Resonator with liquid crystal and compensation element, as well as a filter with such a resonator

Abstract

Resonator (2) for a filter, comprising: a resonator housing (4) in which a resonator chamber (6) is formed; a container (8) with a cavity (16) in which a liquid crystal (10) is received, wherein the container (8) is at least partially arranged in the resonator chamber (6); a compensation element (50) which is arranged in the cavity (16), wherein the compensation element has a coefficient of thermal expansion which is lower than a coefficient of thermal expansion of the liquid crystal; wherein the container (8) has a first longitudinal section (83) and a second longitudinal section (85), wherein the second longitudinal section (85) adjoins an opening (87) of the container and the first longitudinal section (83) adjoins the second longitudinal section (87); wherein a diameter (84) of the first longitudinal section (83) is smaller than a diameter (86) of the second longitudinal section (85),wherein the compensation element (50) is arranged in the second longitudinal section (85), wherein the second longitudinal section (85) is arranged completely outside the resonator space (6), wherein the compensation element (50) has a larger diameter than the first longitudinal section (83), and wherein the compensation element (50) has a smaller diameter than the second longitudinal section (85).

Description

TECHNICAL AREA

[0001] The present invention relates to a resonator, in particular a high-frequency resonator, and a filter comprising such a resonator. BACKGROUND

[0002] Resonators and filters can utilize a dielectric whose permittivity can be adjusted to define a resonant frequency or center frequency within the resonator. This is achieved using an electric control field generated by an electrode structure deposited over resistive layers on LTCC (low-temperature cofired ceramic). The LTCC, and thus the electrode structures, are mounted on the boundary walls of the cavity resonator.

[0003] When such resonators are used in satellites, they are subject to significant temperature fluctuations in space, sometimes exceeding 100 K. These temperature fluctuations can cause the components to expand or contract to different degrees due to their coefficients of thermal expansion. These differences can be compensated for, for example, by a compensation volume.

[0004] DE 10 2016 107 955 A1 and EP 3 240 102 A1 describe a resonator with a dielectric container which is filled with a liquid crystal. SUMMARY OF THE INVENTION

[0005] The object of the present invention is to provide an improved compensation for volume fluctuations of components in an adjustable resonator.

[0006] This problem is solved by the subject matter of the independent claim. Further developments of the invention are described in the dependent claims and in the following description.

[0007] According to one aspect, a resonator for a filter is specified. The resonator comprises a resonator housing, a container with a liquid crystal, and a compensation element. A resonator chamber is formed within the resonator housing. The container has a cavity in which a liquid crystal is held, with the container being at least partially located within the resonator chamber. The compensation element is arranged in the cavity of the container. The compensation element has a coefficient of thermal expansion that is lower than the coefficient of thermal expansion of the liquid crystal.

[0008] The container does not need to be completely located within the resonator chamber. It is sufficient if only a portion of the container is located within the resonator chamber. In particular, the container is positioned such that at least part of the liquid crystal is located within the resonator chamber. The container thus forms a dielectric that influences the resonator's resonant frequency.

[0009] The resonator housing can, for example, have a base section that is integrally formed with the side walls that define the resonator chamber, so that the resonator housing is at least partially cup-shaped. The open end of this structure can be closed by a lid, which then forms part of the resonator housing. These elements of the resonator housing can be made of the same material, such as metal. The resonator housing can have threaded holes into which mounting screws can be inserted to attach the lid.

[0010] The resonator chamber can have an inner wall, for example a cylindrical inner wall, which at least partially delimits the resonator chamber and extends around it. The inner wall can be interrupted by two aperture openings, or aperture openings can be provided in the inner wall.

[0011] An electrode configuration for generating an electrical control field can be arranged on the container.

[0012] Liquid crystal materials have a dielectric constant that can be controlled. This allows a filter, for example on a satellite in space, to be detuned at its center frequency if the resonators are (partially) filled with liquid crystal material. This is very advantageous. However, additional measures must be taken to compensate for the property of liquid crystals that they exhibit significant volume expansion with temperature.

