A dielectric waveguide filter

Abstract

The present invention provides a dielectric waveguide filter, which comprises three interconnected dielectric waveguide resonant cavities and metallized grooves. The metallized grooves are arranged across the interface of two adjacent dielectric waveguide resonant cavities and connect the two adjacent dielectric waveguide resonant cavities. A ridge waveguide structure is formed between the metallized grooves and the metallized top surface of the dielectric waveguide filter. When working, all dielectric waveguide resonators work in a TE101 mode, and the electric field of the ridge waveguide structure is perpendicular to the metallized top surface of the dielectric waveguide filter. The TE101 mode electric field used by the two adjacent dielectric waveguide resonant cavities is also perpendicular to the metallized top surface of the dielectric waveguide filter. Therefore, one of the two adjacent dielectric waveguide resonant cavities can excite the electric field of the ridge waveguide structure, and then excite the electric field of the other resonant cavity, thereby generating negative coupling between the two adjacent dielectric waveguide resonant cavities. It is beneficial to improve the selectivity of ceramic dielectric waveguide filters and realize the miniaturization of ceramic dielectric filters.

Description

Technical Field

[0001] The present invention relates to the technical field of communication equipment components, and in particular to a dielectric waveguide filter. Background Art

[0002] Microwave filters are one of the core components of the RF front end of communication systems. With the development of communication technology and the increase in communication frequency bands, there is an increasing demand for microwave filters with low loss and high power capacity. Ceramic dielectric filters have attracted more and more attention due to their small size, high no-load quality factor, low loss, high power capacity and excellent stability. With the development of 5G communication technology, ceramic dielectric filters are expected to become mainstream technology with broad market prospects.

[0003] As the frequency bands of communication systems increase, the selectivity and miniaturization of filters are challenged. The introduction of cross-negative coupling between resonators will introduce transmission zeros, thereby improving the selectivity of the filter and reducing the order requirements of the filter, thus achieving miniaturization. However, due to the characteristics of ceramic dielectrics, its processing technology cannot realize some negative coupling structures of traditional microstrip filters and metal waveguide filters, which affects the selectivity of ceramic dielectric filters and is not conducive to the miniaturization of ceramic dielectric filters. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that it is difficult to add a negative coupling structure to the ceramic dielectric filter in the prior art, thereby affecting the selectivity of the ceramic dielectric filter.

[0005] To this end, the present invention provides a dielectric waveguide filter, comprising

[0006] at least three interconnected dielectric waveguide resonant cavities;

[0007] The metallized groove is arranged across the interface of two adjacent dielectric waveguide resonant cavities; the two adjacent dielectric waveguide resonant cavities are connected through the metallized groove to achieve negative coupling.

[0008] Optionally, in the above-mentioned dielectric waveguide filter, a first coupling window is provided between the two adjacent dielectric waveguide resonant cavities, and the center of the metallized groove coincides with the center of the first coupling window.

[0009] Optionally, in the above-mentioned dielectric waveguide filter, the metallized groove is perpendicular to the interface.

[0010] Optionally, in the above-mentioned dielectric waveguide filter, the metallized slot is a rectangular slot.

[0011] Optionally, in the above-mentioned dielectric waveguide filter, all the dielectric waveguide resonant cavities have polygonal cross-sections.

[0012] Optionally, in the above-mentioned dielectric waveguide filter, cross-sections of all the dielectric waveguide resonant cavities are regular hexagonal, and all the dielectric waveguide resonant cavities are arranged in a honeycomb shape.

[0013] Optionally, in the above-mentioned dielectric waveguide filter, other two adjacent dielectric waveguide resonant cavities are connected via coupling windows to achieve positive coupling.

[0014] Optionally, the above-mentioned dielectric waveguide filter further comprises two coaxial connectors (201) respectively arranged in the dielectric waveguide resonant cavity on both sides of the metallized slot.

[0015] Optionally, in the above-mentioned dielectric waveguide filter, the coaxial connector is arranged at the center of the dielectric waveguide resonant cavity.

[0016] Optionally, in the above-mentioned dielectric waveguide filter, half of the length of the metallized slot is smaller than the distance from the center of the metallized slot to the edge of the coaxial connector.

