Comb waveguide filter with omnidirectional resonators

Abstract

The invention relates to a comb waveguide filter 1 obtained by metal additive manufacturing, comprising at least two resonators 2 connected to each other by a main aperture 24, each resonator comprising a cavity 20 provided with a first axis, each cavity 20 being delimited in particular by a flat base 21 extending perpendicular to the first axis z, characterized in that the first axis z is substantially perpendicular to the first axis z, and the second axis z is substantially perpendicular to the first axis z. Each cavity 20 is additionally defined by a top 22 converging toward a single point 23. The invention also relates to a method for manufacturing the comb waveguide filter. The method comprises additive manufacturing of at least two resonators and a main aperture connected with the resonators.

Description

Technical Field

[0001] The invention relates to a comb waveguide filter with omnidirectional resonators obtained by additive manufacturing. Background Art

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

[0003] An example of such a conventional waveguide is described in patent application WO2017208153, the contents of which are incorporated by reference. A conventional waveguide comprises a hollow device whose shape and proportions determine the propagation characteristics of a given wavelength of an electromagnetic signal. The cross section of the inner channel of the device is rectangular. Other channel cross sections, including circular, are suggested herein.

[0004] This prior art waveguide comprises a core produced by additive manufacturing by superimposing one layer on top of another. The core defines an inner channel for guiding the waves, the cross section of which is determined by the frequency of the electromagnetic signal to be transmitted. 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, which contributes to the rigidity of the device.

[0005] Waveguide devices are used to guide RF signals or to manipulate RF signals in the spatial or frequency domain, for example to form a waveguide filter. The present invention particularly relates to passive waveguide filters, which allow filtering of RF signals without the use of active electronic components.

[0006] Conventional waveguide filters for radio frequency signals usually have an internal aperture of rectangular or circular cross-section. The main purpose of these filters is to suppress unwanted frequencies and pass desired frequencies with minimal attenuation. For example, filters intended for receive and / or transmit systems in the spatial domain may require attenuation of more than 100 dB or even 120 dB.

[0007] Space and aerospace applications also require compact, lightweight waveguide filters. Therefore, a lot of research work has been done to come up with waveguide filter geometries that meet these different objectives.

[0008] For example, evanescent mode filters or comb filters are known. They basically consist of several small cavities (below the size corresponding to the cut-off frequency) that transmit electromagnetic energy between an input port and an output port. Successive cavities are connected by apertures, the size of which helps to determine the bandwidth of the filter. Several peaks or poles allow the fundamental mode to propagate. Due to the high selectivity and reduced weight and size of this type of filter, this type of filter is used, for example, in the input and output stages of satellite payloads.

[0009] Conventional comb waveguide filters are manufactured by machining and assembling various metal subcomponents. These operations are complex and expensive. In addition, filters manufactured in this way are heavy.

[0010] In addition, the geometry of conventional comb waveguide filters is usually limited because the resonant cavities (or resonators) and the apertures connecting the resonant cavities are designed so that the resonant cavities and the apertures must be arranged continuously along the propagation axis of the electromagnetic wave. This axial configuration makes the comb waveguide filter bulky because the comb waveguide filter can be very long. In addition, the frequency range of filtering is limited by the axial configuration because only continuous cavities are connected by apertures. Summary of the invention

[0011] It is an object of the present invention to provide a comb waveguide filter which does not have the limitations of known waveguide filters.

[0012] Another object of the present invention is to provide a comb waveguide filter suitable for additive manufacturing.

[0013] Another object of the present invention is to provide a more compact and smaller comb waveguide filter.

[0014] Another object of the present invention is to provide a comb waveguide filter that can filter a wider frequency range.

[0015] According to the invention, these objects are achieved in particular by a comb waveguide filter obtained by metal additive manufacturing, comprising at least two resonators connected together by a main aperture,

[0016] Each resonator comprises a cavity having a first axis,

[0017] Each cavity is in particular delimited by a flat base extending perpendicularly to the first axis, characterised in that each cavity is also delimited by a top converging towards a single point.

[0018] The fact that the resonators have tops that converge towards a single point makes additive manufacturing of waveguide filters easier or even possible by avoiding the manufacture of complex cantilevered parts. Secondly, the fact that the tops converge towards a single point means that the "axial" nature of conventional filters is avoided, in which the geometry of the resonators is constrained in the direction of propagation of the electromagnetic signal in the filter.

