Cavity filter and phased array radar
By introducing a flying rod and a second ridge waveguide into the cavity filter, a zero point is formed where the new signal path cancels out the original signal path, thus solving the problem of poor out-of-band suppression performance caused by the size limitation of traditional cavity filters and achieving a highly efficient out-of-band suppression effect.
Patent Information
- Application Number
- CN202423192184.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-24
AI Technical Summary
Traditional cavity filters suffer from poor out-of-band suppression performance due to size limitations, making it difficult to achieve ideal suppression effects in phased array radar systems.
By adding a flying rod and a second ridge waveguide to the air window coupling, a new signal path is introduced that cancels out the original signal path at a specific frequency, forming a null to increase the out-of-band suppression effect.
A compact, low-loss, and high out-of-band rejection cavity filter performance was achieved within a limited size, enhancing the filter's out-of-band rejection effect.
Smart Images
Figure CN223625198U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of filter technology, and in particular relates to a cavity filter and a phased array radar. Background Technology
[0002] A cavity filter is a metal-cut resonant cavity structure, belonging to microwave filters. It can select the frequency of signals and is widely used in radar, broadcasting, electronic warfare, satellite communications and other fields.
[0003] In phased array radar systems, cavity filters are widely used due to their high stability, low insertion loss, and high out-of-band suppression rectangularity. Traditional filters generally employ a comb-like structure and utilize air windows for signal coupling. To achieve good out-of-band suppression, a high-order filter is often chosen, resulting in a large filter size, or size limitations lead to poor out-of-band suppression. Utility Model Content
[0004] The purpose of this invention is to provide a cavity filter and a phased array radar to solve the problem of poor out-of-band suppression performance of the filter due to size limitations.
[0005] This utility model solves the above-mentioned technical problems through the following technical solution: a cavity filter, including a filter body, a cover plate, multiple tuning screws, and multiple coupling screws; the cover plate is disposed on the filter body and seals the filter body; multiple cavities are provided inside the filter body, and air windows are opened between adjacent cavities; a resonant cavity is provided in each cavity, and each resonant cavity corresponds to a tuning screw, one end of the tuning screw is disposed on the cover plate and the other end passes through the cover plate and is inserted into the corresponding resonant cavity; each pair of adjacent resonant cavities corresponds to a coupling screw, one end of the coupling screw is disposed on the cover plate, and the other end passes through the cover plate and is located above the midpoint of the two adjacent resonant cavities; a flybar and / or a first ridge waveguide are provided between two non-adjacent resonant cavities and between which there are no other resonant cavities; probes are provided in the first and last cavities.
[0006] Furthermore, a second ridge waveguide is provided between two adjacent resonant cavities.
[0007] Furthermore, a support post is provided at the bottom of the flying stick.
[0008] Furthermore, the flying stick is made of copper, and the support column is made of polytetrafluoroethylene.
[0009] Furthermore, each cavity is plated with silver.
[0010] Furthermore, the plurality of cavities or the plurality of resonant cavities are arranged in an M-shape, U-shape or L-shape.
[0011] Furthermore, the cover plate is fixed to the filter body by countersunk screws.
[0012] Furthermore, the filter body and cover plate are provided with fixing holes for filter installation.
[0013] Furthermore, the filter body is rectangular or circular.
[0014] Based on the same concept, this utility model also provides a phased array radar, which includes the cavity filter as described above.
[0015] Beneficial effects
[0016] Compared with the prior art, the advantages of this utility model are:
[0017] The cavity filter provided by this utility model adds a fly rod to the air window coupling. The fly rod introduces a new signal path, which cancels out the original signal path at a specific frequency point, thereby forming a zero point on the transmission curve. The zero point increases the out-of-band suppression effect. Attached Figure Description
[0018] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of the cavity filter structure in an embodiment of this utility model;
[0020] Figure 2 This is an exploded view of the cavity filter in an embodiment of this utility model;
[0021] Figure 3 This is a schematic diagram of the filter body in an embodiment of this utility model;
[0022] Figure 4 This is a schematic diagram of the coupling example of each cavity in an embodiment of this utility model;
[0023] Figure 5 This is a schematic diagram of the coupling example of each cavity in the embodiments of this utility model;
[0024] Figure 6 This is a schematic diagram of the coupling of the cavities in the embodiments of this utility model;
[0025] Figure 7 This is the performance curve of the cavity filter in this embodiment of the present invention.
