Comb waveguide filter with omnidirectional resonators

Abstract

Additively manufacture a comb waveguide filter with a degree of freedom in configuration. 【Solution means】The present invention is a comb waveguide filter (1) manufactured by metal additive manufacturing, comprising at least two resonators (2) interconnected by a main iris (24), each resonator comprising a cavity (20) having a first axis (z), each cavity (20) is in particular delimited in the range of the cavity by a flat bottom (21) extending perpendicular to the first axis (z), relating to a waveguide filter (1). The present invention also relates to a method for manufacturing the described comb waveguide filter, which method includes additive manufacturing of the at least two resonators and the main iris connecting those resonators.

Description

Technical Field

[0001] The present invention relates to a comb waveguide filter having an all-directional resonator obtained by additive manufacturing.

Background Art

[0002] Radio frequency (RF) signals can propagate in free space or waveguide devices.

[0003] An example of such a conventional waveguide is described in Patent Document 1. The content thereof is incorporated herein by reference. The waveguide consists of a hollow device, and its shape and dimensions determine the propagation characteristics for a predetermined wavelength of electromagnetic signals. The cross-section of the internal waveguide of this device is rectangular. Other waveguide cross-sections including circular shapes are proposed in this document.

[0004] This prior art waveguide includes a core manufactured by additive manufacturing by stacking layers one by one. This core defines an internal waveguide as a wave guide having a cross-section determined by the frequency of the electromagnetic signal to be propagated. The inner surface of the core is covered with a conductive metal layer. The outer surface may also be covered with a conductive metal layer that contributes to the rigidity of the device.

[0005] Waveguide devices are used, for example, to form waveguide filters, propagate RF signals, or operate in the spatial or frequency domain. The present invention relates to a passive waveguide filter that can filter RF signals without using active electronic components.

[0006] Conventional waveguide filters used for radio frequency signals generally have internal openings with rectangular or circular cross-sections. The main purpose of these filters is to suppress unwanted frequencies and pass the desired frequencies with minimal attenuation. For example, one or both filters for a receiving system and a transmitting system in the spatial domain may require attenuation exceeding 100 dB or 120 dB.

Prior Art Documents

[0007] [Patent Document 1] International Publication No. 2017 / 208153 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] One object of the present invention is to provide a comb-type waveguide filter that is not limited by known waveguide filters.

[0009] Another object of the present invention is to provide a comb-shaped waveguide filter suitable for additive manufacturing.

[0010] Another objective of the present invention is to provide a more compact and less bulky comb-shaped waveguide filter.

[0011] Another objective of the present invention is to provide a comb-shaped waveguide filter that can filter a wider frequency range (allowing only signals of a certain frequency to propagate and preventing signals of other frequencies from propagating). [Means for solving the problem]

[0012] According to this invention, these objectives are particularly, A comb-shaped waveguide filter manufactured by metal addition manufacturing, comprising at least two resonators interconnected by a main iris, Each resonator has a cavity with a first axis, In the waveguide filter, each cavity is defined in particular by a flat bottom extending perpendicular to the first axis, This is achieved by a waveguide filter, characterized in that each cavity is further defined by a roof that converges toward a single point.

[0013] The fact that the resonator has a roof that converges towards a single point makes the additive manufacturing of waveguide filters easier, or even possible, by avoiding (or eliminating) the complex cantilever sections that are difficult to manufacture. Secondly, the fact that the roof converges towards a single point means that the "axial" nature of conventional filters, where the shape of the resonator is constrained by the direction of propagation of electromagnetic signals within the filter, is avoided.

[0014] Each roof may comprise a first lateral portion adjacent to a flat bottom and a second lateral portion converging toward a single point.

[0015] Each resonator may possess rotational symmetry about the first axis.

[0016] Each flat base is circular or a polygon with at least three sides, preferably circular, square, pentagonal, hexagonal, or octagonal.

[0017] Each resonator may further include a post that rises from a flat bottom parallel to the first axis.

[0018] At least one post can be fabricated integrally with the flat bottom of the resonator.