[0019] Each top portion may include a first side portion adjacent to and perpendicular to the planar base and a second side portion converging toward a single point.

[0020] Each resonator may have rotational symmetry about the first axis.

[0021] Each flat base may be circular or a polygon having at least three sides, preferably a circle, a square, a pentagon, a hexagon or an octagon.

[0022] Each resonator may also include a post rising from the planar base parallel to the first axis.

[0023] At least one post may be integrally formed with the planar base of the resonator.

[0024] The pillars of the resonator may have a circular cross section or a polygonal cross section including at least three sides, preferably a circular cross section, a square cross section, a pentagonal cross section, a hexagonal cross section or an octagonal cross section.

[0025] Advantageously, the resonator post may be helical and extend along a first axis. Such a configuration makes it possible to increase the length of the post and thus allows greater adaptability to the impedance of the resonator cavity.

[0026] In one embodiment, the diameter of the helical column may be variable along the first z-axis.

[0027] The top of at least one of the resonators may include a protrusion extending parallel to the first axis into the cavity of the at least one resonator.

[0028] The at least one main aperture may include a connecting portion that is non-parallel to the flat base, the connecting portion extending between two resonators connected by the at least one main aperture.

[0029] The connection portion may connect the single points of the resonators connected by the at least one main aperture.

[0030] At least one resonator may comprise several primary apertures arranged in different axes.

[0031] The waveguide filter may include at least three resonators connected in series through the primary aperture, and the first resonator and the second resonator are connected together through the secondary aperture.

[0032] This cross-coupling of the resonators ("couplage croisé" in French) allows the selectivity of the filter to be increased in certain frequency ranges.

[0033] The secondary aperture may have a different cross-section than the primary aperture, for example to filter a different frequency range.

[0034] At least one of the secondary apertures may include a secondary connection portion extending between resonators connected by the at least one of the secondary apertures.

[0035] The main aperture of the resonator is arranged coaxially along the electromagnetic signal propagation axis.

[0036] The waveguide filter may include at least four resonators, one resonator of the at least four resonators being connected to at least three independent resonators.

[0037] In particular, this feature makes it possible to obtain a filter combining the functionalities of, for example, a filter and a power divider and / or a polarizer.

[0038] At least one of the resonators may include a polarizer and / or a membrane.

[0039] According to the invention, these objects are also achieved by a method for manufacturing a comb waveguide filter having at least one of the above characteristics, the method comprising additive manufacturing of at least two resonators and a main aperture connecting the resonators. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] An example of an implementation of the invention is shown in the description shown in the accompanying drawings, in which:

[0041] · Figures 1a to 1f Several possible geometries for comb filter resonators are shown. Figure 2a A comb filter is shown in which the resonators connected by apertures have a square base and are arranged in a straight line.

[0042] · Figure 2b A comb filter is shown in which the resonators connected by apertures have a square base and are arranged in a matrix.

[0043] · Figure 3a and 3b A resonator having a circular base and staggered

[0044] Perspective and top views of a patterned comb filter.

[0045] · Figures 4a to 4e Several possible geometries for the posts in the cavity of a resonator with a circular base are shown.

[0046] · Figure 5a and Figure 5b A side view and a top view of a comb filter are shown, in which resonators with a square base are arranged in a matrix and the first and last resonators are connected via a secondary aperture.

[0047] · Figure 6a A top view of a comb filter comprising a resonator connected to three other resonators is shown.

[0048] · Figure 6b A top view of a comb filter comprising two resonators connected to three other resonators is shown.

[0049] · Figure 7 A profile view of a resonator comprising a helical post is shown.

[0050] · Figure 8 A top view of a resonator comprising a helical post is shown.

[0051] · Fig. 9 A top view of a comb filter comprising two resonators, each having a spiral post, is shown. DETAILED DESCRIPTION

[0052] The invention relates to a comb waveguide filter 1 obtained by additive manufacturing and comprising at least two resonators 2 connected together by a main aperture 24. Each resonator 2 comprises a cavity 20 delimited in particular by a flat base 21 perpendicular to a first axis z and by a top 22. The top 22 is characterized by the fact that it converges towards a single point 23, also called zenith point. In other words, each resonator 2 is provided with a pointed top 22.