[0026] Explanation of reference numerals in the attached drawings: 1-cover plate, 10-fixing hole, 11-tuning screw, 12-countersunk screw, 13-coupling screw, 2-filter body, 20-cavity, 21-resonant cavity, 22-air window, 23-flying rod, 24-first ridge waveguide, 25-second ridge waveguide, 26-support post, 3-probe. Detailed Implementation
[0027] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0028] like Figures 1 to 3 As shown, the cavity 20 filter provided in this embodiment of the present invention includes a filter body 2, a cover plate 1, multiple tuning screws 11, and multiple coupling screws 13; the cover plate 1 is disposed on the filter body 2 and seals the filter body 2; multiple cavities 20 are provided inside the filter body 2, and an air window 22 is provided between two adjacent cavities 20; a resonant cavity 21 is provided in each cavity 20, and each resonant cavity 21 corresponds to a tuning screw 11, one end of the tuning screw 11 is disposed on the cover plate 1 and the other end passes through the cover plate 1 and is inserted into the corresponding resonant cavity 21; each pair of adjacent resonant cavities 21 corresponds to a coupling screw 13, one end of the coupling screw 13 is disposed on the cover plate 1, and the other end passes through the cover plate 1 and is located above the midpoint of the two adjacent resonant cavities 21; a fly rod 23 and / or a first ridge waveguide 24 are provided between two non-adjacent resonant cavities 21 and there are no other resonant cavities 21 between them; a probe 3 is provided in the first and last cavities 20.
[0029] In a specific embodiment of this utility model, the multiple cavities 20 or multiple resonant cavities 21 are arranged in an M-shape, U-shape, or L-shape, preferably in an M-shape, which results in a more compact structure and reduced size. Figure 3As shown, the filter body 2 contains seven cavities 20, corresponding to seven resonant cavities 21, seven tuning screws 11, and eight coupling screws 13. In this embodiment, the resonant cavity 21 is cylindrical. The seven tuning screws 11 are all located directly above their respective resonant cavities 21 and are mounted on the cover plate 1 via nuts. The resonant frequency of the resonant cavity 21 is changed by adjusting the depth of the tuning screws 11 entering the resonant cavity 21; the deeper the screws, the lower the resonant frequency. The eight coupling screws 13 are all located above the midpoint of two adjacent resonant cavities 21 and are mounted on the cover plate 1 via nuts. The coupling coefficient between two adjacent resonant cavities 21 is changed by adjusting the depth of the coupling screws 13 entering the filter body 2; the deeper the screws, the larger the coupling coefficient.
[0030] like Figures 1 to 3 As shown, fixing holes 10 are provided on the filter body 2 and the cover plate 1. The fixing holes 10 penetrate the entire cover plate 1 and the filter body 2 and are used for the installation of the filter in the cavity 20. The cover plate 1 is fixed to the filter body 2 by 12 countersunk screws 12, and the cover plate 1 and the filter body 2 are locked together by the countersunk screws 12 to form a closed cavity 20. In this embodiment, silver plating is applied inside each cavity 20 to improve the metal conductivity and reduce the filter insertion loss. The filter body 2 is rectangular or circular; in this embodiment, the filter body 2 is rectangular.
