Dielectric Filter Unit and Dielectric Filter

Abstract

The present application discloses a dielectric filter unit and a dielectric filter, the dielectric filter unit including a first dielectric resonant cavity and a second dielectric resonant cavity, the first dielectric resonant cavity having a first frequency hole at an upper end surface or a lower end surface, the second dielectric resonant cavity being connected to the first dielectric resonant cavity and having a second frequency hole at an upper end surface or a lower end surface, a coupling slot being provided at a connection portion between the first dielectric resonant cavity and the second dielectric resonant cavity, and a third frequency hole being further provided at a connection portion between the first dielectric resonant cavity and the second dielectric resonant cavity.

Description

Technical Field

[0001] This application is filed based on a Chinese patent application with an application number of 202111130983.7 and a filing date of September 26, 2021, claims the priority of the Chinese patent application, and incorporates all the contents of the Chinese patent application by reference into this application.

[0002] This application relates to the field of communication devices, and particularly to a dielectric filter unit and a dielectric filter.

Background Art

[0003] Using the theory that the wavelength of electromagnetic waves can be shortened when propagating in a high-permittivity material, instead of using conventional metal materials, a dielectric material can be used to reduce the volume of the filter under the same specifications. The research on dielectric filters has been attracting attention in the conventional communication industry. Filters are important components of wireless communication products, and dielectric filters are particularly important for the miniaturization of communication products.

[0004] A dielectric filter is usually composed of a plurality of resonant cavities. The more the number of resonant cavities, the higher the order of the filter, so the suppression performance is better. However, in many cases, the volume of the dielectric filter also becomes larger. Conventional general dielectric filters cannot simultaneously meet the requirements in many aspects such as volume, multiple resonance modes, and suppression performance.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of this application is to solve at least one of the technical problems existing in the prior art and provide a dielectric filter unit and a dielectric filter.

Means for Solving the Problems

[0006] In a first aspect, an embodiment of this application provides a dielectric filter unit, and the dielectric filter unit includes A first dielectric resonance cavity provided with first frequency holes on its upper end face or lower end face, A second dielectric resonance cavity connected to the first dielectric resonance cavity and provided with second frequency holes on its upper end face or lower end face, wherein a coupling slot is provided at the connection portion between the first dielectric resonance cavity and the second dielectric resonance cavity, and a third frequency hole is further provided at the connection portion between the first dielectric resonance cavity and the second dielectric resonance cavity.

[0007] In a second aspect, an embodiment of the present application provides a dielectric filter including two or more of the dielectric filter units described in the embodiment of the first aspect above.

[0008] Other features and advantages of the present application will be described in the following specification, will be partially revealed from the specification, or will be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained by the configurations specifically pointed out in the specification, claims, and drawings. The accompanying drawings provide a further understanding of the technical solution of the present application, constitute a part of the specification, and are used together with the embodiments of the present application to interpret the technical solution of the present application, and do not constitute a limitation to the technical solution of the present application. In the following, the present application will be further described in combination with the drawings and embodiments.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0010] This section details the specific embodiments of the present application. The accompanying drawings show the preferred embodiments of the present application. The role of the drawings is to supplement the written description in the specification with graphics, enabling an intuitive and specific understanding of each technical feature and the overall technical solution of the present application. However, it should not be understood as a limitation to the protection scope of the present application.

[0011] In the description of this application, "several" means one or more, "plural" means two or more, and expressions such as "greater than", "less than", and "exceeding" are understood not to include the reference number, while "greater than or equal to", "less than or equal to", and "within" are understood to include the reference number. When "first" and "second" are mentioned, it is only for distinguishing technical features and should not be understood as presenting or implying relative importance, or implicitly specifying the number of presented technical features, or implicitly specifying the context of technical features.

[0012] In the description of this application, unless otherwise clearly defined, terms such as "installation", "mounting", and "connection" should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meaning of the above terms in this application in combination with the specific content of the technical means.

[0013] Using the theory that the wavelength of electromagnetic waves can be shortened when propagating in a high dielectric constant material, a dielectric material can be used instead of the conventional metal material to reduce the volume of the filter under the same indicators. The research on dielectric filters has been attracting attention in the conventional communication industry. Filters are important components of wireless communication products, and dielectric filters are particularly important for the miniaturization of communication products.

