A coaxial-to-waveguide filter

Abstract

This utility model belongs to the field of filters, specifically a coaxial-to-waveguide filter, including a cavity with a waveguide port on the inner side. A coaxial connector is bolted to the top side of the waveguide port. Multiple resonant cavities are formed inside the cavity, and a coupling grounding post is installed inside the cavity through the resonant cavities. A coupling conductor is fixed between the waveguide port and one of the resonant cavities through a supporting insulating medium. One end of the coupling conductor is soldered to the coupling grounding post in the corresponding resonant cavity, and the other end extends into the waveguide port, realizing bidirectional coupling transmission of electromagnetic waves. This utility model introduces cross-coupling technology inside the filter, which significantly improves the out-of-band suppression compared to relying on natural attenuation, reduces the number of resonant cavities required to achieve the same suppression, thereby effectively reducing the product size and also reducing the filter insertion loss. This device achieves low port return loss through high out-of-band suppression.

Description

Technical Field

[0001] This utility model relates to the field of filters, specifically a coaxial-to-waveguide filter. Background Technology

[0002] A filter is an electronic device or algorithm commonly used in signal processing to remove or suppress unwanted parts of an input signal, typically noise or signals in a specific frequency band.

[0003] In traditional filters, the capacitive cross-coupling component provides a fixed coupling capacitance value. Furthermore, when used in high-power loop branch modules, the transmission passband can easily shift with temperature due to heat generation.

[0004] Therefore, a coaxial-to-waveguide filter is proposed to address the above problems. This coaxial-to-waveguide filter is used in the ring branch module (OCU) of the communication backbone network. By utilizing the passband transmission and stopband reflection characteristics of the filter, it is cascaded with the circulator to achieve frequency selection filtering and anti-interference suppression of electromagnetic waves of different frequency bands in the transmitting and receiving paths. Utility Model Content

[0005] To overcome the shortcomings of existing technologies, the coupling capacitance value of the capacitive cross-coupling component in traditional filters is fixed, and the filters used in high-power loop branch modules are prone to transmission passband shift with temperature due to equipment heat generation. This invention proposes a coaxial-to-waveguide filter.

[0006] The technical solution adopted by this utility model to solve its technical problem is as follows: The coaxial-to-waveguide filter of this utility model includes a cavity, a waveguide port is provided on the inner side of the cavity, a coaxial connector is installed on the top side of the waveguide port by bolts, multiple resonant cavities are provided inside the cavity, a coupling grounding post is installed inside the cavity through the resonant cavities, a coupling conductor is fixed between the waveguide port and one of the resonant cavities through a supporting insulating medium, one end of the coupling conductor is welded to the coupling grounding post in the corresponding resonant cavity, and the other end extends into the waveguide port to realize bidirectional coupling transmission of electromagnetic waves, wherein a capacitive cross-coupling conductor is installed between two of the resonant cavities through a supporting insulating medium, and an adjustable through hole is provided on the supporting insulating medium of this capacitive cross-coupling conductor.

[0007] Preferably, a welding hole is provided on the side of the cavity and below the coaxial connector.

[0008] Preferably, cylindrical steps are fixedly connected inside each of the plurality of resonant cavities, and the resonator body is mounted inside each of the plurality of cylindrical steps by means of a second mounting screw.

[0009] Preferably, a coupling window is provided between two adjacent resonant cavities, and an inductive cross-coupling window is provided between two adjacent resonant cavities close to the coupling window.

[0010] Preferably, the top of the cavity is fitted with an aluminum-plated silver shielding cover plate by a plurality of first mounting screws, and the top of the cavity has a plurality of mounting screw holes that mate with the first mounting screws.

[0011] Preferably, copper-plated silver tuning screws are installed on the cover plate corresponding to the center of multiple resonator bodies, the center of the coupling window between adjacent cavities, and the center of the through hole supporting the capacitive cross-coupled conductor insulating medium.

