Single-cavity resonance unit and filter

Abstract

Provided in the present application are a single-cavity resonance unit and a filter. The single-cavity resonance unit comprises a first dielectric body, a second dielectric body and a metal casing covering the outer surface of the second dielectric body; wherein the second dielectric body is of a cavity structure; the first dielectric body is located inside the cavity of the second dielectric body; and the dielectric constant of the first dielectric body is higher than the dielectric constant of a second dielectric resonant cavity, and the shape of the first dielectric body in a first direction is reciprocal to the shape thereof in a second direction, thereby forming dual-mode resonance. The filter comprises a plurality of the single-cavity resonance units arranged in cascade, the metal casing of each single-cavity resonance unit is provided with a coupling window used for carrying out resonance coupling with other single-cavity resonance units.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims priority to Chinese Patent Application No. 202310151978.7, filed on February 10, 2023, entitled "Single-cavity resonance unit and filter", the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present application relates to the technical field of filters, and in particular to a single-cavity resonance unit and a filter.BACKGROUD

[0003] In the field of communications, there is a lot of signal interference among spectra of different service providers, and thus a filter is usually needed to ensure normal work of a base station.

[0004] There are various filters applied to different frequency ranges and occasions at present, among which a dielectric filter is a typical one used in the field of communications. A dielectric filter is composed of dielectric resonance units in cascade. A dielectric resonance unit shortens electromagnetic waves passing through by means a dielectric material therein, and thus achieves microwave resonance.

[0005] The quality factor (Q value) refers to the ratio of inductive reactance to equivalent loss resistance thereof when a filter works at an AC voltage of a certain frequency. The higher the Q value of a filter, the smaller the loss and the higher the efficiency. With the progress of wireless technology, dielectric filters in the wireless communication system are becoming smaller in size, higher in performance and lower in cost.

[0006] At present, a traditional dielectric filter adopts a dielectric resonance unit structure of single cavity and single dielectric material. Compared with other types of filters (such as an air resonance filter), such structure can improve the dielectric constant by the dielectric material inside the cavity, and achieve the operating frequency by means of a smaller volume; however, there is no component of the electric field being formed in the propagation direction of electromagnetic waves inside the cavity, resulting in a distinct resistance effect of the electric field, high power consumption, and neglect of improvement of the Q value into account. Generally, the Q value of traditional dielectric filter is lower than those of other types of filters.

[0007] In view of this, how to improve the resistance effect generated by the electric field in a dielectric filter, and thus achieve the higher quality factor (Q value) by a smaller volume is a technical problem to be solved by the present application.SUMMARY

[0008] The objective of the present application is to provide a single-cavity resonance unit and a filter, which can solve the problem that a dielectric filter of a traditional structure causes high power consumption due to the resistance effect of the electric field.

[0009] In order to achieve the above-mentioned objective, the embodiments of the present specification are implemented as follows.

[0010] In a first aspect, there is provided a single-cavity resonance unit including a first dielectric body, a second dielectric body and a metal casing covering an outer surface of the second dielectric body; wherein the second dielectric body is of a cavity structure, the first dielectric body is located inside a cavity of the second dielectric body; and a dielectric constant of the first dielectric body is higher than a dielectric constant of the second dielectric body, and a shape of the first dielectric body in a first direction is reciprocal to a shape thereof in a second direction, thereby forming dual-mode resonance.

[0011] In a second aspect, an embodiment of the present application provides a filter including a plurality of single-cavity resonance units of the first aspect that are arranged in cascade, wherein a metal casing of each single-cavity resonance unit is provided with a coupling window used for carrying out resonance coupling with other single-cavity resonance units.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the drawings required for use in the description of the embodiments or the prior art will be briefly introduced below, obviously, the drawings described below are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art based on these drawings without involving creative work. FIG. 1 is a first schematic structural diagram of a single-cavity resonance unit in embodiments of the present application. FIG. 2 is a second schematic structural diagram of a single-cavity resonance unit in embodiments of the present application. FIG. 3 is a third schematic structural diagram of a single-cavity resonance unit in embodiments of the present application. FIG. 4 is a fourth schematic structural diagram of a single-cavity resonance unit in embodiments of the present application. FIG. 5 is a schematic structural diagram of a filter in embodiments of the present application. DETAILED DESCRIPTION

[0013] In order to enable those skilled in the art to better understand the technical solutions in the specification, technical solutions in embodiments of the application will be described clearly and thoroughly below with reference to the accompanying drawings in embodiments of the application. Obviously, the embodiments described are part of the embodiments of the specification rather than all of the embodiments. All other embodiments obtained by those skilled in the art without creative work based on embodiments in the present specification shall fall within the scope of the present specification.

