Cavity dielectric filter

Abstract

A main body of the cavity dielectric filter is a solid multi-cavity core composed of a plurality of resonant cavities arranged in the same direction and coupling pieces for coupling the resonant cavities, the surface of the solid multi-cavity core is coated with a metal layer, the two ends of the solid multi-cavity core are each provided with a feed port, and specifically, the feed ports are formed in the mode that notches are formed in the metal layer; a metal rectangular part is arranged on the surface of the solid multi-cavity core in the notch, and a gap is reserved between the metal rectangular part and the metal layer; the interior of the solid multi-cavity core is provided with a blind hole which penetrates through the metal rectangular part, and the interior of the blind hole is electroplated and filled. According to the dielectric cavity filter using the novel feed mode, only the notch is formed in the bottom of the metal layer, the metal rectangular part is reserved to form the bonding pad, then the blind hole extends from the bonding pad at the bottom to the interior of the cavity to serve as the feed probe for feeding, only the bottom face needs to be windowed, and the side face needs to be directly coated with copper; the process flow and the process difficulty are reduced, and the selectivity of the process is widened.

Description

Technical Field

[0001] The invention relates to the technical field of filters, and in particular to a surface-mount high-performance RF dielectric cavity filter composed of six dielectric cavities with metal coated outer surfaces. Background Art

[0002] In the past decade, wireless communication technology has developed rapidly, and the frequency bands used by wireless communication technology have been increasing. In the high-frequency working band above 10G, dielectric cavity filters have many advantages: low insertion loss, high roll-off, simple structure and easy to manufacture. The mainstream feeding methods of dielectric cavity filters are currently coaxial probe feeding and surface mount feeding.

[0003] Coaxial probe feeding requires two coaxial connectors to be connected at both ends of the dielectric cavity filter for feeding. In addition, the two coaxial interfaces are large in size and heavy in weight, which is not conducive to integration into the PCB motherboard.

[0004] Surface mount feeding refers to a device that can be directly mounted on the surface of the PCB by welding. The general implementation method is to open a U-shaped groove at the bottom of the device, and the area enclosed by the U-shaped groove is used as a pad, which is connected to the pad of the test board. The two arms of the U-shaped groove extend to the side of the device. By changing the shape and size of the two arms, a suitable displacement current is generated to feed the dielectric resonant cavity. No additional coaxial probe feeding is required, it is light in weight and small in size, and it is easy to integrate into the PCB. Surface mount feeding is relatively convenient to use, but it requires U-shaped grooves to be opened in the silver-coated layer on the bottom and sides. There are many process steps, and there are certain requirements for the alignment accuracy of the bottom and side grooves. Summary of the invention

[0005] The present invention provides a cavity dielectric filter, which reduces the process flow and process difficulty and broadens the selectivity of the process.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical scheme:

[0007] A cavity dielectric filter, the main body of which is a solid multi-cavity core composed of multiple resonant cavities arranged in the same direction and coupling plates coupling each resonant cavity, the surface of the solid multi-cavity core is coated with a metal layer, and a feeding port is respectively arranged at both ends of the solid multi-cavity core.

[0008] According to a further aspect of the present invention, on the horizontal plane where the upper surface of the solid multi-cavity core is located, the dimensions of each resonant cavity perpendicular to the arrangement direction are the same, the dimensions parallel to the arrangement direction are different, and the dimensions of each coupling plate are different.

[0009] According to a further aspect of the present invention, the feeding ports are symmetrically arranged along the arrangement direction at the locations where both sides of the lower surface of the solid multi-cavity core contact the side surfaces.

[0010] According to a further aspect of the present invention, the feeding port is specifically:

[0011] A notch is provided on the metal layer, and a metal rectangular portion is provided on the surface of the solid multi-cavity core in the notch, and a gap is left between the metal rectangular portion and the metal layer;

[0012] The solid multi-cavity core is provided with a blind hole inside to penetrate the metal rectangular part, and the blind hole is filled with electroplating.

[0013] According to a further aspect of the present invention, the notch is configured as a "mouth"-shaped groove or an "O"-shaped groove.

[0014] The beneficial effects of the present invention are:

[0015] The present invention proposes a dielectric cavity filter using a new feeding method, in which only a notch is opened at the bottom of the metal layer, leaving a metal rectangular part to form a pad, and then a blind hole is extended from the bottom pad to the inside of the cavity as a feeding probe for feeding. Only a window needs to be opened on the bottom surface and copper can be directly covered on the side, which reduces the process flow and process difficulty and broadens the process selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a bottom view schematic diagram of the structure of the present invention;

[0017] Figure 2 It is a top view schematic diagram of the structure of the present invention;

[0018] Figure 3 It is a schematic diagram of the structure plane of the present invention;

[0019] Figure 4 This is a diagram of the metal rectangular part and the blind hole structure. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be further described in detail below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention but not all. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] like Figure 1-4As shown, a cavity dielectric filter is formed by a solid multi-cavity core 100 formed by connecting rectangular parallelepiped resonant cavities 141, 142, 143, 144, 145, 146 and coupling plates 161, 162, 163, 164, 165 of the same dielectric material for coupling each resonant cavity. The bottom surface 120, the side surface 110, the top surface 140, the front curved side surface 130 and the rear flat side surface 150 of the solid multi-cavity core 100 are covered with a metal layer to form the basic structure of the dielectric cavity filter.

