Cavity filter for 5g / 6g

Abstract

This application provides a cavity filter for 5G / 6G, relating to the field of wireless communication technology. The cavity filter for 5G / 6G includes a housing, a first resonator, and two second resonators. The housing forms a resonant cavity; the first resonator is located at the center of the resonant cavity, and the two second resonators are located on either side of the first resonator and are symmetrical about the central axis of the first resonator; the first resonator has a first open-circuit terminal open to the housing and a first short-circuit terminal shorted to the housing; the two second resonators have second open-circuit terminals open to the housing and second short-circuit terminals shorted to the housing. The cavity filter for 5G / 6G provided by this application can improve passband broadening and stopband suppression performance, has a compact structure, is easy to manufacture, and can be widely used in high-end equipment such as 5G base stations, RF test instruments, and smart electronic devices, meeting the high-performance filtering requirements in scenarios where multiple signal standards coexist.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and more particularly to a cavity filter for 5G / 6G. Background Technology

[0002] In application scenarios where multiple signal standards coexist, such as 5G communication, radio frequency test instruments, smart electronic devices, wearable devices, and wind power generation systems, filters need to have characteristics such as ultra-wideband coverage, high selectivity, low insertion loss, and compact structure to achieve efficient gating and interference suppression of multi-band signals.

[0003] In the prior art, common technical solutions for achieving coaxial broadband filtering mainly include: using multiple resonant cavities cascaded to expand the bandwidth; integrating adjustable components such as varactor diodes or mechanical tuning structures in the resonant cavity; combining the coaxial structure with planar circuit structures such as microstrip lines and substrate integrated waveguides; partially or completely filling the resonant cavity with high dielectric constant dielectric materials such as ceramics; and exciting and synthesizing multiple resonant modes in a single cavity through a specific structure.

[0004] However, existing coaxial broadband filters generally suffer from problems such as difficulty in achieving ultra-wideband coverage due to their single-cavity structure, and high overall size and complexity. Summary of the Invention

[0005] In view of the above problems, this application provides a cavity filter for 5G / 6G. The cavity filter for 5G / 6G can form multimode coupling in a single resonant cavity, thereby improving passband broadening and stopband suppression performance.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0007] This application provides a cavity filter for 5G / 6G, comprising: a housing, the housing being configured to form a resonant cavity; a first resonator located at the center of the resonant cavity; the first resonator having a first open-circuit terminal open from the housing and a first short-circuit terminal shorted from the housing; two second resonators respectively located on both sides of the first resonator along a first direction, and the two second resonators being symmetrically arranged about the central axis of the first resonator; the two second resonators having a second open-circuit terminal open from the housing and a second short-circuit terminal shorted from the housing; the first open-circuit terminal and the second open-circuit terminal being located on both sides of the resonant cavity along the height direction; the first short-circuit terminal and the second short-circuit terminal being located on both sides of the resonant cavity along the height direction.

[0008] In one possible implementation, there is a gap between the first open terminal and the housing to open the first open terminal from the housing; there is a gap between the second open terminal of each second resonator and the housing to open the second open terminal from the housing.

[0009] In one possible implementation, the first short-circuit terminal is electrically connected to the housing to short-circuit the first short-circuit terminal to the housing; each second short-circuit terminal is electrically connected to the housing to short-circuit the second short-circuit terminal to the housing.

[0010] In one possible implementation, the first resonator is a cylinder, and the second resonator is an arc-shaped cylinder with an arc-shaped surface facing the first resonator, the arc-shaped surface being coaxially arranged with the outer surface of the first resonator.

[0011] In one possible implementation, a coupling enhancement structure is provided on the side of the first resonator near the first short-circuit end, and the coupling enhancement structure is configured to enhance the coupling strength between the two second resonators.

[0012] In one possible implementation, the coupling enhancement structure is an annular groove formed on the sidewall of the first resonator; the annular groove is located on the side of the first resonator near the first short-circuit end, and the annular groove is opposite to the arc-shaped surface.