[0031] like Figure 3 As shown, a second ridge waveguide 25 is provided between two adjacent resonant cavities 21. The addition of the second ridge waveguide 25 to the air window 22 enhances the coupling between the two adjacent cavities 20. The coupling coefficient between the two adjacent cavities 20 can be coarsely adjusted by changing the width of the air window 22 and the height of the second ridge waveguide 25. Figure 3 and Figure 4 As shown, a second ridge waveguide 25 is provided between the first resonant cavity 21 and the second resonant cavity 21, between the second resonant cavity 21 and the third resonant cavity 21, between the fifth resonant cavity 21 and the sixth resonant cavity 21, and between the sixth resonant cavity 21 and the seventh resonant cavity 21.
[0032] In a specific embodiment of this utility model, a support post 26 is provided at the bottom of the fly stick 23; the fly stick 23 is made of copper, and the support post 26 is made of polytetrafluoroethylene. Figure 3 and Figure 4As shown, a flybar 23 is added between the first resonant cavity 21 and the third resonant cavity 21, and a first ridge waveguide 24 is added between the fifth resonant cavity 21 and the seventh resonant cavity 21. The original signal path (i.e., R1->R2->R3->R4->R5->R6->R7, where Ri represents the i-th resonant cavity) not only has air window 22 coupling and ridge waveguide coupling, but also introduces new signal paths (R1->R3, R5->R7) through the flybar 23 and the first ridge waveguide 24. The new signal path and the original signal path will cancel each other out at a specific frequency point because they have the same amplitude but opposite phase, thus forming a zero on the transmission curve. The existence of the zero increases the out-of-band suppression effect.
[0033] In the second embodiment of this utility model, such as Figure 5 As shown, second ridge waveguides 25 are provided between the first resonant cavity 21 and the second resonant cavity 21, between the fourth resonant cavity 21 and the fifth resonant cavity 21, between the fifth resonant cavity 21 and the sixth resonant cavity 21, and between the sixth resonant cavity 21 and the seventh resonant cavity 21. A first ridge waveguide 24 is added between the fifth resonant cavity 21 and the seventh resonant cavity 21. A flying rod 23 is provided between the second resonant cavity 21 and the fourth resonant cavity 21. The original signal path (i.e., R1->R2->R3->R4->R5->R6->R7) not only has air window 22 coupling and ridge waveguide coupling, but also introduces new signal paths (R2->R4, R5->R7) through the flying rod 23 and the first ridge waveguide 24. The new signal path and the original signal path will cancel each other out at a certain frequency point because they have the same amplitude but opposite phase, thus forming a zero on the transmission curve. The existence of the zero increases the out-of-band suppression effect.
[0034] In the third embodiment of this utility model, such as Figure 6 As shown, second ridge waveguides 25 are provided between the first resonant cavity 21 and the second resonant cavity 21, between the second resonant cavity 21 and the third resonant cavity 21, between the fifth resonant cavity 21 and the sixth resonant cavity 21, and between the sixth resonant cavity 21 and the seventh resonant cavity 21. A first ridge waveguide 24 is added between the fifth resonant cavity 21 and the seventh resonant cavity 21. A flying rod 23 is provided between the third resonant cavity 21 and the fifth resonant cavity 21. The original signal path (i.e., R1->R2->R3->R4->R5->R6->R7) not only has air window 22 coupling and ridge waveguide coupling, but also introduces new signal paths (R3->R5, R5->R7) through the flying rod 23 and the first ridge waveguide 24. The new signal path and the original signal path will cancel each other out at a certain frequency point because they have the same amplitude but opposite phase, thus forming a zero on the transmission curve. The existence of the zero increases the out-of-band suppression effect.
[0035] This invention achieves a compact, low-loss, and high out-of-band suppression cavity filter by employing three coupling methods—air window 22, ridge waveguide, and flying rod 23—within a limited size.
[0036] In a specific embodiment of this utility model, the probe can be a glass insulator, SMP, SMA or other connectors to achieve signal connection. In addition to the signal transmission direction, the probe can be extended in any direction, such as front, back or left or right, and can be flexibly adjusted according to the actual application scenario.
