WO2019109335A1

WO2019109335A1 - Multi-mode resonator

Info

Publication number: WO2019109335A1
Application number: PCT/CN2017/115227
Authority: WO
Inventors: Yunpeng Bai; Shouli JIA; Chao Li
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2017-12-08
Filing date: 2017-12-08
Publication date: 2019-06-13
Also published as: EP3721502A1; CN111448709A; EP3721502A4; CN111448709B

Abstract

Embodiments of the present disclosure relate to a multi-mode resonator. The multi-mode resonator comprises: a cavity; an upper support disposed in the cavity and oriented in a 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 a branch of the dielectric core. The at least one tuning screw is tunable to adjust a resonant mode associated with the branch.

Description

MULTI-MODE RESONATOR

FIELD

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

BACKGROUND

A radio frequency (RF) filter or dielectric filter is a very critical part in a wireless communication system, for example, the Fourth Generation (4G) or the Fifth Generation (5G) communication system. In design of such a filter, it is generally expected that the filter includes a resonator having a high factor of quality (for example, Q-value) . The resonator may be, for example, a single mode resonator or a multi-mode resonator. Generally speaking, the multi-mode resonator operating in two or more modes is more advantageous in improvement of filter performance and size reduction of the resonator.

However, in conventional designs, there are still some issues regarding the multi-mode resonator to be solved. For example, adhesive, which is usually used in the resonator, undesirably reduces the value of Q0. Furthermore, supports of the resonator may have a negative impact on a resonant mode parallel to Z-axis, especially in Q0 and temperature drift. In addition, it is usually difficult to adjust or tune the resonant modes of the resonator, especially in mass production.

SUMMARY

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

In a first aspect, there is provided a multi-mode resonator. The multi-mode resonator comprises: a cavity; an upper support disposed in the cavity and oriented in a 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 a 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 a first and second branches crossing with each other in a radial direction perpendicular with the longitudinal direction.

In some embodiments, the dielectric core further includes a third branches crossing with the first and second branches in the longitudinal direction.

In some embodiments, the dielectric core further includes a third branch crossing with the first and second branches in the radial direction and extending circumferentially along the radial direction.

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

In some embodiments, each of the upper support and the lower support has a cylinder shape or a cube shape, and includes a hole for accommodating a branch of the dielectric core in the longitudinal direction, wherein a wall of the hole is separated with the branch.

In some embodiments, the at least one tuning screw includes a side-cutting screw, the side-cutting screw includes a first part and a second part jointly defining a lateral surface of the side-cutting screw with the first part, wherein the first part has a circular cross section and the second part has a cross section less than a half of the circular cross section.

In some embodiments, the second part has a length in the longitude direction larger than a thickness of a branch of the dielectric core.

In some embodiments, the at least one tuning screw includes at least one of: a first side-cutting screw disposed at an end of a first branch of the plurality of the 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 the 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 ends of the second branch, and operable to adjust the second resonant mode associated with the second branch; and a normal screw disposed in a third branch of the plurality of the 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 for coupling the resonator to an adjacent resonator.

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

In some embodiments, the resonator may further comprise: a lid disposed on the 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 press force of installation of the resonator.

In a second aspect, there is provided a dielectric filter. The dielectric filter comprises the multi-mode resonator according to the first aspect.

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

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 shows a perspective diagram of a resonator in accordance with some embodiments of the present disclosure;

Fig. 2 shows a cross-sectional view of a resonator in accordance with some embodiments of the present disclosure;

Fig. 3 shows a schematic diagram of a dielectric core in accordance with some embodiments of the present disclosure;

Figs. 4A to 4C show distribution of the electric field and magnetic field of a triple-mode resonator in accordance with some embodiments of the present disclosure, respectively;

Fig. 5A to 5D show schematic diagrams of dielectric cores in accordance with some embodiments of the present disclosure, respectively;

Fig. 6 shows a schematic diagram of a support in accordance with some embodiments of the present disclosure;

