Dielectric filter
By setting an inclined negative coupling hole structure in the dielectric filter, the problems of high processing difficulty and poor anti-interference performance of traditional dielectric filters are solved, realizing the compact structure of the dielectric filter and reducing harmonic amplitude, thus improving the performance of communication base stations.
Patent Information
- Application Number
- CN202511477245.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2025-10-11
- Filing Date
- 2025-10-16
- Publication Date
- 2025-12-16
AI Technical Summary
Traditional dielectric filters generate high harmonics on the left side of the passband, are difficult to manufacture, and have poor anti-interference performance, making it difficult to meet the high-performance requirements of communication base stations.
Design a dielectric filter that employs a negative coupling structure between dielectric resonators, including negative coupling holes on the upper and lower surfaces. The hole walls are inclined so that they partially overlap in the vertical direction and the direction of the dielectric resonator connection. The hole shape is rectangular, circular, or elliptical, and the depth is not less than half the thickness of the dielectric filter. The hole walls have an open trumpet-shaped structure in the direction of the dielectric resonator connection.
This invention achieves a compact dielectric filter structure, reduces the harmonic amplitude on the left side of the passband, improves anti-interference performance, and meets the high-performance requirements of communication base stations for dielectric filters.
Smart Images
Figure CN121149643A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of filter, and particularly relates to a dielectric filter. BACKGROUND
[0002] The dielectric filter is an electronic device composed of a ladder-shaped line of a plurality of long resonators in longitudinal multi-stage series or parallel connection, and is designed and manufactured by using the characteristics of low loss, high dielectric constant, small frequency temperature coefficient and thermal expansion coefficient, and high power bearing of dielectric ceramic material. The traditional dielectric filter realizes negative coupling through a negative coupling hole arranged between two dielectric resonators. The depth of the negative coupling hole is deep, the shape is difficult to keep during sintering, the processing difficulty is large, and the dielectric filter of this kind produces a high-amplitude harmonic on the left side of the passband, and has poor anti-interference performance, which is difficult to meet the increasingly high performance requirements of the communication base station on the dielectric filter. SUMMARY
[0003] The purpose of the present application is to overcome one or more shortcomings in the prior art, and to provide a dielectric filter capable of reducing the left side harmonic amplitude.
[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is that the dielectric filter comprises at least two dielectric resonators and a negative coupling structure arranged between the two dielectric resonators, the negative coupling structure comprises a first negative coupling hole opened on the upper surface of the dielectric filter and a second negative coupling hole opened on the lower surface of the dielectric filter, the side wall of the first negative coupling hole has a first inclined surface gradually inclined downward to one of the dielectric resonators, the side wall of the second negative coupling hole has a second inclined surface gradually inclined upward to the other dielectric resonator, the second inclined surface is arranged in spaced relation with the first inclined surface, in the up-down direction, the projection of the second inclined surface and the first inclined surface is fully coincident, and in the direction of the line connecting the two dielectric resonators, the projection of the second inclined surface and the first inclined surface is partially coincident.
[0005] Preferably, the side wall of the first negative coupling hole other than the first inclined surface extends vertically downward, and the side wall of the second negative coupling hole other than the second inclined surface extends vertically upward.
[0006] Further preferably, in the up-down direction, the projection of the first negative coupling hole and the second negative coupling hole is fully coincident.
[0007] Further preferably, the hole opening shape of the first negative coupling hole and the second negative coupling hole is rectangular, circular or elliptical.
[0008] Preferably, the width of the bottom wall of the first negative coupling hole and the second negative coupling hole in the direction of the line connecting the two dielectric resonators is not zero.
[0009] Preferably, the depths of the first negative coupling hole and the second negative coupling hole are not less than half the thickness of the dielectric filter.
[0010] Preferably, in the direction of the connection between the two dielectric resonators, the height of the overlapping portion of the projections of the first inclined plane and the second inclined plane is not less than half the depth of the first negative coupling hole and the second negative coupling hole.
[0011] More preferably, the depth of the first negative coupling hole is equal to the depth of the second negative coupling hole.
[0012] Preferably, the first inclined surface and the second inclined surface are arranged parallel to each other.
[0013] Preferably, the dielectric resonator includes a resonant hole, and the resonant holes of the two dielectric resonators are both opened on the upper or lower surface of the dielectric filter.