[0053] Figures 1a to 1f An example of a resonator 2 which can be used in a comb waveguide filter 1 according to the invention is shown. The main aperture 24 connecting the resonator is not shown in these figures.

[0054] The first z-axis generally corresponds to the direction of additive manufacturing.

[0055] The convergence of the top 22 of each resonator 2 towards a single point 23 makes it possible to avoid cantilevered faces relative to the first axis z, which are difficult or even impossible to produce by additive manufacturing. In addition, making the top 22 convergent towards the zenith point and not towards the ridge of the top makes it possible to obtain a resonator 2 without a preferred propagation direction of the electromagnetic wave. In fact, the two-sided tops meeting at the ridge determine the propagation direction to a certain extent, while the tops converging towards a single point according to the invention allow greater leeway in choosing the propagation direction of the waves in the waveguide filter. In other words, the resonator can be connected to other resonators in almost any direction, in this sense, the resonator is omnidirectional. The flexibility conferred by the geometry of the top 22 according to the invention makes it possible, for example, to create a comb waveguide filter whose resonators are not aligned along an axis but can form a bend. Therefore, the overall size of such a filter can be greatly reduced by choosing a geometry suitable for a specific constraint.

[0056] like Figure 1a , Figure 1c and Figure 1e As shown, the top 22 of the resonator 2 may be inclined away from the flat base 21. Alternatively, as Figure 1b , Figure 1d and Figure 1fAs shown in , the top 22 may include a first side 26 adjacent to and perpendicular to the flat base 21 and a second side 27 converging and inclined toward the single point 23. In this way, the top 22 may be designed as a pyramid having the flat base 21 as its base, or as a combination of a right prism on the flat base 21 and a pyramid arranged on the prism.

[0057] Other embodiments include resonators with a top 22 converging towards a single point 23, the profile of which is not linear, as in the case of a pyramid, but for example polygonal, parabolic, hyperbolic or any other profile that enables additive manufacturing.

[0058] Generally speaking, the angle formed by the inclined portion of the top portion 22 and the first axis is between 10° and 60°, preferably between 25° and 50°, because too large an angle makes additive manufacturing of the inclined portion difficult.

[0059] like Figures 1a to 1f As shown, the resonator may have at least one rotational symmetry about the first z-axis. Preferably, the resonator has several rotational symmetries about the first z-axis.

[0060] Figure 1a and Figure 1b Embodiments are shown in which the top 22 is conical or consists of a cone on top of a cylinder. In these cases, maximum rotational symmetry is achieved, since the top profile is obtained as a surface of revolution around the first axis z.

[0061] Figure 1c and Figure 1d An embodiment is shown in which the top 22 is a pyramid with a square base or consists of a pyramid with a square base on top of a prism with a square base (i.e. a parallelepiped). The top 22 is thus invariant to a rotation of an angle k×90° around the first axis z, where k is an integer.

[0062] Figure 1e and Figure 1f An embodiment is shown in which the top 22 is a pyramid whose base is a regular hexagon, or consists of a pyramid with a regular hexagonal base on top of a prism with a regular hexagonal base. The top 22 is therefore invariant to a rotation about the first axis z through an angle kx60°, where k is an integer.

[0063] More generally, the top 22 may comprise any surface of revolution about the first axis z, as long as this results in the top converging towards a single point 23. Additionally or alternatively, the top 22 may comprise a pyramid whose base is formed by any polygon.

[0064] The first side portion 26 of the top portion 22 may be cylindrical. Alternatively or additionally, it may comprise a right prism whose base is any polygonal shape.

[0065] In a preferred embodiment, the flat base 21 delimiting the cavity 20 of the resonator 2 according to the invention has the same properties as the top 22, which are invariant to rotation about the first axis z. In particular, the flat base may be circular, a polygon with at least three sides, preferably a circle, a square, a pentagon, a hexagon or an octagon. Other geometric shapes of the flat base 21 may be envisaged without departing from the scope of the invention, such as an ellipse or a non-convex surface.

[0066] The resonators 2 of the comb waveguide filter according to the invention are interconnected by primary apertures 24. As explained below, some of the resonators may be provided with secondary apertures, which explains the term "primary" aperture. These primary apertures 24 allow electromagnetic waves to propagate from one resonator to another in the filter.

