CN111448709B

CN111448709B - Multimode resonator

Info

Publication number: CN111448709B
Application number: CN201780097531.9A
Authority: CN
Inventors: 白云鹏; 贾守礼; 李超
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2017-12-08
Filing date: 2017-12-08
Publication date: 2022-03-04
Anticipated expiration: 2037-12-08
Also published as: WO2019109335A1; CN111448709A; EP3721502A4; EP3721502A1

Abstract

Embodiments of the present disclosure relate to a multimode resonator. The multimode resonator includes: a cavity; an upper support disposed in the cavity and oriented in the longitudinal direction; a lower support disposed in the cavity and aligned with the upper support in the longitudinal direction; and a dielectric core disposed between the upper support and the lower support and including a plurality of branches associated with a plurality of resonant modes; and at least one tuning screw disposed in the cavity associated with the branch of the dielectric core. At least one tuning screw is adjustable to adjust a resonant mode associated with the branch.

Description

Multimode resonator

Technical Field

Embodiments of the present disclosure relate generally to the field of communications, and in particular, to a multimode resonator, a dielectric filter including the multimode resonator, and a communication device including the dielectric filter.

Background

Radio Frequency (RF) filters or dielectric filters are a very critical part of wireless communication systems, such as fourth generation (4G) or fifth generation (5G) communication systems. In the design of such filters, it is often desirable for the filter to include resonators having a high quality factor (e.g., Q value). The resonator may be, for example, a single mode resonator or a multimode resonator. Generally, multimode resonators operating in two or more modes are more advantageous in improving filter performance and reducing resonator size.

However, in the conventional design, there are still some problems with the multimode resonator to be solved. For example, adhesives commonly used in resonators may undesirably lower the value of Q0. Furthermore, the support of the resonator may have a negative effect on the resonant modes parallel to the Z-axis, in particular in terms of Q0 and temperature drift. In addition, it is often difficult to tune or tune the resonant modes of the resonator, particularly in mass production.

Disclosure of Invention

In general, example embodiments of the present disclosure provide a multimode resonator, a dielectric filter including the multimode resonator, and a communication device including the dielectric filter.

In a first aspect, a multimode resonator is provided. The multimode resonator includes: a cavity; an upper support disposed in the cavity and oriented in the longitudinal direction; a lower support disposed in the cavity and aligned with the upper support in the longitudinal direction; and a dielectric core disposed between the upper support and the lower support and including a plurality of branches associated with a plurality of resonant modes; and at least one tuning screw disposed in the cavity associated with the branch of the dielectric core, wherein the at least one tuning screw is tunable to adjust a resonant mode associated with the branch.

In some embodiments, the dielectric core includes first and second branches that cross each other in a radial direction perpendicular to the longitudinal direction.

In some embodiments, the dielectric core further comprises a third branch crossing the first branch and the second branch in the longitudinal direction.

In some embodiments, the dielectric core further comprises a third branch intersecting the first branch and the second branch in the radial direction and extending circumferentially along the radial direction.

In some embodiments, the dielectric core further comprises a fourth branch intersecting the first, second and third branches in the longitudinal direction.

In some embodiments, each of the upper and lower supports has a cylindrical or cubic shape and includes a hole for receiving a branch of the dielectric core in the longitudinal direction, wherein a wall of the hole is separated from the branch.

In some embodiments, the at least one tuning screw comprises a side-cut screw comprising a first portion and a second portion that, together with the first portion, defines a lateral surface of the side-cut screw, wherein the first portion has a circular cross-section and the second portion has a cross-section that is less than half of the circular cross-section.

In some embodiments, the length of the second portion in the longitudinal direction is greater than the thickness of the branches of the dielectric core.

In some embodiments, the at least one tuning screw comprises at least one of: a first side-cut screw disposed at an end of a first branch of the plurality of branches and operable to adjust a first resonant mode associated with the first branch; a pair of first side-cutting screws disposed at an end of the first branch and operable to adjust a first resonant mode associated with the first branch; a second side-cutting screw disposed at an end of a second branch of the plurality of branches and operable to adjust a second resonant mode associated with the second branch, wherein the second resonant mode is orthogonal to the first resonant mode; a pair of second side-cutting screws disposed at an end of the second branch and operable to adjust a second resonant mode associated with the second branch; and a common screw disposed in a third branch of the plurality of branches and operable to adjust a third resonant mode associated with the third branch, wherein the third resonant mode is orthogonal to both the first resonant mode and the second resonant mode.

