Low-pass structure and filter

Abstract

The utility model relates to the field of communication, and provides a low-pass structure and a filter. The low-pass structure is arranged in a low-pass cavity of the filter shell, and the low-pass cavity is provided with a first cavity wall. The low-pass structure comprises a low-pass piece, the low-pass piece comprises a high-impedance branch knot of a rod-shaped structure and at least one low-impedance branch knot, the low-impedance branch knot comprises a low-impedance part and a connecting part, the low-impedance part is located on the side, close to the first cavity wall, of the high-impedance branch knot, and the low-impedance part and the first cavity wall are spaced in an insulated mode so that capacitance can be formed between the low-impedance part and the first cavity wall. The connecting part is connected between the low-impedance part and the high-impedance branch knot. Based on the structure, the low-pass structure can generate transmission zero points with the same quantity as the low-impedance branch knots, so that the attenuation speed of out-of-band signals close to the edge of a pass band can be remarkably increased, and the near-end out-of-band rejection performance can be improved. Moreover, the low-pass structure can flexibly adjust the out-of-band rejection characteristic by increasing or decreasing the number of the low-impedance branches and flexibly adjusting the number of the generated transmission zero points, so that the design flexibility and applicability of the low-pass structure can be improved.

Description

Technical Field

[0001] This application belongs to the field of communication technology, and in particular relates to a low-pass structure and filter. Background Technology

[0002] In some cases, the filter includes a cavity, a cover plate, and a low-pass structure. The cavity has a low-pass slot, and the low-pass structure is installed in the low-pass slot. The cover plate closes the cavity and presses the low-pass structure to ensure a tight fit between the low-pass structure and the low-pass slot. The low-pass structure includes a low-pass element and an insulating sleeve. The low-pass element includes a high-impedance section with a small diameter and a low-impedance section with a large diameter. The high-impedance and low-impedance sections are alternately connected to form a string-like low-pass element. The insulating sleeve is fitted around the outer periphery of the low-pass element to insulate between the low-pass element and the slot wall of the low-pass slot, and to form an equivalent capacitance between the low-impedance section and the slot wall of the low-pass slot. However, in this string-like low-pass element, the equivalent inductance (L) formed by the high-impedance section and the equivalent capacitance (C) formed by the low-impedance section are used to form a series distributed LC filter network. Since the poles are generated only through LC resonance, it is difficult to generate transmission zeros, resulting in poor near-end out-of-band rejection. Utility Model Content

[0003] This application provides a low-pass structure and filter, aiming to solve the problem that string-type low-pass devices are difficult to generate transmission zeros, resulting in poor near-end out-of-band suppression.

[0004] To achieve the above objectives, the technical solution adopted in the embodiments of this application is as follows:

[0005] In a first aspect, a low-pass structure is provided, disposed in a low-pass cavity of a filter housing, the low-pass cavity having a first cavity wall, the low-pass structure comprising:

[0006] A low-impedance component includes a high-impedance stub with a rod-like structure and at least one low-impedance stub. The low-impedance stub includes a low-impedance portion and a connecting portion. The low-impedance portion is located on the side of the high-impedance stub near the first cavity wall and is insulated from the first cavity wall to form a capacitor therebetween. The connecting portion connects the low-impedance portion and the high-impedance stub.

[0007] In some embodiments, the connecting portion is bent.

[0008] In some embodiments, the connecting portion includes a first connecting segment, a second connecting segment, a third connecting segment, and a fourth connecting segment that are bent and connected in sequence. The first connecting segment is connected to the high-impedance stub and extends toward the side closer to the low-impedance portion. The third connecting segment extends from the second connecting segment toward the side closer to the low-impedance portion. The third connecting segment is spaced apart from the outer periphery of the low-impedance portion. The end of the fourth connecting segment away from the third connecting segment is connected to the periphery of the low-impedance portion.

[0009] In some embodiments, a plurality of low-impedance branches are provided, and each low-impedance branch is arranged at intervals along the extension path of the high-impedance branch.

[0010] In some embodiments, the low-pass structure further includes an insulating pad disposed between the low-impedance portion and the first cavity wall.

[0011] In some embodiments, all the low-impedance portions share a single insulating pad.

[0012] In some embodiments, the low-resistance portion has a through-hole, and the low-resistance portion is connected and fixed to the first cavity wall by a fastener passing through the fastening hole.

[0013] In some embodiments, the low-impedance portion is disposed parallel to and spaced apart from the first cavity wall.

[0014] In some embodiments, the low-impedance portion is a plate-like structure.

[0015] In some embodiments, the high-impedance stub extends in a straight line.

[0016] In some embodiments, the low-pass component is integrally formed from a sheet metal substrate.

[0017] Secondly, a filter is provided, including a filter housing and a low-pass structure provided in the embodiments of this application, wherein the filter housing is provided with a low-pass cavity and the low-pass structure is disposed in the low-pass cavity.

