KAMMWELLENLEITERFILTER

Description

technical field

[0001] The present invention relates to a comb waveguide filter and a method for manufacturing said filter. State of the art

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

[0003] An example of such a conventional waveguide is described in patent application WO2017208153, the contents of which are incorporated by reference. It consists of a hollow device, the shape and proportions of which determine the propagation characteristics for a given wavelength of the electromagnetic signal. The internal channel cross-section of this device is rectangular. Other channel cross-sections are suggested in this document, including circular shapes.

[0004] The waveguide 1 of this prior art comprises a core manufactured by additive manufacturing, layering components one on top of the other. This core defines an internal channel for wave guidance, the cross-section of which is determined according to the frequency of the electromagnetic signal to be transmitted. The inner surface of the core is coated with a conductive metallic layer. The outer surface may also be coated with a conductive metallic layer, which contributes, in particular, to the rigidity of the device.

[0005] Waveguide devices are used to channel RF signals or to manipulate them in the spatial or frequency domain, for example, to form a waveguide filter. The present invention relates in particular to passive waveguide filters that allow radio frequency signals to be filtered without the use of active electronic components.

[0006] Conventional waveguide filters used for radio frequency signals typically have internal apertures with a rectangular or circular cross-section. The primary purpose of these filters is to suppress unwanted frequencies and allow the desired frequencies to pass through with minimal attenuation. Attenuation levels exceeding 100 dB or even 120 dB may be required for filters intended for receiving and / or transmitting systems in space applications, for example.

[0007] Applications in space and aeronautics, in particular, require compact and lightweight waveguide filters. Consequently, significant research efforts have been undertaken to develop waveguide filter geometries that meet these various requirements.

[0008] Evanescent mode filters, or combline waveguide filters, are well-known examples. They are essentially composed of several small cavities (smaller than the size corresponding to the cutoff frequency) that transmit electromagnetic energy between an input port and an output port. These successive cavities are connected by irises, the dimensions of which determine the filter's bandwidth. Several peaks or poles allow the propagation of the fundamental mode. This type of filter is used, for example, in the input and output stages of satellite payloads due to its high selectivity and low mass and size.

[0009] US patent 2020 / 194855 A1 relates to an additively manufactured comb filter whose successive resonance cavities have an irregular hexagonal cross-section. The cavities may be connected longitudinally and / or vertically by irises whose cross-section is preferably hexagonal or rectangular.

[0010] US patent 2010 / 141357 A1 relates to a comb filter with a plurality of successive cavities having an essentially triangular cross-section. Additive manufacturing of such a comb filter is made very difficult due to the tight angles and the numerous cantilevered surfaces of the resonant cavities and the junctions between cavities.

[0011] US patent 5,534,881 A relates to a comb filter with a relatively complex resonant cavity cross-section due to prominent features within the channel. Additive manufacturing of such a filter is practically impossible because of this complex internal geometry.

[0012] Conventional comb waveguide filters are manufactured by machining and assembling various metal sub-assemblies. These operations are complex and expensive. Furthermore, the resulting filters are quite heavy. Brief summary of the invention

[0013] An object of the present invention is to propose a new type of comb waveguide filters as defined in claim 1 which is simpler to manufacture and whose weight can be reduced.

[0014] According to one aspect, these goals are achieved by means of a comb waveguide filter made of metal by a process as defined in claim 14 comprising an additive manufacturing step.

[0015] The filter can be manufactured by a process including an additive manufacturing step, for example of the SLM type in which a laser or an electron beam melts or sinters several thin layers of a powdered material.

[0016] Additive manufacturing can be observed on the filter thus produced by analyzing the structure of the metallic grains sintered in layers.

[0017] Additive manufacturing of metal makes it possible to create complex shapes by limiting or eliminating assembly steps, thereby reducing manufacturing costs.

[0018] Additive manufacturing also makes it possible to manufacture comb waveguide filters without means of assembly between sub-components, or with a reduced number of such means of assembly, which also makes it possible to reduce the weight of the filter.

