Patent Publication Number: US-11380999-B2

Title: Slot antenna and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 15/576,723, filed on Nov. 24, 2017, which a national stage of International Application No. PCT/CN2015/080123, filed on May 28, 2015. Both of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the antenna field, and in particular, to a slot antenna and an electronic device. 
     BACKGROUND 
     With continuous development of electronic technologies, design of electronic devices such as mobile phones develops towards thinness and metal. Therefore, slot antennas that are less sensitive to metal attract more attention. 
     In the prior art, a main body of a slot antenna is a printed circuit board having a slot. A length of a conventional slot antenna is a quarter of a wavelength of a working frequency. The slot antenna further includes a feeding unit. The feeding unit may be a microstrip. The microstrip extends along a position in which an open end of the slot is located and vertically crosses the slot, and a feeding point is located in a position that can enable a largest electric field of the antenna. The microstrip feeds a signal to the open end of the slot by means of coupling, to stimulate the slot antenna. 
     SUMMARY 
     To resolve the problem in the prior art that a slot antenna has a relatively high requirement on a manufacturing process, and needs relatively large space, embodiments of the present disclosure provide a slot antenna and an electronic device. The technical solutions are as follows: 
     According to a first aspect, a slot antenna is provided, where the slot antenna includes: a printed circuit board having a slot, a first capacitor, a radio frequency signal source, a transmission line, and a ground cable, where 
     the printed circuit board is grounded; one end of the slot is open, and the other end is closed; 
     the first capacitor and the ground cable are disposed on the printed circuit board; the first capacitor is located on the open end of the slot, and is disposed on one side of the slot; and 
     the first capacitor is connected to the radio frequency signal source by using the transmission line, and the radio frequency signal source connects the transmission line to the ground cable; and the radio frequency signal source is configured to: stimulate a feeding signal, and feed the feeding signal to the open end of the slot by using the first capacitor. 
     In one embodiment, the slot antenna further includes: a second capacitor, where 
     the second capacitor is disposed on a middle part of the slot, and the second capacitor connects two sides of the slot. 
     In one embodiment, the second capacitor is a variable capacitor. 
     In one embodiment, the first capacitor is a variable capacitor. 
     In one embodiment, the slot is filled with a dielectric material. 
     According to a second aspect, a slot antenna is provided, where the slot antenna includes: a printed circuit board having a slot, a first capacitor, a radio frequency signal source, a transmission line, a ground cable, and an open radiation branch, where 
     the printed circuit board is grounded; the open radiation branch is disposed in the slot; 
     the ground cable is disposed on the printed circuit board; the first capacitor is disposed on an open radiation branch, and the first capacitor is located on the open end of the slot; and 
     the first capacitor is connected to the radio frequency signal source by using the transmission line, and the radio frequency signal source connects the transmission line to the ground cable; and the radio frequency signal source is configured to: stimulate a feeding signal, and feed the feeding signal to the open end of the slot by using the first capacitor. 
     In one embodiment, the slot antenna further includes: a second capacitor, where 
     the second capacitor is disposed on a middle part of the slot, and the second capacitor connects one side of slot to the open radiation branch. 
     In one embodiment, the second capacitor is a variable capacitor. 
     In one embodiment, the first capacitor is a variable capacitor. 
     In one embodiment, the slot is filled with a dielectric material. 
     According to a third aspect, an electronic device is provided, where the electronic device includes: 
     at least one slot antenna according to the first aspect or any possible implementation manner of the first aspect; 
     and/or 
     at least one slot antenna according to the second aspect or any possible implementation manner of the second aspect. 
     In one embodiment, when the electronic device includes two or more slot antennas, printed circuit boards of the two or more slot antennas are a same printed circuit board. 
     In one embodiment, a printed circuit board of the at least one slot antenna is a housing of the electronic device or a part of a housing of the electronic device. 
