Dielectric filters and communication base stations

Abstract

The present invention relates to a dielectric filter and a communication base station, comprising a body made of a dielectric material and at least a pair of dielectric resonators disposed on the surface of the body. Two coupling slots are disposed between a first dielectric resonator and a second dielectric resonator of the pair of dielectric resonators. The first dielectric resonator and the second dielectric resonator are located on the upper and lower surfaces of the body, respectively. The two coupling slots are located on the upper and lower surfaces of the body, respectively, and are at least partially connected. Capacitive coupling is achieved between the first dielectric resonator and the second dielectric resonator via the coupling slots. The present invention has the technical advantages of simply and flexibly achieving coupling bandwidth, generating no harmonics, and facilitating mass production.

Description

Technical Field

[0001] The present invention relates to a communication device, in particular to a dielectric filter cross-coupling technology. Background Art

[0002] With the construction of 5G communication systems, the requirements for the integration of its equipment are getting higher and higher. The miniaturization and lightweighting of microwave filters are the future application trends. Dielectric waveguides have the advantages of high Q value and small temperature drift, and are a good solution for filter miniaturization.

[0003] Dielectric filters typically require capacitive cross-coupling to achieve strong suppression through transmission zeros. Achieving low-end and symmetrical transmission zeros requires a capacitive coupling structure (a single high-end transmission zero sometimes doesn't require one). Traditional dielectric waveguide filters typically implement capacitive coupling in the following ways: 1. A frequency-variable coupling structure, while simple, introduces additional resonance points. 2. A capacitive coupling structure derived directly from the flying rod structure of a traditional cavity filter is relatively complex and adds additional components and processes.

[0004] CN 108598635 A discloses a dielectric filter that achieves capacitive coupling through a deep blind hole with a depth exceeding half of the body. This solution simplifies the manufacturing process of achieving the capacitive coupling structure, but has the disadvantage of generating harmonics at the low end of the filter passband, thereby reducing the filter's suppression capability.

[0005] CN210468050U discloses a dielectric filter coupling structure for achieving symmetrical transmission zero points, which includes two blind hole resonators located on the same surface, a first blind slot located below the body, and a second blind slot located above the body. The first blind slot extends toward one blind hole resonator, and the second blind slot extends toward the other blind hole resonator. Both the first blind slot and the second blind slot are connected to a through hole that passes through the body. This solution will not generate additional resonance outside the filter passband and can improve the out-of-band suppression capability of the filter. However, in this solution, the two resonators are located on the same surface, the magnetic field coupling is strong, the electric field coupling is weak, and the application scenario is narrow. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to propose a dielectric filter that can avoid parasitic resonance at the low end of the filter resonant frequency and improve the far-end suppression of the filter at the low end of the frequency in response to the above-mentioned defects of the prior art.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A dielectric filter is provided. The dielectric filter comprises a body made of a dielectric material and at least a pair of dielectric resonators arranged on a surface of the body. Two coupling slots are provided between a first dielectric resonator and a second dielectric resonator of the pair of dielectric resonators. The first dielectric resonator and the second dielectric resonator are respectively located on the upper surface and the lower surface of the body. The two coupling slots are respectively located on the upper surface and the lower surface of the body. The two coupling slots are at least partially connected. Capacitive coupling is achieved between the first dielectric resonator and the second dielectric resonator via the coupling slots.

[0009] Further:

[0010] The first coupling slot includes a communicating portion and an extending portion extending toward the second dielectric resonator, and the second coupling slot includes a communicating portion and an extending portion extending toward the first dielectric resonator.

[0011] The extending portion of the first coupling slot extends directly above the second dielectric resonator, and the extending portion of the second coupling slot extends directly below the first dielectric resonator.

[0012] The communication portion of the first coupling slot is located at the center of the upper surface of the body, and the communication portion of the second coupling slot is located at the center of the lower surface of the body.

