Patent Publication Number: US-11664563-B2

Title: Filtering device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/435,552, filed on Jun. 9, 2019, which is a continuation of International Application No. PCT/CN2016/109315, filed on Dec. 9, 2016. All of the aforementioned patent applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     Embodiments of this application relate to the field of communications technologies, and in particular, to a filtering device. 
     BACKGROUND 
     Filters are widely applied to a microwave communication system, a radar navigation system, an electronic countermeasure system, a satellite communications system, a missile guidance system, a meter testing system, and the like. As development of communications, more channels can be selected by a system. This imposes higher requirements on design of the filter. In addition, the filter is an important part of a communications system, and performance of the filter greatly influences quality of the communications system. 
     The filter is a device with a frequency selection function that allows a specific frequency component in a signal to pass through while greatly attenuating other frequency components, thereby filtering out interference. There are many types of filters. A cavity filter, because of its features of high power, a low loss, and a robust structure, availability for a microwave frequency band, and the like, is widely applied to various communications systems. In addition, communication frequency bands are increasingly high, operating bandwidth is becoming wider, and an advantage of the cavity filter is getting obvious. 
     Performance indicators and reliability of the cavity filter have a strong correlation with the structure of the cavity filter. An existing cavity filter includes a cavity, a cover, and a tuning screw. The cover is usually fastened to the cavity by using the screw, and a degree of fastening thereof is uncontrollable, directly affecting filter frequency selectivity. In addition, the tuning screw is mounted on the cover, and it is relatively time-consuming to adjust a resonance characteristic of the filter by screwing the tuning screw. Assembly and tuning processes of the filter are complex. 
     SUMMARY 
     In view of this, embodiments of this application provide a filtering device, to effectively simplify assembly and tuning processes. 
     According to a first aspect, a filtering device is provided. The filtering device includes: 
     a housing, including an inner cavity; 
     a resonant conductor, disposed inside the inner cavity; and 
     a pressing element, having one end disposed on the housing and another end suspended, and facing a position of an open-circuit end of the resonant conductor, where a distance between the pressing element and the resonant conductor is changed by pressing or drawing, to adjust a resonant frequency. 
     Optionally, the filtering device further includes: 
     a cavity terminal, configured to electrically connect a short circuit end of the resonant conductor to the housing, and further configured to support the resonant conductor. 
     Further, the resonant conductor is disposed inside the cavity by inserting and removing. The resonant conductor is vertically or horizontally disposed inside the inner cavity. 
     Optionally, the resonant conductor is a metal strip, a microstrip, a strip line, or a printed circuit board (PCB). 
     Optionally, the housing includes at least one inner cavity, and at least one resonant conductor is disposed inside the inner cavity. Resonant conductors in different inner cavities are electrically connected by using a metal pin, a metal probe, or a printed circuit board. 
     Optionally, the pressing element is of a metal sheet-shaped structure. Optionally, the pressing element may be of a metal peg-shaped structure. 
     Optionally, the filtering device further includes: 
     a fastening terminal, disposed on an outer side of the housing, and configured to fasten the filtering device; and 
     a wiring port, disposed on an outer side of the housing, and configured to connect to a wire. 
     The pressing element, the cavity terminal, the fastening terminal, or the wiring port described above is integrally formed with the housing. For example, a profile housing or an integral model is used. 
     Optionally, the pressing element, the cavity terminal, the fastening terminal, or the wiring port is not integrally formed with the housing. For example, the foregoing component may be connected to the housing by welding. 
     It can be learned that, based on the housing provided in this application, complex steps of mounting a cover and walls can be omitted. The resonant conductor is inserted into and removed from the inner cavity of the housing. This facilitates an adjustment or replacement of the resonant conductor. The pressing element provided in this application is closely connected to the housing, and the resonant frequency is adjusted by pressing or drawing, thereby simplifying a tuning method. In conclusion, it can be learned that the filtering device provided in this application effectively simplifies the assembly and tuning processes. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To describe the technical solutions in the embodiments of this application more clearly, the following briefly describes the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely some embodiments of this application, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts. 
