is manufactured, and in that a cross-section of the waveguide has no side parallel to the side of the cross-section supported by the radiating wall.

[0011] Printing the waveguide with the radiating wall directly against the support platform, i.e., printing the radiating wall against the support platform first, prevents portions of the radiation slots from being overhanging during printing.

[0012] 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.

[0013] A first and a second side of the cross-section may each form an angle with the side of the cross-section belonging to the radiating wall of between 40° and 70°.

[0014] The cross section can be triangular or pentagonal.

[0015] According to one embodiment, at least two sides of the cross-section are connected by a curved portion. This curved portion may, for example, connect two flat sides, so as to obtain a triangular or pentagonal section with certain rounded angles.

[0016] According to one embodiment, at least one side of the cross-section comprises a curved portion.

[0017] Advantageously, the radiation slots have a 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.

[0018] According to one embodiment, the radiating slots are arranged such that a larger dimension of the slots extends in a direction transverse to a direction of propagation of the electromagnetic waves in the waveguide.

[0019] According to one embodiment, the antenna comprises an electromagnetic wave introduction port arranged at one of the longitudinal ends of the waveguide.

[0020] Alternatively, the antenna may comprise an electromagnetic wave introduction port arranged on a wall of the waveguide opposite said radiating wall.

[0021] According to one embodiment, the manufacturing method also comprises manufacturing a plurality of slotted waveguides so as to form an arrayed slotted antenna. In this case, the waveguide is a first waveguide and the method further comprises the step of: forming by additive manufacturing, at least one second waveguide comprising a radiating wall provided with radiation slots for radiating a portion of the energy electromagnetic wave of an electromagnetic wave propagating inside the at least one second waveguide, the waveguides being formed parallel to each other, characterized in that the radiating wall of each waveguide bears against the support platform on which the waveguides are manufactured, and in that a cross-section of each waveguide is devoid of a side parallel to the side of the cross-section supported by the corresponding radiating wall.

[0022] Advantageously, the antenna is produced monolithically without an assembly step.

[0023] According to one embodiment, the method further comprises the step of: forming by additive manufacturing a coupling waveguide making it possible to individually power each waveguide, the coupling waveguide being devoid of a portion parallel to the radiating walls.

[0024] The above-mentioned aims are also achieved by means of a slot antenna obtained by the method described above. Brief description of the figures

[0025] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which: • Figure 1 schematically illustrates a cross-sectional view of a triangular-section slotted waveguide on a printing platform. Figure 2 schematically illustrates a perspective view of a triangular cross-section slotted waveguide. • Figure 3 schematically illustrates a perspective view of a pentagonal section slotted waveguide. • Figure 4 schematically illustrates a perspective view of a slotted waveguide array. • Figure 5 illustrates several possible geometries for the slots of a waveguide according to the invention. Example(s) of embodiment of the invention

[0026] The present invention relates to a method for the additive manufacturing of a slotted antenna enabling the production of slots whose geometry is not restricted by the constraints linked to additive manufacturing.

[0027] For the purposes of this disclosure, the expression “additive manufacturing” includes, but is not limited to, manufacturing techniques such as • laser fusion on powder bed (Selective Laser Melting, SLM); • stereolithography (SLA); • powder binding (Binder Jetting); • the deposition of molten material (Directed Energy Deposition, DED); • lamination of metal sheets (Sheet lamination); metal inkjet printing. Furthermore, the terms “additive manufacturing” and “3D printing” are used interchangeably and are therefore considered synonymous.

[0028] One of the major constraints related to the additive manufacturing of waveguides, and in particular slotted waveguides, is the minimization of overhanging portions during printing. During their manufacture, such portions are likely to sag and often require adjustment of their orientation and / or the presence of support structures which must then be removed by machining or polishing. To overcome this drawback, waveguides are usually arranged such that their longitudinal axis, i.e. the direction of propagation of the waves in the waveguide, essentially coincides with the printing direction. However, printing along the propagation direction of a slotted waveguide remains problematic because the slots are arranged on a side wall of the waveguide, some portions of the slots are then overhanging during manufacturing.As a result, the geometry and / or orientation of the slots must be adapted (and therefore limited) in order to limit the risks of collapse of the cantilevered portions.