[0067] In embodiments in which the geometry of two consecutive resonators 2 of the filter 1 enables them to be arranged against each other in sufficient proportion, i.e. a substantial portion of the top 22 of the first resonator is arranged against a substantial portion of the top 22 of the second resonator, the main aperture 24 may comprise an opening in an adjacent portion of the tops.

[0068] The cross section of this opening determines the cut-off frequency of the waves propagating between the two resonators via the main aperture 24. This cross section is therefore adjusted according to the specific requirements of the filter 1.

[0069] In another embodiment, the geometry of the resonator 2 requires a larger opening than adjacent portions of the resonator. Figure 2a and Figure 2b As shown, the main aperture 24 thus comprises an opening extending on a first side 26 of the top 22 and on a second side 27. The connecting portion 25 extends between at least a portion of the two second sides 27 of the two tops 22 of the resonator connected by the main aperture 24.

[0070] like Figure 2a and Figure 3a As shown, the connection portions between the resonators may include inclined portions to facilitate or even enable their additive manufacturing. The connection portions may, for example, include a gable roof.

[0071] In one embodiment, the connecting portion 25 can connect the two tops 22 over the entire height of the top or over the entire height of the second side 27 of the top. Alternatively or additionally, a single point 23 of the two tops 22 can be connected by the connecting portion 25.

[0072] In an embodiment not shown, the geometry of the resonators 2 does not allow them to be arranged adjacently. Therefore, the main aperture 24 connecting two such resonators comprises a connecting portion 25 connecting the two resonators. This connecting portion can be, for example, a rectangular waveguide with the same cross-section as the opening in the main aperture that determines the cut-off frequency.

[0073] Generally speaking, the length, width and height of the main aperture and the connecting part affect the coupling level between the two resonators. Therefore, these parameters are adjusted as needed.

[0074] like Figure 2a and Figure 2b As shown, the cavity 20 of the resonator 2 may include a post 28 rising from a flat base 21 parallel to the first axis z. The use of a post 28 in the cavity 20 allows the impedance of the cavity to be modified and thus the resonant frequency of the circuit formed by the cavity 20 and the primary aperture 24 to be controlled.

[0075] These posts 28 differ from any adjustment screws in that they do not allow for subsequent adjustment or modification of the resonant frequency.

[0076] These posts 28 may be formed integrally with the flat base 21. This method is advantageous in terms of additive manufacturing as it avoids any subsequent machining for forming such posts.

[0077] The shape of these pillars (and more particularly the cross-section of these pillars in a plane parallel to the flat base 21) can be adjusted as desired and according to the geometry of the top 22. The cross-sectional geometry of the pillars 28 is not necessarily the same as the cross-sectional geometry of the flat base 21 or the cross-sectional geometry of the top 22 of the resonator in question.

[0078] like Figures 4a to 4e As shown, the resonator 2 may include a column 28, the cross section of which is a right prism, and the base of which is a circle or a polygon with at least three sides. Preferably, the base of the prism is a circle, a square, a pentagon, a hexagon or an octagon. Figures 4a to 4e The circular geometry of the top 22 and flat base 21 in is by no means limiting and all the alternative geometries mentioned above can be realized in combination with these posts.

[0079] To facilitate additive manufacturing of such pillars 28, the upper side of the pillars, ie the side opposite to the flat base 21, may comprise curved or inclined portions. These curved portions are also useful when the filter is intended for high power applications.

[0080] exist Figures 7 to 9 In the alternative embodiment shown, the column 28 takes the form of a helix, the main direction of which coincides with the first z-axis. When it is mentioned that the helical column extends parallel to an axis, it is meant that the main direction of the helix is ​​parallel to said axis.

[0081] The use of such a helical column advantageously makes it possible to obtain a column 28 having a length greater than that of a straight column. In particular, this enables a greater adaptability of the impedance of the cavity 20.

[0082] The pitch of the helix (ie the perpendicular distance between two consecutive points of the helix in a plane including the first z-axis) may be constant or variable.

[0083] The diameter of the spiral can also be constant or variable. Figures 7 to 9 In the preferred embodiment shown, the diameter of the helix decreases as a function of height relative to the flat base 21 of the resonator 2. In particular, this configuration makes it possible to adapt the outer diameter of the helical column to the inner diameter of the cavity 20 of the resonator 2. The surface of revolution forming the helix is ​​a cone.