         FIG.  1    is a schematic structural diagram of a filter  100  in the prior art; 
         FIG.  2    is a schematic structural diagram of a filtering device according to an embodiment of this application; 
         FIG.  3    is a schematic structural diagram of a filtering device according to an embodiment of this application; 
         FIG.  4    is a schematic structural diagram of a resonant conductor according to an embodiment of this application; 
         FIG.  5    is a schematic structural diagram of a pressing element according to an embodiment of this application; 
         FIG.  6    is a schematic structural diagram of another pressing element according to an embodiment of this application; and 
         FIG.  7    is a schematic structural diagram of a filtering device according to an embodiment of this application. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are merely some rather than all of the embodiments of this application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the protection scope of this application. 
     “A plurality” refers to two or more than two. The term “and/or” describes an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following three cases: Only A exists, both A and B exist, and only B exists. The character “/” generally indicates an “or” relationship between the associated objects. 
     The terms in this application are described above, to facilitate understanding by a person skilled in the art. 
       FIG.  1    is a schematic structural diagram of a filter  100  in the prior art. As shown in  FIG.  1   , the filter  100  in the prior art includes: a cavity  101 , a cover  102 , a support member  104 , a resonant element  105 , a fastening screw  106 , a tuning screw lever  107 , and the like. There are one or more single resonant cavities  103  in the cavity  101 . The cavity  101  may be formed as an integral component by machining or casting, and the cover  102  is formed by casting or by machining using a molding plate. During assembly, the support member  104  is first assembled as a component to be fastened inside the cavity  101 . Next, the resonant element  105  is fastened at a central position of the single resonant cavity  103  in the cavity  101  to form a resonant unit. Then, the tuning screw lever  107  is fastened on the cover  102 . Finally, a cover component and a cavity component that are assembled are mounted together by using the fastening screw  106 . 
     It can be learned that, a manufacturing and assembly process of the existing filter is relatively complex, and resonance performance of the filter may be affected by a degree of fastening between the cover  102  and the cavity  101 , and may also be affected by stability of grounding of the tuning screw lever  107 . In addition, it is relatively time-consuming to implement tuning by screwing the tuning screw lever  107 . 
     In view of this, an embodiment of this application provides a filter (which is also referred to as a filtering device) that can simplify an assembly process and a tuning process, and can effectively improve filtering performance of the filter. 
     The filtering device provided in this embodiment of this application is applicable to various communications systems, for example, 2G communications systems such as a Global System for Mobile Communications (GSM) and a general packet radio service (GPRS) system; 3G communications systems such as a Code Division Multiple Access (CDMA) system, a Time Division Multiple Access (TDMA) system, a Wideband Code Division Multiple Access (WCDMA) system; and a Long Term Evolution (LTE) system and an LTE-Advanced system. 
     The filtering device provided in some embodiments of this application is applicable to a plurality of communications devices that need to select a signal frequency, for example, may be used in a base station device. 
       FIG.  2    is a schematic structural diagram of a filtering device  200  according to an embodiment of this application. The filtering device  200  includes: 
     a housing  210 , including an inner cavity; 
     a resonant conductor  220 , disposed inside the inner cavity; and 
     a pressing element  230 , having one end disposed on the housing and another end suspended, where the pressing element  230  facing a position of an open-circuit end of the resonant conductor, and a distance between the pressing element  230  and the resonant conductor  220  is changed by pressing or drawing the pressing element  230 , to adjust a resonant frequency. 
     In some embodiments, as shown in  FIG.  2   , the filtering device further includes a cavity terminal  240 , configured to electrically connect a short circuit end of the resonant conductor  220  to the housing  210 , and further configured to support the resonant conductor. When the filtering device shown in  FIG.  2    has no cavity terminal  240 , another replaceable support element may be used to electrically connect the resonant conductor to the housing by welding. 
     Based on the foregoing structure, in a process of assembling the filtering device, a cover does not need to be assembled, an assembly process of the filtering device is simple, and impact of assembly of the cover on performance of the filtering device is reduced. In addition, tuning can be implemented by pressing or drawing the pressing element  230 , thereby simplifying a tuning process, and reducing a tuning time. 
       FIG.  3    is a schematic structural diagram of an example filtering device  300  in accordance with the disclosure. As shown in  FIG.  3   , in addition to a housing  210 , a resonant conductor  220 , and a pressing element  230  that are included in the filtering device shown in  FIG.  2   , and an cavity terminal  340  is included in the filtering device  300 . In this example, the filtering device  300  also includes: 
     a fastening terminal  350 , disposed on an outer side of the housing, and configured to fasten the filtering device; and 
     a wiring port  360 , disposed on an outer side of the housing, and configured to connect to a wire. 
