Three-mode dielectric resonant cavity structure applied to filter
Technical Field
The invention relates to a base station filter, an antenna feed tower amplifier, a combiner, an anti-interference filter and the like in the communication field, in particular to a three-mode dielectric resonant cavity structure applied to a filter.
Background
With the rapid development of fourth-generation mobile communication to fifth-generation mobile communication, the requirements on high performance and miniaturization of communication equipment are increasing, the traditional cavity filter mostly adopts a single-metal resonant rod mode which is simple in structure but only capable of forming TEM single-mode resonance, when TEM multi-mode resonance is required to be realized in some occasions, a resonant single cavity needs to be arranged on each resonant rod, and one single cavity forms resonance; this arrangement results in an excessively large and costly filter.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides a three-mode dielectric resonant cavity structure applied to a filter, which can meet the requirements of the cavity dielectric filter on higher Q value and smaller volume.
The technical scheme adopted by the invention is as follows: a three-mode dielectric resonant cavity structure applied to a filter comprises a cavity, wherein a cubic dielectric resonant block and six supporting blocks are arranged in the cavity, six end faces of the dielectric resonant block are respectively connected with the inner wall of the cavity through the six supporting blocks, and at least one supporting block in the six supporting blocks is of a solid structure;
three edge directions which are vertical to each other in the dielectric resonance block are respectively defined as an x direction, a y direction and a z direction, the dielectric resonance block and a supporting block of a corresponding surface in the x direction, the y direction and the z direction respectively form an x-axis dielectric resonance rod, a y-axis dielectric resonance rod and a z-axis dielectric resonance rod, and the x-axis dielectric resonance rod, the y-axis dielectric resonance rod and the z-axis dielectric resonance rod are matched with the inside of the cavity to form three degenerate modes;
a coupling device is arranged between two of the three degenerate modes, each degenerate mode is provided with a frequency adjustable device, the three degenerate modes form a radio frequency channel which is provided with a heat dissipation device,
the filter is composed of a three-mode dielectric resonance structure, different types of single-mode resonance structures and dual-mode resonance structures which are arranged and combined differently according to requirements.
Furthermore, the six supporting blocks are respectively a first supporting block, a second supporting block, a third supporting block, a fourth supporting block, a fifth supporting block and a sixth supporting block, one end face of the dielectric resonance block along the x direction is connected with the first supporting block, and the other end face of the dielectric resonance block is connected with the second supporting block to form an x-axis dielectric resonance rod; one end face of the dielectric resonance block along the y direction is connected with the third supporting block, and the other end face of the dielectric resonance block is connected with the fourth supporting block to form a y-axis dielectric resonance rod; one end face of the dielectric resonance block along the z direction is connected with the fifth supporting block, and the other end face of the dielectric resonance block is connected with the sixth supporting block to form a z-axis dielectric resonance rod; the resonant rods in the x, y and z directions form a total resonant rod;
the supporting block of the solid structure is in a solid structure with two parallel end surfaces or a tubular structure with a through middle part; the material of the dielectric resonance block is ceramic or dielectric, the material of the supporting block with a solid structure is plastic, ceramic or dielectric, and the material of the supporting block with a non-solid structure is air.
Furthermore, two end faces of the dielectric resonance block along the x direction are connected with the first supporting block and the second supporting block in a gluing, compression joint or screw fastening mode; two end faces of the dielectric resonance block along the y direction are connected with the third supporting block and the fourth supporting block in a gluing, compression joint or screw fastening mode; and the two end surfaces of the dielectric resonance block along the z direction are connected with the fifth supporting block and the sixth supporting block in a gluing, compression joint or screw fastening mode.
Furthermore, a total resonant rod formed by the resonant rods in the x, y and z directions and a cube-like cavity form a three-mode resonant cavity structure; the cavity is shaped like a cube or a cuboid, and is made of a metal material, or is made of a metal material, the inner wall of the metal material is plated with silver or copper, or is made of a non-metal material with a metal layer plated on the surface.
Furthermore, the resonance rods in the x, y and z directions form a connection between the total resonance rod and the inner wall of the cavity in the modes of gluing, compression joint, screw fastening or welding; the resonant rods in the x, y and z directions form a total resonant rod with compensation of frequency variation along with temperature; the resonant rod in the x, y and z directions forms a supporting block of the total resonant rod, the resonant rod is made of a material with certain elasticity or has an elastic structure, the structure of the resonant rod can counteract the influence caused by expansion with heat and contraction with cold under different environments, and the elastic material of the supporting block is plastic, a medium, a composite material, a metal elastic sheet and the like.