In some embodiments, the resonator may further comprise a coupling element operable to couple the resonator to an adjacent resonator.

In some embodiments, the coupling element is a coupling window or a coupling stripline.

In some embodiments, the resonator may further comprise a cover disposed on top of the resonator.

In some embodiments, the resonator may further comprise a spring washer disposed at the bottom of the resonator and providing a pressure of installation of the resonator.

In a second aspect, a dielectric filter is provided. The dielectric filter includes the multimode resonator according to the first aspect.

In a third aspect, a communication device is provided. The communication device comprises a dielectric filter according to the second aspect.

Other features of the present disclosure will become readily apparent from the following description.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent from the following more detailed description of some embodiments of the present disclosure, as illustrated in the accompanying drawings, in which:

figure 1 illustrates a perspective view of a resonator according to some embodiments of the present disclosure;

figure 2 illustrates a cross-sectional view of a resonator according to some embodiments of the present disclosure;

fig. 3 illustrates a schematic diagram of a dielectric core, according to some embodiments of the present disclosure;

figures 4A-4C illustrate distributions of electric and magnetic fields, respectively, of a three-mode resonator according to some embodiments of the present disclosure;

fig. 5A-5D respectively illustrate schematic diagrams of dielectric cores, according to some embodiments of the present disclosure;

figure 6 illustrates a schematic view of a support according to some embodiments of the present disclosure;

figure 7A shows a schematic diagram of a support design according to some embodiments of the present disclosure;

FIG. 7B illustrates a schematic of the effect of support design on three resonant modes according to some embodiments of the present disclosure;

FIG. 8A illustrates a schematic view of a side-cutting screw according to some embodiments of the present disclosure;

FIG. 8B shows a schematic view of a generic screw according to some embodiments of the present disclosure;

figures 9A and 9B respectively illustrate schematic diagrams of dielectric filters according to some embodiments of the present disclosure; and

fig. 10 shows a schematic diagram of a structure of a communication device according to some embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to a few exemplary embodiments. It is understood that these embodiments are described for illustrative purposes only and are presented to aid those skilled in the art in understanding and enabling the disclosure, without placing any limitation on the scope of the disclosure. The disclosure described herein may be implemented in various ways other than those described below.

In the following specification and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "comprising" and its variants are to be understood as open-ended terms meaning "including but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first," "second," and the like may refer to different or the same object. Other definitions (explicit and implicit) may be included below.

Fig. 1 illustrates a perspective view of a multimode resonator 100 according to some embodiments of the present disclosure. For purposes of discussion, in embodiments of the present disclosure, the term "resonant mode" is also referred to as "mode".

As shown, the resonator 100 includes a cavity 101. In the cavity 101, an upper support 102, a lower support 103, and a dielectric core 104 are disposed. In addition, at least one tuning screw, in this case five tuning screws 105, is also provided in the cavity 101₁、105₂、105₃、105₄And 105₅(collectively referred to as "105").

In the example shown in fig. 1, the upper support 102 is oriented in a longitudinal direction. The lower support 103 is aligned with the upper support in the longitudinal direction. The dielectric core 104 is disposed between the upper support 102 and the lower support 103. The dielectric core 104 includes a plurality of branches associated with a plurality of resonant modes. In this example, the dielectric core 104 has three branches that control three resonant modes.

A tuning screw 105 is disposed in the cavity and is associated with a branch of the dielectric core 104 and is tunable to adjust a resonant mode associated with the branch. For example, tuning screw 105₁And 105₂Is disposed at the end of the first branch of the dielectric core 104 and may be tuned to adjust a resonant mode associated with the first branch. Tuning screw 105₃And 105₄Is disposed at the end of the second branch of the dielectric core 104 and may be tuned to adjust a resonant mode associated with the second branch. In addition, tuning screw 105₅Is disposed in the third branch of the dielectric core 104. The third branch is provided in the holes of the upper support 102 and the lower support 103 in the longitudinal direction. For example, tuning screw 105 may be tuned by adjusting the length in the longitudinal direction₅To adjust the resonant mode associated with the third branch.