[0014] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:
[0015] The dielectric filter provided by this invention includes at least two dielectric resonators and a negative coupling structure disposed between the two dielectric resonators. The negative coupling structure includes a first negative coupling hole on the upper surface of the dielectric filter and a second negative coupling hole on the lower surface of the dielectric filter. By making the sidewall of the first negative coupling hole have a first inclined surface that gradually slopes downward toward one of the dielectric resonators, and the sidewall of the second negative coupling hole has a second inclined surface that gradually slopes upward toward the other dielectric resonator, the second inclined surface and the first inclined surface are spaced apart. In the vertical direction, the projections of the second inclined surface and the first inclined surface completely coincide. In the direction of the connection between the two dielectric resonators, the projection portions of the second inclined surface and the first inclined surface coincide. This makes the structure of the dielectric filter more compact, reduces the harmonic amplitude on the left side of the passband, and improves anti-interference performance, thereby meeting the increasingly higher performance requirements of communication base stations for dielectric filters. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of a dielectric filter in the prior art.
[0017] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention.
[0018] Figure 3 yes Figure 2 A cross-sectional view.
[0019] Figure 4 This is a schematic diagram of another type of dielectric filter in the prior art.
[0020] Figure 5 This is a schematic diagram of the structure of Embodiment 2 of the present invention.
[0021] Figure 6 yes Figure 4 Electrical performance diagram.
[0022] Figure 7 yes Figure 5 Electrical performance diagram.
[0023] Wherein: 1. Dielectric filter; 2. First dielectric resonator; 21. First resonant hole; 3. Second dielectric resonator; 31. Second resonant hole; 4. First negative coupling hole; 5. Second negative coupling hole; 6. First inclined plane; 7. Second inclined plane; 8. Third resonator; 81. Third resonant hole; 9. Fourth resonator; 91. Fourth resonant hole; 10. Through slot. Detailed Implementation
[0024] Example 1, as Figure 2 and 3 As shown, the dielectric filter 1 provided by the present invention includes a first dielectric resonator 2 and a second dielectric resonator 3, and a negative coupling structure disposed between the first dielectric resonator 2 and the second dielectric resonator 3. The first dielectric resonator 2 includes a first resonant hole 21 opened on the upper surface of the dielectric filter 1, and the second dielectric resonator 3 includes a second resonant hole 31 opened on the upper surface of the dielectric filter 1. The negative coupling structure includes a first negative coupling hole 4 opened on the upper surface of the dielectric filter 1 and a second negative coupling hole 5 opened on the lower surface of the dielectric filter 1. The first resonant hole 21, the second resonant hole 31, the first negative coupling hole 4, and the second negative coupling hole 5 are all blind holes. The sidewall of the first negative coupling hole 4 has a first inclined surface 6 that gradually slopes downward toward the first dielectric resonator 2, and the sidewall of the second negative coupling hole 5 has a second inclined surface 7 that gradually slopes upward toward the second dielectric resonator 3. The first inclined surface 6 and the second inclined surface 7 are arranged parallel to each other and spaced apart. In the vertical direction, the projections of the first inclined surface 6 and the second inclined surface 7 completely coincide. In the direction of the line connecting the first dielectric resonator 2 and the second dielectric resonator 3, the projections of the first inclined surface 6 and the second inclined surface 7 partially coincide.
[0025] The advantage of this configuration is that it makes the structure of the dielectric filter more compact and reduces the harmonic amplitude on the left side of the passband, thereby improving anti-interference performance and meeting the increasingly higher performance requirements of communication base stations for dielectric filters.
[0026] In this embodiment, the sidewall of the first negative coupling hole 4, excluding the first inclined surface 6, extends vertically downward, and the sidewall of the second negative coupling hole 5, excluding the second inclined surface 7, extends vertically upward. Furthermore, in the vertical direction, the projections of the first negative coupling hole 4 and the second negative coupling hole 5 completely overlap.
[0027] In this embodiment, the openings of the first negative coupling hole 4 and the second negative coupling hole 5 are rectangular. In other embodiments, the openings can also be circular or elliptical. Furthermore, the bottom walls of the first negative coupling hole 4 and the second negative coupling hole 5 are not zero in the direction of the line connecting the first dielectric resonator 2 and the second dielectric resonator 3. This arrangement allows the first coupling hole 4 to be flared upwards and the second coupling hole 5 to be flared downwards, thereby facilitating stress release during sintering and preventing deformation during sintering.
