Dual-band filter with substrate integrated waveguide circular cavity nested with arc cavity

Abstract

The present invention discloses a dual-band filter in which a substrate integrated waveguide circular cavity and an arc cavity are nested, comprising a substrate integrated waveguide circular cavity and two substrate integrated waveguide arc cavities. Metal through holes penetrating each of the substrate integrated waveguide cavities are uniformly distributed along the circumferential direction of each of the substrate integrated waveguide cavities; there is an inductive window between each substrate integrated waveguide arc cavity and the substrate integrated waveguide circular cavity, and an inductive window is also opened between the two substrate integrated waveguide arc cavities; coplanar waveguides are respectively arranged in the two substrate integrated waveguide arc cavities and are connected to output microstrips. The structure of the present invention is simple and convenient for processing. The two passbands of the filter can be controlled separately and can be applied to 5G millimeter wave and 6G mobile communication systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave passive devices, and particularly relates to a dual-band filter in which a substrate integrated waveguide circular cavity and an arc cavity are nested with each other. Background Art

[0002] With the rapid development of communication systems, multi-channel devices have become an important means for future systems to be multi-functional and miniaturized. As an important component in communication systems, the multi-channel technology of filters has also been widely studied by scholars. Traditional waveguide or dielectric filters have a high quality factor, but it is difficult to integrate them into circuits due to their three-dimensional structures; while microstrip filters are relatively easy to integrate into circuits, but due to their large insertion losses, they are not suitable for application in the millimeter-wave band. Substrate integrated waveguide technology is a new type of waveguide device with low insertion loss, high quality factor, and high power capacity that has emerged in the past decade or so. Various substrate integrated waveguide passive and active devices based on processes such as PCB and LTCC have the advantages of both traditional metal waveguides and planar circuits, and have unparalleled advantages in terms of production cost and design complexity in the microwave and millimeter-wave bands. In recent years, many dual-band filters based on substrate integrated waveguide technology have been widely studied and designed.

[0003] In order to achieve the effect of dual bands, traditional substrate integrated waveguide dual-band filters often need to couple two modes simultaneously through the same coupling window, which increases the design complexity and makes it difficult to adjust the two passbands separately. At the same time, it is difficult to directly couple the cavities usually located on both sides of the central cavity due to the limitations of their physical structures. Summary of the Invention

[0004] The purpose of the present invention is to adopt a physical structure combining an arc cavity and a circular cavity to achieve direct coupling of non-adjacent cavities, form a new coupling channel, and realize separate regulation of the two passbands, greatly reducing the design complexity, and provide a dual-band filter in which a substrate integrated waveguide circular cavity and an arc cavity are nested with each other;

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A dual-band filter in which a substrate integrated waveguide circular cavity and an arc cavity are nested with each other, comprising: a substrate integrated waveguide circular cavity, a first substrate integrated waveguide arc cavity, and a second substrate integrated waveguide arc cavity respectively formed by metal through holes, the first substrate integrated waveguide arc cavity and the second substrate integrated waveguide arc cavity are located on both sides of the substrate integrated waveguide circular cavity, the substrate integrated waveguide circular cavity is coupled to the first substrate integrated waveguide arc cavity through a first inductive window, the substrate integrated waveguide circular cavity is coupled to the second substrate integrated waveguide arc cavity through a second inductive window, and the first substrate integrated waveguide arc cavity is coupled to the second substrate integrated waveguide arc cavity through a third inductive window and a fourth inductive window;

[0006] The first substrate integrated waveguide arc cavity is connected to the input microstrip line through a first coplanar waveguide, and the second substrate integrated waveguide arc cavity is connected to the output microstrip line through a second coplanar waveguide.

[0007] Furthermore, the dominant modes of the substrate integrated waveguide circular cavity, the first substrate integrated waveguide arc cavity, and the second substrate integrated waveguide arc cavity operate at the same frequency. The dominant modes of the first substrate integrated waveguide arc cavity and the second substrate integrated waveguide arc cavity are coupled with the substrate integrated waveguide circular cavity to achieve the first passband, and the higher-order modes of the first substrate integrated waveguide arc cavity and the second substrate integrated waveguide arc cavity are directly coupled through the first substrate integrated waveguide arc cavity and the second substrate integrated waveguide arc cavity to achieve the second passband.

[0008] Furthermore, the first inductive window and the second inductive window are mirror-symmetrical.

[0009] Furthermore, the third inductive window and the fourth inductive window are mirror-symmetrical.

[0010] Furthermore, the input microstrip line and the output microstrip line are mirror-symmetrical and present an obtuse angle.

[0011] Furthermore, both the input microstrip line and the output microstrip line are 50 ohms.

[0012] Beneficial effects: The present invention discloses a dual-band filter in which a substrate integrated waveguide circular cavity and an arc cavity are nested. Compared with traditional dual-band filters, direct coupling between non-adjacent cavities is achieved through the combination of an arc cavity and a circular cavity. The dominant mode of the arc cavity is coupled with the circular cavity to achieve the first passband, and the higher-order mode of the arc cavity is directly coupled through two arc cavities to achieve the second passband, thereby realizing separate regulation of the two passbands and greatly reducing the design complexity. Description of the Drawings

[0013] Figure 1 It is the structural diagram of the filter in the specific embodiment of the present invention;

[0014] Figure 2 It is the frequency response curve diagram of the filter in the specific embodiment of the present invention.