     The technical solutions provided in the embodiments of the present disclosure have the following beneficial effects: 
     A signal is fed to an open end of a slot by using a capacitor, and impedance matching can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by a slot antenna can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To describe the technical solutions in various embodiments more clearly, the following briefly describes the accompanying drawings required for describing the embodiments. Apparently, the accompanying drawings in the following description show merely some embodiments, 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 structural diagram of a slot antenna according to the present disclosure; 
         FIG. 2A  is a structural diagram of a slot antenna according to another embodiment of the present disclosure; 
         FIG. 2B  is a curve chart of a relationship between a working frequency and a reflection coefficient for different C 1  according to another embodiment; 
         FIG. 2C  is a curve chart of a relationship between a working frequency and a reflection coefficient for different C 2  according to another embodiment; 
         FIG. 2D  is a curve chart of a relationship between a working frequency and antenna efficiency for different C 2  according to another embodiment; 
         FIG. 3  is a structural diagram of a slot antenna according to the present disclosure; 
         FIG. 4A  is a structural diagram of a slot antenna according to another embodiment; 
         FIG. 4B  is a curve chart of a relationship between a working frequency and a reflection coefficient for different C 1  according to another embodiment; 
         FIG. 4C  is a curve chart of a relationship between a working frequency and a reflection coefficient for different C 2  according to another embodiment; 
         FIG. 4D  is a curve chart of a relationship between a working frequency and antenna efficiency for different C 2  according to another embodiment; 
         FIG. 5A  is a device composition diagram of an electronic device according to the present disclosure; 
         FIG. 5B  is a curve chart of a relationship between a working frequency and an input reflection coefficient of a first slot antenna for different C 2  according to the present disclosure; 
         FIG. 5C  is a curve chart of a relationship between a working frequency and an output reflection coefficient of a second slot antenna for different C 2  according to the present disclosure; 
         FIG. 5D  is a curve chart of a relationship between a working frequency and antenna efficiency of a first slot antenna for different C 2  according to the present disclosure; 
         FIG. 5E  is a curve chart of a relationship between a working frequency and antenna efficiency of a second slot antenna for different C 2  according to the present disclosure; 
         FIG. 5F  is a curve chart of a relationship between a working frequency and antenna efficiency of a first slot antenna, and a relationship between a working frequency and antenna efficiency of a second slot antenna for different C 2  according to the present disclosure; 
         FIG. 5G  is a curve chart of a relationship between an input reflection coefficient and a working frequency of a first slot antenna for different dielectric coefficients of a dielectric material according to the present disclosure; and 
         FIG. 5H  is a curve chart of a relationship between antenna efficiency and a working frequency of a first slot antenna for different dielectric coefficients of a dielectric material according to the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     To make the objectives, technical solutions, and advantages of the present disclosure clearer, the following further describes the embodiments of the present disclosure in detail with reference to the accompanying drawings. 
     In a process of implementing the present disclosure, the inventor finds that the prior art has at least the following problems: 
     The slot antenna provided in the prior art couples and feeds a signal to an open end of a slot by using a microstrip, and it is not easy to implement impedance matching between the microstrip and the open end of the slot. Therefore, a relatively high requirement is imposed on a manufacturing process. In addition, the implementation manner of the feeding needs relatively large space. 
     Referring to  FIG. 1 ,  FIG. 1  is a structural diagram of a slot antenna according to the present disclosure. An upper half of  FIG. 1  is an elevational view of the slot antenna, and a lower half of  FIG. 1  is a side view of the slot antenna. As shown in  FIG. 1 , the slot antenna may include: a printed circuit board  110  having a slot  112 , a first capacitor  120 , a radio frequency signal source  130 , a transmission line  140 , and a ground cable  150 . 
     The printed circuit board  110  is grounded. One end of the slot  112  is open, and the other end is closed. 
     The first capacitor  120  and the ground cable  150  are disposed on a printed circuit board, and the first capacitor  120  is located on an open end of the slot  112 , and is clingingly disposed on one side of the slot  112 . 
     The first capacitor  120  is connected to the radio frequency signal source  130  by using the transmission line  140 , and the radio frequency signal source  130  connects the transmission line  140  to the ground cable  150 . The radio frequency signal source  130  is configured to: stimulate a feeding signal, and feed the feeding signal to the open end of the slot  112  by using the first capacitor  120 . 
     To sum up, in the slot antenna provided in this embodiment, a signal is fed to an open end of a slot by using a capacitor, and impedance matching can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by the slot antenna can be reduced. 
     Based on the foregoing slot antenna shown in  FIG. 1 ,  FIG. 2A  is a structural diagram of a slot antenna according to another embodiment of the present disclosure. An upper half of  FIG. 2A  is an elevational view of the slot antenna, and a lower half of  FIG. 2A  is a side view of the slot antenna. As shown in  FIG. 2A , the slot antenna may include: a printed circuit board  110  having a slot  112 , a first capacitor  120 , a radio frequency signal source  130 , a transmission line  140 , and a ground cable  150 . 