[0019] Each resonator post may have a circular or at least three-sided cross-section, preferably a circular, square, pentagonal, hexagonal, or octagonal cross-section.

[0020] Advantageously, the post may be helical and extend along the first axis. This configuration allows for a longer post, thereby improving the impedance matching of the resonator cavity.

[0021] In one embodiment, the diameter of the post may vary along the first z-axis.

[0022] The roof of at least one resonator may have a projection that extends parallel to a first axis toward the interior of the cavity of at least one resonator.

[0023] At least one main iris may comprise a connection portion that is not parallel to the flat bottom. This connection portion extends between two resonators connected by at least one main iris.

[0024] The connection portion may connect the single point of the plurality of resonators connected by at least one main iris.

[0025] At least one resonator may comprise a plurality of main irises that are not coaxially arranged.

[0026] The waveguide filter may comprise at least three resonators that are continuously connected by main irises. The first and second resonators of the three resonators are connected to each other by a secondary iris.

[0027] This mutual coupling (in French, "couplage croisé") improves the selectivity of the filter in a specific frequency band.

[0028] The secondary iris may have a cross-section different from that of the main iris (24).

[0029] At least one secondary iris may comprise a secondary connection portion that extends between resonators connected by at least one secondary iris

[0030] The plurality of main irises of the plurality of resonators may be coaxially arranged along the propagation axis of the electromagnetic signal.

[0031] The waveguide filter may comprise at least four resonators. One of these at least four resonators may be connected to at least three separate resonators.

[0032] In particular, this matter makes it possible to obtain, for example, a filter and a filter combining the functions of one or both of a distributor and a polarizer.

[0033] At least one resonator may include either a polarizer or a septum (polarization converter), or both.

[0034] According to the present invention, these objectives can also be achieved by a method for manufacturing a comb-shaped waveguide filter having at least one of the above-described characteristics. This method involves additive manufacturing of at least two resonators and a main iris connecting those resonators.

[0035] Embodiments of the present invention are illustrated in the accompanying figures. [Brief explanation of the drawing]

[0036] [Figure 1a] Figure 1a shows one possible configuration of a comb-type filter resonator. [Figure 1b] Figure 1b shows one possible configuration of a comb filter resonator. [Figure 1c] Figure 1c shows one possible configuration of a comb filter resonator. [Figure 1d] Figure 1d shows one possible configuration of a comb-type filter resonator. [Figure 1e] Figure 1e shows one possible configuration of a comb filter resonator. [Figure 1f] Figure 1f shows one possible configuration of a comb-type filter resonator. [Figure 2a] Figure 2a shows a comb-type filter in which multiple resonators connected by irises have a square base and are arranged in a straight line. [Figure 2b] Figure 2b shows a comb-type filter in which multiple resonators connected by irises have a square base and are arranged in a rectangular pattern. [Figure 3a] Figure 3a shows a perspective view of a comb filter in which multiple resonators have circular bases and are arranged alternately. [Figure 3b] Figure 3b shows a top view of a comb-type filter in which multiple resonators have circular bases and are arranged alternately. [Figure 4a] Figure 4a shows one possible shape of a post within the cavity of a resonator with a circular base. [Figure 4b] Figure 4b shows one possible shape of a post within the cavity of a resonator with a circular base. [Figure 4c] Figure 4c shows one possible shape of a post within the cavity of a resonator with a circular base. [Figure 4d] Figure 4d shows one possible shape of a post within the cavity of a resonator with a circular base. [Figure 4e] Figure 4e shows one possible shape of a post within the cavity of a resonator with a circular base. [Figure 5a] Figures 5a and 5b show side views of a comb filter in which square-bottomed resonators are arranged vertically and horizontally, and the first and last resonators are connected by a secondary iris. [Figure 5b] Figure 5b shows a top view of a comb filter in which square-bottomed resonators are arranged vertically and horizontally, and the first and last resonators are connected by a secondary iris. [Figure 6a] Figure 6a shows a top view of a comb filter with a resonator connected to the other three resonators. [Figure 6b] Figure 6b shows a top view of a comb filter in which two resonators are connected to three other resonators. [Figure 7] Figure 7 shows the outline of a resonator with a helical post. [Figure 8] Figure 8 shows a top view of a resonator with a helical post. [Figure 9] Figure 9 shows a top view of a comb filter with two resonators having helical posts. [Modes for carrying out the invention]

[0037] The present invention relates to a comb-shaped waveguide filter 1 comprising at least two resonators 2 obtained by additive manufacturing and connected to each other by a main iris 24. Each resonator 2 comprises a cavity 20 whose range is defined by a flat bottom 21 and a roof 22, particularly perpendicular to the first axis z.