[0013] The extending portion of the first coupling slot and the extending portion of the second coupling slot are both arc-shaped.

[0014] A debugging blind hole for assisting in fine-tuning the frequency of the dielectric resonator is provided coaxially with the dielectric resonator on the surface of the main body opposite to the dielectric resonator.

[0015] The debugging blind hole is circular, polygonal or elliptical, and a surface portion of the debugging blind hole is not covered by the conductive layer.

[0016] A dielectric filter is provided, comprising a body made of a dielectric material and dielectric resonators disposed on the body. Four dielectric resonators are provided, located at four corners of a quadrilateral, wherein a capacitive coupling structure is provided between a pair of adjacent dielectric resonators. A first dielectric resonator and a second dielectric resonator of the pair of dielectric resonators are located on the upper and lower surfaces of the body, respectively. Two coupling slots are located on the upper and lower surfaces of the body, respectively. The two coupling slots are at least partially connected, and capacitive coupling is achieved between the first dielectric resonator and the second dielectric resonator via the coupling slots.

[0017] A communication base station is provided, comprising any one of the dielectric filters described above.

[0018] Compared to existing capacitive coupling structures, the capacitive coupling structure of the present invention offers the following advantages: A pair of dielectric resonators, positioned on the upper and lower surfaces, allows two magnetic fields, one surrounding the upper surface and the other surrounding the lower surface. The opposite arrangement shortens the distance between their electric fields, thereby increasing the amount of capacitive coupling. Furthermore, without the need for additional parts or processes, the coupling bandwidth can be simply and flexibly achieved without harmonic generation, thus ensuring product performance and design flexibility, reducing production complexity, and facilitating mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the three-dimensional structure of an embodiment of a dielectric filter of the present invention;

[0020] Figure 2 This is a schematic diagram of the upper surface structure of an embodiment of a dielectric filter of the present invention;

[0021] Figure 3 This is a schematic diagram of the lower surface structure of an embodiment of a dielectric filter of the present invention;

[0022] Figure 4 yes Figure 2 AA cross-sectional diagram;

[0023] Figure 5 1 is a schematic diagram of the upper surface structure of another embodiment of the dielectric filter of the present invention;

[0024] Figure 6 1 is a schematic diagram of the lower surface structure of another embodiment of the dielectric filter of the present invention;

[0025] Figure 7 yes Figure 5 AA cross-sectional diagram;

[0026] Figure 8 2 is a schematic diagram of the upper surface structure of an embodiment of a dielectric filter with 4 cavities and 2 transmission zero points according to the present invention;

[0027] Figure 9 2 is a schematic diagram of the lower surface structure of an embodiment of a dielectric filter with 4 cavities and 2 transmission zero points according to the present invention;

[0028] Figure 10 is a topological structure diagram of capacitive coupling and inductive coupling according to an embodiment of the present invention;

[0029] Figure 11 is a passband near-end frequency response curve diagram of a dielectric filter embodiment of the present invention;

[0030] Figure 12 1 is a passband far-end frequency response curve of a dielectric filter embodiment of the present invention. DETAILED DESCRIPTION

[0031] Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0032] A dielectric filter, such as Figures 1 to 4 As shown, the device comprises a body 10 made of a dielectric material and at least a pair of dielectric resonators disposed on the surface of the body 10. A coupling window 16 and two coupling slots are disposed between a first dielectric resonator 11 and a second dielectric resonator 12 of the pair of dielectric resonators. The first dielectric resonator 11 and the second dielectric resonator 12 are located on the upper and lower surfaces of the body 10, respectively. A first coupling slot 13 is located on the upper surface of the body, and a second coupling slot 14 is located on the lower surface of the body. The first coupling slot 13 and the second coupling slot 14 are at least partially connected, achieving capacitive coupling between the first dielectric resonator 11 and the second dielectric resonator 12 via the coupling slots. The strength of the capacitive coupling is adjusted by removing portions of the conductive layer of the coupling slots and the coupling window. The resonant frequency of the dielectric resonator is adjusted by removing portions of the conductive layer on the surface of the dielectric resonator.