[0019] It is known to manufacture waveguide devices by additive manufacturing. However, the complex shapes of comb waveguide filters are not well-suited to additive manufacturing due to the numerous cantilevered surfaces, particularly the surfaces forming the roof of the resonator cavities.

[0020] Most additive manufacturing processes, particularly selective laser melting (SLM), require a minimum angle, for example 20 or 40°, to prevent the risk of a newly deposited layer sagging. Consequently, it is impossible to print certain sections of waveguide filters, or at least to print them with the desired precision.

[0021] There figure 27aThis illustrates a process that can be implemented for the additive manufacturing of a comb waveguide filter 1. In this manufacturing method, the filter has a rectangular cross-section, for example, and is printed with the longitudinal direction x of the filter 1 inclined relative to the printing direction p, that is, relative to the direction p perpendicular to the printing layers. To achieve this, printing is performed on a printing substrate S with a printed plane. This oblique arrangement avoids or minimizes overhanging horizontal surfaces during printing. However, this results in manufacturing tolerance issues, related on the one hand to the manufacturing tolerances of the substrate and its positioning on the printing table, and on the other hand to the printing layers being oblique relative to the main dimensions of the filter.These tolerance issues degrade the filter's characteristics, particularly its selectivity, the accuracy of the cutoff frequency, and the attenuation of the useful radio frequency signal. Furthermore, the printed object occupies a significant area on the printing table and requires a large number of printing layers, resulting in both slow printing and additional inaccuracies due to the combined manufacturing tolerances of the layers.

[0022] To avoid these drawbacks, it is proposed from another perspective to produce in additive printing a comb waveguide filter with an unconventional geometry which makes it easier to print additively with high precision.

[0023] To this end, according to one aspect, the comb waveguide filter is provided with at least two resonators, preferably at least four resonators, comprising a cavity provided with a longitudinal axis (x), a transverse axis (y) and a vertical axis (z), each cavity being delimited in particular by two walls each extending in a plane perpendicular to the longitudinal axis, the cross-section of said cavities being substantially triangular.

[0024] The term "comb waveguide filter" implies that the different resonators are connected to each other by irises. This does not necessarily imply that the resonators are aligned along a single longitudinal or transverse line.

[0025] Choosing a non-rectangular cross-section offers additional freedom in creating cavities that can be produced using metal additive manufacturing with a printing direction p parallel to the longitudinal axis x of the filter, as on the figure 27b , or perpendicular to this longitudinal direction, as on the figure 27c .

[0026] It is therefore possible to produce metallic waveguide filters in which the layers resulting from additive printing are not parallel to the roof surfaces of the cavities and can be printed without overhang.

[0027] This eliminates the precision problems caused by additive printing on a substrate with an oblique printing surface.

[0028] We also increase the density of filters that can be printed simultaneously on a given surface, or we reduce the height and number of printing layers, which in both cases improves the speed of additive printing and therefore reduces the cost.

[0029] Each cavity has a post extending parallel to the vertical axis inside the cavity.

[0030] Using a post in the cavity allows the impedance of the cavity to be modified, and thus the resonant frequency of the circuit formed by the cavity and the iris to be controlled.

[0031] In one embodiment, each cavity has a base perpendicular to the vertical axis and substantially flat, and a roof above said base, said roof having no flat surface parallel to said base. It is thus possible to fabricate the resonators by starting with the base supported by a horizontal printing surface, and then printing the walls and roof of the cavity, which do not have any cantilevered horizontal surfaces.

[0032] A said post can extend from said base.

[0033] The roof can consist of exactly two sections formed of oblique faces connecting said walls and inclined with respect to said base.

[0034] The roof can consist of several flat sections, for example two sections, connected to each other and / or at the base by curved surfaces.

[0035] The roof can consist exclusively of curved surfaces connecting the walls. This variant allows for a vaulted roof that is easier to print using additive manufacturing.

[0036] The cross-section of the resonator can vary in the longitudinal direction.