[0017] The technical solution of the present invention has the following advantages:

[0018] 1. The dielectric waveguide filter provided by the present invention has a metallized groove arranged across the interface of two adjacent dielectric waveguide resonant cavities and connects the two adjacent dielectric waveguide resonant cavities. A ridge waveguide structure is formed between the metallized groove and the metallized top surface of the dielectric waveguide filter. When working, all dielectric waveguide resonators work in the TE101 mode. The electric field of the ridge waveguide structure is perpendicular to the metallized top surface of the dielectric waveguide filter. The TE101 mode electric field used by the two adjacent dielectric waveguide resonant cavities is also perpendicular to the metallized top surface of the dielectric waveguide filter. Therefore, one of the two adjacent dielectric waveguide resonant cavities can excite the electric field of the ridge waveguide structure, and then excite the electric field of the other resonant cavity, thereby generating negative coupling between the two adjacent dielectric waveguide resonant cavities. It is beneficial to improve the selectivity of the ceramic dielectric waveguide filter and realize the miniaturization of the ceramic dielectric filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the three-dimensional structure of a dielectric waveguide filter provided in an embodiment of the present invention;

[0021] Figure 2A top view of a dielectric waveguide filter provided by an embodiment of the present invention;

[0022] Figure 3 A diagram showing simulation results of insertion loss and return loss of the dielectric waveguide filter provided in an embodiment of the present invention.

[0023] Description of reference numerals:

[0024] 101 - first dielectric waveguide resonant cavity; 102 - second dielectric waveguide resonant cavity; 103 - third dielectric waveguide resonant cavity; 201 - coaxial connector; 3 - metallized groove. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Example

[0030] This embodiment provides a dielectric waveguide filter, such as Figure 1 and Figure 2 As shown, it includes three interconnected dielectric waveguide resonant cavities and a metallized slot 3.

[0031] The metallized groove is arranged across the interface of two adjacent dielectric waveguide resonant cavities; the two adjacent dielectric waveguide resonant cavities are connected by the metallized groove to realize negative coupling. The dielectric waveguide filter body is made of ceramic material. The three dielectric waveguide resonant cavities are respectively the first dielectric waveguide resonant cavity 101, the second dielectric waveguide resonant cavity 102 and the third dielectric waveguide resonant cavity 103. The metallized groove 3 is arranged between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103.

[0032] The metallized groove is arranged across the interface of two adjacent dielectric waveguide resonant cavities and connects the two adjacent dielectric waveguide resonant cavities. A ridge waveguide structure is formed between the metallized groove and the metallized top surface of the dielectric waveguide filter. When working, all dielectric waveguide resonators work in the TE101 mode. The electric field of the ridge waveguide structure is perpendicular to the metallized top surface of the dielectric waveguide filter. The TE101 mode electric field used by the two adjacent dielectric waveguide resonant cavities is also perpendicular to the metallized top surface of the dielectric waveguide filter. Therefore, the first dielectric waveguide resonant cavity can excite the electric field of the ridge waveguide structure, and then excite the electric field of the third dielectric waveguide resonant cavity; similarly, the third dielectric waveguide resonant cavity can excite the electric field of the ridge waveguide structure, and then excite the electric field of the first dielectric waveguide resonant cavity, thereby generating negative coupling between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. It is beneficial to improve the selectivity of the ceramic dielectric waveguide filter and realize the miniaturization of the ceramic dielectric filter.

[0033] See also Figure 1 and Figure 2 The metallized groove is a rectangular groove. A first coupling window is provided between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. The first coupling window is located in the middle of the adjacent side walls of the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. The center of the metallized groove coincides with the center of the first coupling window, and the metallized groove is perpendicular to the interface between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103.

[0034] The electric field is strongest at the center of the first coupling window, and the metallized groove is opened here for the best coupling effect. The metallized groove is perpendicular to the interface between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103, which is easy to process.

[0035] See also Figure 1 and Figure 2, the cross-sections of the three dielectric waveguide resonant cavities are all regular hexagonal, and all dielectric waveguide resonant cavities are arranged in a honeycomb shape. The regular hexagonal resonant cavity has a higher Q value than the square resonant cavity, and the frequency interval between its high-order mode and main mode is also larger. The size of the dielectric waveguide resonant cavity is related to the operating frequency of the dielectric filter. The lower the operating frequency, the longer the side length and the thicker the thickness of the dielectric waveguide resonant cavity. For example, the side lengths of the first dielectric waveguide resonant cavity 101, the second dielectric waveguide resonant cavity 102, and the third dielectric waveguide resonant cavity 103 are L1=9.88mm, L2=9.47mm, and L3=9.88mm, respectively, and the thickness of the resonant cavity is Hr=10mm.