[0013] The container is made of a specific material, and this material has a coefficient of thermal expansion. Similarly, the liquid crystal has a specific coefficient of thermal expansion. Typically, the coefficients of thermal expansion of the container and the liquid crystal differ. This means that the container and the liquid crystal expand or contract to different degrees under large temperature fluctuations. Typically, the liquid crystal has a higher coefficient of thermal expansion than the container. For example, when heated, the liquid crystal has a thermally induced linear expansion of 200 ppm / K. Furthermore, the liquid crystal is incompressible. The container material, for example, has a thermally induced linear expansion of 70 ppm / K. This means that with increasing temperatures, the pressure inside the container can rise significantly.To avoid damage to the container, a variable volume compensating device may be provided, wherein the compensating device is connected to the cavity of the container in such a way that liquid crystal can flow from the cavity of the container into the compensating device or vice versa when the volume of the liquid crystal changes due to thermal influences.

[0014] A compensating device requires a certain amount of installation space and must also be fluid-tightly connected to the cavity of the container. To eliminate the issues associated with the compensating device, it is proposed here to compensate for the difference in thermal expansion coefficients between the container and the liquid crystal using the compensating element.

[0015] The container is made of a material that is transparent to high-frequency electromagnetic fields, exhibits low losses in these fields, and is also characterized by low outgassing rates, making it suitable for aerospace applications. Such a material could be a cross-linked polystyrene, which is marketed, for example, under the name Rexolite.

[0016] The compensating element, like the liquid crystal, is positioned within the cavity of the container. However, the compensating element has a coefficient of thermal expansion that is lower, or even significantly lower, than that of the liquid crystal. Therefore, when the liquid crystal expands and occupies more volume due to rising temperatures, the compensating element expands to a lesser extent. This helps to keep the resulting internal pressure within the container at a lower level.

[0017] The compensation element occupies a certain volume within the cavity of the container. This allows for a further reduction in the amount of liquid crystal required. Furthermore, the amount of liquid crystal needed is reduced by eliminating the need for a compensating device, which would also have to be filled with liquid crystal.

[0018] According to one embodiment, the coefficient of thermal expansion of the compensation element is lower than the coefficient of thermal expansion of the container.

[0019] This means that the container expands as the temperature rises, thus increasing the volume of the cavity. The liquid crystal also expands as the temperature rises, but the compensating element has a lower coefficient of thermal expansion than both the container and the liquid crystal. The volume occupied by the compensating element within the container's cavity can remain nearly constant or change only slightly over a wide temperature range. The increased cavity volume resulting from the container's expansion can then be used exclusively by the liquid crystal. This compensates for the different coefficients of thermal expansion of the container and the liquid crystal.

[0020] According to a further embodiment, the container is rod-shaped and arranged in the resonator housing in such a way that the container projects into the resonator space from an inner wall of the resonator housing, with the compensation element being arranged in the cavity of the container in such a way that it is located outside the resonator space.

[0021] In other words, the liquid crystal should be located in the resonator chamber in order to be able to adjust the frequency of the resonator chamber, and the compensation element should not be located in the resonator chamber.

[0022] According to a further embodiment, the container has a first longitudinal section and a second longitudinal section, wherein the second longitudinal section adjoins an opening of the container and the first longitudinal section adjoins the second longitudinal section, wherein a diameter of the first longitudinal section is smaller than a diameter of the second longitudinal section.

[0023] The container is cylindrical or rod-shaped, and the cavity is a longitudinal depression extending from one end face towards the other. The cavity is therefore a blind hole with an opening at one end face of the container. Extending from this opening towards the bottom of the cavity, or towards the other end face, the cavity is divided into two longitudinal sections with different diameters. The first longitudinal section runs within the resonator chamber of the resonator.

[0024] According to another embodiment, the compensation element is arranged in the second longitudinal section.

[0025] Thus, the compensation element is located outside the resonator chamber. Conversely, the longitudinal section of the container that is filled solely with liquid crystal is located within the resonator chamber.

[0026] According to another embodiment, the second longitudinal section is arranged completely outside the resonator space.

[0027] This means that the longitudinal section of the container which extends into the resonator space has a constant cavity diameter across the extent of the resonator space.

[0028] According to another embodiment, the compensation element has a larger diameter than the first longitudinal section.

[0029] Therefore, the compensation element cannot move into the first longitudinal section, even if the compensation element is freely movable in the cavity of the container.

[0030] The compensation element can be a cylindrical body. However, the compensation element can also have other shapes, for example, cube-shaped or cuboid-shaped.

[0031] According to another embodiment, the compensation element has a smaller diameter than the second longitudinal section.