[0037] The cross-sectional area can increase from each longitudinal end of the cavity towards its longitudinal center. The maximum height of the resonator roof can thus be located at the resonator's longitudinal center, and the minimum height at one or both longitudinal ends. This increasing and then decreasing slope of the roof along its length facilitates printing, as the roof's longitudinal edge forms a self-supporting arch during printing.

[0038] At least two adjacent cavities in the longitudinal direction can be connected to each other by an iris.

[0039] This iris can pass through the vertical walls of two adjacent resonators. An iris between two adjacent resonators in the longitudinal direction is called a longitudinal iris.

[0040] The longitudinal section of the iris can be triangular.

[0041] The longitudinal section of the iris can be polygonal, for example forming a quadrilateral, for example a rhombus, a rectangle or a square.

[0042] It is possible to provide several irises, for example two irises, between two adjacent resonators in the longitudinal direction. The cross-section of these irises can be slit-shaped. The slit can extend vertically.

[0043] At least two adjacent cavities in the transverse direction can be connected to each other by an iris.

[0044] This iris can pass through the roof of two adjacent resonators. An iris between two adjacent resonators in the transverse direction is called a transverse iris.

[0045] Transverse irises can form a polyhedron

[0046] The transverse iris can form a polyhedron with 4 triangular faces, two of the faces in the planes of the two adjacent roofs being hollow in order to allow the radio frequency signal to pass between the resonators.

[0047] The transverse iris can form a polyhedron with two pentagonal faces, two triangular faces and two trapezoidal faces, the pentagonal faces in the planes of the two roofs being hollow in order to allow the radio frequency signal to pass between the resonators.

[0048] Transverse irises may have a rectangular cross-section whose upper edge is formed by the intersection of two sides of two cavities that fit together.

[0049] Transverse irises can occupy a curved volume, for example if they rest on flat roofs.

[0050] A single comb waveguide filter can have several longitudinal irises of different shapes, and / or several transverse irises of different shapes or sections.

[0051] At least one cavity of a resonator may be fitted with an adjustment screw to create an obstruction within the cavity and adjust the resonant frequency. The adjustment screw may extend vertically above the pole and be inserted more or less deeply into the cavity.

[0052] At least one iris may be fitted with an adjustment screw to adjust the filter's bandwidth. The screw may extend vertically through the upper wall of the iris and penetrate into the iris.

[0053] At least one cavity may include a hole for chemical cleaning of the cavity interior after additive manufacturing. This hole may be removed or modified after cleaning.

[0054] The comb waveguide filter may have at least two resonators, for example four or eight or more than eight resonators, connected together by irises.

[0055] The resonators and irises can be made monolithically.

[0056] The comb waveguide filter may have an input port for a radio frequency electromagnetic signal into the filter and an output port for the radio frequency electromagnetic signal out of the filter.

[0057] The ports can be formed in machined flanges and assembled, for example glued, to the portion of the filter produced by additive printing.

[0058] The ports can be equipped with a connector for a coaxial cable.

[0059] According to one aspect, the invention also relates to a method for manufacturing a comb waveguide filter, comprising the additive manufacturing of said resonators by superimposing layers extending in planes perpendicular to the vertical axis.

[0060] The process may include machining a flange with an inlet port and a flange with an outlet port, and bonding said flanges to said cavities. Brief description of the figures

