A dielectric waveguide filter

Abstract

The present invention provides a dielectric waveguide filter, which includes at least three interconnected dielectric waveguide resonant cavities and metallized blind holes. The metallized blind holes have at least one row, and each row has at least two metallized blind holes. The periodically arranged metallized blind holes and the metallized top surface of the dielectric waveguide filter constitute an artificial magnetic conductor structure. The artificial magnetic conductor structure is an electromagnetic bandgap structure. In the stop band of the electromagnetic bandgap structure, electromagnetic waves will exponentially attenuate through the periodically arranged metallized blind holes, that is, the stop band of the electromagnetic bandgap structure can hinder the propagation of electromagnetic waves. And for the periodically arranged metallized blind holes, the electric field is distributed between the metallized blind holes and the metal top surface of the dielectric waveguide filter, 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 filter.

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 blind holes are arranged between two adjacent dielectric waveguide resonant cavities; the metallized blind holes have at least one row, each row has at least two metallized blind holes, and the at least two metallized blind holes in each row are periodically arranged with equal spacing along the interface direction of the two adjacent dielectric waveguide resonant cavities.

[0008] Optionally, in the above-mentioned dielectric waveguide filter, the metallized blind holes have at least two rows, and the metallized blind holes in each row are periodically arranged with equal spacing.

[0009] Optionally, in the above-mentioned dielectric waveguide filter, the number of rows of the metallized blind holes is an even number, and each row of the metallized blind holes is symmetrical about the interface.

[0010] Optionally, in the above-mentioned dielectric waveguide filter, all the dielectric waveguide resonant cavities have polygonal cross-sections.

[0011] 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.

[0012] Optionally, in the above-mentioned dielectric waveguide filter, the metallized blind hole is a sub-wavelength periodic structure.

[0013] Optionally, in the above-mentioned dielectric waveguide filter, the cross-section of the metallized blind hole is square.

[0014] Optionally, in the above-mentioned dielectric waveguide filter, other two adjacent dielectric waveguide resonant cavities are connected via a rectangular coupling window to achieve positive coupling.

[0015] Optionally, the above-mentioned dielectric waveguide filter further includes two coaxial connectors respectively arranged in the dielectric waveguide resonant cavity on both sides of the metallized blind hole.

[0016] Optionally, in the above-mentioned dielectric waveguide filter, the coaxial connector is arranged at the center of the dielectric waveguide resonant cavity.

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

[0018] 1. The dielectric waveguide filter provided by the present invention has metallized blind holes arranged periodically at equal intervals between two adjacent dielectric waveguide resonant cavities, and the periodically arranged metallized blind holes and the metallized top surface of the dielectric waveguide filter constitute an artificial magnetic conductor structure. The artificial magnetic conductor structure is an electromagnetic bandgap structure. In the stopband of the electromagnetic bandgap structure, electromagnetic waves will exponentially attenuate through the periodically arranged metallized blind holes, that is, the stopband of the electromagnetic bandgap structure can hinder the propagation of electromagnetic waves. And for the periodically arranged metallized blind holes, the electric field is distributed between the metallized blind holes and the metal top surface of the dielectric waveguide filter, 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 blind hole. 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 plurality of metallized blind holes 3.

[0031] 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 blind holes 3 are arranged between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. For example, the metallized blind holes 3 have two rows, and the two rows of metallized blind holes 3 are symmetrical about the interface between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103, and each row of metallized blind holes 3 has five. The multiple metallized blind holes 3 in each row and the metallized blind holes 3 in two adjacent rows are arranged periodically with equal spacing.

[0032] Two rows of metallized blind holes 3 arranged periodically with equal spacing are symmetrically arranged on both sides of the interface between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. The periodically arranged metallized blind holes 3 and the metallized top surface of the dielectric waveguide filter constitute an artificial magnetic conductive structure. The artificial magnetic conductive structure is an electromagnetic bandgap structure. When the frequency of the electromagnetic wave is within the stop band of the electromagnetic bandgap structure, the electromagnetic wave will be exponentially attenuated through the periodically arranged metallized blind holes 3, that is, the stop band of the electromagnetic bandgap structure can hinder the propagation of the electromagnetic wave. For the periodically arranged metallized blind holes 3, when the electromagnetic wave of the first dielectric waveguide resonant cavity 101 is partially attenuated and reaches the third dielectric waveguide resonant cavity 103, the electric field is distributed between the metallized blind holes 3 and the metal top surface of the dielectric waveguide filter, 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] The multiple metalized blind holes 3 in each row are arranged periodically with equal spacing, and the metalized blind holes 3 in each row are also arranged periodically with equal spacing. The metalized blind holes 3 are arranged periodically with equal spacing in both directions of each row and each column, and the coupling effect is good. In addition, the two rows of metalized blind holes 3 are symmetrically arranged about the interface between the first dielectric waveguide resonant cavity 101 and the third dielectric waveguide resonant cavity 103. The multiple metalized blind holes 3 are not biased towards a certain dielectric waveguide resonant cavity as a whole, and the overall coupling strength is good. The two rows of metalized blind holes 3 are arranged to facilitate processing while satisfying the periodic arrangement in two directions.