According to an embodiment of the present disclosure, the gaps between the three branches and the wall of the cavity 101 may be substantially the same, and thus the temperature drift of the three modes may be reduced to the same level. Further, the dielectric core 104 is supported by the upper support 102 and the lower support 103, and is open-circuited to the wall of the cavity 101. In this way, the resonator 100 is not affected by short circuit quality issues. In addition, no adhesive material is used in the mounting of the resonator 100, and therefore the value of Q0 of the multimode resonator 100 is high.

It should be understood that although the embodiment described with respect to fig. 1 shows the dielectric core 104 to include three branches, this is for illustrative purposes only and to assist those skilled in the art in understanding and implementing embodiments of the present disclosure without placing any limitation on the scope of the present disclosure. The disclosure described herein may be implemented with a dielectric core 104 that includes two branches or more than three branches.

In some embodiments, the resonator 100 may further include a cover disposed on top of the resonator. The tuning screw 105 may for example be mounted in the cover and extend in the longitudinal direction to the cavity 101. Therefore, it is more suitable for mass production.

In some embodiments, the resonator 100 may further include a spring washer disposed at the bottom of the resonator. The spring washer may provide a pressure for mounting of the resonator. More details of the multimode resonator 100 are discussed below with respect to fig. 2.

Fig. 2 illustrates a cross-sectional view of a resonator 100 according to some embodiments of the present disclosure. As shown in fig. 2, the chamber 101 may be made of metal. The dielectric core 104 may be mounted in the metal cavity 101 by the pressing force of the spring washer 107 and the cover 106. The dielectric core 104 includes three branches supported by the upper support 102 and the lower support 103. These three branches produce three transverse electric modes (e.g., TM01 mode). The TM01 modes are parallel to the x, y, and z axes, respectively, and are referred to as TM01x, TM01y, and TM01z modes, respectively. One or more tuning screws 105 may be implemented for frequency tuning of each mode. In the cross-sectional view of fig. 2, three tuning screws 105 are shown₁、105₂And 105₅。

In some embodiments of the present disclosure, the longitudinal direction may be a direction parallel to the y-axis, and the radial direction is perpendicular to the longitudinal direction. It is to be understood that this is discussed for purposes of illustration and not limitation. In some other embodiments, the longitudinal direction may be a different direction, for example, a direction parallel to the x-axis or z-axis.

In some embodiments, the lid 106 and/or the cavity 101 may be made of a metal such as aluminum. In some embodiments, silver may be plated on the surface of the lid 106 and/or the cavity 101. In this way, the conductivity can be improved.

In some embodiments, a spring washer 107 may be located between the lower support 103 and the bottom of the chamber body 101. Spring washer 107 may provide the pressure of the installation.

The dielectric core 104 is a critical part of the resonator 100. Fig. 3 illustrates a schematic diagram of the structure of the dielectric core 104, according to some embodiments of the present disclosure. In embodiments of the present disclosure, the dielectric core 104 may be made of a high dielectric constant Er, low loss, and temperature stable ceramic material.

In the embodiment shown with respect to fig. 3, the dielectric core 104 includes three branches, namely an x-branch 310, a y-branch 320, and a z-branch 330. These

branches

310, 320 and 330 respectively implement three resonant modes. The three modes are referred to as TM01x, TM01y, and TM01z, respectively, with respect to the axis (x, y, or z axis) of the electric field parallel to each mode. The three modes are orthogonal and therefore there is no coupling between them. The frequency of each mode can be controlled by a number of factors, for example, the dielectric constant Er of the material of the dielectric core, the length of the branches corresponding to that mode, the gap between the branches and the walls of the cavity, etc.

As shown in fig. 3, the z-branch 330 may have a hole 340 to accommodate a tuning screw in the longitudinal direction. Additionally, the x-branch 310 may have two ends 350 and the y-branch 320 may have two ends 360. Each end may be configured to be suitable for adjusting the frequency of a TM01 mode (such as a TM01x mode, a TM01y mode, etc.) and the shape of the associated tuning screw.

The three modes TM01x, TM01y, and TM01z may have different distributions of electric field (E-field) and magnetic field (M-field). Fig. 4A-4C illustrate distributions of electric and magnetic fields, respectively, of a three-mode resonator according to some embodiments of the present disclosure. As shown in fig. 4A to 4C, solid arrows indicate the direction of an electric field, and dashed arrows indicate the direction of a magnetic field. In particular, as shown in FIG. 4B, the symbols

Indicating that the direction of the electric field is "in", i.e., perpendicular to the plane shown in fig. 4B.