[0038] Figures 1a to 1f show examples of resonators 2 that can be used in the comb-type waveguide filter 1 according to the present invention. The main iris 24 that connects multiple resonators is not shown in these figures.

[0039] The first z-axis generally corresponds to the direction of additive manufacturing.

[0040] By having the roofs 22 of each resonator 2 converge toward a single point 23, it is possible to avoid the formation of cantilevered surfaces with respect to the first axis z, which would be difficult or impossible to manufacture using additive manufacturing. Furthermore, since the roofs 22 that converge toward the apex do not converge toward the raised portion of the roof, it is possible to obtain resonators 2 that do not have a favorable direction for electromagnetic wave propagation. In fact, the propagation direction is determined to some extent by the two intersecting roofs at the raised section, whereas the roof according to the present invention converges to a single point, allowing for more freedom in selecting the wave propagation direction in the waveguide filter. In other words, the resonator is omnidirectional in the sense that it can be connected to other resonators in almost any direction. The flexibility (in terms of arrangement) provided by the shape of the roof 22 according to this invention allows, for example, the creation of a comb-shaped waveguide filter where the resonators are not aligned in a straight line along the axis but form a bent section. Therefore, by selecting a shape that fits specific constraints, it becomes possible to significantly reduce the overall dimensions of such a filter.

[0041] The roof 22 of the resonator 2 may be sloped away from the flat base 21, as shown in Figures 1a, 1c, and 1e. Alternatively, the roof 22 may comprise a vertical first lateral portion 26 adjacent to the flat base 21 and a second lateral portion 27 that slopes and converges toward a single point 23, as shown in Figures 1b, 1d, and 1f. In this way, the roof 22 can be designed as a pyramid with the flat base 21 as its base, or as a combination of a rectangular prism with the flat base 21 and a pyramid placed on the rectangular prism.

[0042] Other embodiments include a resonator having a roof 22 that converges toward a single point 23, the contour of which is not linear as in the case of a pyramid, but is, for example, a polygon, a parabola, a hyperbola, or other contour that allows for additive manufacturing.

[0043] Generally, the angle that the sloping portion of the roof 22 makes with the first axis is between 10° and 60°, preferably between 25° and 50°. This is because if the angle is too large, it becomes difficult to manufacture the sloping portion.

[0044] As shown in Figures 1a to 1f, the resonator may have at least one rotational symmetry about the first z-axis. Preferably, the resonator has multiple rotational symmetries about the z1-axis.

[0045] Figures 1a and 1b show embodiments in which the roof 22 is conical or consists of a cone that extends over a cylinder. In these cases, the roof contour is obtained as a plane of revolution about the first axis z, thus achieving maximum rotational symmetry.

[0046] Figures 1c and 1d show embodiments in which the roof 22 is a pyramid with a square base, or a pyramid with a square base is constructed on top of a prism (i.e., a parallelepiped) with a square base. Thus, the roof 22 is invariant with respect to rotations around the first axis z at an angle kx90° where k is an integer.

[0047] Figures 1e and 1f show embodiments in which the roof 22 is a pyramid with a hexagonal base, or a pyramid resting on a prism with a hexagonal base. Thus, the roof 22 is invariant under rotation about a first axis z passing through angle kx60°, where k is an integer.

[0048] More generally, the roof 22 may have any plane of revolution about the first axis z, so that the roof converges toward a single point 23. Supplementarily or alternatively, the roof 22 may have a pyramid whose base is formed by any polygon.

