Capacitive coupling structure of ceramic dielectric waveguide duplexer

Abstract

The invention discloses a capacitance coupling structure of a ceramic dielectric waveguide duplexer, belongs to the technical field of dielectric waveguide duplexers, and aims to solve the problem that ceramic is easy to deform or crack after being sintered due to the fact that a negative coupling hole is too deep in the prior art. The capacitance coupling structure is arranged between two adjacent resonators and comprises a first through hole and a second through hole which penetrate through the upper surface and the lower surface of the duplexer body, and a negative coupling blind hole located between the first through hole and the second through hole. The depth of the negative coupling blind hole is larger than the debugging holes but smaller than the total thickness between the upper surface and the lower surface of the duplexer body, and the negative coupling blind hole is arranged on the midperpendicular of the connecting line of the adjacent debugging holes. Through the structure, not only are the channel isolation, the rectangular coefficient and the out-of-band rejection performance of the duplexer improved, but also the design flexibility is enhanced; and meanwhile, the required weak capacitance coupling can be realized by adopting the relatively shallow negative coupling hole, so that the structural defect caused by the deep hole in the high-temperature sintering process of the ceramic is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of microwave communication technology, and more specifically, to a capacitive coupling structure for a ceramic dielectric waveguide duplexer. Background Technology

[0002] With the increasing demands for spectral efficiency and signal isolation in 5G and future mobile communication systems, the need for high-performance duplexers in base station RF front-ends is becoming increasingly urgent. Ceramic dielectric waveguide filters, due to their advantages such as high Q value, low insertion loss, high power capacity, and miniaturization, have become one of the mainstream solutions for high-power base station filters. In duplexer design, to achieve good out-of-band suppression and passband edge steepness, transmission zeros are typically introduced, and capacitive cross-coupling is a key technology for generating such transmission zeros.

[0003] However, achieving effective capacitive coupling in ceramic dielectric waveguide filters presents significant challenges. On one hand, the high dielectric constant and highly localized electromagnetic field of the dielectric material itself limit the electric field coupling path between resonators. On the other hand, traditional methods of introducing capacitive coupling through slotting, perforation, or metallization are susceptible to factors such as uneven mechanical strength and shrinkage during ceramic green pressing and high-temperature sintering, leading to deformation, dimensional deviations, or even failure of the coupling structure, making it difficult to stably reproduce the design performance. Precise control of capacitive coupling is even more challenging in complex structures like duplexers with multi-channel and high isolation requirements.

[0004] Existing technologies, such as patent CN201380046875.9, attempt to achieve specific coupling characteristics by setting deep negative coupling holes. However, due to the significant difference in hole depth compared to other tuning holes, collapse or distortion easily occurs during sintering, affecting yield and electrical performance consistency. Patent CN202211406592.8 proposes a coaxial double blind hole capacitive coupling structure to solve the problem of excessive depth of a single negative coupling hole. However, the coaxial double blind hole structure does not increase the thickness of the ceramic at the bottom of the hole, and excessively thin ceramic thickness can lead to cracking during sintering. Therefore, there is an urgent need for a novel dielectric waveguide duplexer design scheme that is structurally reliable, has strong process compatibility, and can effectively achieve stable capacitive coupling, in order to overcome the current technical bottleneck of ceramic dielectric filters in high-performance duplexer applications. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a capacitive coupling structure for a ceramic dielectric waveguide duplexer, which addresses the shortcomings of the prior art and solves the problem of easy deformation and cracking after sintering due to excessively deep capacitive coupling holes.

[0006] The technical solution of the present invention is as follows: the capacitive coupling structure is disposed between two adjacent dielectric resonant cavities; it includes a negative coupling blind hole located on the upper surface of the dielectric waveguide duplexer body and a first through hole and a second through hole penetrating the upper and lower surfaces of the dielectric waveguide duplexer body, wherein the negative coupling blind hole and the first through hole and the second through hole form capacitive coupling; the negative coupling blind hole is located between the first through hole and the second through hole, and its depth is less than the distance between the upper and lower surfaces of the dielectric waveguide duplexer body.

[0007] Furthermore, the dielectric waveguide duplexer has multiple debugging holes, the diameter of the first through hole and the diameter of the second through hole are the same and less than 40% of the diameter of the debugging hole.

[0008] Furthermore, the depth of the negative coupling blind hole is less than the distance between the upper and lower surfaces of the dielectric waveguide duplexer body.

[0009] Furthermore, the diameter of the negative coupling blind hole is between 50% and 70% of the diameter of the debugging hole.