[0032] This allows the compensating element to move freely within the second longitudinal section of the cavity and does not exert pressure on an inner wall of the container. The compensating element can be dimensioned such that the diameter of the second longitudinal section (inner diameter of the cavity) is larger than the diameter of the compensating element (outer diameter) even when the container has shrunk to its smallest size at the lowest expected temperature.

[0033] According to another embodiment, the container has a lid, wherein the compensation element is arranged on an inside of the lid and projects into the cavity of the container.

[0034] This embodiment has the advantage that the compensating element is arranged immovably within the cavity. For example, the compensating element can be arranged on the lid such that it is centered with respect to a longitudinal axis of the container cavity.

[0035] The compensating element can be glued or otherwise attached to the inside of the lid. For example, the compensating element can be mechanically connected to the lid via a plug connection, clamp connection, or screw connection. Alternatively, the compensating element can also be positioned or attached to the inner wall of the cavity.

[0036] According to another embodiment, the lid is made of the same material as the container.

[0037] The lid serves to seal the container fluid-tight and prevent any leakage or escape of the liquid crystal. After the container cavity has been filled with the liquid crystal and the compensating element, the cavity is closed with the lid. Because the container and the lid are made of the same material, a simple joining technique can be used. In other words, no different materials need to be joined together at this point, as might be the case, for example, when using a compensating device.

[0038] The container and the lid can be joined together, for example, by means of a material-bonded connection with or without auxiliary material (welding, soldering, gluing).

[0039] According to another embodiment, the compensation element comprises quartz glass.

[0040] The compensation element can be made entirely of quartz glass. Quartz glass has a very low coefficient of thermal expansion, which can be in the range of 1 ppm / K.

[0041] An alternative material would be the metal Invar, which has a coefficient of thermal expansion still less than 2 ppm / K. It is also conceivable that two or more materials could be combined in the compensation element.

[0042] The approach described herein can be summarized in other words as follows:

[0043] The design involves placing a compensating element (also called a body, for example, a freely movable or floating body, or a body connected to part of the container) into a container filled with liquid crystal. This compensating element has a very low coefficient of thermal expansion. A step or change in the inner diameter of the container ensures that the compensating element does not enter areas of the container where it could interfere with the high-frequency properties of the resonator. The body could, for example, be made of fused silica. Fusing has a very low coefficient of thermal expansion of approximately 1 ppm / K. It is a material well-known in the aerospace industry. When this arrangement is heated, the liquid crystal occupies significantly less additional volume, as the absolute volume of the liquid crystal is reduced by the volume of the floating body.Furthermore, due to its very low coefficient of thermal expansion, the compensating element itself occupies almost no additional volume when the temperature increases. With suitable design (adjusting the volume of the floating body for a given internal volume of the container and for given coefficients of thermal expansion of the container, the liquid crystal, and the compensating element), it is possible to adjust the system so that no overpressure or underpressure occurs during temperature changes. In this case, it is no longer necessary to provide a flexible metal bellows (compensating device). Instead, the container can be closed off on the side where the metal bellows were attached by a simple wall (lid). If this wall is also made of the same material as the container, the joining technique is simplified, as only similar materials now need to be joined together.

[0044] According to another aspect, a filter is specified which has at least one resonator as described herein.

[0045] The filter can be an imux filter for a communications system on a communications satellite. The filter can be used in the high-frequency range, for example, in the range of several GHz to several tens of GHz, or in the frequency bands commonly used for satellite communications. List of characters Fig. Figure 1 shows a perspective sectional view of a resonator according to an exemplary embodiment; Fig. Figure 2 shows a schematic representation of a container for a resonator according to an exemplary embodiment; Fig. Figure 3 shows a schematic representation of a container for a resonator according to an exemplary embodiment; Fig. Figure 4 shows a schematic representation of a container for a resonator according to an exemplary embodiment; Fig. Figure 5 shows a schematic representation of a container for a resonator according to an exemplary embodiment; Fig. Figure 6 shows a schematic representation of a filter according to an exemplary embodiment. DETAILED DESCRIPTION OF AN EXAMPLE OF EXECUTION

[0046] An embodiment of the present invention is described below with reference to the figures. It should be noted that identical or similar elements in the figures are identified by the same reference numerals. The representations in the figures are schematic and not to scale.

[0047] Fig. Figure 1 shows a perspective cross-sectional view of a resonator 2 According to one exemplary embodiment. The sectional view is chosen such that the resonator is cut approximately vertically in the middle. However, the illustration is only schematic and serves to explain the design of the resonator. 2.