The dielectric core may be configured in various ways to produce various resonant modes. Fig. 5A-5D respectively illustrate schematic diagrams of dielectric cores, according to some embodiments of the present disclosure.

In some embodiments, the dielectric core may include first and second branches that cross each other in a radial direction perpendicular to the longitudinal direction, as shown in fig. 5A. In this way, the dielectric core can provide two modes (TM01z + TM01 y). In this case, the resonator 100 may be implemented as a dual-mode resonator.

In some alternative embodiments, the dielectric core may include first and second branches crossing each other in a radial direction perpendicular to the longitudinal direction, and a third branch crossing the first and second branches in the longitudinal direction, as shown in fig. 5B. In this case, the dielectric core may provide three modes (TM01x + TM01y + TM01z) for the three-mode resonator.

In a further alternative embodiment, the dielectric core may include first and second branches crossing each other in a radial direction perpendicular to the longitudinal direction, and a third branch crossing the first and second branches in the radial direction and extending circumferentially along the radial direction, as shown in fig. 5C. In this case, the dielectric core may provide three modes (TM01x + TM01y + TE01) for the three-mode resonator, where TE represents the transverse magnetic mode.

In a further alternative embodiment, the dielectric core may include first and second branches crossing each other in a radial direction perpendicular to the longitudinal direction, a third branch crossing the first and second branches in the radial direction and extending circumferentially along the radial direction, and a fourth branch crossing the first, second, and third branches in the longitudinal direction. This is shown in fig. 5D. Thus, the dielectric core may provide four modes (TM01x + TM01y + TM01z + TE01) for a four-mode resonator.

It should be understood that the above examples shown in fig. 5A-5D are described for purposes of illustrating the dielectric core, and are not limiting. One skilled in the art will appreciate that the dielectric core may be implemented in other suitable forms.

The upper and lower supports 102, 103 (collectively referred to as "supports" in some embodiments) may have a cylindrical shape, a cubic shape, or other suitable shape. In some embodiments, the upper support 102 and/or the lower support 103 are made of a low-loss, low-dielectric constant Er dielectric material (such as alumina or other low Er ceramic material).

Fig. 6 illustrates a schematic view of a support 600 according to some embodiments of the present disclosure. As shown, the support 600 has a cylindrical shape and may include an aperture 610 for receiving a branch of a dielectric core (e.g., z-branch 330) in a longitudinal direction. Figure 7A illustrates a schematic diagram of a support design according to some embodiments of the present disclosure. The wall 710 of the aperture 610 is separated from the z-branch 330, for example by a distance denoted d.

The larger the distance d, the smaller the strut effect on the TM01z mode and the larger the effect on the TM01x/TM01y mode. By adjusting the distance d, the influence of the support on the three modes can be adjusted accordingly. In some cases, the distance d is configured to similarly affect all three modes. Fig. 7B shows a schematic of the effect of support design on three resonant modes according to some embodiments of the present disclosure. As shown in fig. 7B, when d is 4.3mm, the influence of the support member on the three modes is the same.

The tuning screws 105 may be of different types or forms, e.g., side-cutting screws, ordinary screws, etc. In some embodiments, tuning screw 105₁To 105₅Any of which may be implemented as a side-cut screw, a plain screw, etc. For example, tuning screw 105₁And 105₂Both may be side cut screws or both may be plain screws, or one may be side cut screws and the other plain screws. Fig. 8A illustrates a schematic view of a sidecut screw 810 according to some embodiments of the present disclosure. Side cut screw 810 may include a first portion 811 and a second portion 812. The second portion 812 cooperates with the first portion 811 to define a lateral surface 813 of the undercut screw 810. The first portion 811 and the second portion 912 may be integrally formed or constructed as separate components.

The first portion 811 has a circular cross-section and the second portion has a cross-section less than half of the circular cross-section. In some embodiments, the cross-sectional area of the second portion 812 may be 40%, 30% or less of the cross-sectional area of the second portion 811.

In some embodiments, the length of the second portion 812 in the longitudinal direction may be greater than the thickness of the branches (e.g., x-branch 310, y-branch 320, etc.). In this way, the frequency of the resonant mode can be adjusted in a more dynamic and flexible manner.

One or more side-cut screws may be used in resonators according to embodiments of the present disclosure. In some embodiments, a first side-cutting screw may be disposed at an end of a first branch of the plurality of branches and may be operable to adjust a first resonant mode associated with the first branch.