[0049] The first lateral portion 26 of the roof 22 may be cylindrical. Alternatively or complementary, it may include a rectangular parallelepiped with an arbitrary polygonal base.

[0050] In one preferred embodiment, the flat bottom 21 that demarcates the cavity 20 of the resonator 2 according to the present invention, like the roof 22, has the property of being invariant under rotation around the first axis z. In particular, the flat bottom may be circular, a polygon with at least three sides, preferably circular, square, pentagonal, hexagonal, or octagonal. Other shapes of the flat bottom 21, such as elliptical or non-convex, can also be envisioned without departing from the scope of the present invention.

[0051] The multiple resonators 2 of the comb-shaped waveguide filter according to the present invention are interconnected by a main iris 24. As described below, some resonators may have a secondary iris, which is the basis for the term "main" iris. These main irises 24 enable the propagation of electromagnetic waves from one resonator to another within the filter.

[0052] In one embodiment, where the two consecutive resonators 2 of the filter 1 have a geometric shape that allows them to be positioned in a sufficient proportion to each other, i.e., where a large portion of the roof 22 of the first resonator is positioned relative to a large portion of the roof 22 of the second resonator, the main iris 24 may be composed of an opening in the consecutive portion of the roof.

[0053] The cross-section of this opening determines the cutoff frequency of the waves propagating between these two resonators via the main iris 24. Therefore, this cross-section conforms to the specific requirements for which filter 1 is intended.

[0054] In another embodiment, the shape of the resonator 2 requires an opening larger than the continuous portion of the resonator. As shown in Figures 2A and 2B, the main iris 24 has an opening that extends into both the first lateral portion 26 and the second lateral portion 27 of the roof 22. The connecting portion 25 extends between at least a portion of the two second lateral portions 27 of the two roofs 22 of the resonator connected by the main iris 24.

[0055] As shown in Figures 2a and 3a, the connection between resonators may have an inclined portion to facilitate additive manufacturing, or to enable additive manufacturing of the connection portion itself. The connection portion may be composed of, for example, a gable roof.

[0056] In one embodiment, the connecting portion 25 can connect two roofs 22 over the entire height of the roof 22 or over the entire height of the second lateral portion 27 of the roof. Alternatively or complementaryly, a single point 23 of the two roofs 22 can be connected by the connecting portion 25.

[0057] In one embodiment not shown, the shape of the resonators 2 prevents them from being placed adjacent to each other. Therefore, the main iris 24 connecting such two resonators includes a connecting portion 25 that connects the two resonators. This connecting portion may be, for example, a rectangular waveguide having the same cross-section as the opening of the main iris that determines the cutoff frequency.

[0058] Generally speaking, the length, width, and height of the main iris and connecting section affect the coupling position (level) between the two resonators. Therefore, these variables are adapted according to the requirements.

[0059] As shown in Figures 2A and 2B, the cavity 20 of the resonator 2 may be provided with a post 28 rising from a flat bottom 21 parallel to the first axis z. By using the post 28 in the cavity 20, the impedance of the cavity can be changed, thereby controlling the resonant frequency of the circuit formed by the cavity 20 and the main iris 24.

[0060] These posts 28 differ from any adjustment screws in that they cannot adapt or modify the resonant frequency.

[0061] These posts 28 can be formed integrally with the flat bottom 21. This method is advantageous from an additive manufacturing standpoint because it avoids subsequent machining to form such posts.

[0062] The shape of these posts, and more specifically, their cross-sections in a plane parallel to the flat base 21, can be adapted as needed and as a function of the geometry of the roof 22. The cross-sectional geometry of the post 28 does not necessarily have to be the same as the cross-sectional geometry of the flat base 21 or the cross-sectional geometry of the roof 22 of the resonator.

[0063] As shown in Figures 4a to 4e, the resonator 2 may include a post 28 whose cross-section is a rectangular parallelepiped with a circular or polygonal base having at least three sides. Preferably, the base of the post is circular, square, pentagonal, hexagonal, or octagonal. The circular geometric shapes of the flat base 21 and roof 22 in Figures 4a to 4e are by no means limiting, and all of the alternative structures described above can be realized by combining these posts.