[0061] Examples of implementation of the invention are given in the description illustrated by the accompanying figures, in which: THE figures 1 to 6 illustrate different perspective views of various examples of resonators that can be implemented in a metal comb waveguide filter, the iris not being shown in these figures; The figures 7a and 7billustrate two perspective views of an example of a resonator that can be implemented in a metal comb waveguide filter, the iris being fitted with two longitudinal triangular-section irises for connecting to two other resonators of a waveguide filter; The figures 8a and 8b Figures 9a and 9b illustrate different perspective views of two resonators of a comb waveguide filter connected by an example of a transverse iris; The Figure 10 illustrates a perspective view of two resonators of a comb waveguide filter connected by an example of a transverse iris; The figures 11a and 11b illustrate different perspective views of two resonators of a comb waveguide filter connected by a longitudinal iris with a triangular cross-section; The figures 12a and 12billustrate different perspective views of two resonators of a comb waveguide filter connected by a longitudinal iris with a quadrilateral cross-section; The figures 13a and 13b illustrate different perspective views of two resonators of a comb waveguide filter connected by two longitudinal slotted irises; figures 14a and 14b illustrate different perspective views of two resonators of a comb waveguide filter connected by a longitudinal iris of triangular cross-section, defined by an obstacle; The figures 15a and 15b illustrate different perspective views of two resonators of a comb waveguide filter connected by a longitudinal iris of trapezoidal cross-section, defined by an obstacle; The figures 16a and 16b illustrate different perspective views of two resonators of a comb waveguide filter connected by a longitudinal iris with a triangular cross-section; The figures 17a and 17billustrate different perspective views of two resonators of a comb waveguide filter connected by a longitudinal iris with a quadrilateral cross-section; The figures 18a and 18b illustrate different perspective views of two resonators of a comb waveguide filter connected by two longitudinal slotted irises; figures 19a to 19c illustrate different views of a slot-guided filter, comprising two rows of two resonators each, the two rows being connected to each other by a longitudinal iris with a quadrilateral cross-section; The figures 20a to 20c illustrate different views of a slot-guided filter, comprising two rows of two resonators each, the two rows being connected to each other by a longitudinal iris with a quadrilateral cross-section and by a longitudinal iris with a triangular cross-section; The figures 21a to 21billustrate different views of a slot-guided filter, comprising four rows of two resonators each, with adjacent rows connected by a longitudinal iris of quadrilateral cross-section; figures 22a to 22c illustrate different views of a slot-guided filter, comprising four rows of two resonators each, the adjacent rows being connected to each other by a longitudinal iris with a quadrilateral cross-section and by another longitudinal iris with a triangular cross-section; The figures 23a to 23c illustrate different views of a slot-guided filter, comprising two rows of four resonators each, the adjacent rows being connected to each other by several longitudinal irises of different cross-sections; The figure 24illustrates a perspective view of an example of a resonator that can be implemented in a metal comb waveguide filter, equipped with a tapped hole for a filter cutoff frequency adjustment screw and a radio frequency signal input or output port; The figure 24 illustrates a front view (along the longitudinal axis) of an example of a resonator that can be implemented in a metal comb waveguide filter, equipped with a tapped hole for a filter cutoff frequency adjustment screw, a radio frequency electromagnetic signal input or output port, and holes for a resonator cavity cleaning fluid; The figure 26 illustrates a perspective view of a full-comb waveguide filter, here a filter equipped with eight resonators connected in line along the longitudinal axis, and two flanges; The figure 27aillustrates a view of an example of waveguide filter layout during additive manufacturing; The figure 27b illustrates a view of another example of waveguide filter layout during additive printing; The figure 27c illustrates a view of an example of waveguide filter layout during additive printing; Example(s) of an embodiment of the invention

[0062] There figure 1 illustrates a perspective view of an example of a resonator 3 that can be implemented in a metal comb waveguide filter. Only the resonator cavity is shown in this figure, and in the figures 2 to 6 the iris(es) not being illustrated.

[0063] The illustrated resonator 3 has an input port 51 for an input radio frequency signal and an output port for the filtered signal, although in practice this resonator is intended to be connected to other resonators via one or more irises 4, as will be seen later.

[0064] The resonator 3 comprises a cavity 30 bounded by a base 34, a gabled roof 35-36, and two vertical walls 31 and 32. The roof slope 35 is connected to the base by a curved surface 350, and to the other slope 36 by a second curved surface 361 forming the roof ridge. The slope 36 is connected to the base 34 by a third curved surface 360. As in other embodiments, the curved surfaces 350, 360, and 361 are curved in the transverse xy plane. In this example, the curved surfaces 350, 360, and 361 are not curved in other planes.