Alternatively, a pair of first side-cutting screws may be provided at the ends of the first branches. They may be operable to adjust a first resonant mode associated with the first branch.

As a further alternative, a second sidecut screw may be disposed at an end of a second branch of the plurality of branches and may be operable to adjust a second resonant mode associated with the second branch. The second resonant mode is orthogonal to the first resonant mode.

As yet another alternative, a pair of second side-cutting screws may be provided at the ends of the second branch and may be operable to adjust a second resonant mode associated with the second branch. In this case, the second resonant mode is orthogonal to the first resonant mode.

For example, side-cut screw 810 may be used to tune TM01x and TM01y modes. By rotating the tuning screw from 0 ° to 180 °, the distance between the side-cutting screw and the branch will be changed, and thus the frequency can be tuned. To increase the tuning range, two side-cutting screws (e.g., tuning screw 105)₁And 105₂) Located at the end of the x-branch 310 for frequency tuning of TM01 x. Also, two side-cutting screws (e.g., tuning screw 105)₃And 105₄) At the end of the y-branch 320 for frequency tuning of TM01 y.

In some embodiments, a common screw may be disposed in a third branch of the plurality of branches and operable to adjust a third resonant mode associated with the third branch. In this case, the third resonant mode is orthogonal to both the first resonant mode and the second resonant mode. In some embodiments, the common screw disposed in the third branch (e.g., z-branch 330) may be a metal or ceramic disk.

For example, a common screw may be used to tune TM01 z. Fig. 8B shows a schematic view of a generic screw 820 according to some embodiments of the present disclosure. For example, the frequency of TM01z can be tuned by adjusting the length of a common screw 820 inserted into the cavity. The head of a conventional screw may be self-locking or nut-locking.

The resonator 100 discussed with respect to the embodiments of the present disclosure has several advantages. For example, the upper and lower supports are positioned along the z-axis, but at a distance from the z-branch 330. In this way, the influence of the support on the three modes can be the same, which is advantageous for reducing temperature drift. At the same time, the three resonant modes are independently controlled by the three branches, so that the frequency of each mode can be independently tuned. Furthermore, there is no coupling inside the three-mode resonator, and thus the tuning of a filter comprising such a resonator is more efficient and more suitable for mass production. In addition, the side cut screw is suitable for mass production.

Embodiments of the present disclosure also provide a dielectric filter including the multimode resonator according to embodiments of the present disclosure. In a filter, a multimode resonator may be coupled to an adjacent metal resonator by one or more coupling elements. The coupling elements may be, for example, coupling windows, coupling striplines, and other suitable elements capable of coupling resonators.

Fig. 9A and 9B show schematic diagrams of the structures of

dielectric filters

910 and 920, respectively, according to some embodiments of the present disclosure.

In the example of fig. 9A, the filter 910 may include three

resonators

911, 912, and 913. The resonator 912 is a multimode resonator, e.g., resonator 100, in accordance with embodiments of the present disclosure. The

resonators

911 and 913 are single-mode resonators, respectively. The

resonators

911 and 912 are coupled through a coupling window and the

resonators

912 and 913 are coupled through another coupling window. Filter 910 may also include two

ports

914 and 915, also referred to as port 1 and port 2, for signal input and output, respectively.

In the example of fig. 9B, filter 920 may include three

resonators

921, 922 and 923. The resonator 922 is a multimode resonator, for example, the resonator 100, in accordance with embodiments of the present disclosure. The

resonators

921 and 923 are single-mode resonators, respectively. The

resonators

921 and 922 are coupled by a coupling stripline, and the

resonators

922 and 923 are coupled by another coupling stripline. Filter 920 may also include two ports 924 and 925 for signal input and output, also referred to as port 1 and port 2, respectively.

The structure of a communication apparatus according to some embodiments of the present disclosure will be described based on fig. 10.

Fig. 10 shows a schematic diagram of a structure of a communication device according to some embodiments of the present disclosure. In the communication device, the transmission filter and the reception filter constitute a duplexer formed as an antenna sharing device. The transmit circuit is connected to a transmit signal input port of the duplexer and the receive circuit is connected to a receive signal output port. By connecting the antenna to the input port and the output port of the duplexer, a high frequency of the communication device is formed.