[0022] On the horizontal plane where the upper surface 140 is located, the dimensions of each resonant cavity perpendicular to the arrangement direction are the same, and the dimensions parallel to the cavity arrangement direction are different. On the horizontal plane where the upper surface 140 is located, the dimensions of each coupling plate are different. During design, the resonant frequency is adjusted by changing the dimensions of each resonant cavity, and the coupling strength between each cavity is adjusted by changing the dimensions of each coupling plate, thereby adjusting the bandwidth.

[0023] The two feeding ports are symmetrically distributed at both ends of the solid multi-cavity core 100 along the cavity arrangement direction. The two feeding ports are exactly the same in size and can be interchanged. A "mouth"-shaped groove 123 is opened at the contact between the two sides of the lower surface 120 of the solid multi-cavity core 100 and the side surface 110 along the cavity arrangement direction. The grooved part is not covered with silver / appropriate metal, and the internal dielectric is directly exposed. The metal rectangular part 121 surrounded by the "mouth"-shaped groove is still covered with silver / appropriate metal. The metal rectangular part 121 serves as the input / output port of the device. A blind hole 122 is drilled from the metal rectangular part 121 to the inside of the device, and then the blind hole 122 is electroplated or other suitable metallization treatments are performed. A feeding port includes a metal rectangular part 121, a blind hole 122, and a copper-free "mouth"-shaped groove 123.

[0024] By adjusting the size of the "mouth"-shaped slot 123, the size of the metal rectangular part 121, and the relative position of the "mouth"-shaped slot 123 and the metal rectangular part 121, the coupling strength of the feeding port can be adjusted, thereby adjusting the passband bandwidth of the bandpass filter. Similarly, adjusting the radius and length of the blind hole 122, and the relative position of the metal rectangular part 121 and the blind hole 122 can also adjust the port coupling strength, thereby adjusting the bandwidth. Therefore, the above-mentioned dimensions for adjustment can be set to any appropriate size according to requirements.

[0025] The "mouth"-shaped groove 123 is deformed on the original basis, such as changing to an "O"-shaped groove or other annular structure, and any deformation is within the protection range.

[0026] The metal rectangular part 121 plays a feeding role and can be arbitrarily deformed. As long as the shape is still an isolated conductor structure inside the "mouth"-shaped slot, such as a round metal sheet, it is within the protection range.

[0027] The blind hole 122 is used to feed electromagnetic energy into the cavity and can be appropriately deformed. As long as the cavity can be fed with electricity in the form of a metal probe, it is within the protection range, for example, using a double metallized blind hole or a ring feeding probe.

[0028] The coupling plates 161, 162, 163, 164, 165 between the resonant cavities can be designed into any other suitable shape or structure as long as the purpose of adjusting the mutual coupling strength between the cavities can be achieved. For example, the right angle formed by the coupling plate 161 and the resonant cavities 141, 142 can be made into a stepped shape or a rounded corner, which is also within the protection scope.

[0029] The resonant cavities 141, 142, 143, 144, 145, and 146 can be appropriately deformed based on the rectangular cavity as long as they can generate the required resonant mode in the working frequency band, and are also within the protection range.

[0030] Compared with the coaxial probe feeding, the present invention has the advantages of small size, light weight and easy integration into PCB.

[0031] Compared with conventional surface-mount feeders, the present invention only needs to open windows in the bottom metal layer, and the side metal layer does not need windows, and can be directly silver-plated or silver-brushed. This simplifies the process, saves costs, does not require control of the alignment of the bottom and side surfaces, and reduces the requirements for manufacturing accuracy.

[0032] The above advantages are because the present invention combines the advantages of the above two feeding methods, adopts a metalized blind hole similar to a coaxial probe to feed the filter, and replaces the coaxial structure with a pad and ground structure, which reduces the volume and weight while making it adaptable to microstrip line feeding and integrated into a PCB. On the basis of achieving the above advantages, the low insertion loss, high roll-off, and good standing wave ratio characteristics of the dielectric cavity filter are still maintained.

[0033] In this article, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0034] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A cavity dielectric filter, characterized in that: The main body is a solid multi-cavity core composed of multiple resonant cavities arranged in the same direction and coupling plates coupling each resonant cavity. The surface of the solid multi-cavity core is covered with a metal layer, and a feeding port is respectively arranged at both ends of the solid multi-cavity core.

2. A cavity dielectric filter according to claim 1, characterized in that: On the horizontal plane where the upper surface of the solid multi-cavity core is located, the dimensions of each resonant cavity perpendicular to the arrangement direction are the same, and the dimensions parallel to the arrangement direction are different, and the dimensions of each coupling plate are different.

3. A cavity dielectric filter according to claim 1, characterized in that: The feeding ports are symmetrically arranged along the arrangement direction at the locations where both sides of the lower surface of the solid multi-cavity core contact with the side surfaces.

4. A cavity dielectric filter according to claim 1, characterized in that: The feeding port is specifically: A notch is provided on the metal layer, and a metal rectangular portion is provided on the surface of the solid multi-cavity core in the notch, and a gap is left between the metal rectangular portion and the metal layer; The solid multi-cavity core is provided with a blind hole inside to penetrate the metal rectangular part, and the blind hole is filled with electroplating.

5. A cavity dielectric filter according to claim 4, characterized in that: The notch is configured as a "mouth"-shaped groove or an "O"-shaped groove.

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