[0048] The in Fig. 1 shown resonator 2 features a resonator housing 4 on, which contains a resonator chamber 6 It features a resonator chamber in which the resonant frequency is adjustable. 6 In the illustrated embodiment, this is achieved by a floor surface. 30 limited and is furthermore constructed in such a way that the upper end of the resonator space 6 It can be closed by a suitable lid (not shown). For this purpose, the resonator housing contains 4 several threaded holes 36 , 38 , 40 , 42 provided, in which mounting screws for attaching the cover to the resonator housing 4 can be recorded. Furthermore, in the illustrated embodiment, the resonator chamber 6 through a cylindrical inner wall 14 limited, which surround the resonator space 6extends around and is only separated by two apertures. 32 , 34 is interrupted. These two apertures 32 , 34 qualify the resonator 2 according to the embodiment shown here for use in a filter. In this context, however, it should be mentioned that the design of the resonator housing 4 The setup is not limited to the one shown here. Depending on the application of the resonator, the resonator housing can also be used without the baffles. 32 or 34 and be designed in a different form. In other words, the resonator space does not have to be, for example, as in Fig. 1 shown, essentially cylindrical in shape.

[0049] To determine the resonator's resonant frequency 2 The resonator indicates that it can be adjusted. 2 according to the present embodiment, an electrically adjustable dielectric. 7on, which in the described case is in the form of a container 8 is provided for, in which a liquid crystal 10 is recorded. The container 8 In the illustrated embodiment, it is designed in a rod-like shape. In other words, the container has 8 a shape resembling a right circular cylinder. Furthermore, the container 8 made from a dielectric material.

[0050] As it is in Fig. As shown in 1, the container extends 8 in a substantially horizontal direction and in particular parallel to the ground surface 30 of the resonator housing 4 Furthermore, the container 8 arranged so that it is essentially perpendicular to the direction of extension of the two apertures 32 , 34 is oriented. Accordingly, one longitudinal axis of the container extends 8essentially perpendicular to the direction of extension of the two apertures 32 , 34 and parallel to the ground surface 30 of the resonator housing 4 The longitudinal axis of the container 8 This coincides with the axis of a circular cylinder. It should be noted that the container 8 It does not have to be completely cylindrical. Rather, the container can 8 for example on the right side in Fig. 1, i.e., outside the resonator housing 4 , may also have a shape other than a circular cylinder. The container must also 8 inside the resonator housing 4 It need not be in the form of a straight circular cylinder, but can have any conceivable shape which serves a function of the electrically adjustable dielectric. 7 ensures.

[0051] To use the electrically adjustable dielectric 7to be arranged in the manner described above, the resonator housing 4 in its inner wall 14 an opening 28 , in which the electrically adjustable dielectric 7 , especially the container 8 , is inserted and fastened in such a way that the front end of the electrically adjustable dielectric 7 from the inner wall 14 protrudes and into the interior 6 of the resonator 2 protrudes into the opening. 28 It has a shape that corresponds to the shape of the outer circumference of the electrically adjustable dielectric. 7 or of the container 8 is formed. In the embodiment shown, the opening 28 circular-cylindrical in shape, with the axis of extension of the opening 28 like the extension axis of the container 8 parallel to the ground surface 30and essentially perpendicular to the axes of extension of the apertures 32 , 34 is oriented. Furthermore, the opening 28 at a predetermined distance from the ground surface 30 arranged, whereby the container 8 at the in Fig. 1 shown structure from the floor area 30 is spaced apart. Although this is in Fig. 1 is not shown, the opening 28 also at a predetermined distance from an upper end of the inner wall 14 arranged so that the electrically adjustable dielectric 7 or its container 8 also at a predetermined distance from the upper end of the resonator housing 4 and is thus arranged at a predetermined distance from a lid (not shown), which is used to close the resonator housing. 4 is used. The container protrudes overall. 8 thus from the inner wall 14into the resonator chamber 6 that the one in the resonator chamber 6 located part of the container 8 of at least the floor area 30 and is spaced apart from the lid (not shown). However, in addition to the preferred configuration described above, a different arrangement of the container within the resonator housing is also possible. 4 This can be done as long as such an arrangement results in a change of the resonance frequency inside the resonator 2 made possible.