[0084] However, in certain configurations where it is not necessary to reduce the diameter of the helix, the diameter of the helix can be kept constant to further increase the overall length of the helical column.

[0085] Alternatively or additionally, the surface of revolution on which the helix lies may be an inverted cone, a cylinder, a sphere, or even a surface with alternating positive and negative curvatures, so that the diameter of the helix may alternately increase and decrease.

[0086] Such a helical post 28 may be additively manufactured integrally with the rest of the resonator.Alternatively or additionally, the helical post may be manufactured separately from the resonator and placed in the cavity during or after additive manufacturing of the resonator.

[0087] like Fig. 9 As shown, two adjacent resonators 2 may each comprise a helical post 28. The orientation (ie winding direction) of the helices may be the same or alternatively opposite.

[0088] The upper portion of the cavity 20 of the resonator 2 may also be provided with protrusions extending from the inner surface of the top 22 toward the interior of the cavity to change the impedance of the cavity. These protrusions extend substantially parallel to the first axis. These protrusions are integral with the resonator and are therefore also distinguished from conventional adjustment screws as elements movable relative to the resonator.

[0089] In a preferred embodiment, the protrusion is integral with the resonator top 22. In a similar manner to the post 28, the face of the protrusion opposite the top 22 may be flat or curved, depending on specific requirements, in particular with regard to additive manufacturing and high power use of the filter.

[0090] The resonator 2 of the waveguide filter 1 may include tuning screws that allow fine tuning when the filter is in use. Unlike the posts 28, these screws are movable elements relative to the resonator structure and are used to slightly change the impedance of the resonator cavity 20.

[0091] As mentioned above, one of the main advantages of the waveguide filter according to the present invention lies in the omnidirectional nature of the resonators, ie they can be connected together non-coaxially, ie not necessarily along one axis.

[0092] Figure 3a and Figure 3b An embodiment is shown in which several resonators 2 are arranged non-coaxially. More specifically, a first resonator 2 (e.g. Figure 3a The first resonator (the resonator on the left) has a port 31 so that it can receive an electromagnetic signal at the input of the filter. This first resonator is connected to the second resonator 2 via a main aperture 24 comprising a connecting portion 25. The main aperture 24 is not diametrically opposite the port 31. Straight lines passing through the port 31 and the center of the flat base 21 on the one hand and through the center of the flat base and the main aperture 24 on the other hand intersect and form an angle between 90° and 150°.

[0093] The second resonator itself is also connected to the main aperture 24 via a main aperture 24 which also includes a connecting portion 25. Figure 3a The third resonator 2 is the rightmost in the filter 1. The third resonator comprises a port 31 allowing electromagnetic signals to leave the filter 1. In a similar manner, the angles formed by the straight lines passing through the main aperture 24 connecting the second resonator to the third resonator and the centre of the flat base 21 on the one hand and through the centre of the flat base and the port 31 on the other hand, these lines are secants and form an angle between 90° and 150°.

[0094] The filter obtained by this arrangement of resonators thus forms a bend at the second resonator, which makes it possible to significantly reduce the overall length of the filter for a given number of resonators compared to a conventional coaxial arrangement.

[0095] In this design, the circular geometry of the top 22 of the resonator allows a great deal of freedom in the relative positioning of the resonators with respect to each other. In fact, due to the rotational invariance of the circular resonators about the first z-axis, a circular resonator can be placed in almost any position around another circular resonator. Thus, a wide variety of filter geometries can be obtained by linking resonators in this manner.

[0096] Another advantage arising from the omnidirectional nature of the resonators lies in the fact that, due to the introduction of an "elbow" in the filter, certain discontinuous resonators (in the sense that they are not connected by a main aperture) can be placed very close together. Figure 3bIn , the two resonators, each comprising a port 31, are not connected by the main aperture, but are still very close to each other. Therefore, due to the proximity of the discontinuous resonators, secondary coupling can be introduced between the discontinuous resonators.