[0013] In one possible implementation, the sidewalls of the resonant cavity along both sides of the second direction are configured to form recesses; the recesses are recessed toward the first resonator, and there is a gap between the first resonator and the recesses; the second direction is perpendicular to the first direction and perpendicular to the height direction of the resonant cavity.

[0014] In one possible implementation, the first resonator is filled with an insulating dielectric body on both sides along the second direction; the first resonator is spaced apart from the insulating dielectric body, and the second direction is perpendicular to the first direction and perpendicular to the height direction of the resonant cavity.

[0015] In one possible implementation, it further includes a first feed probe and a second feed probe; the first feed probe and the second feed probe are respectively connected to the side of the two second resonators near the second open end; the first feed probe and the second feed probe are symmetrically arranged about the central axis of the first resonator.

[0016] In one possible implementation, the system further includes a first loading stub and a second loading stub; one end of the first loading stub is connected to the first feed probe and extends into the resonant cavity, and the other end of the first loading stub is spaced from the resonant cavity; one end of the second loading stub is connected to the second feed probe and extends into the resonant cavity, and the other end of the second loading stub is spaced from the resonant cavity.

[0017] The cavity filter for 5G / 6G provided in this application includes a housing, a first resonator, and two second resonators. The housing is configured to form a resonant cavity. The first resonator is located at the center of the resonant cavity, and the two second resonators are located on either side of the first resonator along a first direction, and are symmetrically arranged about the central axis of the first resonator. The first resonator and the two second resonators can work together within a single resonant cavity to excite and stably control multiple resonant modes. Therefore, the cavity filter for 5G / 6G provided in this application does not require the cascading of multiple resonant cavities; a filter structure with multiple resonant modes can be constructed within a single resonant cavity, thereby achieving a broadband filtering response.

[0018] The first resonator has a first open-circuit terminal that is open-circuited from the housing and a first short-circuit terminal that is short-circuited from the housing. The two second resonators each have a second open-circuit terminal that is open-circuited from the housing and a second short-circuit terminal that is short-circuited from the housing. The first and second open-circuit terminals are located on opposite sides of the resonant cavity along the height direction. This configuration allows for the establishment of asymmetric electromagnetic boundary conditions within the resonant cavity, exciting and controlling the coupling relationships between multiple resonant modes within the cavity, and promoting the fusion of resonant poles to form an ultra-wide bandwidth. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the structure of a cavity filter for 5G / 6G provided in an embodiment of this application;

[0021] Figure 2 A top view and dimension annotations of a cavity filter for 5G / 6G provided in an embodiment of this application;

[0022] Figure 3 A front view and dimension annotations of a cavity filter for 5G / 6G provided in an embodiment of this application;

[0023] Figure 4 The S-parameter frequency response curve of the cavity filter for 5G / 6G provided in the embodiments of this application when it does not contain the first loading stub and the second loading stub;

[0024] Figure 5The S-parameter frequency response curves of the cavity filter for 5G / 6G provided in the embodiments of this application when it includes a first loading stub and a second loading stub.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10 - Cavity filters for 5G / 6G;

[0027] 100 - Outer shell; 200 - First resonator; 300 - Second resonator; 300a - First arc-shaped surface; 300b - Second arc-shaped surface; 400 - First feed probe; 500 - Second feed probe; 600 - First loading stub; 700 - Second loading stub;

[0028] 110 - Resonant cavity; 120 - Recessed portion; 120a - Third arc-shaped surface; 120b - Connecting portion; 210 - First open-circuit end; 220 - First short-circuit end; 230 - Annular groove; 310 - Second open-circuit end; 320 - Second short-circuit end;

[0029] X - First direction; Y - Second direction; Z - Height direction. Detailed Implementation

[0030] As described in the background section, with the development of mobile communication technology, indoor distribution systems need to be compatible with and process signals of multiple standards and frequency bands simultaneously. This requires filters to achieve low-loss signal gating over an extremely wide frequency range, and to have sufficient suppression capabilities for adjacent frequency and harmonic interference. At the same time, their physical structure must meet the requirements of miniaturization and high reliability for indoor deployment scenarios.