[0064] To facilitate the additional manufacturing of such posts 28, the upper surface of the post, i.e., the surface facing the flat bottom 21, may have a curved or inclined portion. These curved portions are also useful when the filter is intended for high-power applications.

[0065] In the alternative embodiments shown in Figures 7 to 9, the post 28 has a helical shape with its principal direction coinciding with the first z-axis. When a helical post extends parallel to an axis, it means that the principal direction of the helix is ​​parallel to that axis.

[0066] Using such a helical post allows for a longer post 28 than a straight post can provide. In particular, this allows for a greater impedance match for the cavity 20.

[0067] The propeller pitch, i.e., the vertical distance between two consecutive points on the propeller in the plane containing the first z-axis, can be constant or variable.

[0068] The diameter of the helix can also be constant or variable. In one preferred embodiment shown in Figures 7 to 9, the diameter of the helix decreases as a function of the height relative to the flat bottom 21 of the resonator 2. In particular, this configuration makes it possible to match the outer diameter of the helical post to the inner diameter of the cavity 20 of the resonator 2. The plane of rotation on which the helix is ​​formed is conical.

[0069] However, in certain configurations where it is not necessary to reduce the diameter of the helix, the diameter of the helix may be kept constant in order to further increase the overall length of the helical post.

[0070] Alternatively or supplementally, the rotating surface on which the propeller rests may be an inverted cone, a cylinder, a sphere, or a surface with alternating positive and negative curvature. This allows the propeller diameter to alternately increase and decrease.

[0071] Such helical posts 28 can be added together with the rest of the resonator. Alternatively or additionally, the helical posts may be manufactured separately from the resonator and placed in the cavity during or after the addition of the resonator.

[0072] As shown in Figure 9, each of the two adjacent resonators 2 may be equipped with a helical post 28. The winding direction of the helix, i.e., the direction, may be the same, or alternatively, it may be opposite.

[0073] The upper part of the cavity 20 of the resonator 2 may have projections extending from the inner surface of the roof 22 into the interior of the cavity to alter the impedance of the cavity. These projections extend substantially parallel to the first axis. These projections are integral with the resonator and are therefore distinct from conventional adjustment screws, which are movable elements relative to the resonator.

[0074] In one preferred embodiment, the projection is integrated with the roof 22 of the resonator. Similar to the post 28, the surface of the projection facing the roof 22 may be flat or curved, depending on specific requirements, particularly with respect to additive manufacturing and high-power use of the filter.

[0075] The resonator 2 of the waveguide filter 1 may be equipped with adjustment screws to allow for fine-tuning while the filter is in use. Unlike the post 28, these screws are movable elements relative to the resonator structure and are used to make slight changes to the impedance of the resonator cavity 20.

[0076] As mentioned above, one of the main advantages of the waveguide filter according to the present invention is its omnidirectional nature (meaning the resonators are non-coaxial, i.e., do not necessarily need to be connected along a single axis).

[0077] Figures 3a and 3b show one embodiment in which multiple resonators 2 are arranged non-coaxially. More specifically, for example, the first resonator 2, which is the left resonator in Figure 3a, has a port 31 that allows an electromagnetic signal to be received at the filter input. This first resonator is connected to the second resonator 2 by a main iris 24 with a connecting portion 25. The main iris 24 is not directly opposite the port 31. On one hand, a line passing through the center of the port 31 and the flat bottom 21 intersects with a line passing through the center of the flat bottom and the main iris 24, and on the other hand, a line passing through the center of the flat bottom intersects with an angle between 90° and 150°.

[0078] The second resonator is also connected to the third resonator 2 (the rightmost in Figure 3a) via a main iris 24 which also includes a connector 25. The third resonator has a port 31 from which an electromagnetic signal can be emitted from the filter 1. Similarly, the angle between the line passing through the main iris 24 connecting the second and third resonators and the center of the flat bottom 21, and the line passing through the center of the flat bottom and the port 31, is between 90° and 150°.

[0079] The filter obtained with this resonator arrangement forms a bent section at the second resonator, allowing for a significant reduction in the overall length of the filter compared to a conventional coaxial arrangement for a given number of resonators.