     It can be learned that for the filtering device  300  having the fastening terminal and the wiring port, it can be very convenient to fasten the filtering device on another device, and it is convenient to connect to a signal input or output wire. 
     The following further describes, with reference to  FIG.  4    that is a schematic diagram of a resonant conductor  400  according to an embodiment, a structure of the resonant conductor  400 . As shown in  FIG.  4   , the resonant conductor  400  includes: 
     an open-circuit end  410 , configured to assist a pressing element in adjusting a resonance characteristic; 
     a short circuit end  420 , configured to be grounded, where the short circuit end  420  may be optionally grounded by using a cavity terminal; and 
     a wiring end  430 , configured to connect to a wire to output a signal or input a signal, and further configured to connect to a wiring port such as the wiring port  360  in  FIG.  3   . 
     The resonant conductor  400  may be disposed inside an inner cavity of a filtering device by inserting and removing. In the filtering device shown in  FIG.  2    or  FIG.  3   , the resonant conductor is horizontally disposed inside the inner cavity. In some other embodiments, the resonant conductor may be vertically disposed inside the inner cavity. Details are not described herein. 
     It should be noted that the resonant conductor  400  is merely an example, and a quantity of open-circuit ends, a quantity of short circuit ends, and a quantity of wiring ends are not limited herein. The resonant conductor  400  is a conductor with resonance performance, for example, may be a metal strip, a microstrip, a strip line, or a printed circuit board (PCB). A specific implementation form of the resonant conductor is not limited herein. 
     The following further describes, with reference to  FIG.  5    that is a schematic structural diagram of a pressing element  500  according to one embodiment, a structure of the pressing element  510 . As shown in  FIG.  5   , in this embodiment, the pressing element  510  is of a sheet-shaped structure having one end disposed on a housing  510 , and other three ends suspended. 
       FIG.  6    is a schematic diagram of another pressing element according to the present disclosure. As shown in  FIG.  6   , the pressing element  600  is of a pin-shaped structure, including a pin cap  620  and a pin bar  630 , and is connected to a housing  610  of the filtering device by using the pin cap  620  of the pin-shaped structure, and extends into an inner cavity of the housing by using the pin bar  630  of the pin-shaped structure. 
     It should be noted that the foregoing pressing element is merely an example, and a specific shape of the pressing element is not limited in this application. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this disclosure. Any method for adjusting a resonance characteristic by pressing or drawing a pressing element shall fall within the protection scope of this disclosure. 
     For the filtering device shown in the foregoing embodiment, a housing including one inner cavity is used as an example. In some embodiments, the housing may include a plurality of inner cavities, such as a combiner.  FIG.  7    is a schematic structural diagram of another filtering device  700  according to an embodiment of this application. As shown in  FIG.  7   , the filtering device  700  has a housing including two inner cavities, such as an inner cavity  710  and an inner cavity  720  in  FIG.  7   . One resonant conductor is disposed inside each inner cavity, that is, a resonant conductor  730  is disposed inside the inner cavity  710 , and a resonant conductor  740  is disposed inside the inner cavity  720 . For other components such as a pressing element and a cavity terminal, refer to  FIG.  2   . Details are not described herein. 
     When the housing includes a plurality of inner cavities, resonant conductors in the plurality of inner cavities may be electrically connected. For example, the electrical connection is implemented by using a metal pin, a metal probe, or a printed circuit board PCB. For example, the resonant conductor  730  and the resonant conductor  740  in  FIG.  7    may be electrically connected by using a metal pin, a metal probe, or a PCB. 
     It should be noted that in the filtering device  700  in the foregoing embodiment, only a case in which one resonant conductor is disposed inside each inner cavity is illustrated. Optionally, a plurality of resonant conductors may be disposed inside each inner cavity. Details are not described herein. 
     Regardless of one or more inner cavities that a single housing includes in a filtering device, the pressing element, the cavity terminal, the fastening terminal, or the wiring port may be integrally formed with the housing. An advantage of the integral forming is that a grounding characteristic of the element, the terminal, or the port is good. 
     In some embodiments, the pressing element, the cavity terminal, the fastening terminal, or the wiring port is not integrally formed with the housing, for example, is connected to the housing by welding. An advantage of the non-integral forming is that replaceability of the element, the terminal, or the port is strong, that is, operability of changing a new replacement component is strong if there is damage. 
     The foregoing descriptions include merely some implementations in accordance with the disclosure, but are not intended to limit the protection scope of this application. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed shall fall within the protection scope of this application.