[0010] Furthermore, the depth of the negative coupling blind hole is more than 1.5 times the depth of the debugging hole.

[0011] Furthermore, the negative coupling blind hole is located on the vertical line of the line connecting two adjacent debugging holes, close to the side of the line connecting the first through hole and the second through hole.

[0012] Furthermore, a metal conductive shielding layer is provided inside and at the bottom of the negative coupling blind hole, inside the first through hole, and inside the second through hole. Beneficial effects

[0013] The advantages of this invention are as follows: Two through-holes penetrating the upper and lower surfaces are provided on the dielectric waveguide duplexer body between two adjacent debugging holes, and a negative coupling blind hole is provided between the two through-holes, thus forming a novel capacitive coupling structure. Compared with the traditional capacitive coupling structure, this structure requires a smaller blind hole depth to achieve the same capacitive coupling coefficient, effectively avoiding the problem of deformation or cracking of the dielectric waveguide duplexer during sintering due to excessively deep negative coupling holes. Furthermore, this capacitive coupling structure can achieve a smaller negative coupling coefficient, thereby introducing a transmission zero within the duplexer's passband. This not only improves the duplexer's bandwidth isolation and out-of-band suppression performance but also significantly enhances the duplexer's design flexibility. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the upper surface of the ceramic dielectric waveguide duplexer body of the present invention; Figure 2 This is a schematic diagram of the lower surface of the ceramic dielectric waveguide duplexer body of the present invention; Figure 3This is a schematic diagram of the capacitive coupling structure of the ceramic dielectric waveguide duplexer body of the present invention; Figure 4 The curve showing the coupling coefficient of the capacitive coupling of the ceramic dielectric waveguide duplexer body of the present invention as a function of hole depth; Figure 5 This is a schematic diagram of the capacitive coupling structure of a traditional ceramic dielectric waveguide duplexer. Figure 6 The curve showing the coupling coefficient of a traditional ceramic dielectric waveguide duplexer as a function of aperture depth. Figure 7 This is the frequency response curve of the dielectric waveguide duplexer of the present invention. Detailed Implementation

[0015] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0016] refer to Figure 1 In this embodiment, the dielectric waveguide duplexer body is a solid dielectric powder, and the solid dielectric powder is ceramic. The dielectric waveguide duplexer body has a geometric shape, including a common dielectric coupling window 10 and a TX (Transmitter) dielectric waveguide filter 20 and an RX (Receiver) dielectric waveguide filter 30 connected to the common dielectric coupling window 10. The dielectric waveguide duplexer body is provided with ten resonators, and each of the TX dielectric waveguide filter 20 and the RX dielectric waveguide filter 30 has five resonators, and each resonator has a tuning hole. That is, the dielectric waveguide duplexer body is provided with ten tuning holes, namely the first tuning hole 21, the second tuning hole 22, the third tuning hole 23, the fourth tuning hole 24, and the fifth tuning hole 25 of the TX dielectric waveguide filter 20, and the first tuning hole 31, the second tuning hole 32, the third tuning hole 33, the fourth tuning hole 34, and the fifth tuning hole 35 of the RX dielectric waveguide filter 30. The present invention discloses a capacitive coupling structure for a dielectric waveguide duplexer, wherein the capacitive coupling structure is disposed between the second tuning hole 22 and the fourth tuning hole 24 of two adjacent resonators at one end of the TX dielectric waveguide filter 20. (See also...) Figure 2 The bottom surfaces of the TX dielectric waveguide filter 20 and the RX dielectric waveguide filter 30 have electrode coupling blind hole 1 61 and electrode coupling blind hole 2 62, respectively.

[0017] See Figure 1 and Figure 3The capacitive coupling structure includes a first through-hole 41, a second through-hole 42, and a negative coupling blind hole 51 located on the TX dielectric waveguide filter 20. The first through-hole 41 and the second through-hole 42 penetrate the upper and lower surfaces of the dielectric waveguide duplexer body. The negative coupling blind hole 51 is located on the upper surface of the dielectric waveguide duplexer body but does not penetrate the lower surface. The negative coupling hole 51 is located on the perpendicular bisector of the line connecting the tuning holes 22 and 24, close to the line connecting the first through-hole 41 and the second through-hole 42. Both the interior of the first through-hole 41 and the second through-hole 42, and the bottom of the negative coupling blind hole 51, are provided with a conductive metal shielding layer. Furthermore, the surface of the dielectric waveguide duplexer body is also covered with a conductive metal shielding layer. The diameter of the first through-hole 41 is the same as the diameter of the second through-hole 42 and is less than 40% of the diameter of the tuning hole. A larger through-hole diameter would significantly reduce the filter's Q value, while a diameter less than 40% of the tuning hole diameter can significantly reduce the depth of the negative coupling blind hole while maintaining the filter's Q value. The diameter of the negative coupling blind hole 51 is between 50% and 70% of the diameter of the debugging hole. Within this diameter range, the negative coupling blind hole has the smallest hole depth when achieving the same negative coupling coefficient.