The communication devices may include, for example, network devices, satellite devices, radar devices, and the like. As used herein, the term "network device" refers to a device or Base Station (BS) that is capable of providing or hosting a cell or coverage area in which a terminal device may communicate. Examples of network devices include, but are not limited to, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a next generation NodeB (gnb), a Transmission Reception Point (TRP), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a low power node (such as a femto node, pico node, etc.). For purposes of discussion, some embodiments will be described hereinafter with reference to TRPs as examples of network devices.

The communication device may perform communication in a wireless system. The communications discussed in this disclosure may conform to any suitable standard including, but not limited to, new radio access (NR), LTE evolution, LTE-advanced (LTE-a), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), and global system for mobile communications (GSM), among others. Further, the communication may be performed in accordance with any generation of communication protocols, currently known or to be developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communication protocols.

It is to be understood that the above detailed embodiments of the present disclosure are only intended to illustrate or explain the principles of the present disclosure, and not to limit the present disclosure. Therefore, any modifications, equivalents, improvements, and the like, which do not depart from the spirit and scope of the present disclosure, should be included within the scope of the present disclosure. Also, it is intended that the appended claims cover all such variations and modifications that fall within the scope and boundaries of the claims or the equivalents of such scope and boundaries.

Claims

1. A multimode resonator comprising:

a cavity;

a lower support disposed in the cavity and oriented in a longitudinal direction; and

a dielectric core disposed above the lower support and including a plurality of branches associated with a plurality of resonant modes, the plurality of branches protruding outward; and

at least one tuning screw disposed in the cavity and associated with a branch of the dielectric core, wherein the at least one tuning screw is tunable to adjust a resonant mode associated with the branch, one of the at least one tuning screw being disposed outside one of the plurality of branches in a radial direction perpendicular to the longitudinal direction;

wherein the at least one tuning screw comprises a side-cut screw comprising a first portion and a second portion that, together with the first portion, defines a lateral surface of the side-cut screw, wherein the first portion has a circular cross-section and the second portion has a cross-section that is less than half of the circular cross-section.

2. The resonator of claim 1, wherein the dielectric core comprises a first branch and a second branch that cross each other in a radial direction perpendicular to the longitudinal direction.

3. The resonator according to claim 2, wherein the dielectric core further comprises a third branch crossing the first branch and the second branch in the longitudinal direction.

4. The resonator of claim 2, wherein the dielectric core further comprises a third branch intersecting the first and second branches in the radial direction and extending circumferentially along the radial direction.

5. The resonator according to claim 4, wherein the dielectric core further comprises a fourth branch crossing the first, second and third branches in the longitudinal direction.

6. The resonator according to claim 1, wherein the lower support has a cylindrical or cubic shape and comprises a hole for accommodating a branch of the dielectric core in the longitudinal direction, wherein a wall of the hole is separated from the branch.

7. The resonator according to claim 1, wherein the length of the second portion in the longitudinal direction is greater than the thickness of the branches of the dielectric core.

8. The resonator of claim 1, wherein the side-cut screw is at least one of:

a first side-cutting screw disposed at an end of a first branch of the plurality of branches and operable to adjust a first resonant mode associated with the first branch;

a pair of first side-cutting screws disposed at ends of the first branch and operable to adjust the first resonant mode associated with the first branch;

a second side-cutting screw disposed at an end of a second branch of the plurality of branches and operable to adjust a second resonant mode associated with the second branch, wherein the second resonant mode is orthogonal to the first resonant mode; and

a pair of second side-cutting screws disposed at ends of the second branch and operable to adjust the second resonant mode associated with the second branch; and

the at least one tuning screw further comprises:

a common screw disposed in a third branch of the plurality of branches and operable to adjust a third resonant mode associated with the third branch, wherein the third resonant mode is orthogonal to both the first resonant mode and the second resonant mode.

9. The resonator of claim 1, further comprising:

a coupling element operable to couple the resonator to an adjacent resonator.

10. The resonator of claim 9, wherein the coupling element is a coupling window or a coupling stripline.

11. The resonator of claim 1, further comprising:

a cover disposed on top of the resonator.

12. The resonator of claim 1, further comprising:

a spring washer disposed at a bottom of the resonator and providing a pressure of installation of the resonator.

13. The resonator according to any one of claims 1 to 12, further comprising an upper support disposed in the cavity and aligned with the lower support in the longitudinal direction,

wherein the dielectric core is disposed between the upper support and the lower support.

14. A dielectric filter comprising a resonator as claimed in any one of claims 1 to 13.

15. A communication device comprising the dielectric filter of claim 14.