[0014] Cross coupling is significant in that when electromagnetic waves pass through different coupling paths, the phase and polarity are reversed, resulting in an infinitesimal notch point, i.e., a transmission zero point, outside the filter's passband. This can improve the out-of-band rejection ability of the filter without increasing the number of cavities.

[0015] Out-of-band zeros occur on both sides or one side of the high and low frequency sides of the operating passband of the filter. When the out-of-band zeros are on both sides of the filter passband, their strengths, i.e., the frequency distances from the passband, are different. The above-described characteristics require that the design can be flexibly adjusted according to specific out-of-band rejection index requirements.

[0016] A dielectric filter is usually composed of a plurality of resonant cavities. The larger the number of resonant cavities, the higher the order of the filter, and thus the better the suppression performance. However, in many cases, the volume of the dielectric filter also becomes larger. Conventional general dielectric filters cannot simultaneously satisfy various requirements such as volume, multi-resonance mode, and suppression performance.

[0017] Embodiments of the present invention provide a dielectric filter unit and a dielectric filter that can simultaneously achieve miniaturization, multi-resonance mode, and generation of out-of-band transmission zeros.

[0018] Hereinafter, the embodiments of the present application will be further described in connection with the accompanying drawings.

[0019] Referring to FIGS. 1 to 3, FIG. 1 is a perspective view of a dielectric filter unit provided by an embodiment of the first aspect of the present application, FIG. 2 is a plan view of a dielectric filter unit provided by an embodiment of the present application, and FIG. 3 is a front view of a dielectric filter unit provided by an embodiment of the present application. The dielectric filter unit provided by an embodiment of the present application includes a first dielectric resonant cavity 100 and a second dielectric resonant cavity 200.

[0020] The first dielectric resonant cavity 100 is provided with a first frequency hole 110 on its upper end face or lower end face.

[0021] The second dielectric resonant cavity 200 is connected to the first dielectric resonant cavity 100. The second dielectric resonant cavity 200 is provided with a second frequency hole 210 on its upper end face or lower end face. A coupling slot 300 is provided at the connection portion between the first dielectric resonant cavity 100 and the second dielectric resonant cavity 200. A third frequency hole 400 is further provided at the connection portion between the first dielectric resonant cavity 100 and the second dielectric resonant cavity 200.

[0022] The dielectric filter unit includes a first dielectric resonance cavity 100 and a second dielectric resonance cavity 200. Since a coupling slot 300 is provided between the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200, a certain amount of coupling occurs between the two resonance cavities. In addition, a third frequency hole 400 is provided at the connection part between the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200. Since there is cooperation between the third frequency hole 400 and the coupling slot 300, the third resonance mode is excited within the double-cavity structure. Thereby, the dielectric filter can achieve the performance of a third-order filter and generate out-of-band transmission zeros by utilizing only the physical forms and volume dimensions of the two cavities, and has high debuggability and productivity.

[0023] In the embodiments shown in FIGS. 1 to 3, it can be seen that the opening of the third frequency hole 400 faces the side surface of the dielectric filter unit. Note that the opening of the third frequency hole 400 may face the upper end surface or the lower end surface of the dielectric filter unit, may face the connection part between the upper end surface and the side surface of the dielectric filter unit, or may face the connection part between the side surface and the lower end surface of the dielectric filter unit. As long as the cooperation between the third frequency hole 400 and the coupling slot 300 is ensured and the third resonance mode can be excited within the double-cavity structure, the opening of the third frequency hole 400 may face different positions.

[0024] Note that the shapes of the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200 may be polygons or irregular-shaped cubes. In this embodiment, both the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200 are rectangular parallelepipeds.

[0025] As shown in FIG. 1, the first frequency hole 110 is a frequency blind hole formed by being recessed from the upper end surface of the first dielectric resonance cavity 100 into the interior. Similarly, the second frequency hole 210 is a frequency blind hole formed by being recessed from the upper end surface of the second dielectric resonance cavity 200 into the interior. There is a coupling slot 300 between the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200, and the coupling slot 300 functions to form a coupling window so that a certain amount of coupling occurs between the two resonance cavities. Further, a third frequency hole 400 is formed by being recessed from the side surface of the dielectric filter unit into the interior. The third frequency hole 400 is located between the two cavities, and the entire outer surface of the dielectric filter unit including the plane, holes, and slots of the outer surface is all metallized. It is also possible to remove the metallization of some regions during debugging.