Fig. 7A shows a schematic diagram of support design in accordance with some embodiments of the present disclosure;

Fig. 7B shows a schematic diagram of impact of the support design to the three resonant modes in accordance with some embodiments of the present disclosure;

Fig. 8A shows a schematic diagram of a side cutting screw in accordance with some embodiments of the present disclosure;

Fig. 8B shows a schematic diagram of a normal screw in accordance with some embodiments of the present disclosure;

Figs. 9A and 9B show schematic diagrams of a dielectric filter in accordance with some embodiments of the present disclosure, respectively; and

Fig. 10 shows a schematic diagram of a structure of a communication device in accordance with some embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills 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 “includes” and its variants are to be read as open terms that mean “includes, but is not limited to. ” The term “based on” is to be read as “at least in part based on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The terms “first, ” “second, ” and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

Fig. 1 shows a perspective diagram of a multi-mode resonator 100 in accordance with some embodiments of the present disclosure. For purpose of discussion, the term “resonant mode” is also called as “mode” in embodiments of the present disclosure.

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 105₁, 105₂, 105₃, 105₄ and 105₅ (collectively referred to as “105” ) are also disposed in the cavity 101.

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 which control three resonant modes.

The tuning screws 105 are disposed in the cavity associated with a branch of the dielectric core 104, and are tunable to adjust a resonant mode associated with the branch. For example, the tuning screws 105₁ and 105₂ are arranged at ends of a first branch of the dielectric core 104, and may be tuned to adjust a resonant mode associated with the first branch. The tuning screws 105₃ and 105₄ are arranged at ends of a second branch of the dielectric core 104, and may be tuned to adjust a resonant mode associated with the second branch. In addition, the tuning screw 105₅ is arranged in a third branch of the dielectric core 104. The third branch is disposed in the longitudinal direction in holes of the upper support 102 and the lower support 103. The tuning screw 105₅ may be tuned, for example, by adjust the length in the longitudinal direction, to adjust a resonant mode associated with the third branch.

According to embodiments of the present disclosure, gaps between the three branches and a wall of the cavity 101 may be substantially the same, so the temperature drift for the three modes may be reduced to the same level. Furthermore, the dielectric core 104 is supported by the upper and

lower supports

102 and 103 and open-circuited with the wall of the cavity 101. As such, the resonator 100 is not affected by short-circuit quality issue. In addition, no adhesive materials are used in the installation of the resonator 100, thus the value of Q0 of the multi-mode resonator 100 is high.

It is to be understood that although the embodiments described with respect to Fig. 1 illustrate that the dielectric core 104 include three branches, this is only for the purpose of illustration and help those skilled in the art to understand and implement embodiments of the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented with the dielectric core 104 including two branches or more than three branches.

In some embodiments, the resonator 100 may further include a lid disposed on the top of the resonator. The tuning screws 105 may be, for example, mounted in the lid and extend to the cavity 101 in the longitudinal direction. It is thus 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 press force of installation of the resonator. More details of the multi-mode resonator 100 are discussed below with respect to Fig. 2.

Fig. 2 shows a cross-sectional view of the resonator 100 in accordance with some embodiments of the present disclosure. As shown in Fig. 2, the cavity 101 may be made of metal. The dielectric core 104 may be installed in the metal cavity 101 by a pressing force of a spring washer 107 and a lid 106. The dielectric core 104 includes three branches which are supported by the upper support 102 and lower support 103. These three branches produce three transverse electric modes (for example, TM01 modes) . The TM01 modes are parallel to x-axis, y-axis and z-axis, respectively, and are referred to as TM01x, TM01y and TM01z modes, respectively. One or more tuning screws 105 may be implemented for the frequency tuning of each mode. In the cross-sectional view of Fig. 2, three tuning screws 105₁, 105₂ and 105₅ are shown.