[0018] The advantages of the low-pass structure provided in this application are as follows:

[0019] In the low-pass structure provided in this application embodiment, the low-pass component can form an equivalent inductance through high-impedance stubs; it can be connected between the low-impedance portion and the high-impedance stubs through a connecting portion, so that the low-impedance stubs can act as branches of the high-impedance stubs; and it can be insulated from the first cavity wall through the low-impedance portion, so that an equivalent capacitance can be formed between the low-impedance portion and the first cavity wall, thereby enabling each low-impedance stub to independently form an equivalent capacitance. Based on this, the low-pass component can achieve high impedance requirements through the equivalent inductance formed by the high-impedance stubs and low impedance requirements through the equivalent capacitance formed by the low-impedance stubs, thereby enabling the low-pass structure to block and weaken high-frequency signals exceeding a set threshold value while allowing low-frequency signals to pass normally, thus achieving the effect of low-pass filtering. Furthermore, the structure of a low-pass filter can be equivalent to "one or more equivalent capacitors connected in parallel to the same equivalent inductor." Each low-impedance stub can be considered a parallel LC resonant circuit (the equivalent capacitance C formed by each low-impedance stub resonates with the partial equivalent inductance L formed by the high-impedance stub). Therefore, each low-impedance stub can generate a transmission zero through LC parallel resonance, enabling the low-pass structure to generate an equal number of transmission zeros as the low-impedance stubs. This significantly improves the attenuation rate of out-of-band signals near the passband edge and enhances near-end out-of-band rejection performance. Moreover, the number of transmission zeros generated can be flexibly adjusted by increasing or decreasing the number of low-impedance stubs, thereby flexibly adjusting the out-of-band rejection characteristics and improving the design flexibility and applicability of the low-pass structure. Attached Figure Description

[0020] To clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram illustrating the cooperation between the low-pass structure and the low-pass cavity provided in some embodiments of this application;

[0022] Figure 2 for Figure 1 A three-dimensional schematic diagram of the provided low-pass structure;

[0023] Figure 3 for Figure 2 A side view of the provided low-pass structure;

[0024] Figure 4 for Figure 2 The provided simulation waveform diagram of the low-pass structure.

[0025] The following are the labeling elements in the figure:

[0026] 10-Low-pass cavity, 11-First cavity wall; 20-Low-pass component, 21-High-impedance stub, 211-Input terminal, 212-Output terminal; 22-Low-impedance stub, 221-Low-impedance section, 2211-Fastening hole, 222-Connecting section, 2221-First connecting section, 2222-Second connecting section, 2223-Third connecting section, 2224-Fourth connecting section; 30-Insulating pad. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clear, the application will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application. Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0028] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0031] In filter products, low-pass structures are used to block and attenuate high-frequency signals exceeding a set threshold while allowing low-frequency signals to pass normally, thus achieving low-pass filtering. In some cases, the filter includes a cavity, a cover plate, and a low-pass structure. The cavity has a low-pass slot, and the low-pass structure is installed in the low-pass slot. The cover plate closes the cavity and presses the low-pass structure to ensure a tight fit between the low-pass structure and the low-pass slot. The low-pass structure includes a low-pass element and an insulating sleeve. The low-pass element includes a high-impedance section with a small diameter and a low-impedance section with a large diameter. The high-impedance and low-impedance sections are alternately connected to form a string-like low-pass element. The insulating sleeve is fitted around the outer periphery of the low-pass element to insulate between the low-pass element and the slot wall of the low-pass slot, and to create an equivalent capacitance between the low-impedance section and the slot wall of the low-pass slot.

[0032] However, in this way, the string low-pass filter only forms a series distributed LC filter network through the equivalent inductance (L) formed by the high impedance section and the equivalent capacitance (C) formed by the low impedance section. It only generates poles through LC resonance (slow roll-off attenuation) and it is difficult to generate transmission zeros, resulting in poor near-band rejection.

[0033] Furthermore, due to the tight fit between the low-pass structure and the low-pass slot, the insulating sleeve is prone to uneven compression due to uneven contact pressure, resulting in poor capacitance consistency and unstable low-pass performance. Moreover, the tight fit between the low-pass structure and the low-pass slot relies primarily on the pressure of the cover plate, which can easily lead to poor contact between the low-pass structure and the cavity / cover plate due to accumulated fit tolerances, resulting in poor intermodulation performance and stability.

[0034] The embodiments provided in this application will solve the above problems.

[0035] To illustrate the technical solutions provided in this application, the following detailed description is provided in conjunction with specific drawings and embodiments.

[0036] Please see Figure 1 , Figure 2 , Figure 3 Some embodiments of this application provide a low-pass structure disposed in a low-pass cavity 10 of a filter housing (not shown in the figure), the low-pass cavity 10 having a first cavity wall 11. The low-pass structure includes a low-pass element 20, the low-pass element 20 including a high-impedance stub 21 of a rod-like structure, and at least one low-impedance stub 22, the low-impedance stub 22 including a low-impedance portion 221 and a connecting portion 222, the low-impedance portion 221 being located on the side of the high-impedance stub 21 near the first cavity wall 11 and insulated from the first cavity wall 11 to form a capacitor therebetween, the connecting portion 222 connecting the low-impedance portion 221 and the high-impedance stub 21.

[0037] It should be noted that the filter housing is the outer shell of the filter product. The filter housing has a closed internal cavity that provides shielding and prevents signal leakage. This internal cavity can be divided into a relatively enclosed low-pass cavity 10, which can accommodate a low-pass structure. One side of the cavity wall of the low-pass cavity 10 is a first cavity wall 11, which can be the top wall, bottom wall, or side wall of the low-pass cavity 10. The shape and size of the low-pass cavity 10 can be flexibly configured as needed; for example, the low-pass cavity 10 can be rectangular.

[0038] It should also be noted that the low-pass component 20 can be made entirely of metal, or it can be coated with a metal layer (the part used to support the metal layer can be made of non-metallic material). The low-pass component 20 includes a high-impedance stub 21 and at least one low-impedance stub 22.