[0026] The first frequency hole 110 and the second frequency hole 210 are located on the same end surface of the dielectric filter unit. For example, they are both located on the upper end surface or the lower end surface of the dielectric filter unit. As in the embodiments of FIGS. 1 to 3, the first frequency hole 110 and the second frequency hole 210 are both located on the upper end surface of the dielectric filter unit. That is, the first frequency hole 110 is located on the upper end surface of the first dielectric resonance cavity 100, and the second frequency hole 210 is located on the upper end surface of the second dielectric resonance cavity 200. The first frequency hole 110 and the second frequency hole 210 are both blind holes formed by being recessed from the surface into the interior, and are used to generate and tune the frequency of the resonance cavity.

[0027] Note that the first frequency hole 110 and the second frequency hole 210 may be located on different end surfaces of the dielectric filter unit. That is, the first frequency hole 110 and the second frequency hole 210 may be located on the upper end surface and the lower end surface of the dielectric filter unit, respectively. For example, referring to FIG. 4, when the first frequency hole 110 is located on the upper end surface of the first dielectric resonance cavity 100 and the second frequency hole 210 is located on the lower end surface of the second dielectric resonance cavity 200, it functions to invert the transmission phase and switch the transmission zero point between the high-frequency side and the low-frequency side of the filter passband.

[0028] In addition, when the first frequency hole 110 and the second frequency hole 210 are located on different end faces of the dielectric filter unit, a fourth frequency hole may be further provided in the dielectric filter unit. The fourth frequency hole is provided on the other end face of the first dielectric resonance cavity, which is opposite to the end face where the first frequency hole is located, or on the other end face of the second dielectric resonance cavity, which is opposite to the end face where the second frequency hole is located. In the embodiment shown in FIG. 4, a fourth frequency hole 220 is further provided on the upper end face of the second dielectric resonance cavity 200. By adding the fourth frequency hole 220, the ease of debugging can be improved.

[0029] The first frequency hole 110, the second frequency hole 210, and the fourth frequency hole 220 are all turned holes, and their cross-sectional shapes may be circular, rectangular, regular polygonal, or irregular polygonal.

[0030] In addition, the coupling slot 300 is located in the region between the two dielectric resonance cavities. The coupling slot 300 may be a through slot that penetrates the upper end face and the lower end face of the dielectric filter unit, or a blind slot that does not penetrate. Also, the number of coupling slots 300 in one dielectric filter unit may be only one, or two or more. In the embodiments shown in FIGS. 1 to 3, one coupling slot 300 is provided, and in the embodiment shown in FIG. 5, two coupling slots 300 are provided.

[0031] Furthermore, the coupling slot 300 may be in a form where the edge is locally open with respect to the dielectric filter unit, or may be in a form completely embedded within the dielectric filter unit. In the embodiment shown in FIG. 6, a form where the coupling slot 300 is embedded within the dielectric filter unit is shown, that is, the coupling slot 300 is located inside the connection part between the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200. On the other hand, in the embodiment shown in FIG. 1, a form where the edge of the coupling slot 300 is locally open is shown, that is, the coupling slot 300 is located at the edge of the connection part between the first dielectric resonance cavity 100 and the second dielectric resonance cavity 200. Here, the cross-sectional shape of the coupling slot 300 may be circular, rectangular, regular polygon, or irregular polygon.

[0032] Referring to FIGS. 1 and 6, the third frequency hole 400 is a recessed hole formed by recessing from the side surface of the dielectric filter unit to the inside. The cross-sectional shape of the third frequency hole 400 may be circular, rectangular, regular polygon, or irregular polygon. Note that the center line of the third frequency hole 400 may be perpendicular to the side surface of the dielectric filter unit, or may not be perpendicular to the side surface of the dielectric filter unit. When the center line of the third frequency hole 400 is not perpendicular to the side surface of the dielectric filter unit, the center line of the third frequency hole 400 forms an acute angle with the side surface of the dielectric filter unit. FIGS. 7 and 8 are respectively a plan view and a front view of the dielectric filter unit when the center line of the third frequency hole 400 is not perpendicular to the side surface of the dielectric filter unit. As can be seen from the drawings, it can be understood that the horizontally projected area of the third frequency hole 400 completely or partially overlaps with the horizontally projected area of the coupling slot 300. Here, the coupling window 310 in FIGS. 7 and 8 is the projected area of the coupling slot 300 on the horizontally dielectric filter unit, and the third frequency hole 400 is located on the coupling window 310, that is, the third frequency hole 400 has an area 410 that completely or partially overlaps with the coupling window 310.