[0037] To demonstrate the effectiveness of the filter of this invention, simulation experiments were conducted, and the results were as follows: Figure 7 The filter performance curves are shown. S-parameters (i.e., scattering parameters) are used to describe the input-output characteristics of a microwave network. For a two-port network (i.e., with two ports, usually labeled port 1 and port 2), the S-parameters include S11, S12, S21, and S22. S11 represents the reflection coefficient of port 1, which is the ratio of the signal reflected back to port 1 from the signal input at port 1 to the input signal; S21 represents the forward transmission coefficient, which is the ratio of the signal transmitted from port 1 to port 2 to the input signal; S22 represents the reflection coefficient of port 2, which is the ratio of the signal reflected back to port 2 from the signal input at port 2 to the input signal; and S12 represents the reverse transmission coefficient, which is the ratio of the signal transmitted from port 2 to port 1 to the input signal.
[0038] The cavity filter is a two-port device. Taking the left side of the filter as port 1 and the right side as port 2 as an example, S11 represents the magnitude of the reflected electromagnetic wave at port 1, S22 represents the magnitude of the reflected electromagnetic wave at port 2, and S21 represents the magnitude of the electromagnetic wave from port 1 to port 2. Figure 7 It can be seen that in the 5.3–5.7 GHz range, both S11 and S22 are below -15 dB, indicating very low reflection, while S21 is below -0.5 dB, indicating very low loss. However, in the 5–5.2 GHz and 5.8–6 GHz ranges, S21 is below -40 dB, indicating that most electromagnetic waves do not pass through and are suppressed within the filter. Therefore, it can be concluded that the cavity filter of this invention only allows electromagnetic waves in the 5.3–5.7 GHz range to pass through, thus achieving the purpose of filtering. Figure 7 It can be seen that the in-band loss is less than 1dB in the 5.3-5.7GHz range, the out-of-band rejection reaches about 40dB at 5200MHz and 5800MHz, the transition band is 100MHz, and the rectangular coefficient of 40dB is only 1.2, which has a very good filtering effect.
[0039] The above description only discloses specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.
Claims
1. A cavity filter, characterized in that, The cavity filter includes a filter body, a cover plate, multiple tuning screws, and multiple coupling screws. The cover plate is disposed on the filter body and seals the filter body. Multiple cavities are provided within the filter body, and air windows are provided between adjacent cavities. A resonant cavity is provided in each cavity, and each resonant cavity corresponds to a tuning screw. One end of the tuning screw is disposed on the cover plate, and the other end passes through the cover plate and is inserted into the corresponding resonant cavity. Each pair of adjacent resonant cavities corresponds to a coupling screw. One end of the coupling screw is disposed on the cover plate, and the other end passes through the cover plate and is located above the midpoint of the two adjacent resonant cavities. A flybar and / or a first ridge waveguide are provided between two non-adjacent resonant cavities that have no other resonant cavities between them. Probes are provided in the first and last cavities.
2. The cavity filter according to claim 1, characterized in that, A second ridge waveguide is provided between two adjacent resonant cavities.
3. The cavity filter according to claim 1, characterized in that, A support post is provided at the bottom of the flying stick.
4. The cavity filter according to claim 3, characterized in that, The fly stick is made of copper, and the support column is made of polytetrafluoroethylene.
5. The cavity filter according to claim 1, characterized in that, Each cavity is plated with silver.
6. The cavity filter according to claim 1, characterized in that, The multiple cavities or multiple resonant cavities are arranged in an M-shape, U-shape or L-shape.
7. The cavity filter according to claim 1, characterized in that, The cover plate is fixed to the filter body by countersunk screws.
8. The cavity filter according to claim 1, characterized in that, The filter body and cover plate are provided with fixing holes for filter installation.
9. The cavity filter according to any one of claims 1 to 8, characterized in that, The filter body is rectangular or circular.
10. A phased array radar, characterized in that, The phased array radar includes a cavity filter as described in any one of claims 1 to 9.