Further, the dimensions of the x, y, z resonant rods forming the total resonant rod and the dimensions of the cavity determine the three-mode resonant frequency of the resonant cavity and also the volume of the resonant cavity.
Furthermore, the tuning frequency of the degenerate three-mode in the X-axis direction is realized by additionally arranging a debugging screw rod or a tuning disc on one surface or two surfaces of the X-axis corresponding to the cavity to change the distance or change the capacitance; the tuning frequency in the Y-axis direction can be realized by additionally arranging a debugging screw rod or a tuning disc on one surface or two surfaces of the Y-axis corresponding to the cavity to change the distance or change the capacitance; the tuning frequency in the z-axis direction can be realized by additionally arranging a debugging screw rod or a tuning disc on one surface or two surfaces of the z-axis corresponding to the cavity to change the distance or change the capacitance;
the tuning screw or the tuning disc is made of metal, or the tuning screw or the tuning disc is made of metal, the surface of the metal is electroplated with copper or silver, or the tuning screw or the tuning disc is made of a medium with a metalized surface;
the tuning screw rod is in the shape of any one of a metal rod, a medium rod, a metal disc, a medium disc, a metal rod-matched metal disc, a metal rod-matched medium disc, a medium rod-matched metal disc and a medium rod-matched medium disc.
Furthermore, in the three degenerate modes, coupling between the degenerate mode in the x direction and the degenerate mode in the y direction is formed by a first plane in which an edge angle is formed by intersecting x and y planes of the dielectric resonator block A and a part of the edge angle is cut off along the z-axis direction, and a coupling screw is arranged on an edge formed by intersecting the x and y planes of the cavity to realize fine adjustment of the coupling amount; coupling between the degenerate mode in the y direction and the degenerate mode in the z direction is formed by a second plane formed by intersecting y and z planes of the dielectric resonant block and cutting off part of edges along the x-axis direction, and a coupling screw is arranged on the edges formed by intersecting the y and z planes of the cavity to realize fine adjustment of the coupling amount; coupling between the degenerate mode in the z direction and the degenerate mode in the x direction is formed by a third plane formed by cutting off part of edges of the dielectric resonant block along the y-axis direction along the edges formed by crossing the z and x planes, and a coupling screw is arranged on the edges formed by crossing the z and x planes of the cavity to realize fine adjustment of the coupling amount;
the coupling screw is made of metal, or the coupling screw is made of metal and the surface of the metal is plated with copper or silver, or the coupling screw is made of a medium with a metalized surface;
the shape of the coupling screw rod is any one of a metal rod, a medium rod, a metal disc, a medium disc, a metal rod and metal disc, a metal rod and medium disc, a medium rod and metal disc and a medium rod and medium disc.
Further, radio frequency signals form a radio frequency channel through coupling between the resonance mode in the X direction and the resonance mode in the Y direction and coupling between the resonance mode in the Y direction and the resonance mode in the Z direction, loss and heat are generated, and heat conduction and heat dissipation are formed by fully connecting the six supporting blocks and the inner wall of the cavity.
Furthermore, the three-mode dielectric resonant cavity and different forms of single-mode resonant cavities or dual-mode resonant cavities and three-mode resonant cavities are combined in different forms to form filters with different volumes;
the functional characteristics of the filter comprise band-pass, band-stop, high-pass, low-pass and a combiner formed by the band-pass, the band-stop, the high-pass and the low-pass;
the coupling between any two resonant cavities formed by the three-mode medium resonant cavity structure and the single-mode resonant cavity, the dual-mode resonant cavity and the three-mode resonant cavity due to arrangement and combination can be realized through the size of a window between the two resonant cavities under the condition that the resonant rods in the two resonant cavities are parallel.
The invention has the beneficial effects that: by introducing the three-mode dielectric structure, the defects of the prior art can be overcome, the Q value of a single cavity can be greatly improved, the Q value of the traditional TM single-dielectric-constant resonator is improved by more than 50% -100%, and compared with the traditional TM single mode, the volume of the three-mode dielectric structure is greatly reduced by 1/3 or more.