[0033] The first coupling slot 13 includes a connecting portion and an extending portion extending toward the second dielectric resonator 12. The second coupling slot 14 includes a connecting portion and an extending portion extending toward the first dielectric resonator 11. The extending portion of the first coupling slot extends directly above the second dielectric resonator, while the extending portion of the second coupling slot extends directly below the first dielectric resonator. Because the strongest electric field of the dielectric resonator is near the bottom of the blind hole of the resonator, and the strongest magnetic field is near the opening of the blind hole of the resonator, this method can increase the distance between the coupling slot and the opening of the dielectric resonator located on the same surface, thereby reducing the electromagnetic coupling between the first coupling slot and the first resonator, thereby reducing the weakening effect of electromagnetic coupling on electric field coupling.

[0034] The connecting portion can be cylindrical, square, U-shaped, etc., and the extending portion can be arc-shaped, long strip, U-shaped, etc. Figures 5 to 7 As shown in the figure, the connecting part of the coupling slot is cylindrical and the extended part is arc-shaped. Its advantage is that it can divert more electric field from one dielectric resonator to another dielectric resonator, thereby enhancing the capacitive coupling between the resonators. Therefore, while maintaining the same coupling strength, Figure 2 The structure shown can increase the distance between the coupling slot and the resonator, thereby facilitating the processing and shaping of the medium.

[0035] like Figure 5 and Figure 7As shown, a debugging blind hole 15 is coaxially provided on the surface of the body 10 opposite the dielectric resonator, for assisting in fine-tuning the dielectric resonator frequency. In this embodiment, a debugging blind hole 15 is coaxially provided on the upper surface of the body, coaxially with the second dielectric resonator 12, for assisting in fine-tuning the dielectric resonator frequency. The debugging blind hole is circular, polygonal, or elliptical in shape. The surface of the debugging blind hole is partially uncovered by the conductive layer, which is achieved by removing a portion of the conductive layer, such as the silver layer, from the surface of the debugging blind hole.

[0036] The dielectric filter can be applied to a wireless communication base station.

[0037] The following is a detailed description of the technical solution of the present invention using a 4-cavity 2-transmission zero dielectric filter.

[0038] like Figure 8 and Figure 9 As shown, the entire outer layer of the dielectric filter body 10 in this embodiment is silver-plated. Four dielectric resonators are provided on the body, with coupling windows positioned between each pair. Capacitive coupling structures and inductive coupling structures are positioned within the corresponding open coupling windows. The capacitive coupling structure in this embodiment is positioned between dielectric resonators 2 and 3, which are located on the upper and lower surfaces of the body, respectively. The capacitive coupling structure includes coupling slots 6 and 7, located on the upper and lower surfaces of the body, respectively. Both the first and second coupling slots include a connecting portion and an extended portion. In this embodiment, the connecting portion of the first and second coupling slots is cylindrical, while the extended portion is arc-shaped.

[0039] In this embodiment, except for the capacitive coupling between dielectric resonator 2 and dielectric resonator 3, all other couplings are inductive couplings, which are achieved through the dielectric coupling window between the two resonators, such as Figure 4 The topology shown. The debugging blind holes for dielectric resonators 1, 2, and 4 are located on the back of the main body. The debugging blind hole 5 for resonator 3 is located on the front of the main body. The debugging blind hole is a shallow hole used to fine-tune the frequency of resonator 3. The resonator frequency is adjusted by removing the silver layer on the surface of the dielectric resonator, and the coupling is adjusted by removing the conductive layer of the coupling window and coupling slot structure. The debugging blind holes in this technical solution can have special shapes such as circular, polygonal, and elliptical structures.