[0036] The first dielectric waveguide resonant cavity 101 and the second dielectric waveguide resonant cavity 102 are connected through a rectangular coupling window to achieve positive coupling, and the second dielectric waveguide resonant cavity 102 and the third dielectric waveguide resonant cavity 103 are connected through a rectangular coupling window to achieve positive coupling. The width of the rectangular coupling window is related to the working bandwidth. The wider the working bandwidth, the wider the width of the rectangular coupling window. For example, the width of the rectangular coupling window between the first dielectric waveguide resonant cavity 101 and the second dielectric waveguide resonant cavity 102 is S12 = 6.5 mm, the width of the rectangular coupling window between the second dielectric waveguide resonant cavity 102 and the second dielectric waveguide resonant cavity 103 is S23 = 6.5 mm, and the first coupling window is also a rectangular coupling window, and the width of the first coupling window is S13 = 4 mm.

[0037] The dielectric waveguide filter also includes two coaxial connectors 201 for exciting the dielectric waveguide filter. The two coaxial connectors 201 are respectively arranged at the center of the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. For example, the length of the inner conductor of the coaxial connector 201 is 4.1 mm.

[0038] The negative coupling strength is proportional to the length, width and height of the metallized slot. The greater the length, width and height, the greater the negative coupling strength. One-half of the length of the metallized slot should be less than the distance from the center of the metallized slot to the edge of the coaxial connector, the width of the metallized slot should be less than the width of the first coupling window, and its height should be less than the thickness of the resonant cavity Hr. For example, the width of the metallized slot Wrid = 2mm, the height Hrid = 9.5mm, and the length Lrid = 5.5mm.

[0039] Figure 3 The simulation results of the insertion loss and return loss of the dielectric waveguide filter provided in the embodiment of the present invention are shown. The working frequency of the dielectric waveguide filter is 1920MHz-1980MHz, the in-band insertion loss is 0.12dB, the in-band return loss is greater than 22dB, and the transmission zero point of the filter is located at 1868MHz, that is, the transmission zero point is located on the left side of the passband. The simulation results also prove that there is a negative coupling between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103.

[0040] As an alternative implementation of the embodiment, the cross-section of the metallized groove can also be elliptical, circular, etc. The metallized groove can be arranged on the bottom surface or the top surface of the dielectric waveguide filter. When the metallized groove is arranged on the bottom surface, it forms a ridge waveguide structure with the top surface of the dielectric waveguide filter; when the metallized groove is arranged on the top surface, it forms a ridge waveguide structure with the bottom surface of the dielectric waveguide filter. The metallized groove may also not be perpendicular to the interface between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103, as long as the metallized groove is arranged across two adjacent dielectric waveguide resonant cavities and can generate negative coupling between the two adjacent dielectric waveguide resonant cavities.

[0041] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A dielectric waveguide filter, characterized in that: include at least three interconnected dielectric waveguide resonant cavities; A metallized groove (3) is arranged across the interface between two adjacent dielectric waveguide resonant cavities; the two adjacent dielectric waveguide resonant cavities are connected through the metallized groove (3) to achieve negative coupling; A first coupling window is provided between the two adjacent dielectric waveguide resonant cavities, and the center of the metallized groove (3) coincides with the center of the first coupling window; The metallized groove (3) is perpendicular to the interface; The metallized groove (3) is a rectangular groove; It also includes two coaxial connectors (201) respectively arranged in the dielectric waveguide resonant cavity on both sides of the metallized groove (3).

2. The dielectric waveguide filter according to claim 1, characterized in that All the dielectric waveguide resonant cavities have polygonal cross sections.

3. The dielectric waveguide filter according to claim 2, characterized in that: The cross sections of all the dielectric waveguide resonant cavities are regular hexagonal, and all the dielectric waveguide resonant cavities are arranged in a honeycomb shape.

4. The dielectric waveguide filter according to any one of claims 1 to 3, characterized in that: The other two adjacent dielectric waveguide resonant cavities are connected via coupling windows to achieve positive coupling.

5. The dielectric waveguide filter according to any one of claims 1 to 3, characterized in that: The coaxial connector (201) is arranged at the center of the dielectric waveguide resonant cavity.

6. The dielectric waveguide filter according to claim 5, characterized in that One half of the length of the metallized groove (3) is smaller than the distance from the center of the metallized groove (3) to the edge of the coaxial connector (201).

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