[0065] The longitudinal axis x is parallel to the roof edge and perpendicular to the vertical walls 31-32. The transverse axis y is perpendicular to the longitudinal axis x. The base 34 extends in the xy plane, also known as the horizontal plane. The z-axis, also known as the vertical axis, is perpendicular to the xy plane. It should be noted that the vertical axis corresponds to the printing direction p during additive printing; this direction is therefore vertical during printing, but not necessary when using the filter, which can be implemented in any orientation.

[0066] The resonator preferably includes a post 33 which extends perpendicularly into the cavity 30 from the base, without reaching the roof 35-36. The height of the post defines the impedance of the resonator and therefore the cutoff frequency of the filter for the fundamental mode.

[0067] The cross-section of cavity 30, in the yz plane, is not rectangular, and is essentially triangular in this example. The resonator is printed with its base 34 perpendicular to the printing direction on the print bed. This geometry avoids overhanging surfaces during printing.

[0068] Other examples of resonators and filters incorporating such resonators are illustrated in the other figures and described below. For the sake of brevity, the characteristics of these other resonators have already been presented and described in relation to the figure 1 The characteristics described in relation to the resonator in the figure, or with other figures, are not systematically repeated. However, all the characteristics described in relation to the resonator in the figure can be used with other resonators, unless otherwise specified.

[0069] There figure 24illustrates a resonator equipped with a cavity 30 with a tapped hole, obtained by additive printing and / or machining, above the post 33.

[0070] The threaded hole allows the insertion of an adjustment screw 38 from the roof edge 35-36 and vertically from the post 33; by adjusting the insertion depth of this screw in the cavity, the cutoff frequency is adjusted. Inserting the screw deeper reduces the filter's cutoff frequency fc.

[0071] Such an adjustment screw can be provided with all the resonators described later.

[0072] The input port 51 allows a radio frequency signal to be introduced into the cavity 30, for example from a waveguide or coaxial cable. The height h along the z-axis of the center of the input port determines both the coupling quality and the quality factor Qe; the higher h, the better the coupling, but at the expense of the resonator's quality factor.

[0073] There figure 2 illustrates another resonator 3 in which the roof sections 35-36 are connected to the base 34 by sharp edges, and connected to each other by a curved surface of greater radius than the embodiment of the figure 1 .

[0074] There figure 3 Figure 3 illustrates another resonator in which the roof sections 35-36 are connected to the base 34 by curved surfaces of large radius, and connected to each other by a curved surface of large radius. Furthermore, the cross-sectional area of ​​the resonator increases progressively from each longitudinal end of the resonator towards its longitudinal midpoint; in this example, the height of the resonator is therefore maximum at its center along the longitudinal axis x. This feature also facilitates additive printing, as the edge 361 is arched along the longitudinal axis, which reduces the risk of sagging.

[0075] THE figures 4 And 6illustrate a cross-sectional and flat view of a resonator 3 comparable to that of the figure 3 but in which the width of the flat base 34 gradually widens from each longitudinal end of the resonator towards its longitudinal midpoint; in this example, the base 34 therefore has a maximum width at the center of the resonator along the longitudinal axis x. The cross-section of the cavity (ignoring the post 33 and any adjusting screw above the post) is maximum at the center of the resonator along the longitudinal axis x.

[0076] THE Figures 5A And 5B This illustrates a resonator 3 in which the roof sections 35-36 are connected to the base 34 by curved surfaces 350, 360 of large radius, and to each other by a curved surface 361 of large radius. The width of the base 34 and the height of the resonator are constant along the longitudinal axis x.