[0018] The ceramic dielectric waveguide duplexer of this invention employs a capacitive coupling structure, wherein the depth of the negative coupling blind via 51 is greater than 1.5 times the depth of the tuning via. This design allows the resonator containing the second tuning via 22 or the fourth tuning via 24 to have a resonant frequency lower than the resonant frequencies of its adjacent resonators, thereby forming capacitive coupling between them. Furthermore, the introduction of two metallized vias (the first via 41 and the second via 42) reduces the coupling strength between adjacent resonators, acting similarly to deepening the negative coupling blind via, thus effectively reducing the actual depth of the required negative coupling blind via.

[0019] See Figure 3 , Figure 4 , Figure 5 and Figure 6 Compared to the traditional capacitive coupling structure of ceramic dielectric waveguide duplexers, the capacitive coupling structure of this invention reduces the hole depth required to achieve the same negative coupling value by approximately 0.5 mm. In this example, the distance between the upper and lower surfaces of the dielectric waveguide duplexer is 3 mm. Using the capacitive coupling structure of this invention avoids the problem of excessively deep negative coupling blind holes in the prior art, which leads to easy deformation and cracking of the ceramic body of the dielectric waveguide filter during sintering. Furthermore, this capacitive coupling structure forms a transmission zero at the low end of the passband of the TX dielectric waveguide filter 20, such as... Figure 7 As shown, this not only improves the rectangularity factor of the duplexer but also enhances its channel isolation, thereby increasing the design flexibility of the duplexer.

[0020] The above descriptions are merely some preferred embodiments of the present invention and do not exhaust all possible implementations. Without departing from the basic structure and technical principles of the present invention, those skilled in the art can make various conventional adjustments and optimizations, all of which fall within the protection scope of the present invention and will not affect its practicality and actual application effects.

Claims

1. A capacitive coupling structure for a ceramic dielectric waveguide duplexer, characterized in that: The capacitive coupling structure is disposed between two adjacent dielectric resonant cavities; it includes a negative coupling blind hole (51) located on the upper surface of the dielectric waveguide duplexer body and a first through hole (41) and a second through hole (42) penetrating the upper and lower surfaces of the dielectric waveguide duplexer body. The negative coupling blind hole (51) and the first through hole (41) and the second through hole (42) form capacitive coupling. The negative coupling blind hole (51) is located between the first through hole (41) and the second through hole (42), and its depth is less than the distance between the upper and lower surfaces of the dielectric waveguide duplexer body.

2. The capacitive coupling structure of a ceramic dielectric waveguide duplexer according to claim 1, characterized in that, The dielectric waveguide duplexer has multiple debugging holes, the diameter of the first through hole (41) is the same as the diameter of the second through hole (42) and is less than 40% of the diameter of the debugging hole.

3. The capacitive coupling structure of a ceramic dielectric waveguide duplexer according to claim 1, characterized in that, The depth of the negative coupling blind hole (51) is less than the distance between the upper and lower surfaces of the dielectric waveguide duplexer body.

4. The capacitive coupling structure of a ceramic dielectric waveguide duplexer according to claim 2, characterized in that, The diameter of the negative coupling blind hole (51) is between 50% and 70% of the diameter of the debugging hole.

5. The capacitive coupling structure of a ceramic dielectric waveguide duplexer according to claim 2, characterized in that, The depth of the negative coupling blind hole (51) is more than 1.5 times the depth of the debugging hole.

6. The capacitive coupling structure of a ceramic dielectric waveguide duplexer according to claim 1, characterized in that, The negative coupling blind hole (51) is located on the vertical line of the line connecting two adjacent debugging holes, close to the line connecting the first through hole (41) and the second through hole (42).

7. The capacitive coupling structure of a ceramic dielectric waveguide duplexer according to claim 1, characterized in that, The interior and bottom of the negative coupling blind hole (51), the interior of the first through hole (41), and the interior of the second through hole (42) are all provided with a metal conductive shielding layer.

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