In some embodiments of the present disclosure, a longitudinal direction may be the direction parallel to the y-axis, and a radial direction is perpendicular with the longitudinal direction. It is to be understood this is discussed for purpose of illustration, rather than 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 metal, such as aluminum. In some embodiments, silver may be plated on surfaces of the lid 106 and/or the cavity 101. In this way, electrical conductivity can be improved.

In some embodiments, the spring washer 107 may be located between the lower support 103 and the bottom of the cavity 101. The spring washer 107 may provide the press force of the installation.

The dielectric core 104 is a key part for the resonator 100. Fig. 3 shows a schematic diagram of a structure of the dielectric core 104 in accordance with some embodiments of the present disclosure. In embodiments of the present disclosure, the dielectric core 104 may be made by high dielectric constant Er, low loss, and temperature stable ceramic materials.

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

branches

310, 320 and 330 realize three resonant modes, respectively. In terms of the axis (x, y or z axis) parallel to the electric field of each mode, these three modes are named TM01x, TM01y, and TM01z, respectively. The three modes are orthogonal, and thus there is no coupling among them. The frequency of each mode may be controlled by a variety of factors, for example, a dielectric constant Er of a material of the dielectric core, length of a branch corresponding to the mode, a gap between the branch and the wall of the cavity, and so on.

As shown in Fig. 3, the z-branch 330 may have a hole 340 for accommodating the tuning screw in the longitudinal direction. In addition, the x-branch 310 may have two ends 350 and the y-branch 320 may have two ends 360. Each of the ends may be constructed as a suitable shape for adjusting the frequency of the TM01 mode (such as the TM01x mode, the TM01y mode, and so on) together with the associated tuning screw.

The three modes TM01x, TM01y, and TM01z may have different distribution of the electric field (E-field) and magnetic field (M-field) . Figs. 4A to 4C show distribution of the electric field and magnetic field of a triple-mode resonator in accordance with some embodiments of the present disclosure, respectively. As shown in Figs. 4A to 4C, a solid arrow indicates the direction of the electric field, and a dotted arrow indicates the direction of the magnetic field. In particular, as shown in Fig. 4B, the sign

indicates that the direction of the electric field is “in” , that is, a direction perpendicular with the plane shown in Fig. 4B.

The dielectric core may be constructed in a variety of ways to produce various resonant modes. Fig. 5A to 5D show schematic diagrams of dielectric cores in accordance with some embodiments of the present disclosure, respectively.

In some embodiments, the dielectric core may include a first and second branches crossing with each other in a radial direction perpendicular with the longitudinal direction, as shown in Fig. 5A. In this way, the dielectric core may provide two modes (TM01z+TM01y) . In such cases, the resonator 100 may be implemented as a dual-mode resonator.

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

In further alternative embodiments, the dielectric core may include a first branch and a second branch crossing with each other in a radial direction perpendicular with the longitudinal direction, as well as a third branch crossing with the first branch and the second branch in the radial direction and extending circumferentially along the radial direction, as shown in Fig. 5C. In such cases, the dielectric core may provide three modes (TM01x+TM01y+TE01) for a triple-mode resonator, wherein TE represents a transverse magnetic mode.

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

It is to be understood that the above examples shown in Figs. 5A-5D are described for illustration of the dielectric core, rather than limitation. Those skilled in the art would appreciate that the dielectric core can be implemented in other suitable forms.

The upper support 102 and the lower support 103 (collectively referred to as the “support” in some embodiments) may have a cylinder shape, a cube shape, or other suitable shape. In some embodiments, the upper support 102 and/or the lower support 103 are made by low loss, low dielectric constant Er dielectric materials, such as alumina or other low Er ceramic materials.

Fig. 6 shows a schematic diagram of a support 600 in accordance with some embodiments of the present disclosure. As shown, the support 600 has a cylinder shape may include a hole 610 for accommodating a branch of the dielectric core in the longitudinal direction, for example the z-branch 330. Fig. 7A shows a schematic diagram of support design in accordance with some embodiments of the present disclosure. A wall 710 of the hole 610 is separated from the z-branch 330, for example with a distance, denoted as d.