[0031] To improve the bandwidth performance of filters, existing technologies typically involve cascading multiple coaxial resonators, using coupling windows or probe coupling to construct a wide passband, and relying on the inherent characteristics of the resonators to achieve out-of-band suppression. However, this approach requires multiple cavities connected in series, resulting in a large resonator size that is difficult to meet miniaturization requirements.

[0032] Another common approach is to integrate adjustable components such as varactor diodes or mechanical tuning structures into the resonant cavity, thereby extending the bandwidth by dynamically adjusting the resonant frequency. However, this approach introduces additional active components or complex mechanical structures, increasing the complexity of circuit design and control, and may affect the long-term stability of the filter under environmental stresses such as temperature changes and vibrations.

[0033] Existing technologies also combine coaxial structures with different transmission line forms such as microstrip lines and substrate-integrated waveguides, leveraging the flexible coupling characteristics of microstrip lines to broaden bandwidth. However, this design often involves multiple materials and processing techniques, leading to increased manufacturing costs and challenges in structural integration. Alternatively, dielectric materials such as ceramics can be filled into the resonant cavity to alter its electromagnetic properties. However, the introduction of dielectric materials may impose requirements on processing precision and introduce additional losses at high frequencies. Another approach is to use a single cavity to excite multiple resonant modes to form a wide passband. However, this scheme requires strict mode control, is difficult to design, and waveguide-based multimode cavities are typically still quite large.

[0034] Therefore, existing coaxial broadband filter solutions struggle to achieve a balance between ultra-wideband coverage and miniaturization within a single cavity.

[0035] In view of this, embodiments of this application provide a cavity filter for 5G / 6G, comprising a housing, a first resonator, and two second resonators. The housing forms a resonant cavity. The first resonator is located at the center of the resonant cavity, and the two second resonators are located on either side of the first resonator along a first direction, and are symmetrically arranged about the central axis of the first resonator. The first resonator and the two second resonators can work together within a single resonant cavity to excite and stably control multiple resonant modes. Therefore, the cavity filter for 5G / 6G of this application does not require the cascading of multiple resonant cavities; a filter structure with multiple resonant modes can be constructed within a single resonant cavity, thereby achieving a broadband filtering response.

[0036] The first resonator has a first open-circuit terminal that is open-circuited from the housing and a first short-circuit terminal that is short-circuited from the housing. The two second resonators each have a second open-circuit terminal that is open-circuited from the housing and a second short-circuit terminal that is short-circuited from the housing. The first and second open-circuit terminals are located on opposite sides of the resonant cavity along the height direction. This configuration allows for the establishment of asymmetric electromagnetic boundary conditions within the resonant cavity, exciting and controlling the coupling relationships between multiple resonant modes within the cavity, and promoting the fusion of resonant poles to form an ultra-wide bandwidth.

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Figure 1A schematic diagram of a cavity filter for 5G / 6G provided in an embodiment of this application. (Refer to...) Figure 1 This application provides a cavity filter (hereinafter referred to as cavity filter) 10 for 5G / 6G. The cavity filter 10 can be used in modern wireless communication systems, and is especially suitable for RF front-end filtering scenarios with strict requirements for multi-band compatibility, high selectivity and miniaturization.

[0039] For example, cavity filter 10 can be used in a fifth-generation mobile communication indoor distribution system to perform gating and combining processing on Sub-6GHz band signals. Alternatively, cavity filter 10 can also be used in the radio frequency unit of a WiFi 6 wireless access point to filter 2.4GHz band signals to suppress out-of-band interference and improve signal purity.

[0040] The above is merely an illustrative description of the application scenarios of the cavity filter 10 in this application embodiment, and is not intended to limit the application scenarios of the cavity filter 10 in this application embodiment.

[0041] Reference Figure 1 The cavity filter 10 includes a housing 100, which may be made of a metal material with good electrical conductivity. For example, the housing 100 may be made of aluminum alloy, copper alloy, or silver-plated steel to ensure its structural strength and electromagnetic shielding effectiveness.