Drawings
Fig. 1 is a schematic structural diagram of a three-mode dielectric resonant structure of the present invention.
Fig. 2 is a schematic diagram of the filter of the present invention.
Fig. 3 shows simulation results of a 10-cavity filter according to an embodiment of the present invention.
In the figure, 1, a cavity, 2, a dielectric resonant block, 3, a support block, B1, a first support block, B2, a support block, B3, a third support block, B4, a fourth support block, B5, a fifth support block, B6, a sixth support block, 4, a single-mode metal resonant column, 5, a coupling device, j1, a first plane, j2, a second plane, j3, a third plane, 6 and a frequency tunable device.
Detailed Description
The invention will be further described in detail with reference to the following drawings and specific examples, which are not intended to limit the invention, but are for clear understanding.
As shown in fig. 1, the three-mode dielectric resonator structure applied to the filter of the present invention includes a cavity 1, a dielectric resonator block 2 and six support blocks 3 are arranged in the cavity 1, six end surfaces of the dielectric resonator block 2 are respectively connected with an inner wall of the cavity 1 through the six support blocks 3, and at least one support block of the six support blocks 3 is a solid structure; the dielectric resonance block 2 is of a cubic structure and can be of a cubic or rectangular structure.
Three edge directions which are perpendicular to each other in the dielectric resonance block 2 are respectively defined as an x direction, a y direction and a z direction, the three directions are relative position directions and are not determined uniquely, the dielectric resonance block and a supporting block of a corresponding surface in the x direction, the y direction and the z direction respectively form an x-axis dielectric resonance rod, a y-axis dielectric resonance rod and a z-axis dielectric resonance rod, and the x-axis dielectric resonance rod, the y-axis dielectric resonance rod and the z-axis dielectric resonance rod are matched with the inside of the cavity to form three degenerate modes; the resonant frequency of the three degenerate modes is determined by the lengths of three mutually perpendicular edges of the dielectric resonant block, and the longer the length of the edge is, the lower the frequency is, and the higher the frequency is. The tuning frequency in the x-axis direction can be realized by additionally arranging a debugging screw on the side wall corresponding to the metal cavity to change the distance or the capacitance; the tuning frequency in the y-axis direction can be realized by additionally arranging a debugging screw on the side wall corresponding to the metal cavity to change the distance or the capacitance; the tuning frequency in the z-axis direction can be realized by additionally arranging a debugging screw on the side wall corresponding to the metal cavity to change the distance or the capacitance.
The radio frequency signal generates loss after three-mode resonance, the three degenerate modes in the x direction, the y direction and the z direction generate heat during working, and the heat can be fully contacted with the wall of the metal cavity through the dielectric resonance block and the supporting blocks to form heat conduction, so that the filter can stably work for a long time.
A coupling device 5 is arranged between two of the three degenerate modes, and specifically comprises: the dielectric resonator block 2 is provided with a first plane j1 for coupling the resonant modes in the x direction and the y direction, a second plane j2 for coupling the resonant modes in the y direction and the z direction, and a third plane j3 for coupling the resonant modes in the x direction and the z direction, wherein the first plane j1, the second plane j2 and the third plane j3 are mutually perpendicular in pairs, the first plane j1 is parallel to an edge arranged along the z direction, the second plane j2 is parallel to an edge arranged along the x direction, and the third plane is parallel to an edge arranged along the y direction. Namely, the coupling between the degenerate mode in the x direction and the degenerate mode in the y direction in the three degenerate modes is formed by a first plane j1 formed by cutting off partial edges along the z-axis direction along the intersection of x and y planes of the dielectric resonator A; the coupling between the degenerate mode in the x direction and the degenerate mode in the z direction is formed by a second plane j2 with an edge angle formed by intersecting y and z planes of the dielectric resonator block and a part of the edge angle cut off along the x-axis direction; the coupling between the degenerate mode in the y-direction and the degenerate mode in the z-direction is formed by a third plane j3 where the z, x planes of the dielectric resonator intersect to form an edge with a partial cut-off in the y-direction. The larger the area of the coupling surface is, the larger the coupling amount is, and conversely, the smaller the coupling amount is. Three degenerate modes formed by the dielectric resonant block can form transmission zero points through cross coupling, and if the coupling among the x-direction resonant mode, the y-direction resonant mode and the z-direction resonant mode is main coupling, the coupling among the x-direction resonant mode and the z-direction resonant mode is cross coupling.