[0014] As mentioned above, a traditional dielectric filter adopts a dielectric resonance unit structure of single cavity and single dielectric material. Compared with other types of filters (such as an air resonance filter), such structure can improve the dielectric constant by the dielectric material inside the cavity, and thus achieve the operating frequency by means of a smaller volume; however, there is no component of the electric field being formed in the propagation direction of electromagnetic waves inside the cavity, resulting in a distinct resistance effect of the electric field, high power consumption, and neglect of improvement of the Q value into account. Generally, the Q value of traditional dielectric filter is lower than those of other types of filters.

[0015] In view of this, the present application is intended to provide a single-cavity resonance unit that can achieve dual-mode resonance, and a filter formed by a plurality of the single-cavity resonance units in cascade, which can reduce the resistance effect caused by the electric field of the dielectric filter, thereby achieving a higher quality factor (Q value) with a smaller volume.

[0016] Referring to FIG. 1, FIG. 1 is a schematic structural diagram of a single-cavity resonance unit in embodiments of the present application, the single-cavity resonance unit includes a first dielectric body 1, a second dielectric body 2 of a cavity structure and a metal casing 3 covering an outer surface of the second dielectric body 2.

[0017] In an embodiment of the present application, the first dielectric body 1 is located inside a cavity of the second dielectric body 2, and the dielectric constant of the first dielectric body 1 is higher than the dielectric constant of the second dielectric body, such that the second dielectric body 2 forms a boundary effect relative to the first dielectric body 1 therein, and further the first dielectric body 1 is electrically floating (not grounded) so as to form a TE mode with full magnetic boundary (TE mode refers to a propagation mode in which the longitudinal component of the electric field is zero, while the longitudinal component of the magnetic field is non-zero in the propagation direction of electromagnetic waves). That is, the electric field is concentrated in the first dielectric body 1 with a high dielectric constant, and generates lower resistance effect with the second dielectric body 2 in the outside, thereby reducing the resonance loss, and increasing the Q value of the single-cavity resonance unit. It should be understood that the filter consists of a plurality of single-cavity resonance units in cascade, in the embodiments of the present application, after the Q value of the single-cavity resonance unit is increased, the Q value of the filter may be increased as well.

[0018] Further, a shape of the first dielectric body 1 in a first direction is reciprocal to a shape thereof in a second direction, i.e., the shapes of the first dielectric body in the first direction and the second direction are symmetrical or approximately symmetrical, thereby forming dual-mode resonance for electromagnetic waves in the first direction and the second direction. The first direction and the second direction may be two directions perpendicular to each other, for ease of understanding, as used herein, the first direction is defined as the X-axis direction of a coordinate system, and the second direction as the Y-axis direction of the coordinate system. In practical applications, the cross-sections of the first dielectric body 1 in the X-axis and Y-axis directions may be, but is not limited to, a regular polygon, a circle, a cross, or other shapes that are symmetrical with respect to the X- axis and the Y-axis.

[0019] Hereinafter, an exemplary introduction will be made by taking the cross-shaped cross-section for example.

[0020] Referring to FIG. 2, in an embodiment of the present application, the metal casing 3 is provided with coupling windows 211 and 221 used for carrying out resonance coupling with other single-cavity resonance units, after the plurality of single-cavity resonance units arranged in cascade, the resonance units cascaded with each other may implement resonance coupling by means of the coupling windows, thereby implementing filter effect. It should be noted that the coupling windows in the embodiments of the present application may be flexibly configured according to actual needs, and may be a rectangular structure, a circular structure, a cross-shaped structure, etc., or other irregular structures, which is not specifically limited here.

[0021] In some cases, the second dielectric body 2 in the present application comprises a first part 21 and a second part 22 that are independent of each other. The first part 21 and the second part 22 are bonded by means of a bonding layer 4 (adhesives such as solder paste, silver layer, etc.), and the metal casing 3 is disposed on non-bonded outer surfaces of the first part 21 and the second part 22. A groove structure that extends inwards is formed in the outer surface of the first part 21, the cross-section of the groove structure in an inward-extending direction matches the cross-section shape of the first dielectric body 1, and the cross-section of the groove structure in the inward-extending direction is larger than the cross-section of the first dielectric body 1. In this way, the first dielectric body 1 may be assembled in the groove structure 212 of the first part 21 before the first part 21 and the second part 22 are bonded, and then the first part 21 and the second part 22 are bonded by means of the bonding layer 4, so as to form the cavity of the second dielectric body 2.

[0022] With respect to the present application, the second dielectric body 2 may be integrally formed by injection molding, that is, the material of the second dielectric body 2 is filled into molds corresponding to the first part 21 and the second part 22, and molten metal is cast on the outer surface where a metal casing is to be formed. In addition, in the subsequent assembling process, it is only necessary to directly insert the first dielectric body 1 into the groove structure 212 whose shape matches the cross-section of the first dielectric body, and then close the first part 21 and the second part 22 by the bonding layer 4.