[0042] The outer shell 100 forms a resonant cavity 110. The resonant cavity 110 provides a sealed space for electromagnetic resonance. At the same time, the resonant cavity 110 can also shield external electromagnetic interference and ensure the stability of the internal electromagnetic field distribution.

[0043] The resonant cavity 110 is provided with a first resonator 200 and two second resonators 300. The first resonator 200 is located at the center of the resonant cavity 110, and the two second resonators 300 are respectively disposed on both sides of the first resonator 200 along the first direction X, and the two second resonators 300 are symmetrically arranged about the central axis of the first resonator 200.

[0044] This configuration allows the first resonator 200 and the two second resonators 300 to interact within a single resonant cavity 110, forming multiple closely distributed resonant poles. This enables the cavity filter 10 to achieve a multi-resonant mode filter structure within a single resonant cavity 110 without relying on the cascading of multiple resonant cavities 110, thus realizing a broadband filtering response.

[0045] In addition, the first resonator 200 works in conjunction with two symmetrically distributed second resonators 300 to extend the passband width of the cavity filter 10 and optimize the signal transmission characteristics within the passband. This allows the cavity filter 10 to improve its integration and miniaturization while ensuring its performance.

[0046] In this embodiment, the first resonator 200 has a first open-circuit end 210 that is open to the housing 100, and the two second resonators 300 have second open-circuit ends 310 that are open to the housing 100. The first open-circuit end 210 and the second open-circuit end 310 are respectively located on both sides of the resonant cavity 110 along the height direction. The first resonator 200 also has a first short-circuit end 220 that is short-circuited to the housing 100, and the second resonator 300 has a second short-circuit end 320 that is short-circuited to the housing 100. The first short-circuit end 220 and the second short-circuit end 320 are respectively located on both sides of the resonant cavity 110 along the height direction.

[0047] This configuration allows the first resonator 200 and the two second resonators 300 to achieve complete periodic exchange of electromagnetic energy within the resonant cavity 110, forming stable oscillations. This enables the excitation of multiple tightly coupled resonant modes within a single resonant cavity 110, enhancing the electromagnetic coupling strength between the first resonator 200 and the second resonators 300, as well as between the two second resonators 300. This allows multiple resonant poles to be closely arranged in the frequency domain, thereby achieving an ultra-wideband passband response covering 1.8 GHz to 4.0 GHz.

[0048] Furthermore, the cavity filter 10 of this application, by placing the first open-circuit terminal 210 and the second open-circuit terminal 310 on both sides of the resonant cavity 110 along the height direction, and the first short-circuit terminal 220 and the second short-circuit terminal 320 on both sides of the resonant cavity 110 along the height direction, can improve the roll-off characteristics of the passband edge and the stopband suppression capability. This enables the cavity filter 10 to achieve efficient gating of target signals and strong suppression of out-of-band interference in complex electromagnetic environments such as indoor distribution systems where multiple frequency bands coexist. At the same time, it meets the application requirements of miniaturization, low insertion loss and high reliability of the cavity filter 10.

[0049] In some possible embodiments, there may be a gap between the first open-circuit terminal 210 and the resonant cavity 110, so that the first open-circuit terminal 210 and the resonant cavity 110 form an electrically open-circuit state. Similarly, there may be a gap between the second open-circuit terminal 310 of each second resonator 300 and the resonant cavity 110, so that the second open-circuit terminal 310 and the resonant cavity 110 form an electrically open-circuit state. This simplifies the structure of the cavity filter 10 by eliminating the need for additional materials, avoids dielectric losses that may arise from the insulating dielectric material itself, and facilitates achieving lower passband insertion loss.

[0050] In some possible embodiments, the first short-circuit terminal 220 is electrically connected to the resonant cavity 110 to form an electrical short-circuit connection between the first short-circuit terminal 220 and the resonant cavity 110. Each second short-circuit terminal 320 is electrically connected to the resonant cavity 110 to form an electrical short-circuit connection between the second short-circuit terminal 320 and the resonant cavity 110.