[0039] The high-impedance stub 21 is a rod-shaped structure, with one end serving as the input terminal 211 and the other end as the output terminal 212. The input terminal 211 of the high-impedance stub 21 can be coupled to a signal input component outside the low-pass cavity 10, allowing signal and energy to be transmitted from the signal input component to the high-impedance stub 21. The signal input component can be, but is not limited to, a filter's signal input port, a resonant rod, a tapped structure, etc. Signal and energy can be transmitted along the high-impedance stub 21 from the input terminal 211 to the output terminal 212. The output terminal 212 of the high-impedance stub 21 can be coupled to a signal output component outside the low-pass cavity 10, allowing signal and energy to be transmitted from the high-impedance stub 21 to the signal output component. The signal output component can be a filter's signal output port, a resonant rod, a tapped structure, etc. The high-impedance stub 21 can form an equivalent inductance. The extension path of the high-impedance stub 21 can be set as needed. The high-impedance stub 21 can extend in a straight line, a curve, or a broken line. The extension length, cross-sectional shape (i.e., the cross-section of the high-impedance stub 21 perpendicular to the extension path), and cross-sectional dimensions of the high-impedance stub 21 can be set as needed. For example, the cross-sectional shape of the high-impedance stub 21 can be rectangular, or it can be thicker at both ends and thinner in the middle, etc. The cross-sectional shape (i.e., the cross-sectional shape of the high-impedance stub 21 perpendicular to the extension path) at various points along the extension path can be the same or different; the cross-sectional dimensions (i.e., the cross-sectional dimensions of the high-impedance stub 21 perpendicular to the extension path) at various points along the extension path can also be the same or different.

[0040] One end of the connector 222 is connected to the high-impedance stub 21, allowing the low-impedance stub 22 to act as a branch and shunt of the high-impedance stub 21. This enables signal and energy to be shunted and transmitted to the low-impedance stub 22 at the connection point between the high-impedance stub 21 and the low-impedance stub 22. The connector 222 and the high-impedance stub 21 can be integrally connected or separately connected. Separate connection methods can include, but are not limited to, welding, fusion, threaded connection, snap-fit, riveting, screw fastening, and bonding.

[0041] The end of the connecting portion 222 away from the high-impedance stub 21 is connected to the low-impedance portion 221, allowing the connecting portion 222 to connect between the high-impedance stub 21 and the low-impedance portion 221. This supports and stabilizes the position and state of the low-impedance portion 221 relative to the high-impedance stub 21, and facilitates the transmission of signals and energy shunted from the high-impedance stub 21 to the low-impedance portion 221 along the connecting portion 222. The connecting portion 222 and the low-impedance portion 221 can be integrally connected or separately connected. Separate connection methods include, but are not limited to, welding, fusion, threaded connection, snap-fit, riveting, screw fastening, and bonding. In some embodiments, the connecting portion 222 can be connected to the periphery of the low-impedance portion 221. This is particularly suitable when the connecting portion 222 and the low-impedance portion 221 are integrally connected, and especially suitable when the low-impedance component 20 is a one-piece molded structure. In some other embodiments, the connecting part 222 may be connected to the side of the low impedance part 221 facing away from the first cavity wall 11. This is particularly suitable for the case where the connecting part 222 and the low impedance part 221 are connected separately. In this case, the area used to realize the connection operation is larger, which helps to reduce the difficulty of separate connection and improves the connection convenience, connection reliability and connection stability of separate connection.

[0042] The low-impedance portion 221 is insulated from the first cavity wall 11 to form an equivalent capacitance between them. The low-impedance portion 221 and the first cavity wall 11 can be directly spaced apart, or they can be mutually insulated by an insulating medium (e.g., insulating pad 30, insulating adhesive layer, insulating coating, etc.) disposed between them. The low-impedance portion 221 can be, but is not limited to, a plate-like structure, a sheet-like structure, a block-like structure, etc. The shape and size of the low-impedance portion 221 can be customized as needed; for example, the shape of the low-impedance portion 221 can be circular, elliptical, rectangular, square, polygonal, irregular, etc. When multiple low-impedance branches 22 are provided, the shape and size of the low-impedance portions 221 of the multiple low-impedance branches 22 can be the same or different.

[0043] The low-impedance section 221 is located on the side of the high-impedance stub 21 that is close to the first cavity wall 11. This not only facilitates the arrangement of the low-impedance section 221 close to the first cavity wall 11 to form an equivalent capacitance with the first cavity wall 11, but also ensures that the high-impedance stub 21, the connecting section 222 and the low-impedance section 221 are not on the same plane parallel to the first cavity wall 11. This allows for effective utilization of the space in the height direction of the low-pass cavity 10 (i.e., the direction perpendicular to the first cavity wall 11), thereby reducing the overall footprint of the low-pass component 20 (i.e., the planar projection area on the first cavity wall 11).

[0044] The low-pass component 20 can stabilize its installation position and installation state in the low-pass cavity 10 by connecting its opposite ends of the high-impedance stub 21 to other components (such as signal input components, signal output components; or, for example, in the case where the cavity wall of the low-pass cavity 10 has an opening for the high-impedance stub 21 to pass through, an insulating support sleeve fitted between the outer periphery of the high-impedance stub 21 and the opening; etc.). Alternatively, it can stabilize its installation position and installation state in the low-pass cavity 10 by connecting and fixing at least one low-impedance part 221 to the first cavity wall 11.