[0077] THE figures 7a and 7bThese figures illustrate perspective views of an example of a resonator 3 of a metal comb waveguide filter. The cross-section of the cavity 30 is triangular. The vertical walls 31 and 32 are each provided with an iris 4 to connect this cavity to an adjacent cavity in the longitudinal direction x. In this example, the two irises 4 have a triangular cross-section and form an opening in the corresponding wall. As will be seen, other iris cross-sections can be provided. In one variant, as will be seen, the cavity 30 can be connected to the cavity of other resonators by irises provided on the lateral edges, i.e., on the edges of the roof 35-36. Such longitudinal or transverse irises, of any cross-section, can also be provided with the resonators in the preceding figures.

[0078] THE figures 8a and 8bThey illustrate two adjacent resonators 3 along the transverse axis y and connected by a transverse iris 4, between the roof face 36 of one resonator and the roof 36 of the other resonator. In this example, the iris 4 has a volume forming a polyhedron with 4 triangular faces, the two faces parallel to the roof faces 35 and 36 respectively being hollow to form an opening between the two cavities.

[0079] The dimensions of the iris determine the properties of the filter. Increasing the height of the iris improves the coupling between cavities, but also increases the bandwidth of the filter.

[0080] There figure 9This illustrates two adjacent resonators 3 along the transverse axis y, connected by a transverse iris 4, between the roof face 36 of one resonator and the roof 36 of the other. In this example, the iris 4 has a volume forming a polyhedron with two pentagonal faces parallel to the roof faces 35 and 36 respectively, two triangular faces, and two trapezoidal faces. The two pentagonal faces are hollow to create an opening between the two cavities.

[0081] There Figure 10This illustrates two adjacent resonators 3 along the transverse axis y, connected by a transverse iris 4, between the roof face 36 of one resonator and the roof 36 of the other. The iris 4 is formed in this case by the intersection of the two roof faces 35 of one resonator and the roof face 36 of the adjacent resonator; its cross-section is thus rectangular, and its upper edge is formed by the edge at the intersection of the two roof faces. This edge is advantageously non-straight, the roofs of each cavity being higher at the longitudinal center of the cavity, which facilitates the additive impression of the thus arched edge.

[0082] THE figures 11a and 11b They illustrate two adjacent resonators 3 along the longitudinal axis x and connected by a longitudinal iris 4, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator. In this example, the iris 4 has a triangular cross-section in the transverse plane yz.

[0083] THE figures 12a and 12b They illustrate two adjacent resonators 3 along the longitudinal axis x and connected by a longitudinal iris 4, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator. In this example, the iris 4 has a cross-section in the transverse plane yz in the shape of a quadrilateral, for example a square or a rhombus.

[0084] THE figures 13a and 13b illustrate two adjacent resonators 3 in the longitudinal axis x and connected to each other by two irises 4 in the form of oblong slits, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator.

[0085] THE figures 14a and 14bThey illustrate two adjacent resonators 3 along the longitudinal axis x and connected by a longitudinal iris 4, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator. In this example, the iris 4 has a triangular cross-section in the transverse plane yz at the apex of the intersection between the two cavities, this triangle being defined by an obstacle 40 between the two cavities, here a trapezoidal transverse striation extending from the plane of the base 34 of the two resonators 3.

[0086] THE figures 15a and 15billustrate two adjacent resonators 3 along the longitudinal axis x and connected by a longitudinal iris 4, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator. In this example, the iris 4 has a trapezoidal cross-section in the transverse plane yz extending from the base of the intersection between the two cavities, this trapezoid being defined by an obstacle 40 between the two cavities, here a transverse striation of triangular cross-section extending from the edge of the roof of the two resonators 3.

[0087] THE figures 16a and 16b They illustrate two resonators 3 of different shape and / or cross-section, adjacent along the longitudinal axis x and connected by a longitudinal iris 4, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator. In this example, the iris 4 has a triangular cross-section in the transverse plane yz.

[0088] THE figures 17a and 17billustrate two resonators 3 of different shape and / or cross-section, adjacent along the longitudinal axis x and connected by a longitudinal iris 4, between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator. In this example, the iris 4 has a quadrilateral cross-section in the transverse plane yz.