[0029] The terms "slot", "radiating slot" and "radiating slot" here designate an opening arranged in a side wall of a waveguide and intended to radiate a portion of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide.

[0030] Such waveguides are particularly suitable for the satellite domain due to their low profile and wide bandwidth, but also in radar, navigation and surveillance applications.

[0031] Thus, the present invention can be implemented in antennas intended for frequency bands between 6GHz and 40GHz.

[0032] The method of the present invention allows the production of slotted waveguides whose geometry does not require any adaptation or limitation.

[0033] The method comprises a step of forming by additive manufacturing a waveguide 1 comprising a radiating wall 10 provided with radiation slots 100 making it possible to radiate a portion of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide 1.

[0034] As illustrated in Figure 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.

[0035] 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 manufacture and which risk sagging.

[0036] During manufacturing, the radiating wall 10 is thus typically produced first on the support platform 11 and then the rest of the waveguide is printed above.

[0037] According to an embodiment illustrated in Figure 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, as well as a second side forming a second angle P with the side of the cross-section belonging to the radiating wall 10. These first and second angles α and P are between 40° and 70°. Such an inclination relative to the side of the cross-section belonging to the radiating wall makes it possible to limit the risks of collapse of the walls including the first and second sides.

[0038] In order to avoid portions of the cross-section being too overhanging, the cross-section of the waveguide is advantageously triangular or pentagonal.

[0039] According to an embodiment illustrated in Figure 2, the waveguide 1 comprises two side walls in addition to the radiating wall 10 so that its cross section is triangular. The triangle may be equilateral, isosceles or any other shape depending on the application and the geometric constraints targeted. In order to minimize the risks 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°.

[0040] According to an embodiment illustrated in Figure 3, the waveguide 1 comprises four side walls in addition to the radiating wall 10 so that its cross section is pentagonal. In order to minimize the risks 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°.

[0041] In the particular embodiment illustrated in Figure 3, the angles between the side walls and the radiating wall 10 are angles essentially equal to 90°. Two other side walls opposite the wall radiating 10 are joined together so as to form an angle typically less than or equal to 100°.

[0042] To further limit the risk of sagging during printing, some portions of the waveguide can be curved. Curved, or arched, portions generally require less support during printing and are therefore well suited to joining cantilevered portions.

[0043] Thus, in an embodiment not shown, the junction between the side walls and the radiating wall may comprise a curved portion. Similarly, the junctions between the different side walls, depending on their number, may comprise curved portions.

[0044] In addition to the junctions between different side and / or radiating walls, certain portions of the side walls can also be curved depending on the geometry of the waveguide in order to limit the risks of sagging.

[0045] Due to the orientation of the waveguide during its printing, the radiation slots 100 arranged on the radiating wall 10 have virtually no geometric constraints. Indeed, the support platform 11 being in contact with the radiating wall 10 during printing, all sections of the radiation slots are fully supported by the platform during additive manufacturing.

[0046] Various examples of radiation slot sections 100 are illustrated in a non-limiting manner in FIG. 5. In particular, the radiation slots may be circular, elliptical, triangular, square, rectangular, pentagonal, hexagonal, octagonal, cross-shaped, etc. The polygons cited may be regular or irregular.

[0047] The number of radiation slots 100 arranged on the radiating wall 10 may depend on the particular applications for which the antenna is intended. This number may vary between a few units and several dozen, or even more.

[0048] The dimensions of the sections of the radiation slots 100 may also be variable depending on the particular applications for which the antenna is intended. In particular, the dimensions of the radiation slots of the same waveguide may be identical or vary from one another.

[0049] The orientation of the radiation slots 100 may be identical over the entire radiating wall 10 or alternatively vary over all or part of the radiating wall.

[0050] 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.

[0051] 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 section and are inclined relative to the longitudinal direction of the waveguide. In addition, the angle of inclination varies between two successive radiating slots.

[0052] The present method advantageously allows the additive manufacturing of waveguides in which the largest dimension of the sections of the radiation slots extends transversely to the direction of propagation of the waves in the waveguides. Indeed, such sections are difficult to produce without special support in the usual additive manufacturing methods, particularly when the largest dimension of the slots forms a significant angle (for example more than 45°) with the direction of propagation (usually corresponding to the printing direction), and therefore they must be printed in cantilever.