[0045] In summary, in the low-pass structure provided in this application embodiment, the low-pass component 20 can form an equivalent inductance through the high-impedance stub 21; it can be connected between the low-impedance portion 221 and the high-impedance stub 21 through the connecting portion 222, so that the low-impedance stub 22 can serve as a branch of the high-impedance stub 21; and it can be insulated from the first cavity wall 11 through the low-impedance portion 221, so that an equivalent capacitance can be formed between the low-impedance portion 221 and the first cavity wall 11, thereby enabling each low-impedance stub 22 to independently form an equivalent capacitance. Based on this, the low-pass component 20 can achieve the high impedance requirement through the equivalent inductance formed by the high-impedance stub 21, and can achieve the low impedance requirement through the equivalent capacitance formed by the low-impedance stub 22, thereby enabling the low-pass structure to block and weaken high-frequency signals exceeding a set threshold value, while allowing low-frequency signals to pass normally, thus achieving the low-pass filtering effect. Furthermore, the structure of the low-pass component 20 can be equivalent to "one or more equivalent capacitors connected in parallel to the same equivalent inductor". Each low-impedance stub 22 can be considered as a parallel LC resonant circuit (the equivalent capacitance C formed by each low-impedance stub 22 resonates with the partial equivalent inductance L formed by the high-impedance stub 21). Therefore, each low-impedance stub 22 can generate a transmission zero through LC parallel resonance, thereby enabling the low-pass structure to generate an equal number of transmission zeros as the low-impedance stub 22. This significantly improves the attenuation rate of out-of-band signals near the passband edge and enhances near-end out-of-band rejection performance. Moreover, the number of transmission zeros generated can be flexibly adjusted by increasing or decreasing the number of low-impedance stubs 22, thus flexibly adjusting the out-of-band rejection characteristics and improving the design flexibility and applicability of the low-pass structure. For example, as... Figure 1 , Figure 4As shown, in a specific example of the low-pass structure, the number of low-impedance stubs 22 is three, and in the simulation waveform diagram, the number of transmission zeros generated by the low-pass structure is also three.

[0046] Furthermore, the low-pass structure of this embodiment does not need to be tightly fitted with the low-pass cavity 10, and does not cause uneven compression of the insulating sleeve due to tight fitting as in the prior art, thus affecting the capacitance consistency. The low-pass structure of this embodiment can directly form an equivalent capacitance by means of the air or insulating medium between the low-impedance part 221 and the first cavity wall 11 through the insulating gap. This makes the equivalent capacitance unaffected by assembly pressure, thereby improving the controllability, stability and consistency of the capacitance, and improving the stability and consistency of the low-pass performance of the low-pass structure.

[0047] Furthermore, the low-pass structure in this embodiment does not require a tight fit with the low-pass cavity 10, does not require a tight fit achieved by pressing with a cover plate as in the prior art, and does not require physical pressing force to achieve capacitive coupling between the low-impedance stub 22 and the first cavity wall 11. This essentially eliminates the dependence on pressing assembly, thereby reducing the sensitivity to cumulative tolerances, reducing the requirements for overall assembly accuracy, and reducing the interference of assembly stress on electrical performance (such as intermodulation distortion), thereby improving intermodulation performance and intermodulation stability.

[0048] Furthermore, in the low-pass structure of this embodiment, the high-impedance stub 21 and the low-impedance stub 22 adopt a three-dimensional non-coplanar layout, that is, the high-impedance stub 21, the connecting part 222 and the low-impedance part 221 are not on the same plane parallel to the first cavity wall 11. Based on this, the space in the height direction of the low-pass cavity 10 can be effectively utilized, the overall footprint of the low-pass component 20 can be reduced, and the space utilization rate can be optimized through the three-dimensional layout, so that the low-pass structure can be applied to more usage scenarios and application scenarios, especially making the low-pass structure suitable for arrangement in narrow low-pass cavities 10, and especially making the low-pass structure suitable for miniaturized filters.

[0049] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the connecting portion 222 is bent.

[0050] It should be noted that the connecting part 222 is bent, meaning that the connecting part 222 includes multiple connecting segments that are bent and connected in sequence. Adjacent connecting segments are arranged at an angle, which can be a right angle, an acute angle, or an obtuse angle, and the angle value is not limited. The bending shape of the connecting part 222 can be set as needed, for example, it can be Z-shaped, L-shaped, V-shaped, S-shaped, N-shaped, U-shaped, bow-shaped, etc.

[0051] By adopting the above scheme, and by bending the connecting part 222, the connection path formed by the connecting part 222 can be changed from a straight line to a broken line. This allows the high-impedance stub 21, the connecting part 222, and the low-impedance part 221 to achieve a staggered distribution, three-dimensional arrangement, and compact layout. Based on this, the footprint and volume of the low-pass component 20 can be effectively reduced, the three-dimensional space of the low-pass cavity 10 can be efficiently utilized to arrange the low-pass component 20 three-dimensionally, and the space utilization rate can be optimized. This improves the applicability of the low-pass structure and expands its application range. In particular, it enables the low-pass structure to be used in narrow low-pass cavities 10 and miniaturized filters. Furthermore, the bent connecting part 222 can act as a mechanical buffer section to absorb dimensional deviations during processing or assembly, allowing for a certain degree of deviation. This reduces tolerance sensitivity, reduces the requirements for processing and assembly accuracy, improves assembly tolerance, increases processing yield and assembly yield, and reduces manufacturing costs.

[0052] Of course, in other embodiments, the connecting portion 222 may be provided in a straight line to connect the low impedance portion 221 and the high impedance branch 21 in a straight line.