[0051] For example, the first short-circuit terminal 220 and the second short-circuit terminal 320 can be electrically connected to the resonant cavity 110 through processes such as integral molding, welding, pressing or threaded connection, to ensure that the first short-circuit terminal 220 and the second short-circuit terminal 320 have extremely low contact resistance and good mechanical strength with the resonant cavity 110, so that the electrical short-circuit characteristics of the first resonator 200 and the second resonator 300 will not deteriorate significantly when subjected to vibration, impact or temperature cycling, thereby ensuring the long-term stability and reliability of the resonant frequency of the cavity filter 10.

[0052] In some other possible embodiments, a conductive connector (not shown in the figure) may also be provided between the first short-circuit terminal 220 and the resonant cavity 110 to achieve an electrical connection between the first short-circuit terminal 220 and the resonant cavity 110. A conductive connector (not shown in the figure) may also be provided between each second short-circuit terminal 320 and the resonant cavity 110 to achieve an electrical connection between the second short-circuit terminal 320 and the resonant cavity 110.

[0053] For example, the conductive connector can be in the form of a welded metal sheet, a conductive adhesive layer, a metallized elastomer, etc. The conductive connector is configured to establish a low-resistance, high-mechanical-stability conductive path between the first short-circuit end 220, the second short-circuit end 320, and the inner wall of the resonant cavity 110, respectively.

[0054] Continue to refer to Figure 1 In this embodiment of the application, the first resonator 200 can be a cylinder, and the second resonator 300 can be an arc-shaped cylinder. The arc-shaped cylinder can have an arc-shaped surface facing the first resonator 200, and the arc-shaped surface is coaxially arranged with the outer surface of the first resonator 200.

[0055] In this way, a uniform and controllable annular coupling gap can be formed between the arcuate surface of the second resonator 300 and the outer surface of the first resonator 200. This optimizes the transmission path of electromagnetic energy between the first resonator 200 and the two second resonators 300, enhances the strength and controllability of the cross-coupling, and helps to achieve a close distribution of multiple resonant poles and an ultra-wideband response. In addition, the arcuate surface can achieve a larger coupling area in a limited space, thereby improving the space utilization of the resonant cavity 110 and contributing to the miniaturization and compactness of the cavity filter 10.

[0056] Continue to refer to Figure 1A coupling enhancement structure may be provided on the side of the first resonator 200 near the first short-circuit terminal 220. The coupling enhancement structure is configured to enhance the coupling strength between the two second resonators 300. The coupling enhancement structure can change the local geometry of the first resonator 200 to controllably perturb the electromagnetic field distribution around the first resonator 200, thereby forming a more concentrated electric or magnetic field distribution. This provides an additional, efficient coupling path between the two second resonators 300, enhances the coupling between the two second resonators 300, and causes multiple resonant poles to be closely aligned in frequency, thus merging to form an ultra-wide bandwidth.

[0057] In some possible embodiments, the coupling enhancement structure may be an annular groove 230 formed on the sidewall of the first resonator 200. The annular groove 230 is located on the side of the first resonator 200 near the first short-circuit end 220, and the annular groove 230 is opposite to the arcuate surface.

[0058] The annular groove 230 can alter the distribution path of the surface current of the first resonator 200 and create a specific electromagnetic field disturbance in its surrounding area, providing an indirect energy coupling path for the two second resonators 300 via the first resonator 200. This coupling path can enhance the cross-coupling between the two second resonators 300, causing multiple discrete resonant modes to merge into a continuous broadband passband, thereby helping the cavity filter 10 achieve an ultra-wideband frequency response.

[0059] Continue to refer to Figure 1 The cavity filter 10 further includes a first feed probe 400 and a second feed probe 500. The first feed probe 400 and the second feed probe 500 can be SMA connector feed probes. One of the first feed probe 400 and the second feed probe 500 is configured as a signal input port for coupling external signals into the resonant cavity 110, and the other is configured as a signal output port for coupling the filtered signal out of the resonant cavity 110. For ease of description, in this embodiment, the first feed probe 400 is defined as the signal input port, and the second feed probe 500 is defined as the signal output port.