[0033] When the number of coupling slots 300 is greater than 1, the coupling window 310 refers to the sum of the projection areas of all the coupling slots 300. Also, when there is an area where the projection areas of any two coupling slots 300 do not overlap, the coupling window 310 includes the non-overlapping area between the projection areas.

[0034] Note that the number of the third frequency holes 400 in the dielectric filter unit may be only one, as shown in FIG. 1. The number of the third frequency holes 400 in the dielectric filter unit may be more than one, that is, two or more third frequency holes 400 may be provided. When two or more third frequency holes 400 are provided, the horizontal projection area of each third frequency hole 400 completely or partially overlaps with the horizontal projection area of the coupling slot 300.

[0035] Referring to FIG. 3, the third frequency hole 400 is on the side surface of the dielectric filter unit. In the figure, D is the distance between the center point of the cross section of the third frequency hole 400 and the upper end surface of the dielectric filter unit. The dielectric filter unit can adjust the transmission zero point by adjusting the distance D. Referring to FIG. 2, in the figure, B is the horizontal depth of the coupling slot 300. The dielectric filter unit can flexibly adjust the position of the transmission zero point by adjusting the depth B of the coupling slot 300. In FIG. 2, C is the distance between the bottom of the third frequency hole 400 and the coupling slot 300. The dielectric filter unit can flexibly adjust the frequency of the third mode by adjusting the distance C.

[0036] Note that the dielectric of the dielectric filter unit is a material having a certain dielectric constant, such as ceramics with a dielectric constant of 20, 40, 60, etc. The dielectric of the dielectric filter unit may use one material or may use a mixture of materials with different dielectric constants.

[0037] In addition, an embodiment according to the second aspect of the present application provides a dielectric filter including two or more dielectric filter units of the embodiment of the first aspect described above. As shown in FIG. 9, FIG. 9 shows a design example of a dielectric filter including two dielectric filter units of the embodiment of the first aspect described above. This only shows one of the entire dielectric filter products realized using the dielectric filter unit of the present application. By cascading a plurality of such dielectric filter units, filters of different orders, different topologies, different modes, and different materials may be configured.

[0038] The generation of the transmission zero point of the dielectric filter is to block the signal at a specific frequency outside the passband by causing the cross-coupling path of non-adjacent cavities to superpose with the signal of the main coupling path in the opposite phase, thereby generating a theoretically infinitesimal notch point, that is, a transmission zero point.

[0039] Referring to FIG. 11, FIG. 11 shows a CT dipole structure composed of three general cavities. The signal transmission paths are two, namely 1→2→3 and 1→3 respectively. The opposite phases of the two paths are superposed to generate a zero point. The symbol + represents a positive coupling (inductive coupling), and the symbol - represents a negative coupling (capacitive coupling). Due to the positive coupling between signal transmission paths 1→3, as shown in FIG. 12, it is determined that the filter transmission zero point is located on the high-frequency side of the passband. Due to the negative coupling between signal transmission paths 1→3, as shown in FIG. 13, it is determined that the filter transmission zero point is located on the low-frequency side of the passband.

[0040] In the realization of the physical structure, as shown in FIG. 10, there is a cooperation between the third frequency hole 400 and the coupling slot 300 in the dielectric filter unit provided by this embodiment, and the third operation mode, that is, the mode shown as 2 in the figure, is excited within the double-cavity structure. Under this specific structure, the three modes complete the coupling structure of the CT dipole shown in FIG. 11 above.

[0041] According to the dielectric filter unit provided by the embodiment of the present application, without increasing the volume, a third resonance mode is generated, that is, by adding one more stage of resonance cavity, the out-of-band suppression performance of the filter's transmission response is improved. Alternatively, the volume can be significantly reduced while maintaining the number of cavities. Since the dielectric filter unit generates transmission zeros, the out-of-band suppression performance of the filter's transmission response is further improved. The third resonance mode of the dielectric filter unit can be independently adjusted, and the generated transmission zeros can also be independently adjusted, so the productivity is very high. The quality factor Q value of the dielectric filter unit does not decrease due to the generation of the third resonance mode. The processing and shaping of the dielectric filter unit are easy, and for the same order, the material cost is lower and it is lighter.