[0080] The circular shape of the resonator roof 22 in this design provides a great degree of freedom in the relative positioning of the resonators. In fact, because it is invariant with respect to rotation around the first z-axis, it is virtually possible to position a circular resonator at any position around other circular resonators. Therefore, by connecting resonators in this way, a wide variety of filter shapes can be obtained.

[0081] Another advantage arising from the omnidirectional nature of the resonator is that by introducing an "elbow" into the filter, it is possible to place specific resonators that are not contiguous in the sense that they are not connected by the main iris very close together. In Figure 3b, the two resonators with port 31 are not connected by the main iris, but are very close together. Therefore, by taking advantage of their proximity, it is possible to introduce secondary coupling (sub-coupling) between the discontinuous resonators.

[0082] In particular, these sub-couplers allow for the introduction of alternative propagation paths for the waves within the filter. Depending on the phase of the signal, transfer zeros may appear in the filter's transfer function as a result of multiplying the wave paths within the filter. This means that subcoupling between discontinuous resonators can be applied, for example, to achieve a linear phase response or to generate finite propagation zeros to improve filter selectivity by enhancing filtering at specific locations at specific frequencies. By introducing zero propagation into the frequency response in this way, the number of resonators required to meet specific filter selectivity specifications can be reduced. As a result, insertion loss, footprint, and manufacturing costs can be reduced.

[0083] These sub-connectors take the form of sub-irises 29. These sub-irises 29 may include a sub-connecting portion between the two roofs 22 of the resonator connected by the sub-iris. As with the main connection portion, the sub-connecting portion may include a portion inclined with respect to the first axis to facilitate additive manufacturing.

[0084] Figure 3b shows a second connection section 29 that connects a first resonator having an input port 31 and a third resonator having an output port 31.

[0085] The cross-section of the secondary iris 29 may differ from that of the main iris 24. The cross-section of the secondary iris may be, for example, rectangular (with the longest side of the rectangle positioned parallel or perpendicular to the first z-axis).

[0086] Another embodiment of the filter in which the resonators are arranged non-coaxially is shown in Figures 5a and 5b. Multiple resonators 2 designed according to a square base model are arranged vertically and horizontally so that each resonator has at least two sides continuous with the other resonators. A main iris 24 with connecting section 25 connects the resonators 2 and forms the propagation path of electromagnetic waves in the filter 1. For example, in Figure 5b, electromagnetic waves enter filter 1 via port 31 of resonator 2 on the far right, then propagate 90° counterclockwise through the main iris, and reach the second resonator 2 (second resonator) (bottom of Figure 5b). Then, the signal propagates 90° clockwise through the main iris to the third resonator 2 (third resonator) (left in Figure 5b), and then propagates 90° clockwise through the main iris to the fourth resonator 2 (fourth resonator) (top in Figure 5b). Finally, the signal is rotated 90° counterclockwise from the filter and output from port 31 of the fourth resonator.

[0087] As shown in Figures 5a and 5b, the first and fourth resonators are further connected by a second iris 29 having a second connecting portion 30. The cross-section of the secondary iris 29 differs from that of the primary iris in order to improve filtering. In this embodiment, the secondary iris 29 has a square cross-section, with one of its diagonals parallel to the first z-axis.

[0088] The shape of the resonators allows for a non-coaxial arrangement of the filters, but it is also possible to obtain a filter in which all resonators 2 are aligned on the same axis of electromagnetic signal propagation, as illustrated in Figure 2a.

[0089] In one particular embodiment, the waveguide filter of the present invention comprises at least four resonators, one of which is connected to at least three separate resonators via a main iris 24. Such a configuration makes it possible to obtain filters with multiple resonator branches, in other words, filters with, for example, one input port and multiple output ports, or multiple input ports and one output port. This makes it possible to create, for example, a comb-type waveguide filter with power distribution or polarization functions.