[0012] Preferably, one side of the waveguide port is designed with two layers of anti-electromagnetic leakage bosses, with multiple mounting screw through holes in the middle of the two layers of anti-electromagnetic leakage bosses, and the internal threads of the welding hole are connected with plug screws.

[0013] The advantages of this utility model are:

[0014] 1. This utility model introduces cross-coupling technology inside the filter, which significantly improves the out-of-band suppression compared to relying on natural attenuation. It reduces the number of resonant cavities required to achieve the same suppression, thereby effectively reducing the product size. At the same time, it also reduces the filter insertion loss. This device achieves low port return loss through high out-of-band suppression.

[0015] 2. This device has high power capacity and low temperature drift and frequency deviation characteristics, and the waveguide port has excellent mechanical contact, which fully guarantees the intermodulation performance requirements of the system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a perspective view of the present invention;

[0018] Figure 2 This is an assembly diagram of the present invention;

[0019] Figure 3 This is a cross-sectional view of the present invention;

[0020] Figure 4 This is a schematic diagram of the internal structure of the present invention;

[0021] Figure 5This is a schematic diagram of the waveguide port connection surface of this utility model;

[0022] Figure 6 This is a perspective view of the capacitive cross-coupled conductor in this utility model;

[0023] Figure 7 This is a three-dimensional view of the coupling conductor in this utility model.

[0024] In the diagram: 1. Cavity; 2. Cover plate; 3. Mounting screw through hole; 4. Capacitive cross-coupled conductor; 5. Supporting insulating medium; 6. Coupled conductor; 7. Electromagnetic leakage protection boss; 8. Coaxial connector; 9. Tuning screw; 10. First mounting screw; 11. Plug screw; 12. Welding hole; 13. Coupled grounding post; 14. Resonator body; 15. Second mounting screw; 16. Waveguide port; 17. Mounting screw hole; 18. Coupled window; 19. Cylindrical step; 20. Inductive cross-coupled window. Detailed Implementation

[0025] The technical solutions of the present 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 the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Example 1

[0027] Please see Figure 1-7 As shown, a coaxial-to-waveguide filter includes a cavity 1, a waveguide port 16 is provided on the inner side of the cavity 1, a coaxial connector 8 is installed on the top side of the waveguide port 16 by bolts, multiple resonant cavities are provided inside the cavity 1, and coupling grounding posts 13 are installed inside the cavity 1 through the resonant cavities, and a coupling conductor 6 is fixed between the waveguide port 16 and one of the resonant cavities through a supporting insulating medium 5. One end of the coupling conductor 6 is welded to the coupling grounding post 13 in the corresponding resonant cavity, and the other end extends into the waveguide port 16 to realize bidirectional coupling transmission of electromagnetic waves. A capacitive cross-coupling conductor 4 is installed between two resonant cavities through the supporting insulating medium 5, and an adjustable through hole is provided on the supporting insulating medium 5 of the capacitive cross-coupling conductor 4.

[0028] During operation, a circular deep hole is machined on the top of the supporting insulating medium 5. The depth of the tuning screw 9 installed on the filter cover plate 2 into this hole is adjusted to change the capacitance of the capacitive cross-coupled conductor 4 to ground, thereby changing its capacitance value between the two resonant cavities. One end of the coupling conductor 6 extends into the waveguide port 16, and the other end is welded to the grounding post inside the resonant cavity, forming a grounding coupling loop with the resonator body 14 inside the resonant cavity. This enables bidirectional transmission of electromagnetic energy between the waveguide port and the resonant cavity. To address the issue of transmission passband shifting with temperature due to equipment heating when the filter is used in a high-power ring branch module, this coaxial-to-waveguide filter employs six resonant cavities plus two cross-zero suppression mechanisms to achieve its... Electrical performance requirements necessitate the use of windows between adjacent cavities to couple electromagnetic waves. Cavities 1 and 3 are fitted with capacitive cross-coupling components, creating a coupling zero with a -90° phase difference, generating a suppression trough outside the low-frequency band of the filter's transmission characteristic curve. Conversely, an inductive cross-coupling window is opened between cavities 4 and 6, creating a coupling zero with a +90° phase difference, generating a suppression trough outside the high-frequency band of the filter's transmission characteristic curve. Introducing cross-coupling technology within the filter significantly improves out-of-band suppression compared to relying on natural attenuation, reducing the number of resonant cavities required to achieve the same suppression, thereby effectively reducing product size and decreasing filter insertion loss.