[0097] In particular, these secondary couplings make it possible to introduce alternative propagation paths for waves within the filter. Depending on the phase of the signal, the effect of the multiplication of the path of the wave in the filter may be the appearance of transmission zeros in the transfer function of the filter. This means that secondary couplings between discontinuous resonators can be applied, for example, to achieve a linear phase response or to generate finite transmission zeros, thereby improving the selectivity of the filter by increasing the filtering of specific frequencies at specific locations. In this way, the introduction of transmission zeros in the frequency response reduces the number of resonators required to meet a specific filter selectivity specification. The result is a reduction in insertion losses, footprint and manufacturing costs.

[0098] These secondary couplings take the form of secondary apertures 29. This secondary aperture 29 may comprise a secondary connection portion between two top portions 22 of the resonator connected by the secondary aperture. As in the case of the connection portion, the secondary connection portion may comprise a portion inclined relative to the first axis to facilitate their additive manufacturing.

[0099] The secondary connecting portion 29 is Figure 3b , in which the secondary connecting portion 29 connects the first resonator provided with the input port 31 and the third resonator provided with the output port 31 .

[0100] The cross section of the secondary aperture 29 may be different from the cross section of the primary aperture 24. The cross section of the secondary aperture is, for example, rectangular (the longest side of the rectangle is placed parallel or perpendicular to the first z-axis).

[0101] Figure 5a and Figure 5b Another embodiment of a filter in which the resonators are arranged non-coaxially is shown in FIG. A number of resonators 2 designed according to a square base model are placed in a matrix so that each resonator has at least two sides adjacent to other resonators. A main aperture 24 including a connecting portion 25 connects the resonators 2 to form a propagation path for electromagnetic waves in the filter 1. For example, in Figure 5b In the example, the electromagnetic wave can enter the filter 1 through the port 31 of the rightmost resonator 2, and then propagate counterclockwise 90° through the main aperture to the second resonator 2 ( Figure 5b The bottom of the image is then propagated clockwise 90° through the main aperture to the third resonator 2 ( Figure 5b The left side of the image) and then propagates clockwise 90° through the main aperture to the fourth resonator 2 ( Figure 5b and finally propagates 90° counterclockwise through port 31 of the fourth resonator to the outside of the filter.

[0102] like Figure 5a and Figure 5b As shown, the first resonator and the fourth resonator are additionally connected via a secondary aperture 29 comprising a secondary connecting portion 30. The cross section of the secondary aperture 29 is different from the cross section of the primary aperture to improve filtering. In this embodiment, the secondary aperture 29 has a square cross section, one of the diagonals of the square cross section being parallel to the first z-axis.

[0103] Although the geometry of the resonators allows the filter to be arranged in a non-coaxial manner, it is still possible to obtain a filter in which all resonators 2 are aligned on the same propagation axis of the electromagnetic signal (e.g. as Figure 2a shown).

[0104] In a particular embodiment, the waveguide filter of the invention comprises at least four resonators, one of the four resonators being connected to at least three individual resonators via a main aperture 24. Such a configuration makes it possible in particular to obtain a filter with several resonator branches, or in other words, to obtain a filter with, for example, one input port and several output ports or with several input ports and one output port. This makes it possible to produce a comb waveguide filter with, for example, the function of a power divider or polarizer.

[0105] Figure 6a FIG. 1 shows a comb waveguide filter 1 in which at least one of the resonators 2 (the third one counted from the left side of the figure) is connected to three other resonators. Figure 6a The resonator 2 on the left side of the filter has a port 31 for inputting an electromagnetic signal into the filter and is located Figure 6a The two resonators on the right side of the center filter each have a port 31 for outputting electromagnetic signals out of the filter.

[0106] Figure 6b Another embodiment of the invention is shown in which the first resonator on the left side of the figure has an input port 31 for inputting an electromagnetic signal into the filter 1 and propagating the signal into two separate resonators via the main aperture 24. The final resonator on the right side of the figure receives two electromagnetic signals via the main aperture and propagates the two electromagnetic signals to the outside of the filter via the output port 31.

[0107] At least one resonator of the filter may include a polarizer and / or a membrane to separate and / or combine one or more electromagnetic signals.Other standard passive RF components may also be combined with the filter without departing from the scope of the invention.

[0108] The present invention also relates to a method for manufacturing the above-mentioned waveguide filter.