[0090] Figure 6a shows a comb-type waveguide filter 1 in which at least one of the resonators 2 (third from the left in the figure) is connected to the other three resonators. Thus, resonator 2, located on the left side of the filter in Figure 6a, has a port 31 for inputting electromagnetic signals to the filter, and the two resonators located on the right side of the filter in Figure 6a each have a port 31 for outputting electromagnetic signals from the filter.

[0091] Figure 6b shows yet another embodiment of the present invention, in which the first resonator on the left side of the figure has an input port 31 for electromagnetic signals to filter 1 and propagates the signals to two separate resonators via a main iris 24. The last resonator on the right side of the figure receives the two electromagnetic signals via the main iris and propagates them outside the filter via an output port 31.

[0092] At least one resonator of the filter may include one or both of a polarizer and / or a septum (polarization converter) to perform one or more of the splitting and coupling of electromagnetic signals. Other standard passive RF components may also be combined with the filter without departing from the scope of the present invention.

[0093] The present invention also relates to a method for manufacturing the waveguide filter described above. This application offers, for example, the following perspectives. [Perspective 1] A comb-shaped waveguide filter (1) manufactured by metal addition manufacturing, comprising at least two resonators (2) interconnected by a main iris (24), Each resonator has a cavity (20) with a first axis (z), In the waveguide filter (1), each cavity (20) is defined in particular by a flat bottom (21) that extends perpendicular to the first axis (z), Waveguide filter (1), characterized in that each cavity (20) is further defined by a roof (22) that converges toward a single point (23). [Perspective 2] Waveguide filter (1) according to viewpoint 1, characterized in that each roof (22) comprises a first lateral portion (26) adjacent to and perpendicular to the planar bottom portion (21), and a second lateral portion (27) converging toward the single point (23). [Perspective 3] A waveguide filter (1) according to viewpoint 1 or 2, characterized in that each resonator (2) has rotational symmetry about the first axis (z). [Perspective 4] Waveguide filter (1) according to any one of views 1 to 3, characterized in that each flat bottom (21) is circular or a polygon having at least three sides, preferably circular, square, pentagonal, hexagonal, or octagonal. [Perspective 5] A waveguide filter according to any one of viewpoints 1 to 4, characterized in that each resonator (2) further comprises a post (28) rising from the planar bottom (21) parallel to the first axis (z). [Perspective 6] Waveguide filter (1) according to viewpoint 5, characterized in that at least one post (28) is integrally formed with the flat bottom (21) of the resonator (2). [perspective 7] Waveguide filter (1) according to viewpoint 6, characterized in that the post (28) of each resonator has a circular or cross-section having at least three sides, preferably a circular, square, pentagonal, hexagonal, or octagonal cross-section. [Perspective 8] Waveguide filter (1) according to any one of viewpoints 1 to 6, characterized in that the post (28) is helical and extends along the first axis (z). [Perspective 9] Waveguide filter (1) according to viewpoint 8, characterized in that the diameter of the post (28) changes along the first axis (z). [Perspective 10] A waveguide filter (1) according to any one of viewpoints 1 to 9, characterized in that the roof (22) of at least one resonator (2) has a projection that extends parallel to the first axis (z) toward the interior of the cavity (20) of at least one resonator. [Perspective 11] A waveguide filter (1) according to any one of views 1 to 10, characterized in that at least one main iris (24) has a connecting portion (25) that is not parallel to the flat bottom (21), the connecting portion extending between two resonators connected by the at least one main iris (24). [Perspective 12] The waveguide filter (1) according to viewpoint 11, characterized in that the connecting portion (25) connects the single point (23) of a plurality of resonators (2) connected by at least one main iris (24). [Perspective 13] A waveguide filter (1) according to any one of views 1 to 11, characterized in that at least one resonator (2) comprises a plurality of main irises (24) that are not arranged coaxially. [Perspective 14] The waveguide filter (1) according to any one of views 1 to 13, characterized in that the waveguide filter comprises at least three resonators (2) continuously connected by the main iris (24), and the first and second resonators (2) are connected to each other by a secondary iris (29). [Perspective 15] Waveguide filter (1) according to viewpoint 14, characterized in that the sub-iris (29) has a different cross-section from the main iris (24). [Perspective 16] A waveguide filter (1) according to viewpoint 13 or 14, characterized in that at least one sub-iris (29) comprises a sub-connection portion (30) extending between a plurality of resonators (2) connected by at least one sub-iris (29). [Perspective 17] A waveguide filter (1) according to any one of viewpoints 1 to 11, characterized in that the multiple main irises (24) of the multiple resonators (2) are arranged coaxially along the propagation axis (x) of the electromagnetic signal. [Perspective 18] A waveguide filter (1) according to any one of views 1 to 17, characterized in that the waveguide filter comprises at least four resonators (2), and one of the at least four resonators is connected to at least three separate resonators. [Perspective 19] A waveguide filter (1) according to any one of views 1 to 18, characterized in that at least one resonator (2) comprises a polarizer and / or a septum. [perspective 20] A method for manufacturing a comb-shaped waveguide filter (1) according to any one of viewpoints 1 to 19, comprising an additional manufacturing step of at least two resonators (2) and the main iris (24) connecting the resonators. [Explanation of symbols]