The larger of the distance d, the less impact of the support to the TM01z mode, the more impact on the TM01x/TM01y mode. By adjusting the distance d, the impacts of the support on the three modes may be adjust accordingly. In some cases, the distance d is configured to impact all three modes similarly. Fig. 7B shows a schematic diagram of impact of the support design to the three resonant modes in accordance with some embodiments of the present disclosure. As shown in Fig. 7B, when d = 4.3mm, the impacts of the support on the three modes are the same.

The tuning screws 105 may have different types or forms, for example, a side-cutting screw, a normal screw, and so on. In some embodiments, any one of the tuning screws 105₁ to 105_s may be implemented as the side-cutting screw, the normal screw or the like. For example, the tuning screws 105₁ and 105₂ may be both the side-cutting screws, both the normal screws, or one is the side-cutting screw and the other is the normal screw. Fig. 8A shows a schematic diagram of a side cutting screw 810 in accordance with some embodiments of the present disclosure. The side-cutting screw 810 may include a first part 811 and a second part 812. The second part 812 jointly defines a lateral surface 813 of the side-cutting screw 810 with the first part 811. The first part 811 and the second part 912 can be integrally formed or constructed as separate components.

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

In some embodiments, the second part 812 may have a length in the longitude direction larger than a thickness of a branch, for example, the x-branch 310, the y-branch 320, and so on. In this way, the frequency of the resonant mode can be adjusted in a more dynamic and flexible way.

There may be one or more side-cutting screws used in the resonator 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 the 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 disposed at ends of the first branch. They may be operable to adjust the first resonant mode associated with the first branch.

As a further alternative, a second side-cutting screw may be disposed at an end of a second branch of the plurality of the 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 a still further alternative, a pair of second side-cutting screws may be disposed at ends of the second branch, and may be operable to adjust the second resonant mode associated with the second branch. In this case, the second resonant mode is orthogonal to the first resonant mode.

For example, the side-cutting screw 810 may be used for tuning 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, so the frequency could be tuned. To increase the tuning range, two side-cutting screws (for example, tuning screws 105₁ and 105₂) are located at ends of x-branch 310 for frequency tuning of TM01x. Likewise, two side-cutting screws (for example, tuning screws 105₃ and 105₄) are located at ends of y-branch 320 for frequency tuning of TM01y.

In some embodiments, the normal screw may be disposed in a third branch of the plurality of the 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 normal screw disposed in the third branch (for example, the z-branch 330) may be a metallic Disk or a ceramic Disk.

For example, the normal screw may be used for tuning TM01z. Fig. 8B shows a schematic diagram of a normal screw 820 in accordance with some embodiments of the present disclosure. For example, by adjusting the length of the normal screw 820 insert into the cavity, the frequency of the TM01z can be tuned. The screw head of the normal screw may be self-locking or nut-locking.

The resonator 100 discussed with respect to embodiments of the present disclosure has quite a few of advantages. For example, the upper and lower supports are located along the z-axis, but keep a distance with the z-Branch 330. In this way, impacts of the supports may be the same to the three modes, which is benefit to reduce the temperature drift. Meanwhile, the three resonates modes are controlled by the three branches independently, so the frequency of each mode can be tuned independently. Furthermore, there is no coupling inside the triple-mode resonator, and thus the tuning of a filter including such a resonator is more efficient and more suitable for mass production. In addition, the side-cutting screw is suitable for mass production.

Embodiments of the present disclosure also provide a dielectric filter including the multi-mode resonator in accordance with embodiments of the present disclosure. In the filter, the multi-mode resonator may be coupled to an adjacent metal resonator by one or more coupling elements. A coupling element may be, for example, a coupling window, a coupling strip line, and other suitable elements capable of coupling resonators.