[0053] In one embodiment, the waveguide 1 is manufactured so that it comprises an electromagnetic wave introduction port at one of its longitudinal ends. This introduction port makes it possible to introduce a signal into the waveguide so that it can radiate towards the outside of the antenna when it operates in transmission and to transmit a signal from the outside towards the electronic components of the antenna when it operates in reception.

[0054] Either or both ends of the waveguide may include a signal introduction port.

[0055] Alternatively, the waveguide 1 is manufactured so that it comprises an electromagnetic wave introduction port arranged on a wall of the waveguide opposite the radiating wall 10. This introduction port makes it possible to introduce a signal into the waveguide so that it can radiate towards the outside of the antenna when it operates in transmission and to transmit a signal from the outside to the electronic components of the antenna when it operates in reception.

[0056] As illustrated in Figure 4, the present invention also relates to a method of additively manufacturing an arrayed slot antenna formed by adding a plurality of slotted waveguides as described above.

[0057] Thus, the method further comprising a step of additive manufacturing of at least one second waveguide 1 also comprising a radiating wall 10 provided with radiation slots 100 making it possible to radiate part of the electromagnetic energy of an electromagnetic wave propagating inside the at least one second waveguide. The second waveguide (as well as the additional waveguides if any) are formed parallel to each other, that is to say that the directions of propagation of the waves of the waveguides are all parallel. The radiating wall 10 of each waveguide advantageously bears against the support platform 11 on which the waveguides are printed and the cross-section of each waveguide is devoid of a side parallel to the side of the cross-section supported by the corresponding radiating wall 10.

[0058] 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, i.e. this method makes it possible to obtain arbitrary radiation slot geometries 100 since there is no constraint linked to the risk of collapse of certain portions of these slots 100 due to the orientation.

[0059] This process thus allows the production of 2-array slot antennas that are monolithic and therefore require very little or no assembly after printing. This results in savings in terms of cost and production time. In addition, the radiation slots can be produced during printing, which replaces post-manufacturing machining.

[0060] Each individual waveguide of the array antenna may have the characteristics described above, in particular regarding waveguide sections, cross-sections, dimensions, orientations and number of radiation slots.

[0061] The method may also include an additional step of additive manufacturing of a coupling waveguide making it possible to individually feed each waveguide of the array antenna.

[0062] In an embodiment not shown, a coupling waveguide is printed transverse to the propagation directions in the waveguides.

[0063] Advantageously, this coupling waveguide is devoid of a wall parallel to the radiating walls 10 of the waveguides so as to limit the overhanging portions during printing.

[0064] For this purpose, the section of the coupling waveguide may be, for example, triangular or pentagonal and / or include curved portions.

[0065] Finally, the present invention also relates to a slotted waveguide and / or slotted waveguide array obtained by the method described above. 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 Direction of printing a First angle P Second angle

Claims

Claims 1. A method of 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 part of the electromagnetic energy of an electromagnetic wave propagating inside the waveguide (1), characterized in that the radiating wall (10) bears against a support platform (11) on which the waveguide is manufactured, and in that a cross-section of the waveguide (1) has no side parallel to the side of the cross-section supported by the radiating wall (10).

2. 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 belonging to the radiating wall (10) of between 40° and 70°.

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

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

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

6. Manufacturing method according to one of the preceding claims, characterized in that the radiation slots (100) have a 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. Manufacturing method according to one of the preceding claims, characterized in that the radiating slots (100) are arranged such that a larger dimension of the slots extends in a direction transverse to a direction of propagation of the electromagnetic waves in the waveguide (1).

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

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

10. Manufacturing method according to one of the preceding claims, the waveguide being a first waveguide, the method further comprising the step of: forming by additive manufacturing, at least one second 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 at least one second waveguide, the waveguides being formed parallel to each other, characterized in that the radiating wall (10) of each waveguide bears 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 the 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 produced monolithically without an assembly step.

12. Method according to one of claims 10 to 11, further comprising: forming by additive manufacturing a coupling waveguide making it possible to individually power each waveguide, the coupling waveguide being devoid of a portion parallel to the radiating walls 10.

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

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