[0034] The attenuation rate of the electromagnetic wave passing through the periodically arranged metallized blind vias 3 is related to the size of the metallized blind vias 3. The smaller the cross-sectional size of the metallized blind vias 3, the larger the distance between two rows of metallized blind vias 3, the deeper the hole depth, and the denser the arrangement, the greater the attenuation rate of the electromagnetic wave passing through the metallized blind vias 3, and the stronger the negative coupling strength.

[0035] The metallized blind hole 3 is a sub-wavelength periodic structure, and its characteristic size is smaller than the working wavelength of the dielectric filter. For example, the cross section of the metallized blind hole 3 is a square, and its side length is smaller than the working wavelength of the dielectric filter, and its side length Wpin=1mm, the depth of the metallized blind hole 3 Hpin=6mm, and the spacing between two rows of metallized blind holes 3 is Dpin=2mm. When the cross section of the metallized blind hole 3 is circular, its diameter should be smaller than the working wavelength of the dielectric filter.

[0036] 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.

[0037] 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, and the width of the rectangular coupling window between the second dielectric waveguide resonant cavity 102 and the third dielectric waveguide resonant cavity 103 is S23 = 6.5 mm.

[0038] 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.

[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 a first alternative implementation of the embodiment, the number of rows of metallized blind holes 3 can also be one row, three rows, four rows, etc.; the number of metallized blind holes 3 in each row can be any value of more than two. When the metallized blind holes 3 are in one row, the connecting line of the axes of each metallized blind hole 3 can coincide with the interface between two adjacent dielectric waveguide resonant cavities; when the number of rows of metallized blind holes 3 is an odd number, one more row of metallized blind holes 3 can be arranged in one of the dielectric waveguide resonant cavities. When the number of rows of metallized blind holes 3 is an even number, each row of metallized blind holes 3 is symmetrically distributed about the interface between two adjacent dielectric waveguide resonant cavities to obtain the best negative coupling effect.

[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 blind hole (3) is arranged between two adjacent dielectric waveguide resonant cavities; the metallized blind holes (3) have at least two rows, and the metallized blind holes (3) in each row are arranged periodically at equal intervals; each row of the metallized blind holes (3) has at least two metallized blind holes (3), and the at least two metallized blind holes (3) in each row are arranged periodically at equal intervals along the interface direction of the two adjacent dielectric waveguide resonant cavities, and the periodically arranged metallized blind holes (3) and the metallized top surface of the dielectric waveguide filter form an artificial magnetic conductor structure, and an electric field is distributed between the metallized blind holes (3) and the metal top surface of the dielectric waveguide filter, so as to generate negative coupling between the two adjacent dielectric waveguide resonant cavities; All the dielectric waveguide resonant cavities have cross sections in the form of regular hexagons, and all the dielectric waveguide resonant cavities are arranged in a honeycomb shape; The metalized blind hole (3) is a sub-wavelength periodic structure; The other two adjacent dielectric waveguide resonant cavities are connected via rectangular coupling windows to achieve positive coupling.

2. The dielectric waveguide filter according to claim 1, characterized in that The number of rows of the metallized blind holes (3) is an even number, and each row of the metallized blind holes (3) is symmetrical about the interface.

3. The dielectric waveguide filter according to claim 1 or 2, characterized in that: The cross section of the metallized blind hole (3) is a square.

4. The dielectric waveguide filter according to claim 1 or 2, characterized in that: It also includes two coaxial connectors (201) respectively arranged in the dielectric waveguide resonant cavity on both sides of the metallized blind hole (3).

5. The dielectric waveguide filter according to claim 4, characterized in that: The coaxial connector (201) is arranged at the center of the dielectric waveguide resonant cavity.

Images