[0029] The cavity 1 has a welding hole 12 on its side below the coaxial connector 8. A cylindrical step 19 is fixedly connected to each of the multiple resonant cavities. The resonator body 14 is installed inside each of the multiple cylindrical steps 19 by a second mounting screw 15. A coupling window 18 is provided between two adjacent resonant cavities. An inductive cross-coupling window 20 is provided between two adjacent resonant cavities near the coupling window 18. An aluminum silver-plated shielding cover 2 is installed on the top of the cavity 1 by multiple first mounting screws 10. A number of mounting screw holes 17 that cooperate with the first mounting screws 10 are provided on the top of the cavity 1. Copper silver-plated tuning screws 9 are installed on the cover 2 corresponding to the center of multiple resonator bodies 14, the center of the coupling window 18 of two adjacent cavities, and the center of the through hole of the capacitive cross-coupling conductor 4 supporting the insulating medium 5.

[0030] Through the above technical solution, the device is designed with two materials with different linear thermal expansion coefficients to design the resonator body 14. Through electromagnetic three-dimensional simulation, it is calculated that the material of the resonator body 14 is free-cutting iron. The resonator body 14 is installed on the cylindrical step 19 inside the cavity 1 using the second mounting screw 15, so as to achieve mutual compensation of the thermal expansion of the two materials, thereby realizing the low temperature drift frequency deviation characteristic of the filter transmission passband.

[0031] Example 2

[0032] Please see Figure 5As shown in the first embodiment, as another implementation of this utility model, the waveguide port 16 is designed with two layers of anti-electromagnetic leakage bosses 7 on one side. There are multiple mounting screw through holes 3 in the middle of the two layers of anti-electromagnetic leakage bosses 7. The internal thread of the welding hole 12 is connected to the plug screw 11.

[0033] During operation, the mechanical contact of the waveguide port 16 connection surface directly affects whether electromagnetic waves leak. The waveguide port 16 in this device is designed with inner and outer anti-electromagnetic leakage bosses 7, with a mounting screw through hole 3 between the two anti-electromagnetic leakage bosses 7. This structure, after being locked with screws, effectively avoids poor mechanical contact caused by insufficient flatness of the two waveguide port mounting surfaces due to processing or material deformation, thus preventing electromagnetic wave leakage. Good mechanical contact not only improves the electromagnetic wave leakage problem, but also enhances the intermodulation suppression index of the entire system.