[0089] THE figures 18a and 18b illustrate two resonators 3 of different shape and / or cross-section, adjacent in the longitudinal axis x and connected to each other by two longitudinal irises 4 forming two elongated slits between the vertical wall 31 of one resonator and the wall 32 of the adjacent resonator.

[0090] The filters described above have two adjacent resonators. A comb waveguide filter, however, can have more than two resonators, for example, at least four, eight, or more. These resonators can be placed side-by-side in the longitudinal x-direction and / or in the transverse y-direction to make the best use of the available volume and create a compact comb filter.

[0091] THE figures 19a to 19c They illustrate four resonators 3 arranged in two rows of two resonators each. The two resonators in each row are connected to each other by transverse irises 4, here irises with a rectangular cross-section. The two rows are connected to each other by a longitudinal iris, here an iris with a square or rectangular cross-section 4.

[0092] Other types of transverse irises can be provided between resonators in the same row. Other longitudinal irises can be provided between different rows.

[0093] It is also possible to plan for several irises between two adjacent rows of a filter 1.

[0094] It is possible to provide longitudinal irises of different sections within the same filter.

[0095] It is possible to incorporate transverse irises of different sections within the same filter.

[0096] THE figures 20a to 20c They illustrate four resonators 3 arranged in two rows of two resonators each. The two resonators in each row are connected to each other by transverse irises 4, here irises with a rectangular cross-section. The two rows are connected by each other by a first longitudinal iris with a triangular cross-section and by a second iris 4 with a quadrilateral cross-section.

[0097] Figures 21a to 21c illustrate a filter comprising eight resonators 3 arranged in four rows of two resonators each. The two resonators in each row are connected by transverse irises 4, here rectangular in cross-section. The different rows are connected by irises offset along the y-axis. In this example, the longitudinal irises 4 all have the same cross-section, here a quadrilateral. Irises with different cross-sections can be used, for example, slit or triangular irises. Irises of different shapes can be combined in the same filter.

[0098] THE figures 22a to 22billustrate a filter comprising eight resonators 3 arranged in four rows of two resonators each. The two resonators in each row are connected to each other by transverse irises 4, here irises with a rectangular cross-section. Adjacent rows are connected to each other by several irises, here by irises of different cross-sections, here by a triangular iris and another iris with a quadrilateral cross-section.

[0099] THE figures 23a to 23c illustrate a filter comprising eight resonators 3 arranged in two rows of four resonators each. The two resonators in each row are connected to each other by transverse irises 4, here irises with a rectangular cross-section. The adjacent rows are connected to each other by several irises, here by irises of different cross-sections, here by two triangular irises and two other irises with a quadrilateral cross-section.

[0100] There figure 25Figure 3 illustrates a resonator 3 equipped with holes 37 formed with the resonator by additive manufacturing, intended to allow chemical cleaning of the cavity 30 inside the resonator by injecting a liquid through these holes after additive manufacturing. Such holes can be provided with all the resonator and filter models described.

[0101] There figure 26This illustrates a filter comprising eight resonators 3 connected by longitudinal irises. Each iris has a screw 39 extending from its upper face and penetrating it to adjust the filter's bandwidth. Inserting the screw 39 deeper increases the filter's bandwidth. The filter is monolithically constructed, with all the resonators forming a single piece. Only the input 51 and output 52 ports are machined on flanges 6 made from subtractive metal and bonded to both ends of the filter. These flanges 6 are fitted with a connector 60 for a coaxial cable.

[0102] The height of the resonators can be between 8 and 15 mm. Their width along the transverse x-axis can be between 15 and 30 mm. Their length can be between 10 and 18 mm. The diameter of the chemical cleaning holes 37 is advantageously less than 2 mm. The frequency adjustment screws 38 can have a diameter between 2 and 5 mm, for example, between 3 and 4 mm. The bandwidth adjustment screws 39 can have a diameter between 1.5 and 2.5 mm, for example, 2 mm. The cutoff frequency can be between 8 and 30 GHz, with a bandwidth between 100 and 300 MHz.