In the above solution, one or more first planes j1 may be provided according to the requirement of the actual coupling amount, and when a plurality of first planes j1 are provided, the plurality of first planes j1 are arranged in parallel; one or more second planes j2 may be provided, and when a plurality of second planes j2 are provided, a plurality of second planes j2 are arranged in parallel; one or more third planes j3 may be provided, and when a plurality of third coupling planes j3 are provided, a plurality of third planes j3 are arranged in parallel.
In the above scheme, one or more supporting blocks 3 may be designed, and when a plurality of supporting blocks 4 are provided, the plurality of supporting blocks 3 are respectively installed between each surface of the dielectric resonant block 2 and the inner wall of the cavity. In the embodiment of the invention, shown in fig. 1 are 6 support blocks 3, a dielectric resonant block is located at the center of the 6 support blocks, 6 surfaces a1-a6 of the dielectric resonant block 2 are respectively connected with the 6 support blocks 3, specifically, the six support blocks 3 are respectively a first support block B1, a second support block B2, a third support block B3, a fourth support block B4, a fifth support block B5 and a sixth support block B6, one end surface a1 of the dielectric resonant block 3 in the x direction is connected with the first support block B1, and the other end surface a2 is connected with the second support block B2 to form an x-axis dielectric resonant rod; one end surface A3 of the dielectric resonant block 2 along the y direction is connected with the third supporting block B3, and the other end surface A4 is connected with the fourth supporting block B4 to form a y-axis dielectric resonant rod; one end face a5 of the dielectric resonator block 2 in the z direction is connected to a fifth support block B5, and the other end face a6 is connected to a sixth support block B6.
The shape of the plurality of supporting blocks 3 includes but is not limited to round, oval and square, the material of the supporting blocks 4 includes but is not limited to plastic, medium and air, and the supporting blocks are solid structures or hollow structures in the middle. The dielectric resonator block 2 and the supporting block 3 are connected by means including but not limited to gluing, crimping and screw fastening. The supporting block and the inner wall of the cavity are connected by means including but not limited to gluing, crimping, screw fastening and welding. The cavity is shaped like a cube or a cuboid and is made of a metal material, or the cavity is made of a metal material, the inner wall of the metal material is plated with silver or copper, or the cavity is made of a non-metal material with a metal layer plated on the surface. In order to reduce the change of frequency under different environmental temperatures, the material proportion of the dielectric resonance block can be adjusted according to different temperature deviations to control the frequency deviation, and in addition, in order to ensure the structural reliability, the supporting block is made of elastic materials such as plastic, so that the supporting block can counteract the influence caused by thermal expansion and cold expansion under different environments.
In the scheme, the tuning frequency of the degenerate three-mode in the X-axis direction is realized by additionally arranging a debugging screw rod or a tuning disc on one surface or two surfaces of the X-axis corresponding to the cavity to change the distance or change the capacitance; the tuning frequency in the Y-axis direction can be realized by additionally arranging a debugging screw rod or a tuning disc on one surface or two surfaces of the Y-axis corresponding to the cavity to change the distance or change the capacitance; the tuning frequency in the z-axis direction can be realized by additionally arranging a debugging screw rod or a tuning disc on one surface or two surfaces of the z-axis corresponding to the cavity to change the distance or change the capacitance;
the tuning screw or the tuning disc is made of metal, or the tuning screw or the tuning disc is made of metal, the surface of the metal is electroplated with copper or silver, or the tuning screw or the tuning disc is made of a medium with a metalized surface;
the tuning screw rod is in the shape of any one of a metal rod, a medium rod, a metal disc, a medium disc, a metal rod-matched metal disc, a metal rod-matched medium disc, a medium rod-matched metal disc and a medium rod-matched medium disc.
In the invention, as shown in fig. 2, three frequency adjustable devices 6 which are orthogonally arranged are arranged on the inner wall of the cavity 1, the three frequency adjustable devices 6 are respectively arranged along the x direction, the y direction and the z direction so as to realize the adjustment of the resonant frequency in the three directions, and the frequency adjustable devices 6 are metal screws, medium screws, metal discs or medium discs.