[0028] In this embodiment, the depths of the first negative coupling hole 4 and the second negative coupling hole 5 are not less than half the thickness of the dielectric filter 1, the depths of the first negative coupling hole 4 and the second negative coupling hole 5 are equal, and in the direction of the connection between the first dielectric resonator 2 and the second dielectric resonator 3, the height of the overlapping portion of the projections of the first inclined plane 6 and the second inclined plane 7 is not less than half the depths of the first negative coupling hole 4 and the second negative coupling hole 5.
[0029] Example 2, as Figure 5 As shown, Embodiment 2 is basically the same as Embodiment 1, except that in Embodiment 2, the dielectric filter 1 further includes a third dielectric resonator 8 and a fourth dielectric resonator 9, as well as a T-shaped through slot 10 disposed between the first dielectric resonator 2, the second dielectric resonator 3, the third dielectric resonator 8, and the fourth dielectric resonator 9. The third dielectric resonator 8 includes a third resonant hole 81 opened on the upper surface of the dielectric filter 1, and the fourth dielectric resonator 9 includes a fourth resonant hole 91 opened on the upper surface of the dielectric filter 1. The third resonant hole 81 and the fourth resonant hole 91 are blind holes, such as... Figure 6 and 7 As shown, under the premise of the same design bandwidth and the same design topology, the harmonic amplitude of the dielectric filter 1 in Embodiment 2 on the left side of the passband is less than -53dB, which is much smaller than the -30dB of the existing single blind hole negative coupling structure dielectric filter. It can significantly reduce the harmonic amplitude on the left side of the passband, improve the anti-interference performance, and meet the increasingly higher performance requirements of communication base stations for dielectric filters.
[0030] The embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A dielectric filter, comprising at least two dielectric resonators and a negative coupling structure disposed between the two dielectric resonators, the negative coupling structure comprising a first negative coupling hole formed on the upper surface of the dielectric filter and a second negative coupling hole formed on the lower surface of the dielectric filter, characterized in that: The sidewall of the first negative coupling hole has a first inclined surface that gradually slopes downward toward one of the dielectric resonators, and the sidewall of the second negative coupling hole has a second inclined surface that gradually slopes upward toward the other dielectric resonator. The second inclined surface is spaced apart from the first inclined surface. In the vertical direction, the projections of the second inclined surface and the first inclined surface completely coincide. In the direction of the line connecting the two dielectric resonators, the projections of the second inclined surface and the first inclined surface partially coincide.
2. The dielectric filter according to claim 1, characterized in that: The sidewall of the first negative coupling hole extends vertically downward except for the first inclined surface, and the sidewall of the second negative coupling hole extends vertically upward except for the second inclined surface.
3. The dielectric filter according to claim 2, characterized in that: In the vertical direction, the projections of the first negative coupling hole and the second negative coupling hole completely overlap.
4. The dielectric filter according to claim 2, characterized in that: The openings of the first negative coupling hole and the second negative coupling hole are rectangular, circular, or elliptical.
5. The dielectric filter according to claim 1, characterized in that: The width of the bottom wall of the first negative coupling hole and the second negative coupling hole in the direction of the connection between the two dielectric resonators is not zero.
6. The dielectric filter according to claim 1, characterized in that: The depths of the first negative coupling hole and the second negative coupling hole are not less than half the thickness of the dielectric filter.
7. The dielectric filter according to claim 1, characterized in that: In the direction of the connection between the two dielectric resonators, the height of the overlapping portion of the projections of the first inclined plane and the second inclined plane is not less than half the depth of the first negative coupling hole and the second negative coupling hole.
8. The dielectric filter according to claim 6 or 7, characterized in that: The depth of the first negative coupling hole is equal to the depth of the second negative coupling hole.
9. The dielectric filter according to claim 1, characterized in that: The first inclined plane is set parallel to the second inclined plane.
10. The dielectric filter according to claim 1, characterized in that: The dielectric resonator includes a resonant hole, and the resonant holes of the two dielectric resonators are both opened on the upper or lower surface of the dielectric filter.