[0060] The first feed probe 400 and the second feed probe 500 are respectively connected to the side of the two second resonators 300 near the second open end 310. By utilizing the specific electric field distribution in the region of the second open end 310, energy exchange and impedance matching between the external transmission line and the resonant cavity 110 are achieved, which helps to reduce the insertion loss of the cavity filter 10 passband.

[0061] Furthermore, the first feed probe 400 and the second feed probe 500 are symmetrically arranged about the central axis of the first resonator 200, which ensures that the electromagnetic path traversed by the signal from input to output is symmetrical. This symmetrical excitation method can excite specific combinations of operating modes within the resonant cavity 110 and suppress parasitic modes or passband distortions that may be caused by structural asymmetry, thereby ensuring that the passband frequency response of the cavity filter 10 has an ideal shape and consistency.

[0062] Continue to refer to Figure 1 The cavity filter 10 may further include a first loading stub 600 and a second loading stub 700. One end of the first loading stub 600 is connected to the first feed probe 400, and the first loading stub 600 extends into the resonant cavity 110, with the other end of the first loading stub 600 spaced apart from the resonant cavity 110. One end of the second loading stub 700 is connected to the second feed probe 500, and the second loading stub 700 extends into the resonant cavity 110, with the other end of the second loading stub 700 spaced apart from the resonant cavity 110.

[0063] The first loading stub 600 and the second loading stub 700 can be electrically equivalent to quarter-wavelength resonators, respectively. When a signal enters through the first feed probe 400, the first loading stub 600 generates a high impedance state near its quarter-wavelength resonant frequency, thereby introducing a transmission zero in the passband of the cavity filter 10. The appearance of the transmission zero disrupts the continuity of the original passband, thus splitting the single wide passband into two independent sub-passbands.

[0064] By adjusting the physical lengths of the first loading stub 600 and the second loading stub 700, the position of the transmission zero point on the frequency axis can be controlled, thereby flexibly adjusting the center frequency and bandwidth of the two sub-passbands. This allows the cavity filter 10 of this application to adapt to different multi-band signal coexistence scenarios, improving the functional flexibility and application range of the cavity filter 10.

[0065] In some possible implementations, recesses 120 can be formed on the sidewalls of the resonant cavity 110 along the second direction Y. The recesses 120 are recessed towards the first resonator 200, and a gap exists between the first resonator 200 and the recesses 120. In this embodiment, the second direction Y is perpendicular to the first direction X and perpendicular to the height direction of the resonant cavity 110. The recesses 120 can reduce the gap between the first resonator 200 and the sidewalls of the resonant cavity 110 along the second direction Y, thereby changing the local electromagnetic boundary conditions of the resonant cavity 110 in the second direction Y, adjusting the frequency spacing and coupling strength between multiple resonant modes excited by the first resonator 200 and the two second resonators 300, which is beneficial for forming a stable and flat passband response over a wider frequency range and improving the frequency selectivity at the passband edge.

[0066] Meanwhile, the design of the recess 120 can reduce the internal volume of the resonant cavity 110 while ensuring the space required for electrical performance, which helps to achieve miniaturization of the overall structure of the cavity filter 10 and facilitates the processing and forming of the overall structure of the cavity filter 10.

[0067] In other possible implementations, the first resonator 200 may also be filled with an insulating dielectric material (not shown in the figure) on both sides along the second direction Y, with the first resonator 200 and the insulating dielectric material spaced apart. Exemplarily, the insulating dielectric material can be an insulating material such as polytetrafluoroethylene or ceramic; this application embodiment does not impose specific limitations on this. This arrangement preserves the necessary gap between the first resonator 200 and the insulating dielectric material while maintaining the multimode strong coupling mechanism between the first resonator 200 and the two second resonators 300.

[0068] In this embodiment of the application, the following structure is used as an example for testing: the first resonator 200 is a cylinder; the second resonator 300 is an arc-shaped cylinder, the arc-shaped cylinder has a first arc-shaped surface 300a and a second arc-shaped surface 300b facing the first resonator 200, the second arc-shaped surface 300b is located on the side of the first arc-shaped surface 300a away from the first resonator 200, and the first arc-shaped surface 300a and the second arc-shaped surface 300b are coaxially arranged with the outer surface of the first resonator 200; the resonant cavity 110 is recessed inward along the two side walls of the second direction Y to form a recessed portion 120, the recessed portion 120 includes a third arc-shaped surface 120a and two connecting portions 120b.