[0053] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the connecting portion 222 includes a first connecting segment 2221, a second connecting segment 2222, a third connecting segment 2223, and a fourth connecting segment 2224 that are bent and connected in sequence. The first connecting segment 2221 is connected to the high-impedance stub 21 and extends toward the side closer to the low-impedance portion 221. The third connecting segment 2223 extends from the second connecting segment 2222 toward the side closer to the low-impedance portion 221. The third connecting segment 2223 is spaced apart from the outer periphery of the low-impedance portion 221. The end of the fourth connecting segment 2224 away from the third connecting segment 2223 is connected to the periphery of the low-impedance portion 221.

[0054] It should be noted that the connecting part 222 includes four connecting segments: a first connecting segment 2221, a second connecting segment 2222, a third connecting segment 2223, and a fourth connecting segment 2224. One end of the first connecting segment 2221 is connected to the high-impedance stub 21 and extends from the high-impedance stub 21 toward the side closer to the low-impedance part 221.

[0055] The second connecting segment 2222 is connected to the end of the first connecting segment 2221 away from the high-impedance stub 21, and is bent relative to the first connecting segment 2221 towards the side away from the central axis of the low-impedance portion 221. For example, Figure 3As shown, in some embodiments, the angle between the second connecting segment 2222 and the first connecting segment 2221 is a right angle, that is, the second connecting segment 2222 is perpendicular to the first connecting segment 2221. In other embodiments, the angle between the second connecting segment 2222 and the first connecting segment 2221 may be an acute angle or an obtuse angle.

[0056] The third connecting segment 2223 is connected to the end of the second connecting segment 2222 away from the first connecting segment 2221, and extends from the second connecting segment 2222 towards the side closer to the low impedance portion 221. The end of the third connecting segment 2223 away from the second connecting segment 2222 is spaced apart from the outer periphery of the low impedance portion 221. Wherein, as Figure 3 As shown, in some embodiments, the angle between the third connecting segment 2223 and the second connecting segment 2222 is a right angle, that is, the third connecting segment 2223 is perpendicular to the second connecting segment 2222. In other embodiments, the angle between the third connecting segment 2223 and the second connecting segment 2222 may be an acute angle or an obtuse angle.

[0057] The fourth connecting segment 2224 is connected to the end of the third connecting segment 2223 away from the second connecting segment 2222, and is bent relative to the third connecting segment 2223 towards the side closer to the central axis of the low-impedance portion 221. The end of the fourth connecting segment 2224 away from the third connecting segment 2223 is connected to the periphery of the low-impedance portion 221. Wherein, as Figure 3 As shown, in some embodiments, the angle between the fourth connecting segment 2224 and the third connecting segment 2223 is a right angle, that is, the fourth connecting segment 2224 is perpendicular to the third connecting segment 2223. In other embodiments, the angle between the fourth connecting segment 2224 and the third connecting segment 2223 may be an acute angle or an obtuse angle.

[0058] By adopting the above scheme, the connecting part 222 can form a meandering serpentine path through the first connecting segment 2221, the second connecting segment 2222, the third connecting segment 2223, and the fourth connecting segment 2224 connected in sequence by bending. This allows for multi-layer stacking in the height direction of the low-pass cavity 10, thereby maximizing the compression of the connecting part 222 in the three-dimensional space of the low-pass cavity 10. This improves the structural compactness of the low-pass component 20, effectively reduces its footprint and volume, and optimizes space utilization. Furthermore, the connecting part 222 can utilize four connecting segments, as well as the angles between the second connecting segment 2222 and the first connecting segment 2221, the third connecting segment 2223 and the second connecting segment 2222, and the fourth connecting segment 2224 and the third connecting segment 2223, allowing for certain tolerances. This reduces tolerance sensitivity, decreases the requirements for machining and assembly accuracy, improves assembly tolerance, increases machining and assembly yield, and reduces manufacturing costs. Furthermore, since the connecting portion 222 is connected to the periphery of the low impedance portion 221 via the fourth connecting segment 2224, this embodiment is particularly suitable for the case where "the connecting portion 222 and the low impedance portion 221 are integrally connected", and particularly suitable for the case where "the low impedance component 20 is an integrally formed structure".

[0059] Of course, in other embodiments, where the connecting portion 222 is bent, the connecting portion 222 may include other numbers of connecting segments, and the connecting portion 222 may have other bending forms. In other embodiments, the connecting portion 222 may be connected to the side of the low-impedance portion 221 facing away from the first cavity wall 11 via connecting segments. This is particularly suitable for cases where the connecting portion 222 and the low-impedance portion 221 are connected separately, because in this case, the area used to realize the connection operation is larger, which helps to reduce the difficulty of separate connection and improves the convenience, reliability and stability of separate connection.

[0060] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, multiple low-impedance branches 22 are provided, and each low-impedance branch 22 is arranged at intervals along the extension path of the high-impedance branch 21.

[0061] It should be noted that at least two low-impedance branches 22 are provided, with each low-impedance branch 22 spaced apart from the others and connected to the high-impedance branch 21, such that each low-impedance branch 22 is arranged at intervals along the extension path of the high-impedance branch 21. For example, as... Figure 2 As shown, in a specific example of the low-pass structure, there are three low-impedance stubs 22, which are arranged sequentially at intervals along the extension path of the high-impedance stub 21.