[0023] It can be seen that the single-cavity resonance unit structure based on the embodiments of the present application can achieve a simple assembly process without use of additional screws for tuning or fixing, which has a distinct advantage in cost control.

[0024] In addition, referring to FIG. 1, a blind-hole structure or a through-hole structure 213 may be further formed in the outer surface of the first dielectric body 1 and / or the first part 21 of the second dielectric body 2 (FIG. 1 illustrates a blind-hole structure in the first part 21, and the principle of the blind-hole structure in the first dielectric body 1 is the same and is not repeated in the figure), the through-hole structure 213 may be used to fine-tune the resonance effect of the single-cavity resonance unit, and the specific number and position of the structure may be flexibly configured according to actual needs.

[0025] With respect to the embodiments of the present application, the first dielectric body 1 is made of a pure dielectric material, the method of forming the blind-hole structure or through-hole structure 213 in the dielectric material is relatively simple, and no examples will be given herein. In addition, the first part 21 of the second dielectric body 2 is different from the first dielectric body 1 and needs to be covered with a metal casing 3, and thus, the blind-hole structure or the through-hole structure 213 may be formed during the injection molding process. Exemplarily, in the present application, after the material of the second dielectric body 2 is filled into the mold of the first part 21, a blocking rod for blocking casting may be further inserted into the material filled in the mold, and the blocking rod may be made of a wax material. Subsequently, molten metal is cast, such that the formed metal casing 3 has an opening at the position of the blocking rod. After casting, the blocking rod is further dewaxed, such that the blind-hole structure or through-hole structure 213 may be formed at the opening corresponding to the first part 21 of the metal casing 3. In addition, in the embodiments of the present application, a metal layer may be further formed on an inner surface of the blind-hole structure or the through-hole structure 213 according to actual tuning needs, that is, molten metal is further cast on the blind-hole structure or the through-hole structure 213, which will not be further described herein.

[0026] In addition, during work of the current resonance unit, a large amount of heat is generated by the first dielectric body 1 and the second dielectric body 2, and in order to avoid the first dielectric body 1 and the second dielectric body 2 from structural damage caused by thermal deformation, the single-cavity resonance unit in the embodiments of the present application may be further provided with a buffer layer 5 for releasing thermal stress. At least a portion of the first dielectric body 1 is separated from an inner surface of the groove structure 212 by means of the buffer layer 5, the buffer layer 5 may be an air layer (i.e., there is a gap between the first dielectric body 1 and the second dielectric body 2), or may be made of a colloidal material, wherein the dielectric constant of the colloidal material is different from that of the first dielectric body 1 and that of the second dielectric body 2, which can provide spatial allowance for deformation of the first dielectric body 1 and the second dielectric body 2, and prevent the two from direct collision and damage to the structure.

[0027] The foregoing introduces examples of a single-cavity resonance unit according to embodiments of the present application. Appropriate structural modifications may be made without altering the fundamental principle. For example, the first dielectric body 1 of embodiments of the present application may not be completely enclosed in the cavity of the second dielectric body 2. As shown in FIG. 3, the groove structure 212 in the embodiments of the present application penetrates the second part 22 in a direction perpendicular to the inward-extending direction (the Y-axis direction in FIG. 3), and the first dielectric body 1 makes contact with a portion, corresponding to the first part 21, of the metal casing 3 in the direction perpendicular to the inward-extending direction of the groove structure 212. For another example, as shown in FIG. 4, in the embodiments of the present application, the cross-section of the first dielectric body 1 may also be a shape, such as a rectangle, which is reciprocal relative to the X-axis and Y-axis directions. It should be understood that these appropriate changes based on the principle of the embodiments of the present application shall fall within the scope of protection of the present specification.

[0028] Furthermore, the embodiments of the present application also provide a filter. FIG. 5 is a schematic structural diagram of a filter, which includes a plurality of the cavity resonance units 100 as described above. Any two single-cavity resonance units 100 cascaded with each other form resonance coupling by means of respective coupling windows thereof.