[0069] Figure 2 A top view and dimension annotations of a cavity filter provided in an embodiment of this application. Figure 3 The front view and dimensions of the cavity filter provided in the embodiments of this application are shown.

[0070] Reference Figure 2In the figure, r1 is the radius of the first resonator 200, r2 is the radius of curvature of the first arc surface 300a, r3 is the distance between the first arc surface 300a and the second arc surface 300b, r4 is the radius of curvature of the third arc surface 120a, and r5 is the length of the connecting part 120b; d1 is the distance between the geometric center of the first arc surface 300a and the center of the first resonator 200, and d2 is defined as the distance between the geometric center of the third arc surface 120a and the center of the first resonator 200. In this embodiment, experiments are conducted using r1=2.6mm, r2=2.8mm, r3=2.5mm, r4=2.8mm, r5=7.2mm, d1=1.13mm, and d2=1.41mm as examples.

[0071] Reference Figure 3 In the figure, h1 is the height of the resonant cavity 110, h3 is the height of the annular groove 230; h2 is the height of the first resonator 200 after removing the annular groove 230; h4 is the height of the second resonator 300; and h5 is the distance between the first feed probe 400 or the second feed probe 500 and the bottom end of the resonant cavity 110. In this embodiment, experiments are conducted using h1=26mm, h2=18.1mm, h3=4mm, h4=25.4mm, and h5=24.7mm as examples.

[0072] Figure 4 The S-parameter frequency response curves of the cavity filter provided in this application embodiment when it does not contain the first loading stub and the second loading stub. Figure 5 The S-parameter frequency response curves of the cavity filter provided in the embodiments of this application when it includes a first loading stub and a second loading stub.

[0073] Reference Figure 4 and Figure 5 In the graph, the horizontal axis represents frequency in gigahertz (GHz), indicating the frequency sweep range from 0.0 GHz to 7.0 GHz; the vertical axis represents amplitude in decibels (dB), indicating the amplitude value of the S-parameters. The S-parameters in the graph... 11 Represents input return loss, used to characterize the impedance matching characteristics of the 10-port cavity filter; S 21 This represents the forward propagation coefficient from the input port to the output port, reflecting the transmission efficiency of the signal through the cavity filter 10, i.e., the insertion loss.

[0074] When the cavity filter 10 does not include the first loading stub 600 and the second loading stub 700, the cavity filter 10 operates in single-passband mode. (Refer to...) Figure 4 The cavity filter 10 exhibits an ultra-wide passband response with a center frequency of approximately 2.9 GHz and a relative bandwidth of approximately 68%. Within this passband, the input return loss (Si) is minimal. 11The impedance is better than -20dB, indicating excellent impedance matching characteristics at the input. Insertion loss (S 21 The signal loss is as low as approximately 0.04 dB within the passband, demonstrating extremely low signal transmission loss. In addition, a transmission zero is visible at approximately 6.92 GHz in the stopband (upper stopband) on the high-frequency side of the passband. This transmission zero can improve the frequency selectivity at the edge of the passband and enhance the out-of-band rejection capability near this frequency.

[0075] Reference Figure 5 When the cavity filter 10 includes a first loading stub 600 and a second loading stub 700, compared to Figure 4 The single-passband response introduces a new transmission zero at approximately 3.1 GHz within the passband. This transmission zero divides the original continuous wide passband into two independent sub-passbands, enabling switching between single and dual passbands. By adjusting the lengths and dimensions of the first loading stub 600 and the second loading stub 700, the frequency position of this transmission zero can be flexibly controlled, thereby allowing for the designability of the bandwidth and spacing of the two sub-passbands.