[0042] The embodiment of the present application includes a dielectric filter unit and a dielectric filter. According to the solution provided by the embodiment of the present application, the dielectric filter unit includes a first dielectric resonance cavity and a second dielectric resonance cavity. Since a coupling slot is provided between the first dielectric resonance cavity and the second dielectric resonance cavity, a certain amount of coupling occurs between the two resonance cavities. In addition, a third frequency hole is provided at the connection part between the first dielectric resonance cavity and the second dielectric resonance cavity. Since there is cooperation between the third frequency hole and the coupling slot, the third resonance mode is excited within the double-cavity structure. Thereby, the dielectric filter utilizes only the physical forms and volume dimensions of the two cavities to realize three transmission modes, so that while achieving the performance of a third-order filter, it can generate out-of-band transmission zeros and has high debuggability and productivity. Miniaturization, multiple resonance modes, and the generation of out-of-band transmission zeros can be realized simultaneously.

[0043] As described above, the embodiments of the present application have been described in detail in combination with the accompanying drawings. However, the present application is not limited to the above embodiments, and various changes can be made without departing from the gist of the present application within the scope of the knowledge possessed by those skilled in the art.

Claims

1. A dielectric filter unit, comprising: The dielectric filter unit includes: a first dielectric resonance cavity having a first frequency hole provided on an upper end face or a lower end face; a second dielectric resonance cavity connected to the first dielectric resonance cavity and having a second frequency hole provided on an upper end face or a lower end face, wherein a coupling slot is provided at a connection portion between the first dielectric resonance cavity and the second dielectric resonance cavity, and a third frequency hole is further provided at the connection portion between the first dielectric resonance cavity and the second dielectric resonance cavity; and a dielectric filter unit, wherein a center line of the third frequency hole is perpendicular to a side surface of the dielectric filter unit or forms an acute angle with the side surface of the dielectric filter unit.

2. An opening of the third frequency hole faces an upper end face of the dielectric filter unit, a side surface of the dielectric filter unit, a lower end face of the dielectric filter unit, a connection portion between the upper end face and the side surface of the dielectric filter unit, or a connection portion between the side surface and the lower end face of the dielectric filter unit. The dielectric filter unit according to Claim 1.

3. The coupling slot is a through slot penetrating the upper end face and the lower end face of the dielectric filter unit or a blind slot that does not penetrate. The dielectric filter unit according to Claim 1.

4. The coupling slot is located inside a connection portion between the first dielectric resonance cavity and the second dielectric resonance cavity or at an edge of the connection portion between the first dielectric resonance cavity and the second dielectric resonance cavity. The dielectric filter unit according to Claim 1.

5. Two or more coupling slots are provided. The dielectric filter unit according to Claim 1.

6. The first frequency hole and the second frequency hole are located on the same end face of the dielectric filter unit. The dielectric filter unit according to Claim 1.

7. The first frequency hole and the second frequency hole are located on different end faces of the dielectric filter unit. The dielectric filter unit according to Claim 1.

8. A fourth frequency hole is provided on another end face of the first dielectric resonance cavity opposite to an end face where the first frequency hole is located, or a fourth frequency hole is provided on another end face of the second dielectric resonance cavity opposite to an end face where the second frequency hole is located. The dielectric filter unit according to claim 7.

9. The first frequency hole, the second frequency hole, and the third frequency hole are all turned holes. The dielectric filter unit according to claim 1.

10. The horizontally projected area of the third frequency hole completely or partially overlaps with the horizontally projected area of the coupling slot. The dielectric filter unit according to claim 1.

11. Two or more of the third frequency holes are provided. The dielectric filter unit according to claim 1.

12. The horizontally projected area of each of the third frequency holes completely or partially overlaps with the horizontally projected area of the coupling slot. The dielectric filter unit according to claim 11.

13. The cross-sectional shapes of the first frequency hole, the second frequency hole, the third frequency hole, and the coupling slot are circular, rectangular, regular polygonal, or irregular polygonal. The dielectric filter unit according to claim 1.

14. Including two or more of the dielectric filter units according to any one of claims 1 to 13. Dielectric filter.

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