[0015] In the figure: 1. Input microstrip line, 2. Output microstrip line, 3. Substrate integrated waveguide circular cavity, 4. First substrate integrated waveguide arc cavity, 5. Second substrate integrated waveguide arc cavity, 6. Metal through hole, 9. First coplanar waveguide, 10. Second coplanar waveguide, 111. First inductive window, 112. Second inductive window, 121. Third inductive window, 122. Fourth inductive window. Specific Embodiment

[0016] The present invention will be further explained below in conjunction with the accompanying drawings.

[0017] As Figure 1 shown, the present invention provides a dual-band filter in which a substrate integrated waveguide circular cavity and an arc cavity are nested, including: a substrate integrated waveguide circular cavity 3, a first substrate integrated waveguide arc cavity 4, and a second substrate integrated waveguide arc cavity 5 formed by metal vias 6 respectively. The first substrate integrated waveguide arc cavity 4 and the second substrate integrated waveguide arc cavity 5 are located on both sides of the substrate integrated waveguide circular cavity 3. The substrate integrated waveguide circular cavity 3 is coupled to the first substrate integrated waveguide arc cavity 4 through a first inductive window 111, and the substrate integrated waveguide circular cavity 3 is coupled to the second substrate integrated waveguide arc cavity 5 through a second inductive window 112. The first substrate integrated waveguide arc cavity 4 is coupled to the second substrate integrated waveguide arc cavity 5 through a third inductive window 121 and a fourth inductive window 122.

[0018] The first substrate integrated waveguide arc cavity 4 is connected to the input microstrip line 1 through a first coplanar waveguide 9.

[0019] The second substrate integrated waveguide arc cavity 5 is connected to the output microstrip line 2 through a second coplanar waveguide 10.

[0020] In this embodiment, the first substrate integrated waveguide arc cavity 4 composed of uniformly distributed metal vias 6 and the second substrate integrated waveguide arc cavity 5 composed of uniformly distributed metal vias 6 enclose the substrate integrated waveguide circular cavity 3. The first inductive window 111 on the left side of the substrate integrated waveguide circular cavity 3 is coupled to the first substrate integrated waveguide arc cavity 4, and the right side of the substrate integrated waveguide circular cavity 3 is coupled to the second substrate integrated waveguide arc cavity 5 through the second inductive window 112. The first substrate integrated waveguide arc cavity 4 and the second substrate integrated waveguide arc cavity 5 form a substrate integrated waveguide ring cavity, and a third inductive window 121 and a fourth inductive window 122 are arranged inside the substrate integrated waveguide ring cavity through metal vias 6. The first substrate integrated waveguide arc cavity 4 is directly coupled to the second substrate integrated waveguide arc cavity 5 through the third inductive window 121 and the fourth inductive window 122. The first inductive window 111, the second inductive window 112, the third inductive window 121, and the fourth inductive window 122 are parallel to each other, and the third inductive window 121 and the fourth inductive window 122 are located on the same straight line. The substrate integrated waveguide circular cavity 3, the first substrate integrated waveguide arc cavity 4, and the second substrate integrated waveguide arc cavity 5 are all composed of an upper metal layer, a dielectric substrate, and a lower metal layer, and the upper metal layer and the lower metal layer are respectively deposited on the dielectric substrate.

[0021] Furthermore, the relative dielectric constant of the dielectric substrate is 2.2, and the dielectric thickness is 0.254 mm. The overall planar size of the filter is 16 mm * 16 mm.

[0022] The first sensing window 111 and the second sensing window 112 are in a mirror symmetry relationship.

[0023] The third sensing window 121 and the fourth sensing window 122 are in a mirror symmetry relationship.

[0024] When the dual-band filter with the substrate integrated waveguide circular cavity nested with the arc cavity is in use, the dominant modes of the substrate integrated waveguide circular cavity 3, the first substrate integrated waveguide arc cavity 4, and the second substrate integrated waveguide arc cavity 5 all operate at the same frequency. The dominant modes of the first substrate integrated waveguide arc cavity 4 and the second substrate integrated waveguide arc cavity 5 are coupled with the substrate integrated waveguide circular cavity 3 to achieve the first passband, and the higher-order modes of the first substrate integrated waveguide arc cavity 4 and the second substrate integrated waveguide arc cavity 5 achieve the second passband through the direct coupling of the first substrate integrated waveguide arc cavity 4 and the second substrate integrated waveguide arc cavity 5.

[0025] In this embodiment, the input microstrip line 1 is the input port, and the output microstrip line 2 is the output port. The input microstrip line 1 and the output microstrip line 2 are mirror symmetric and present an obtuse angle.