[0062] By adopting the above scheme, multiple low-impedance stubs 22 can be spaced out along the extension path of the high-impedance stub 21, so that a transmission zero is generated in the frequency response through each low-impedance stub 22. This allows the low-pass structure to generate multiple transmission zeros equal to the number of low-impedance stubs 22, thereby achieving multiple attenuation at different frequencies outside the passband, making the passband edge roll-off steeper, and improving near-end out-of-band suppression performance. Furthermore, the corresponding frequency and distribution density of the transmission zeros can be adjusted by adjusting the distribution position of each low-impedance stub 22 along the high-impedance stub 21, the spacing of each low-impedance stub 22, the shape of each low-impedance portion 221 of each low-impedance stub 22, the size of each low-impedance portion 221 of each low-impedance stub 22, and the distance between each low-impedance portion 221 of each low-impedance stub 22 and the first cavity wall 11. This allows for flexible adjustment of out-of-band suppression characteristics, thereby improving the design flexibility and applicability of the low-pass structure.

[0063] Of course, in other embodiments, only one low-impedance stub 22 may be provided.

[0064] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the low-pass structure further includes an insulating pad 30 disposed between the low-impedance portion 221 and the first cavity wall 11.

[0065] It should be noted that the insulating pad 30 is an insulating component made of insulating material. The insulating material used in the insulating pad 30 can be flexibly set as needed. For example, the insulating pad 30 can be made of PTFE (Polytetrafluoroethylene), etc.

[0066] An insulating pad 30 is disposed between the low-impedance portion 221 and the first cavity wall 11 to provide insulation between the low-impedance portion 221 and the first cavity wall 11, and to enable the low-impedance portion 221 and the first cavity wall 11 to form a stable equivalent capacitance by using the insulating pad 30 as an insulating medium.

[0067] The number of insulating pads 30 is less than or equal to the number of low-resistance sections 221. For example... Figure 2 As shown, in some embodiments, all low-impedance portions 221 share a single insulating pad 30. In this case, regardless of the number of low-impedance portions 221, the number of insulating pads 30 is always one. In other embodiments, some low-impedance portions 221 share the insulating pad 30, while others use their own insulating pad 30. In this case, the number of insulating pads 30 is less than the number of low-impedance portions 221. In still other embodiments, the insulating pads 30 are provided in a one-to-one correspondence with the low-impedance portions 221. In this case, the number of insulating pads 30 is equal to the number of low-impedance portions 221.

[0068] By adopting the above solution, an insulating pad 30 can be placed between the low-impedance portion 221 and the first cavity wall 11 to reliably insulate and block the space between them. This allows the insulating pad 30 to act as the insulating medium, forming a stable equivalent capacitance between the low-impedance portion 221 and the first cavity wall 11. This facilitates the use of the equivalent capacitance to achieve low impedance requirements in the low-pass structure. Furthermore, using the insulating pad 30 as a physical spacer layer helps maintain a predetermined distance between the low-impedance portion 221 and the first cavity wall 11, reducing gap variations caused by assembly tolerances or vibrations. As an insulating medium layer, the solid insulating pad 30 provides a more stable dielectric constant than air. This stabilizes the equivalent capacitance value between the low-impedance portion 221 and the first cavity wall 11, reducing deviations and fluctuations in the equivalent capacitance value, improving capacitance stability and consistency, and ultimately enhancing the stability and consistency of the low-pass performance of the low-pass structure. Furthermore, by replacing the insulating pads 30 with different dielectric constants, the equivalent capacitance value can be flexibly adjusted to adapt to different frequency band requirements, thereby improving the design flexibility and applicability of the low-pass structure.

[0069] Of course, in other embodiments, the low impedance part 221 and the first cavity wall 11 can be directly spaced apart, or they can be mutually insulated and isolated by other insulating media such as insulating adhesive layer or insulating coating.

[0070] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, all low-impedance portions 221 share a common insulating pad 30.

[0071] It should be noted that regardless of the number of low-impedance parts 221, the number of insulating pads 30 is one, and all low-impedance parts 221 share one insulating pad 30.

[0072] By adopting the above scheme, all low-impedance portions 221 form a capacitor with the first cavity wall 11 through the same insulating pad 30. Based on this, the same insulating pad 30 can provide a uniformly distributed dielectric constant, so as to make the electric field distribution between each low-impedance portion 221 and the first cavity wall 11 consistent. This reduces capacitance differences caused by the thickness, dielectric constant, or assembly deviation of multiple insulating pads 30, and promotes a high degree of matching of the equivalent capacitance values ​​of each low-impedance portion 221, thereby optimizing capacitance consistency and improving the stability and consistency of the low-pass performance of the low-pass structure. Furthermore, the number of insulating pads 30 can be reduced to the minimum, simplifying the structure and assembly process of the low-pass structure, reducing the cumulative error caused by assembling multiple insulating pads 30, improving the assembly convenience, assembly efficiency, and assembly yield of the low-pass structure, saving materials, and reducing costs.

[0073] Of course, in other embodiments, the insulating pad 30 may be provided in a one-to-one correspondence with the low impedance part 221; or, some of the low impedance parts 221 may share the insulating pad 30, while other low impedance parts 221 may each use the insulating pad 30 independently.

[0074] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the low-impedance portion 221 is connected and fixed to the first cavity wall 11.

[0075] It should be noted that the low-resistance part 221 is connected and fixed to the first cavity wall 11, but this does not affect the mutual insulation between the low-resistance part 221 and the first cavity wall 11. The connection and fixing method between the low-resistance part 221 and the first cavity wall 11 can be, but is not limited to, using fasteners, insulating adhesive, etc., to achieve a direct connection and fixation between the low-resistance part 221 and the first cavity wall 11. Alternatively, the low-resistance part 221 and the first cavity wall 11 can also be indirectly connected and fixed by bonding with the insulating pad 30 mentioned above.