[0103] The description above presents various resonators equipped with one or more input ports, various resonators equipped with one or more irises of different types, and various resonators without an input port or irises. These different aspects can be combined. For example, a resonator of any shape, such as one of the shapes described above, can be associated with an iris or a set of irises of any of the types described above, and / or with an input port or an output port. Resonators of different shapes and sizes can be combined in the same waveguide.

[0104] A typical comb-guided filter comprises a resonator with an input port and at least one iris, a resonator with an output port and at least one iris, and several resonators connected, for example, in series or by forming series-parallel circuits between the resonator with the input port and the resonator with the output port, the resonators being connected to each other by longitudinal and / or transverse irises. Reference numbers used in the figures

[0105] 1 Comb waveguide filter 3 Resonator 30 Cavity 31 Wall 32 Wall 33 Pole 34 Base 35 Roof panel 36 Roof panel 350 Curved surface 360 ​​Curved surface 361 Curved surface 37 Conduit 38 Cutoff frequency adjustment screw 39 Bandwidth adjustment screw 4 Iris 40 Obstacle 51 Input port 52 Output port 6 Flange 60 Connector PPrinting direction SPrinting support xLongitudinal axis yTransverse axis zVertical axis

Claims

1. Combline waveguide filter (1) obtained by additive printing of metal, comprising at least two resonators (3) connected together by irises, each resonator (3) comprising a cavity (30) with a longitudinal axis (x), a transverse axis (y) and a vertical axis (z), each cavity (30) being delimited in particular by two walls (31, 32) each extending in a plane perpendicular to the longitudinal axis, characterised in that the cross-section of said cavities is substantially triangular and in that each cavity comprises a post (33) extending parallel to the vertical axis within the cavity.

2. Combline waveguide filter according to claim 1, each cavity (30) comprising a base (34) perpendicular to the vertical axis and substantially flat and a roof (35, 36) above said base, said roof having no flat surface parallel to said base.

3. Comb waveguide filter according to claim 2, said post (33) being formed integrally with said base (34) of the corresponding cavity (30).

4. Combline waveguide filter according to one of claims 2 to 3, said roof comprising exactly two sides (35, 36) formed by oblique faces connecting said walls (31, 32) and inclined relative to said base (34).

5. Combline waveguide filter according to one of claims 2 to 4, said roof comprising several flat sides (35, 36) connected to each other and to the base (34) by curved surfaces (350, 360, 361).

6. Combline waveguide filter according to one of claims 1 to 5, said cross-section being variable in the longitudinal direction (x).

7. Combline waveguide filter according to one of claims 1 to 6, at least two cavities (30) adjacent in the longitudinal direction (x) being connected to each other by a said iris (4).

8. Combline waveguide filter according to claim 7, the cross-section of said iris (4) being triangular.

9. Waveguide filter according to one of claims 1 to 8, at least two cavities (30) adjacent in the transverse direction (y) being connected to each other by a said iris (4).

10. Combline waveguide filter according to claim 9, said iris (4) having a rectangular cross-section whose upper edge is formed by the intersection of two sides (35, 36) of two cavities (30).

11. Combline waveguide filter according to one of claims 1 to 10, at least one cavity (30) being provided with an adjustment screw (38) extending vertically above the post (33) in order to adjust the cut-off frequency of the corresponding resonator.

12. Combline waveguide filter according to one of claims 1 to 11, at least one iris (4) being provided with an adjustment screw (39) in order to adjust the filter bandwidth.

13. Combline waveguide filter according to one of claims 1 to 12, said cavities (30) and said irises (4) being monolithically constructed.

14. Method of manufacturing a combline waveguide filter according to one of the preceding claims, comprising the additive manufacturing of said resonators (3) by superimposing layers extending in planes perpendicular to the vertical axis (z, P).

15. Method according to claim 14, comprising machining a flange (6) provided with an inlet port (51) and a flange (6) provided with an outlet port (52), and bonding said flanges to said resonators (3).