[0076] It should be noted that the terms "an embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," etc., mentioned in the specification may include specific features, structures, or characteristics, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when describing a specific feature, structure, or characteristic in conjunction with embodiments, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0077] Generally speaking, terms should be understood at least in part by their use in context. For example, at least in part by context, the term "one or more" as used in the text can be used to describe any feature, structure, or characteristic of the singular meaning, or a combination of features, structures, or characteristics of the plural meaning. Similarly, at least in part by context, terms such as "one" can be understood to convey either singular or plural usage.

[0078] It should be readily understood that the terms “on,” “above,” and “on top of” in this application should be interpreted in the broadest possible sense, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on something” but also “on something” without an intermediate feature or layer therebetween (i.e., directly on something).

[0079] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90° or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A cavity filter for 5G / 6G, characterized in that, include: An outer casing, wherein the outer casing is configured to form a resonant cavity; A first resonator, located at the center of the resonant cavity; The first resonator has a first open-circuit terminal that is open to the housing and a first short-circuit terminal that is short to the housing; Two second resonators are located on either side of the first resonator along a first direction, and the two second resonators are arranged symmetrically about the central axis of the first resonator. The two second resonators have a second open-circuit terminal that is open to the housing and a second short-circuit terminal that is short to the housing; The first open-circuit end and the second open-circuit end are respectively located on both sides of the resonant cavity along the height direction; the first short-circuit end and the second short-circuit end are respectively located on both sides of the resonant cavity along the height direction.

2. The cavity filter for 5G / 6G according to claim 1, characterized in that, There is a gap between the first open terminal and the outer casing, so that the first open terminal is open from the outer casing; Each of the second resonators has a gap between its second open terminal and the housing, such that the second open terminal is open from the housing.

3. The cavity filter for 5G / 6G according to claim 1, characterized in that, The first short-circuit terminal is electrically connected to the housing, so that the first short-circuit terminal is short-circuited to the housing. Each of the second short-circuit terminals is electrically connected to the housing so that the second short-circuit terminal is short-circuited to the housing.

4. The cavity filter for 5G / 6G according to claim 1, characterized in that, The first resonator is a cylinder, and the second resonator is an arc-shaped cylinder. The arc-shaped cylinder has an arc-shaped surface facing the first resonator, and the arc-shaped surface is coaxially arranged with the outer surface of the first resonator.

5. The cavity filter for 5G / 6G according to claim 4, characterized in that, A coupling enhancement structure is provided on the side of the first resonator near the first short-circuit end, and the coupling enhancement structure is configured to enhance the coupling strength between the two second resonators.

6. The cavity filter for 5G / 6G according to claim 5, characterized in that, The coupling enhancement structure is an annular groove formed on the side wall of the first resonator; the annular groove is located on the side of the first resonator near the first short-circuit end, and the annular groove is opposite to the arc-shaped surface.

7. The cavity filter for 5G / 6G according to any one of claims 1-6, characterized in that, The resonant cavity has recessed portions formed on both sides of its sidewalls along the second direction; the recessed portions are recessed toward the first resonator, and there is a gap between the first resonator and the recessed portions; the second direction is perpendicular to the first direction and perpendicular to the height direction of the resonant cavity.

8. The cavity filter for 5G / 6G according to any one of claims 1-6, characterized in that, The first resonator is filled with an insulating dielectric material on both sides along the second direction; the first resonator and the insulating dielectric material are spaced apart, and the second direction is perpendicular to the first direction and perpendicular to the height direction of the resonant cavity.

9. The cavity filter for 5G / 6G according to any one of claims 1-6, characterized in that, It also includes a first feed probe and a second feed probe; the first feed probe and the second feed probe are respectively connected to the side of the two second resonators near the second open end; the first feed probe and the second feed probe are symmetrically arranged about the central axis of the first resonator.

10. The cavity filter for 5G / 6G according to claim 9, characterized in that, It also includes a first loading stub and a second loading stub; one end of the first loading stub is connected to the first feed probe, and the first loading stub extends into the resonant cavity, and the other end of the first loading stub is spaced from the resonant cavity; One end of the second loading stub is connected to the second feed probe, and the second loading stub extends into the resonant cavity, while the other end of the second loading stub is spaced from the resonant cavity.

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