[0052] As further explained in Fig. As shown in 1, the electrically controllable dielectric 7 in addition to the container already described 8 the liquid crystal 10 , which is in a cavity 26 of the container 8 is recorded. The liquid crystal 10 It can be controlled by an electric control field. More precisely, the permittivity of the liquid crystal can be changed by applying an electric field. 10be affected. The cavity 26 of the container 8 It is also circularly cylindrical in shape, more precisely in such a way that the cylinder axes are located away from the containers. 8 and the cavity 26 collapse. The container 8 It therefore has, at least in sections, the shape of a hollow cylinder.

[0053] For the sake of completeness, an electrode structure is presented here. 12 with electrodes 18 , 22 It is shown, however, that the electrode structure and the electric control field it generates are not functionally related to the function of the compensation element. The electric control field can also be generated in a manner other than that described here, without this affecting the compensation of the different coefficients of thermal expansion by the compensation element.

[0054] Ultimately, the cavity16 of the container 8 a compensation element 50 shown. The compensation element 50 That's how it is in the cavity 16 positioned so that it is not in the longitudinal section of the container 8 is which is in the resonator chamber 6 protrudes. In other words, the compensating element is located there. 50 outside or behind the inner wall 14 .

[0055] In the event of temperature fluctuations, the materials of the components shown expand. The container 8 and the liquid crystal 10 They have different coefficients of thermal expansion due to their material properties. The compensation element 50 It has a coefficient of thermal expansion that is lower than the coefficient of thermal expansion of the container. 8 and also of the liquid crystal 10This allows for the different thermal expansion of containers. 8 and liquid crystal 10 can be compensated without the use of a compensating device.

[0056] Again Fig. The container can be removed from the first part; it is rod-shaped and the cavity 16 extends in the longitudinal direction of the container 8 In particular, the cavity 16 shaped like a circular cylinder. The container 8 is made of a dielectric material.

[0057] Overall, an improved electrically controllable dielectric and an improved resonator have been created, which are particularly suitable for high-frequency applications in space. For example, the resonator created here can be used as a high-frequency resonator in an imux filter. Furthermore, the container 8can be used in a closed state, since the compensation of temperature-related expansion is achieved via the compensation element. 50 This has been done.

[0058] Fig. Figure 2 shows a schematic isometric representation of the container. 8 The container 8 is with a lid 81 sealed. The lid 81 and the container 8 are preferably made from the same material.

[0059] Fig. Figure 3 shows a schematic representation of a container 8 with reference to the resonator housing 4 (shown with dashed lines). The container 8 It has a cavity inside. 16 which run from right to left along the longitudinal direction of the container 8 extends. The cavity 16A bore can extend from one end face (right in this example) towards the opposite end face (left in this example). Thus, there is an opening on the right side. 87 Through this opening 87 The liquid crystal can enter the cavity. 16 to be filled. Also into the cavity. 16 is the compensation element 50 arranged.

[0060] The container 8 is related to the resonator space 6 arranged so that a section of the container 8 into the resonator chamber 6 protrudes (this is the section to the left of the inner wall) 14 ). Another section of the container 8 extends through the resonator housing 4 (this is the section to the right of the inner wall) 14 ). The compensation element 50 is located in that section of the container 8 , which is to the right of the inner wall14 is. In other words, the compensation element is located 50 outside of the resonator chamber 6 .

[0061] In the example shown, the cavity 16 a volume of a few cubic millimeters. Even if in Fig. 3 of the lids 81 ( Fig. 2) if not shown, the lid is an integral part of this and other embodiments.

[0062] Fig. Figure 4 shows another embodiment of the container. 8 The cavity 16 is in a first longitudinal section 83 with an inner diameter 84 and a second longitudinal section 85 with an inner diameter 86 subdivided. The second longitudinal section 85 borders directly on the opening 87 . At the transition between the second longitudinal section 85 and the first longitudinal section 83 Is there a gradation? 82or a jump, because the inner diameter decreases at this transition.

[0063] The second longitudinal section 85 is located outside the resonator chamber 6 behind the inner wall 14 . Both the first longitudinal section 83 as well as the second longitudinal section 85 They have a constant inner diameter in the longitudinal direction (from left to right). Depending on the requirements of the resonator, the inner diameter of the first longitudinal section and / or the second longitudinal section can also vary in the longitudinal direction.

[0064] The compensation element 50 is in the second longitudinal section 85 to the right of the inner wall 14 and outside the resonator chamber 6 arranged. The gradation 82 Its function is the compensation element. 50 to prevent it from entering the first longitudinal section 83 the cavity 16or into the resonator chamber 6 to move.