[0034] Working principle: A circular deep hole is machined on the top of the supporting insulating medium 5. The depth of the tuning screw 9 installed on the filter cover plate 2 into this hole is adjusted to change the capacitance of the capacitive cross-coupled conductor 4 to ground, thereby changing its capacitance value between the two resonant cavities. One end of the coupling conductor 6 extends into the waveguide port 16, and the other end is welded to the grounding post inside the resonant cavity, forming a grounding coupling loop with the resonator body 14 inside the resonant cavity. This enables bidirectional transmission of electromagnetic energy between the waveguide port and the resonant cavity. This addresses the issue of the transmission passband varying with temperature due to equipment heat when the filter is used in a high-power ring branch module. To address the issue of phase shift, this coaxial-to-waveguide filter employs six resonant cavities plus two cross-zero suppression mechanisms to meet its electrical performance requirements. Windows are opened between adjacent cavities to couple electromagnetic waves. Cavities 1 and 3 are coupled with capacitive cross-coupling components, creating a coupling zero with a -90° phase difference, generating a suppression trough outside the low-frequency band of the filter's transmission characteristic curve. Conversely, an inductive cross-coupling window is opened between cavities 4 and 6, creating a coupling zero with a +90° phase difference, generating a suppression trough outside the high-frequency band of the filter's transmission characteristic curve. This introduces cross-coupling technology internally into the filter. The fork coupling technology, compared to relying on natural attenuation, significantly improves out-of-band suppression and reduces the number of resonant cavities required to achieve the same suppression, thereby effectively reducing product size and filter insertion loss. In this device design, two materials with different linear thermal expansion coefficients are used to design the resonator body 14. Through electromagnetic three-dimensional simulation, it was calculated that the material of the resonator body 14 is free-cutting iron. The second mounting screw 15 is used to install the resonator body 14 onto the cylindrical step 19 inside the cavity 1, achieving mutual compensation of the thermal expansion of the two materials, thus realizing a low temperature drift frequency offset in the filter's transmission passband. In the use of waveguide devices, the mechanical contact of the waveguide port 16 connection surface directly affects whether electromagnetic waves leak. The waveguide port 16 in this device is designed with inner and outer anti-electromagnetic leakage bosses 7, with a mounting screw through hole 3 in between the two anti-electromagnetic leakage bosses 7. This structure, after being locked with screws, effectively avoids poor mechanical contact caused by insufficient flatness of the two waveguide port mounting surfaces due to processing or material deformation, which would lead to electromagnetic wave leakage. Good mechanical contact not only improves the problem of electromagnetic wave leakage, but also enhances the intermodulation suppression index of the entire system.

[0035] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A coaxial-to-waveguide filter, comprising a cavity (1), a waveguide port (16) is provided on the inner side of the cavity (1), a coaxial connector (8) is installed on the top side of the waveguide port (16) by bolts, a plurality of resonant cavities are provided inside the cavity (1), a coupling grounding post (13) is installed inside the cavity (1) through the resonant cavity, a coupling conductor (6) is fixed between the waveguide port (16) and one of the resonant cavities through a supporting insulating medium (5), one end of the coupling conductor (6) is welded to the coupling grounding post (13) in the corresponding resonant cavity, and the other end extends into the waveguide port (16) to realize bidirectional coupling transmission of electromagnetic waves; Its features are: A capacitive cross-coupled conductor (4) is installed between the two resonant cavities via a supporting insulating medium (5), and an adjustable through hole is provided on the supporting insulating medium (5) of the capacitive cross-coupled conductor (4).

2. The coaxial-to-waveguide filter according to claim 1, characterized in that: A welding hole (12) is provided on the side of the cavity (1) and below the coaxial connector (8).

3. A coaxial-to-waveguide filter according to claim 2, characterized in that: Each of the resonant cavities is fixedly connected with a cylindrical step (19), and the resonator body (14) is installed inside each of the cylindrical steps (19) by a second mounting screw (15).

4. A coaxial-to-waveguide filter according to claim 2, characterized in that: A coupling window (18) is provided between two adjacent resonant cavities, and an inductive cross-coupling window (20) is provided between two adjacent resonant cavities close to the coupling window (18).

5. A coaxial-to-waveguide filter according to claim 4, characterized in that: The top of the cavity (1) is fitted with an aluminum silver-plated shield cover plate (2) by a plurality of first mounting screws (10), and the top of the cavity (1) is provided with a plurality of mounting screw holes (17) that cooperate with the first mounting screws (10).

6. A coaxial-to-waveguide filter according to claim 5, characterized in that: Copper-plated silver tuning screws (9) are respectively installed on the cover plate (2) at the center of multiple resonator bodies (14), the center of the coupling window (18) of adjacent two cavities, and the center of the through hole of the capacitive cross-coupled conductor (4) supporting the insulating medium (5).

7. A coaxial-to-waveguide filter according to claim 2, characterized in that: The waveguide port (16) has two layers of anti-electromagnetic leakage bosses (7) on one side. There are multiple mounting screw through holes (3) in the middle of the two layers of anti-electromagnetic leakage bosses (7). The welding hole (12) is internally threaded with a plug screw (11).

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