[0094] 1. Comb-type waveguide filter 2 resonator 20 cavities 21 Flat bottom 22 Roof 23 Single point 24 Main Iris 25 Connection part 26 First lateral part 27 Second lateral part 28 posts 29 Vice Iris 30 Sub-connection section 31 Coaxial Ports Z 1st axis X propagation axis

Claims

1. A comb-shaped waveguide filter (1) manufactured by metal addition manufacturing, comprising at least two resonators (2) interconnected by a main iris (24), Each resonator comprises a cavity (20) having a first axis (z), In the waveguide filter (1), each cavity (20) is defined by a flat bottom (21) extending perpendicular to the first axis (z), Waveguide filter (1), characterized in that each cavity (20) is further defined by a roof (22) that converges toward a single point (23).

2. Waveguide filter (1) according to claim 1, characterized in that each roof (22) comprises a first lateral portion (26) adjacent to and perpendicular to the planar bottom portion (21), and a second lateral portion (27) converging toward the single point (23).

3. The waveguide filter (1) according to claim 1, characterized in that each resonator (2) has rotational symmetry about the first axis (z).

4. The waveguide filter (1) according to claim 1, characterized in that each flat bottom (21) is circular or a polygon having at least three sides.

5. The waveguide filter according to claim 1, characterized in that each resonator (2) further comprises a post (28) rising from the planar bottom (21) parallel to the first axis (z).

6. The waveguide filter (1) according to claim 5, characterized in that at least one of the posts (28) is integrally formed with the flat bottom (21) of the resonator (2).

7. Waveguide filter (1) according to claim 5, characterized in that the post (28) is helical and extends along the first axis (z).

8. Waveguide filter (1) according to claim 1, characterized in that at least one main iris (24) has a connecting portion (25) that is not parallel to the flat bottom (21), the connecting portion extending between two resonators connected by the at least one main iris (24).

9. The waveguide filter (1) according to claim 8, characterized in that the connecting portion (25) connects the single point (23) of a plurality of resonators (2) connected by at least one main iris (24).

10. The waveguide filter (1) according to claim 1, characterized in that at least one resonator (2) comprises a plurality of main irises (24) that are not arranged coaxially.

11. The waveguide filter (1) according to claim 1, comprising at least three resonators (2) continuously connected by the main iris (24), wherein the first and second resonators (2) are connected to each other by a secondary iris (29).

12. Waveguide filter (1) according to claim 11, characterized in that at least one sub-iris (29) comprises a sub-connection portion (30) extending between a plurality of resonators (2) connected by at least one sub-iris (29).

13. The waveguide filter (1) according to claim 1, characterized in that the multiple main irises (24) of the multiple resonators (2) are arranged coaxially along the propagation axis (x) of the electromagnetic signal.

14. The waveguide filter (1) according to claim 1, characterized in that the waveguide filter comprises at least four resonators (2), and one of the at least four resonators is connected to at least three separate resonators.

15. A method for manufacturing a comb-shaped waveguide filter (1) according to claim 1, comprising an additional manufacturing step of at least two resonators (2) and the main iris (24) connecting the resonators.

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