[0065] The gradation 82 Viewed from the right, it has a support surface on which the compensation element rests. 50 It may happen that the compensation element 50 the first longitudinal section 83 the cavity 16 closes because the compensation element 50 on the contact surface of the step 82 If, in such a case, the temperature drops and the liquid crystal in the cavity... 16 Its volume is reduced, it can be located in the first longitudinal section 83 A negative pressure occurs when a flow movement of the liquid crystal from the second longitudinal section 85 in the first longitudinal section 83 is blocked. To prevent this, the contact surface of the step can be adjusted. 82have depressions or surface irregularities which can serve as flow channels for the liquid crystal and allow a flow movement of the liquid crystal between the first longitudinal section 83 and the second longitudinal section 85 under all circumstances.

[0066] Fig. Figure 5 shows a schematic side sectional view of a container. 8 The cavity 16 is with a lid 81 sealed. On an inner surface of the lid. 81 is the compensation element 50 arranged or attached.

[0067] Fig. Figure 6 shows a schematic representation of a filter. 100 The filter 100 indicates several resonators connected in series 2 on. Each resonator 2 It can be tuned to an individual resonant frequency. Such a filter can be used in a communication satellite's transmission path.

[0068] It should be further noted that "comprising" or "comprising" does not exclude other elements or steps, and that "a" or "an" does not exclude a plurality. It should also be noted that features or steps described with reference to one of the above embodiments or configurations may also be used in combination with other features or steps from other embodiments or configurations described above. Reference numerals in the claims are not to be considered as limitations. Reference symbol list 2 Resonator 4 resonator housings 6 Resonator chamber 7 adjustable dielectric 8 containers 10 Liquid crystal 12 Electrode structure 14 Interior wall 16 Cavity 18 electrode 22 electrode 26 Cavity 28 Opening 30 floor area 32 aperture 34 aperture 36 threaded holes 38 threaded holes 40 threaded holes 42 threaded holes 50 compensating bodies 81 lids 82 levels 83 first longitudinal section 84 diameter 85 second longitudinal section 86 diameter 87 Opening 100 filters QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102016107955 A1

[0004] EP 3240102 A1

[0004]

Claims

[1] Resonator (2) for a filter having a resonator: a resonator housing (4) in which a resonator chamber (6) is formed, a container (8) with a cavity (16) in which a liquid crystal (10) is received, wherein the container (8) is at least partially arranged in the resonator space (6), a compensation element (50) which is arranged in the cavity (16), where the compensation element has a coefficient of thermal expansion that is lower than the coefficient of thermal expansion of the liquid crystal. [2] Resonator according to claim 1, wherein the coefficient of thermal expansion of the compensation element is lower than the coefficient of thermal expansion of the container. [3] Resonator according to claim 1 or 2, wherein the container (8) is rod-shaped and is arranged in the resonator housing (4) such that the container projects into the resonator chamber (6) from an inner wall (14) of the resonator housing (4), wherein the compensation element (50) is arranged in the cavity (16) of the container (8) such that it is located outside the resonator space (6). [4] Resonator according to any one of the preceding claims, wherein the container (8) has a first longitudinal section (83) and a second longitudinal section (85), wherein the second longitudinal section (85) connects to an opening (87) of the container and the first longitudinal section (83) connects to the second longitudinal section (87), wherein a diameter (84) of the first longitudinal section (83) is smaller than a diameter (86) of the second longitudinal section (85). [5] Resonator according to claim 4, wherein the compensation element (50) is arranged in the second longitudinal section (85). [6] Resonator according to claim 4 or 5, wherein the second longitudinal section (85) is arranged completely outside the resonator space (6). [7] Resonator according to one of claims 4 to 6, wherein the compensation element (50) has a larger diameter than the first longitudinal section (83). [8] Resonator according to one of claims 4 to 7, wherein the compensation element (50) has a smaller diameter than the second longitudinal section (85). [9] Resonator according to any one of the preceding claims, wherein the container (8) has a lid (81), wherein the compensation element (50) is arranged on an inside side of the lid and projects into the cavity (16) of the container (8). [10] Resonator according to claim 9, wherein the lid (81) is made of the same material as the container (8). [11] Resonator according to one of the preceding claims, wherein the compensation element comprises quartz glass. [12] Filter (100) comprising at least one resonator according to any one of the preceding claims.

Images