[0040] The topology of the dielectric filter in this embodiment is as follows Figure 10 As shown, a total of 2 transmission zero points are achieved, thereby achieving the near-end strong suppression index requirement, such as Figure 11 shown. Figure 12The far-end suppression and parasitic resonance of the filter are demonstrated. The present invention has no parasitic resonance at the low end of the filter passband, resulting in good far-end suppression at the low end of the passband. However, parasitic resonance occurs at the high end of the passband, close to the resonator's higher-order mode resonant frequency, resulting in good far-end suppression at the high end of the filter passband.

[0041] The capacitive coupling structure of this technical solution is simple to implement, easy to process, and convenient for mass production.

[0042] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those skilled in the art may modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein; and these modifications and replacements should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A dielectric filter comprising a body made of a dielectric material and at least one pair of dielectric resonators disposed on a surface of the body, wherein two coupling slots are disposed between a first dielectric resonator and a second dielectric resonator of the pair of dielectric resonators, wherein: The first dielectric resonator and the second dielectric resonator are respectively located on the upper surface and the lower surface of the body, and the two coupling slots are respectively located on the upper surface and the lower surface of the body, and the two coupling slots are at least partially connected. Capacitive coupling is achieved between the first dielectric resonator and the second dielectric resonator through the two coupling slots. The first coupling slot includes a connecting portion and an extending portion extending toward the second dielectric resonator, and the second coupling slot includes a connecting portion and an extending portion extending toward the first dielectric resonator. The extending portion of the first coupling slot extends directly above the second dielectric resonator, and the extending portion of the second coupling slot extends directly below the first dielectric resonator. Along the direction from the first dielectric resonator to the second dielectric resonator, the projection of the first coupling slot partially overlaps with the projection of the second dielectric resonator, and the projection of the second coupling slot partially overlaps with the projection of the first dielectric resonator.

2. The dielectric filter according to claim 1, wherein: The communication portion of the first coupling slot is located at the center of the upper surface of the body, and the communication portion of the second coupling slot is located at the center of the lower surface of the body.

3. The dielectric filter according to claim 1, wherein: The extending portion of the first coupling slot and the extending portion of the second coupling slot are both arc-shaped.

4. The dielectric filter according to claim 1, wherein: A debugging blind hole for assisting in fine-tuning the frequency of the dielectric resonator is provided coaxially with the dielectric resonator on the surface of the main body opposite to the dielectric resonator.

5. The dielectric filter according to claim 4, wherein: The debugging blind hole is circular, polygonal or elliptical, and a surface portion of the debugging blind hole is not covered by the conductive layer.

6. A dielectric filter comprising a body made of a dielectric material and a dielectric resonator disposed on the body, characterized in that: There are four dielectric resonators, which are respectively located at the four corners of the quadrilateral, and a capacitive coupling structure is provided between a pair of adjacent dielectric resonators; The first dielectric resonator and the second dielectric resonator of the pair of dielectric resonators are respectively located on the upper surface and the lower surface of the body, and the two coupling slots are respectively located on the upper surface and the lower surface of the body, and the two coupling slots are at least partially connected. Capacitive coupling is achieved between the first dielectric resonator and the second dielectric resonator through the coupling slots. The first coupling slot includes a connecting portion and an extending portion extending toward the second dielectric resonator. The second coupling slot includes a connecting portion and an extending portion extending toward the first dielectric resonator. The extending portion of the first coupling slot extends directly above the second dielectric resonator, and the extending portion of the second coupling slot extends directly below the first dielectric resonator. Along the direction from the first dielectric resonator to the second dielectric resonator, the projection of the first coupling slot partially overlaps with the projection of the second dielectric resonator, and the projection of the second coupling slot partially overlaps with the projection of the first dielectric resonator.

7. The dielectric filter according to claim 6, wherein: The communicating portion of the first coupling slot and the second coupling slot is cylindrical, and the extending portion is arc-shaped.

8. A communication base station, characterized in that: Comprising the dielectric filter according to any one of claims 1 to 7.

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