Based on the three-mode dielectric resonance structure, the three-mode dielectric resonance structure can be arranged and combined with single-mode resonant cavities and dual-mode and three-mode resonant cavities in different forms to form a required filter, and the functional characteristics of the filter include but are not limited to band pass, band stop, high pass, low pass and a combiner formed by the two modes and the three modes. As shown in fig. 2, the filter with a three-mode dielectric structure includes a metal cavity 1, dielectric resonator blocks 2, a single-mode metal resonator column 3, a support block 4, and a coupling device 5, where two dielectric resonator blocks 2 are located at diagonal positions of the metal cavity 1, and the other resonators are metal single-mode resonators. The coupling between the three-mode dielectric resonant structure and other single-mode resonant cavities is realized through windowing in the filter formed by combination, and the larger the windowing is, the larger the coupling amount is. The coupling between any two resonant cavities formed by combining and arranging the single-mode resonant cavity, the double-mode resonant cavity and the three-mode resonant cavity is realized through the size of a window between the two resonant cavities under the condition that the two resonant cavities are parallel.
As is known, a single-cavity structure of a conventional TM mode filter generally employs dielectric resonators with a single dielectric constant, and a single dielectric resonator is grounded up and down to compress the volume in the height direction, but the Q value after volume compression has no obvious advantage relative to a metal cavity filter with the same volume, so that the insertion loss of the filter is not reduced although the dielectric resonators are employed. The three-mode dielectric structure is introduced, so that the defects can be overcome, the Q value of a single cavity can be greatly improved, the Q value of the traditional TM single-dielectric-constant resonator is improved by more than 50% -100%, and compared with the traditional TM single mode, the volume of the three-mode dielectric structure is greatly reduced by 1/3 or more.
In this embodiment, the size of the individual cavities is 36 × 37mm, the size of the dielectric resonator mass 2 is 23.5 × 24 × 29mm, the dielectric constant is 45, and the dielectric resonator mass 2 is raised by the support block 4 by 4mm from the bottom of the cavities. The x, y and z degenerate resonant modes generated by the dielectric resonant block 2 realize energy coupling among the three degenerate resonant modes through three mutually perpendicular cut angles, so that a radio frequency channel is formed, and a radio frequency signal with specific frequency passes through the filter function of the radio frequency signal.
The higher-order mode resonant frequency of the dielectric resonant block 2 is close to the resonant frequency of the three fundamental modes, and is generally 1.1-1.3 times of the resonant frequency of the fundamental modes. Therefore, when the dielectric resonance block is used as a filter, an unnecessary parasitic passband is formed at the high end of the passband, thereby affecting the function of the filter for suppressing the far-end harmonic. And the resonant frequency of the secondary resonant mode of the metal single-mode resonator is far higher than the resonant frequency of the fundamental mode, and is generally 2-3 times of the resonant frequency of the fundamental mode, so that the parasitic passband generated by the higher-order resonant mode of the dielectric resonator block 2 can be damaged by the metal single-mode resonator, and the rejection capability of the filter on far-end harmonics is improved.
Since the dielectric constant of the dielectric resonator block 2 is higher than that of air, most of the generated electromagnetic fields of the three resonant modes are concentrated inside the dielectric resonator block 2, the induced current generated on the cavity wall of the metal cavity 1 is small, and the dielectric loss generated by the dielectric material is smaller than the metal loss, so the unloaded Q value of the three resonant modes generated by the dielectric resonator block 2 is far greater than the Q value of the metal cavity. In this embodiment, the dielectric resonator block 2 has an unloaded Q value of 8500, while the metal cavity having the same volume has a Q value of only 3500, which is improved by 2.4 times by using the dielectric resonator block 2.
In addition, since the dielectric resonator block 2 can generate three independent orthogonal resonance modes, the effect of the near-end suppression is the same as the suppression effect of three single-mode metal resonators, so that the size of the filter can be reduced significantly. In the present embodiment, as shown in fig. 3, since two dielectric resonator blocks 2 are used, the effect of the near-end suppression is the same as that of a single-mode metal filter with 10 cavities, and the volume is reduced by 40% compared with the conventional single-mode metal cavity filter.
It should be understood that the above are only specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily made by those skilled in the art within the technical scope of the present invention disclosed herein should be covered within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.