Figs. 9A and 9B show schematic diagrams of structures of

dielectric filters

910 and 920 in accordance with some embodiments of the present disclosure, respectively.

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

resonators

911, 912 and 913. The resonator 912 is the multi-mode resonator in accordance with embodiments of the present disclosure, for example, the resonator 100. The

resonators

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

resonators

911 and 912 are coupled by a coupling window, and the

resonators

912 and 913 are coupled by another coupling window. The filter 910 may further 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, the filter 920 may include three

resonators

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

resonators

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

resonators

921 and 922 are coupled by a coupling strip line, and the

resonators

922 and 923 are coupled by another coupling strip line. The filter 920 may further include two ports 924 and 925, also referred to as Port 1 and Port 2, for signal input and output, respectively.

A structure of a communication device according to some embodiments of the present disclosure will be described on the basis of Fig. 10.

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

The communication device may include, for example, a network device, a satellite device, a radar device and so on. As used herein, the term “network device” refers to a device or a base station (BS) which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but 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, a pico node, and the like. For the purpose of discussion, in the following, some embodiments will be described with reference to TRP as examples of the network device.

The communication device may perform communication in a wireless system. Communication discussed in the present disclosure may conform to any suitable standards including, but not limited to, New Radio Access (NR) , LTE, LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the First Generation (1G) , the Second Generation (2G) , 2.5G, 2.75G, the Third Generation (3G) , the Fourth Generation (4G) , 4.5G, the Fifth Generation (5G) communication protocols.

It is to be understood that the above detailed embodiments of the present disclosure are only to exemplify or explain principles of the present disclosure and not to limit the present disclosure. Therefore, any modifications, equivalent alternatives and improvement, etc. without departing from the spirit and scope of the present disclosure shall be included in the scope of protection of the present disclosure. Meanwhile, appended claims of the present disclosure aim to cover all the variations and modifications falling under the scope and boundary of the claims or equivalents of the scope and boundary.

Claims

A multi-mode resonator, comprising:

a cavity;

an upper support disposed in the cavity and oriented in a 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 a branch of the dielectric core, wherein the at least one tuning screw is tunable to adjust a resonant mode associated with the branch.
The resonator according to Claim 1, wherein the dielectric core comprises a first and second branches crossing with each other in a radial direction perpendicular with the longitudinal direction.
The resonator according to Claim 2, wherein the dielectric core further comprises a third branches crossing with the first and second branches in the longitudinal direction.
The resonator according to Claim 2, wherein the dielectric core further comprises a third branch crossing with the first and second branches in the radial direction and extending circumferentially along the radial direction.
The resonator according to Claim 4, wherein the dielectric core further comprises a fourth branch crossing with the first, second and third branches in the longitudinal direction.
The resonator according to Claim 1, wherein each of the upper support and the lower support has a cylinder shape or a cube 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 with the branch.
The resonator according to Claim 1, wherein the at least one tuning screw comprises a side-cutting screw, the side-cutting screw comprises a first part and a second part jointly defining a lateral surface of the side-cutting screw with the first part, wherein the first part has a circular cross section and the second part has a cross section less than a half of the circular cross section.
The resonator according to Claim 7, wherein the second part has a length in the longitude direction larger than a thickness of a branch of the dielectric core.
The resonator according to Claim 1, wherein the at least one tuning screw comprises at least one of:

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

a normal screw disposed in a third branch of the plurality of the 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.
The resonator according to Claim 1, further comprising:

a coupling element operable for coupling the resonator to an adjacent resonator.
The resonator according to Claim 10, wherein the coupling element is a coupling window or a coupling strip line.
The resonator according to Claim 1, further comprising:

a lid disposed on the top of the resonator.
The resonator according to Claim 1, further comprising:

a spring washer disposed at the bottom of the resonator and providing a press force of installation of the resonator.
A dielectric filter, comprising the resonator according to any of Claims 1 to 13.
A communication device, comprising the dielectric filter according to Claim 14.