A dielectric filter

Abstract

The medium 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 an upper surface of the medium filter and a second negative coupling hole opened on a lower surface of the medium filter, the side wall of the first negative coupling hole is provided with a first inclined surface gradually inclined downward to one of the dielectric resonators, the side wall of the second negative coupling hole is provided with a second inclined surface gradually inclined upward to the other dielectric resonator, the second inclined surface is arranged in a spaced manner with the first inclined surface, in the up-down direction, the projection of the second inclined surface is fully overlapped with the projection of the first inclined surface, and in the direction of the line connecting the two dielectric resonators, the projection of the second inclined surface is partially overlapped with the projection of the first inclined surface, so that the structure of the medium filter is more compact, the harmonic amplitude on the left side of the passband is reduced, the anti-interference performance is improved, and the increasingly high performance requirement of the communication base station on the medium filter is met.

Description

Technical Field

[0001] This invention belongs to the field of filter technology, and specifically relates to a dielectric filter. Background Technology

[0002] Dielectric filters are electronic devices designed and manufactured using the characteristics of dielectric ceramic materials, such as low loss, high dielectric constant, small frequency temperature coefficient and thermal expansion coefficient, and high power handling capacity. They consist of a trapezoidal circuit composed of several long resonators connected in series or parallel in the longitudinal direction. Traditional dielectric filters mostly achieve negative coupling through negative coupling holes set between two dielectric resonators. The depth of the negative coupling holes is relatively deep, and it is difficult to maintain their shape during sintering, making the processing difficult. In addition, these types of dielectric filters will generate a high-amplitude harmonic on the left side of the passband, resulting in poor anti-interference performance and making it difficult to meet the increasingly high performance requirements of communication base stations for dielectric filters. Summary of the Invention

[0003] The purpose of this invention is to overcome one or more drawbacks in the prior art and provide a dielectric filter capable of reducing the amplitude of the left harmonic.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is a dielectric filter, comprising 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 formed on the upper surface of the dielectric filter and a second negative coupling hole formed on the lower surface of the dielectric filter. 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.

[0005] Preferably, 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.

[0006] More preferably, in the vertical direction, the projections of the first negative coupling hole and the second negative coupling hole completely overlap.

[0007] More preferably, the orifice 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 connection between 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 line connecting 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 dielectric resonator; 81. Third resonant hole; 9. Fourth dielectric 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 have a non-zero width in the direction of the line connecting the first dielectric resonator 2 and the second dielectric resonator 3. This arrangement allows the first negative coupling hole 4 to be flared upwards and the second negative 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.

Images