[0109] Reference Mark List

[0110] 1 Comb waveguide filter

[0111] 2 Resonator

[0112] 20 chambers

[0113] 21 Flat base

[0114] 22 Top

[0115] 23 single point

[0116] 24 Main aperture

[0117] 25 connected parts

[0118] 26 first side

[0119] 27 Second side

[0120] 28 columns

[0121] 29 secondary aperture

[0122] 30 Secondary connection part

[0123] 31 coaxial ports

[0124] zFirst axis

[0125] x-axis of propagation.

Claims

1. A comb waveguide filter (1) obtained by metal additive manufacturing, the comb waveguide filter (1) comprising at least two resonators (2) interconnected by a main aperture (24), Each resonator comprises (20) a cavity having a first axis (z), Each cavity (20) is in particular delimited by a flat base (21) extending perpendicularly to said first axis (z), It is characterized in that Each cavity (20) is also defined by a top portion (22) that converges towards a single point (23).

2. The waveguide filter (1) according to claim 1, characterized in that Each top portion (22) comprises a first side portion (26) adjacent to and perpendicular to the flat base portion (21) and a second side portion (27) converging toward the single point (23).

3. The waveguide filter (1) according to one of the preceding claims, characterized in that Each resonator (2) has rotational symmetry about said first axis (z).

4. The waveguide filter (1) according to one of the preceding claims, characterized in that Each flat base (21) is circular or polygonal with at least three sides, preferably circular, square, pentagonal, hexagonal or octagonal.

5. A waveguide filter (21) according to any one of the preceding claims, characterized in that Each resonator (2) also comprises a post (28) rising from said flat base (21) parallel to said first axis (z).

6. A waveguide filter (1) according to the preceding claim, characterised in that At least one post (28) is integrally formed with the flat base (21) of the resonator (2).

7. A waveguide filter (1) according to the preceding claim, characterised in that The pillar (28) of each resonator has a circular or polygonal cross-section having at least three sides, preferably a circular, square, pentagonal, hexagonal or octagonal cross-section.

8. The waveguide filter (1) according to one of claims 1 to 6, characterized in that The column (28) is helical and extends along the first axis (z).

9. A waveguide filter (1) according to the preceding claim, characterised in that The diameter of the column (28) is variable along the first axis (z).

10. The waveguide filter (1) according to one of the preceding claims, characterized in that The top (22) of at least one resonator (2) comprises a protruding portion extending parallel to the first axis (z) towards the interior of the cavity (20) of the at least one resonator.

11. The waveguide filter (1) according to one of the preceding claims, characterized in that At least one main aperture (24) comprises a connecting portion (25) which is non-parallel to the flat base (21), the connecting portion extending between two resonators connected by the at least one main aperture (24).

12. The waveguide filter (1) according to the preceding claim, characterized in that The connecting portion (25) connects the single point (23) of the resonator (2) connected by the at least one main aperture (24).

13. The waveguide filter (1) according to one of claims 1 to 11, characterized in that At least one resonator (2) comprises a plurality of primary apertures (24) arranged non-coaxially.

14. The waveguide filter (1) according to one of the preceding claims, characterized in that The waveguide filter comprises at least three resonators (2) connected in series by the primary aperture (24), and the first resonator (2) and the second resonator (2) are connected together through a secondary aperture (29).

15. The waveguide filter (1) according to the preceding claim, characterized in that The secondary aperture (29) has a cross section different from that of the primary aperture (24).

16. The waveguide filter (1) according to one of claims 13 to 14, characterized in that At least one of the secondary apertures (29) includes a secondary connection portion (30) extending between the resonators (2) connected via the at least one secondary aperture (29).

17. The waveguide filter (1) according to any one of claims 1 to 11, characterized in that The main aperture (24) of the resonator (2) is arranged coaxially along the propagation axis (x) of the electromagnetic signal.

18. The waveguide filter (1) according to one of the preceding claims, characterized in that The waveguide filter comprises at least four resonators (2), one resonator of the at least four resonators being connected to at least three independent resonators.

19. The waveguide filter (1) according to one of the preceding claims, characterized in that At least one resonator (2) comprises a polarizer and / or a diaphragm.

20. Method for manufacturing a comb waveguide filter (1) according to one of claims 1 to 19, comprising additive manufacturing of at least two resonators (2) and a primary aperture (24) connecting the resonators.

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