[0029] In some cases, the direction in which the groove structure in the single-cavity resonance unit 100 extends inwards is defined as a target direction, and the target direction is perpendicular to a plane that is parallel to both the first direction and the second direction. Portions, corresponding to the first part 21 and the second part 22, of the metal casings are provided with coupling windows 211, 221 respectively, and a projection of the coupling window 211 on the portion corresponding to the first part 21 of the metal casing in the target direction at least partially overlaps with a projection of the coupling window 221 on the portion corresponding to the second part 22 of the metal casing in the target direction. For the single-cavity resonance unit 100 in the embodiments of the present application, cascading may be in the target direction, and the coupling windows 211, 221 of the cascaded single-cavity resonance units 100 are arranged in pairs in the target direction, thereby improving the coupling effect. It should be understood that in actual applications, the angle of the above-mentioned target direction may be adjusted according to resonance requirements. For example, if coupling is required in the X-axis direction, the target direction may be made parallel to the X-axis direction by adjusting the position of the single-cavity resonance unit 100.

[0030] In the embodiments of the present application, the single-cavity resonance unit needs only one cavity structure to implement the dual-mode resonant mode required by a base station, and the Q value is improved as well. After a plurality of single-cavity resonance units are arranged in cascade to form a filter, the filter has the characteristics of miniaturization and high performance.

[0031] According to practice, the filter in the embodiments of the present application has a good effect of suppressing interference signals in a low-frequency band (for example, around 1800 MHz), and due to the small size thereof, the filter is especially suitable for a base station system with limited internal space, thereby solving the problem that a base station is incapable of signal filtering in the low-frequency band at present.

[0032] Specific embodiments of the present specification are described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims may be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require a specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0033] The above are merely embodiments of the present specification and are not intended to limit the present specification. Those skilled in the art will appreciate that, various modification and alteration can be made to the present specification. Any modification, equivalent replacement, improvement, etc., that is made within the spirit and principle of the present specification should fall within the scope of the claims of the present specification. In addition, all other embodiments obtained by a person skilled in the art without creative work shall fall within the scope of the present document.

Claims

1. A single-cavity resonance unit comprising a first dielectric body, a second dielectric body and a metal casing covering an outer surface of the second dielectric body; wherein the second dielectric body is of a cavity structure, the first dielectric body is located inside a cavity of the second dielectric body; a dielectric constant of the first dielectric body is higher than a dielectric constant of the second dielectric body, and a shape of the first dielectric body in a first direction is reciprocal to a shape thereof in a second direction, thereby forming dual-mode resonance.

2. The single-cavity resonance unit according to claim 1, further comprising a bonding layer; wherein the second dielectric body comprises a first part and a second part that are independent of each other, the first part and the second part are bonded by means of the bonding layer, and the metal casing is disposed on non-bonded outer surfaces of the first part and the second part.

3. The single-cavity resonance unit according to claim 2, wherein a groove structure that extends inwards is formed in an outer surface of the first part, and a cross-section of the groove structure in an inward-extending direction is larger than a cross-section of the first dielectric body; the first dielectric body is assembled in the groove structure before the first part and the second part are bonded, and an outer-edge surface, bonded to the second part, of the first part is the outer surface, in which the groove structure is formed, of the first part.

4. The single-cavity resonance unit according to claim 3, wherein the groove structure penetrates the second part in a direction perpendicular to the inward-extending direction, and the first dielectric body makes contact with a portion, corresponding to the first part, of the metal casing in the direction perpendicular to the inward-extending direction of the groove structure.

5. The single-cavity resonance unit according to claim 3, wherein the first dielectric body is provided with a blind-hole structure or a through-hole structure for resonance adjustment; and / or a portion, corresponding to the first part, of the metal casing has an opening, and a blind-hole structure or a through-hole structure for resonance adjustment is formed at the opening.

6. The single-cavity resonance unit according to claim 3, wherein the cross-section of the groove structure in the inward-extending direction is one of a regular polygon, a circle, or a cross; and the cross-section of the first dielectric body is one of a regular polygon, a circle, or a cross.

7. The single-cavity resonance unit according to claim 3, wherein portions, corresponding to the first part and the second part, of the metal casing are provided with coupling windows respectively, and a projection of the coupling window on the portion, corresponding to the first part, of the metal casing in a target direction at least partially overlaps with a projection of the coupling window on the portion, corresponding to the second part, of the metal casing in the target direction, and the target direction is perpendicular to a plane that is parallel to both the first direction and the second direction.

8. The single-cavity resonance unit according to claim 3, further comprising a buffer layer; wherein at least a portion of the first dielectric body is separated from an inner surface of the groove structure by means of the buffer layer.

9. The single-cavity resonance unit according to claim 8, wherein the buffer layer is an air layer, or the buffer layer is made of a colloidal material, wherein a dielectric constant of the colloidal material is different from the dielectric constant of the first dielectric body and the dielectric constant of the second dielectric body.

10. A filter, comprising a plurality of single-cavity resonance units according to any one of claims 1-9 that are arranged in cascade, wherein a metal casing of each single-cavity resonance unit is provided with a coupling window used for carrying out resonance coupling with other single-cavity resonance units.

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