[0076] By adopting the above solution, without affecting the mutual insulation between the low-impedance part 221 and the first cavity wall 11, the stability and robustness of the installation position and state of the low-pass component 20 in the low-pass cavity 10 can be improved by connecting and fixing the low-impedance part 221 to the first cavity wall 11. This enhances the vibration resistance and impact resistance of the low-pass structure, reduces the risk of displacement of the low-pass structure under the influence of external vibrations, impacts, and other factors, and improves the reliability of the low-pass structure. Furthermore, the connection and fixation between the low-impedance part 221 and the first cavity wall 11 also helps to maintain a preset distance between the low-impedance part 221 and the first cavity wall 11, thereby stabilizing the equivalent capacitance value between the low-impedance part 221 and the first cavity wall 11, reducing the deviation and fluctuation of the equivalent capacitance value, improving capacitance stability and consistency, and enhancing the stability and consistency of the low-pass performance of the low-pass structure.

[0077] Of course, in other embodiments, the low-pass component 20 can stabilize its installation position and installation state in the low-pass cavity 10 by connecting to other components at opposite ends of the high-impedance stub 21.

[0078] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the low-resistance part 221 has a fastening hole 2211 through it, and the low-resistance part 221 is connected and fixed to the first cavity wall 11 by a fastener (not shown in the figure) passing through the fastening hole 2211.

[0079] It should be noted that the low-resistance part 221 is provided with a fastening hole 2211, which penetrates the low-resistance part 221 along its thickness direction. The shape and size of the fastening hole 2211 can be flexibly set as needed; for example, the fastening hole 2211 can be a circular hole, a rectangular hole, etc. Fasteners can be inserted into the fastening hole 2211 and connected to the first cavity wall 11, thereby connecting and fixing the low-resistance part 221 and the first cavity wall 11 together.

[0080] The fasteners can be either insulated or metal. When the fastener is insulated, it can be, but is not limited to, plastic screws, insulated pins, etc. When the fastener is metal, it can be fitted with insulating washers, insulating sleeves, insulating cylinders, or other insulating structures on its outer periphery, or it can have an insulating layer on its surface, so as to insulate the metal fastener from the low-resistance part 221, thereby ensuring that the mutual insulation between the low-resistance part 221 and the first cavity wall 11 is not affected. The metal fasteners can be, but are not limited to, metal screws, metal pins, etc.

[0081] By adopting the above solution, fasteners can be inserted into the fastening holes 2211 of the low-impedance part 221 and connected to the first cavity wall 11, thereby achieving a connection and fixation between the low-impedance part 221 and the first cavity wall 11 without affecting the mutual insulation between them. Based on this, the convenience, reliability, and stability of the connection between the low-impedance part 221 and the first cavity wall 11 can be improved, as can the stability and stability of the low-pass component 20 in the low-pass cavity 10. This, in turn, improves the structural reliability, operational reliability, and mechanical stability (e.g., vibration resistance and shock resistance) of the low-pass structure. Furthermore, the fasteners can maintain a preset distance between the low-impedance part 221 and the first cavity wall 11, thereby stabilizing the equivalent capacitance value between them, reducing deviations and fluctuations in the equivalent capacitance value, improving capacitance stability and consistency, and ultimately enhancing the stability and consistency of the low-pass performance of the low-pass structure.

[0082] If the low-resistance part 221 and the first cavity wall 11 are directly bonded or indirectly bonded through the insulating pad 30, it is difficult to guarantee the positional accuracy of the low-impedance component 20 relative to the first cavity wall 11 due to factors such as operational precision, and it is also difficult to guarantee the consistency between the actual installation position and the preset position. In contrast, in this embodiment, since the first cavity wall 11 also has a connecting hole for connection with the fastener, the positioning function can be achieved by the cooperation of the fastening hole 2211, the fastener, and the connecting hole, thereby improving the positional accuracy of the low-impedance component 20 relative to the first cavity wall 11 and improving the consistency between the actual installation position and the preset position.

[0083] Of course, in other embodiments, without affecting the mutual insulation between the low impedance part 221 and the first cavity wall 11, other connection and fixing methods can be used between the low impedance part 221 and the first cavity wall 11, such as bonding.

[0084] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the low impedance portion 221 is arranged parallel to and spaced apart from the first cavity wall 11.

[0085] By adopting the above scheme, and by arranging the low-impedance part 221 and the first cavity wall 11 in parallel intervals, the equidistant characteristics of the parallel intervals can be used to form a parallel plate capacitor between the low-impedance part 221 and the first cavity wall 11, thereby making the electric field distribution between the low-impedance part 221 and the first cavity wall 11 uniform. This can stabilize the equivalent capacitance value between the low-impedance part 221 and the first cavity wall 11, improve the capacitance stability and capacitance consistency, and improve the stability and consistency of the low-pass performance of the low-pass structure.

[0086] Of course, in other embodiments, the low impedance portion 221 may be spaced apart from the first cavity wall 11 without being parallel.

[0087] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the low impedance part 221 is a plate-like structure.

[0088] By adopting the above-described scheme, and making the low-impedance part 221 a plate-like structure, the manufacturing and dimensional accuracy control of the low-impedance part 221 can be facilitated, reducing the processing difficulty and improving the processing convenience, efficiency, and accuracy of the low-impedance part 221. Furthermore, the flat surface of the plate-like structure can form a uniform electric field distribution with the first cavity wall 11, resulting in a larger effective coupling area between the low-impedance part 221 and the first cavity wall 11. This improves the controllability, stability, and consistency of the capacitance between the low-impedance part 221 and the first cavity wall 11, thereby enhancing the stability and consistency of the low-pass performance of the low-pass structure.