[0026] The resistances of the input microstrip line 1 and the output microstrip line 2 can be adjusted according to actual applications. In this embodiment, the optimal resistances of the input microstrip line 1 and the output microstrip line 2 are both 50 ohms.

[0027] In this specific embodiment, a signal is input through the input port 1, input from the input microstrip line 1 to the first substrate integrated waveguide arc cavity 4. The signal with the same frequency as the dominant mode of the first substrate integrated waveguide arc cavity 4 enters the substrate integrated waveguide circular cavity 3 through the first sensing window 111 and then enters the second substrate integrated waveguide arc cavity 5 through the sensing window 112. Finally, the filtered signal is transmitted to the output microstrip line 2 and output through the output microstrip line 2; the signal with the same frequency as the higher-order mode of the first substrate integrated waveguide arc cavity 4 enters the second substrate integrated waveguide arc cavity 5 through the third sensing window 121 and the fourth sensing window 122. Finally, the filtered signal is transmitted to the output microstrip line 2 and output through the output microstrip line 2.

[0028] Figure 2 This is the frequency response curve of the dual-band filter in this specific embodiment. Among them, the two solid lines are the simulation result curves, and the two dashed curves are the test result curves. The center frequencies of the dual-band filter in this specific embodiment are 25 / 27.8 GHz, the bandwidths are 1.25 / 1.14 GHz, the insertion loss in the passband is better than 1.9 / 1.7 dB, and the return loss in the passband is better than 16.8 / 14.5 dB. The simulation and test results have good consistency.

[0029] Compared with the traditional dual-band filter, the present invention realizes the direct coupling between non-adjacent cavities by combining an arc-shaped cavity and a circular cavity. The main mode of the arc-shaped cavity is coupled with the circular cavity to achieve the first passband, and the higher-order mode of the arc-shaped cavity realizes the second passband through the direct coupling of two arc-shaped cavities, thereby realizing the independent regulation of the two passbands, greatly reducing the design complexity, having a simple structure, being convenient for processing, and can be applied to 5G millimeter wave and 6G mobile communication systems.

[0030] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A dual-band filter with a substrate integrated waveguide circular cavity nested with an arc cavity, characterized in that, it includes: A substrate integrated waveguide circular cavity (3), a first substrate integrated waveguide arc cavity (4), and a second substrate integrated waveguide arc cavity (5) formed by metal vias (6) respectively. The first substrate integrated waveguide arc cavity (4) and the second substrate integrated waveguide arc cavity (5) are located on both sides of the substrate integrated waveguide circular cavity (3). The left side of the substrate integrated waveguide circular cavity (3) is coupled to the first substrate integrated waveguide arc cavity (4) through a first inductive window (111), and the right side of the substrate integrated waveguide circular cavity (3) is coupled to the second substrate integrated waveguide arc cavity (5) through a second inductive window (112). The first substrate integrated waveguide arc cavity (4) and the second substrate integrated waveguide arc cavity (5) form a substrate integrated waveguide ring cavity, and a third inductive window (121) and a fourth inductive window (122) are arranged inside the substrate integrated waveguide ring cavity through metal vias (6). The first substrate integrated waveguide arc cavity (4) is coupled to the second substrate integrated waveguide arc cavity (5) through the third inductive window (121) and the fourth inductive window (122); The first substrate integrated waveguide arc cavity (4) is connected to an input microstrip line (1) through a first coplanar waveguide (9), and the second substrate integrated waveguide arc cavity (5) is connected to an output microstrip line (2) through a second coplanar waveguide (10).

2. The dual-band filter with a substrate integrated waveguide circular cavity nested with an arc cavity according to claim 1, characterized in that, The main modes of the substrate integrated waveguide circular cavity (3), the first substrate integrated waveguide arc cavity (4), and the second substrate integrated waveguide arc cavity (5) work at the same frequency. The main modes of the first substrate integrated waveguide arc cavity (4) and the second substrate integrated waveguide arc cavity (5) are coupled to the substrate integrated waveguide circular cavity (3) to realize the first passband, and the higher-order modes of the first substrate integrated waveguide arc cavity (4) and the second substrate integrated waveguide arc cavity (5) are directly coupled through the first substrate integrated waveguide arc cavity (4) and the second substrate integrated waveguide arc cavity (5) to realize the second passband.

3. The dual-band filter with a substrate integrated waveguide circular cavity nested with an arc cavity according to claim 1, characterized in that, The first inductive window (111) and the second inductive window (112) are mirror-symmetrical.

4. The dual-band filter with a substrate integrated waveguide circular cavity nested with an arc cavity according to claim 1, characterized in that, The third inductive window (121) and the fourth inductive window (122) are mirror-symmetrical.

5. The dual-band filter with a substrate integrated waveguide circular cavity nested with an arc cavity according to claim 1, characterized in that, The input microstrip line (1) and the output microstrip line (2) are mirror-symmetrical and present an obtuse angle.

6. The dual-band filter with a substrate integrated waveguide circular cavity nested with an arc cavity according to claim 1, characterized in that, Both the input microstrip line (1) and the output microstrip line (2) are 50 ohms.

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