[0089] Of course, in other embodiments, the low impedance portion 221 may be a sheet structure, a block structure, etc.

[0090] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the high-impedance stub 21 is arranged in a straight line.

[0091] By adopting the above scheme, and by extending the high-impedance stub 21 in a straight line, the processing and manufacturing of the high-impedance stub 21 can be facilitated, and the dimensional accuracy control of the high-impedance stub 21 can be achieved without bending or segmentation design. This reduces processing complexity and difficulty, and improves the processing convenience, efficiency, and accuracy of the high-impedance stub 21. Furthermore, the straight-rod structure of the high-impedance stub 21 makes it less prone to deformation under conditions of vibration and temperature changes, reducing inductance parameter deviations caused by deformation of the high-impedance stub 21, thereby improving the structural reliability, operational reliability, and mechanical stability of the high-impedance stub 21. Moreover, the length of the straight-extended high-impedance stub 21 can be linearly related to the inductance, allowing for precise adjustment of the inductance parameters by adjusting the length of the high-impedance stub 21. This makes the inductance value precisely controllable, and the straight path formed by the high-impedance stub 21 reduces additional losses caused by current bends, thereby improving the controllability, stability, and consistency of the equivalent inductance, and enhancing the stability and consistency of the low-pass structure's performance.

[0092] If the high-impedance stub 21 is extended by a curve or a broken line, it may cause two closely spaced low-impedance stubs 22 to collide and interfere. If the distance between the two low-impedance stubs 22 is increased to avoid collision and interference, it will affect the low-pass performance. In contrast, this embodiment extends the high-impedance stub 21 by a straight line, which facilitates the placement of two closely spaced low-impedance stubs 22 that will not collide and interfere, thereby improving the design flexibility of the low-pass structure and optimizing the low-pass performance.

[0093] Of course, in other embodiments, the high-impedance stub 21 may be provided as a curved extension or a broken line extension.

[0094] Please see Figure 1 , Figure 2 , Figure 3 In some embodiments of this application, the low-pass component 20 is integrally formed from a sheet metal substrate.

[0095] By adopting the above solution, the low-pass component 20 can be integrally formed by stamping and bending sheet metal substrate, that is, the low-pass component 20 is an integral sheet metal component. Based on this, the processing steps of the low-pass component 20 can be simplified, the connection steps between the high-resistance branch 21, the connecting part 222, and the low-resistance part 221 can be simplified, the processing difficulty and processing cost can be reduced, the processing convenience, processing efficiency, processing accuracy, structural strength, structural reliability, and structural compactness of the low-pass component 20 can be improved, the installation and fixing of the low-pass component 20 can be facilitated, and the assembly convenience and assembly efficiency of the low-pass component 20 with the low-pass cavity 10 and the insulating pad 30 can be improved.

[0096] Please see Figure 1Some embodiments of this application provide a filter, including a filter housing and a low-pass structure provided in the embodiments of this application. The filter housing is provided with a low-pass cavity 10, and the low-pass structure is disposed in the low-pass cavity 10.

[0097] By adopting the above scheme, the filter can achieve excellent low-pass filtering effect by applying the low-pass structure provided in the embodiments of this application, thereby maintaining and improving the filtering performance of the filter.

[0098] The above are merely optional embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A low-pass structure disposed in a low-pass cavity of a filter housing, the low-pass cavity having a first cavity wall, characterized in that, The low-pass structure includes: A low-impedance component includes a high-impedance stub with a rod-like structure and at least one low-impedance stub. The low-impedance stub includes a low-impedance portion and a connecting portion. The low-impedance portion is located on the side of the high-impedance stub near the first cavity wall and is insulated from the first cavity wall to form a capacitor therebetween. The connecting portion connects the low-impedance portion and the high-impedance stub.

2. The low-pass structure as described in claim 1, characterized in that, The connecting part is bent.

3. The low-pass structure as described in claim 2, characterized in that, The connecting portion includes a first connecting segment, a second connecting segment, a third connecting segment, and a fourth connecting segment that are bent and connected in sequence. The first connecting segment is connected to the high-impedance stub and extends towards the side closer to the low-impedance portion. The third connecting segment extends from the second connecting segment towards the side closer to the low-impedance portion. The third connecting segment is spaced apart from the outer periphery of the low-impedance portion. The end of the fourth connecting segment away from the third connecting segment is connected to the periphery of the low-impedance portion.

4. The low-pass structure as described in claim 1, characterized in that, The low-impedance stubs are provided in multiples, and each low-impedance stub is arranged at intervals along the extension path of the high-impedance stub.

5. The low-pass structure as described in claim 1, characterized in that, The low-pass structure also includes an insulating pad disposed between the low-impedance portion and the first cavity wall.

6. The low-pass structure as described in claim 5, characterized in that, All of the low-impedance sections share a single insulating pad.

7. The low-pass structure as described in claim 1, characterized in that, The low-resistance part has a through-hole for fastening, and the low-resistance part is connected and fixed to the first cavity wall by a fastener that passes through the fastening hole.

8. The low-pass structure as described in any one of claims 1-7, characterized in that, The low-impedance portion is arranged parallel to and spaced apart from the first cavity wall; And / or, the low-impedance section is a plate-like structure; And / or, the high-impedance stub extends in a straight line.

9. The low-pass structure as described in any one of claims 1-7, characterized in that, The low-pass component is integrally machined from sheet metal substrate.

10. A filter, characterized in that, The filter includes a filter housing and a low-pass structure as described in any one of claims 1-9, wherein the filter housing has a low-pass cavity and the low-pass structure is disposed in the low-pass cavity.

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