     For positions and connection structures of the foregoing components, refer to  FIG. 1 , and details are not described herein again. 
     The first capacitor  120  is close or clinging to one side of the slot  112 . Optionally, the first capacitor  120  may be disposed on a position that enables a largest electric field of the slot antenna. The transmission line  140  is not in contact with the printed circuit board  110 , and a distance between the transmission line  140  and the printed circuit board  110  is set to a thickness of the printed circuit board. 
     The first capacitor  120 , the radio frequency signal source  130 , the transmission line  140 , and the ground cable  150 A constitute a feeding unit of the slot antenna. The feeding unit is configured to: generate a feeding signal and feed the feeding signal to the slot of the antenna. 
     It should be noted that, the structural diagrams of the slot antennas shown in  FIG. 1  and  FIG. 2A  are used to describe connection and position relationships between the components, and do not limit actual shapes and sizes of the components and distances between the components. For example, in actual use, the radio frequency signal sources  130  shown in  FIG. 1  and  FIG. 2A  each may be implemented as a single component, or may be implemented as an integrated circuit consisting of multiple electronic components. 
     In this embodiment, impedance matching of the slot antenna can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by the slot antenna can be reduced. 
     Optionally, the first capacitor  120  may further be a variable capacitor. 
     Optionally, the slot antenna further includes: a second capacitor  160 . 
     The second capacitor  160  is disposed on a middle part of the slot  112 , and the second capacitor  160  connects two sides of the slot. 
     In this embodiment e, a capacitor that connects two sides of the slot may be disposed on a middle part of the slot of the slot antenna, so as to reduce a length of the slot, and reduce a size of the slot antenna. 
     Optionally, the second capacitor  160  may further be a variable capacitor. 
     In this embodiment, the first capacitor and the second capacitor may be variable capacitors. A reflection coefficient and efficiency of the slot antenna are adjusted by separately or simultaneously adjusting capacitances of the two capacitors, so as to implement independent double resonance adjustment, thereby improving efficiency and a bandwidth of performance of the slot antenna. 
     Specifically, it is assumed that the first capacitor  120  in  FIG. 2A  is a variable capacitor C 1 . Refer to  FIG. 2B ,  FIG. 2C , and  FIG. 2D .  FIG. 2B  is a curve chart of a relationship between a working frequency and an input reflection coefficient for different C 1  (in this case, there is no second capacitor  160 ). When a capacitance of C 1  is adjusted from 0.1 pF to 0.5 pF, a resonance frequency of the antenna changes from 1.7 GHz to 2.6 GHz.  FIG. 2C  is a curve chart of a relationship between a working frequency and an input reflection coefficient for different C 2  when a capacitance of the first capacitor  120  is a fixed value 0.3 pF, and the second capacitor  160  is a variable capacitor C 2 . When a capacitance of C 2  is adjusted from 1 pF to 0.1 pF, a resonance frequency of the antenna changes from 2.0 GHz to 1.6 GHz.  FIG. 2D  is a diagram of a relationship between a working frequency and antenna efficiency for different C 2  when a capacitance of C 1  is a fixed value 0.3 pF. 
     It can be seen from  FIG. 2B ,  FIG. 2C , and  FIG. 2D  that a resonance frequency of the slot antenna shown in  FIG. 2A  may be adjusted by using either of the first capacitor and the second capacitor. 
     Optionally, the slot  112  may be filled with a dielectric material  170 . 
     In this embodiment disclosure, the slot of the slot antenna may further be filled with a dielectric material, to improve the working efficiency of the slot antenna in a low frequency, thereby achieving an effect of expanding a use frequency of the slot antenna. 
     To sum up, in the slot antenna provided in this embodiment, a signal is fed to an open end of a slot by using a capacitor, and impedance matching can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by the slot antenna can be reduced. In addition, another capacitor is disposed on a middle part of the slot, to reduce a size of the slot antenna. In addition, the two capacitors are both set to variable capacitors, to implement double resonance adjustment of the slot antenna, and improve performance and efficiency of the antenna. In addition, the slot may further be filled with a dielectric material, to achieve an effect of expanding a use frequency of the slot antenna. 
     The slot antenna shown in the foregoing embodiments corresponding to  FIG. 1  or  FIG. 2A  can implement single-frequency band resonance. An embodiment further provides a slot antenna having dual-band resonance. Referring to  FIG. 3 ,  FIG. 3  is a structural diagram of the slot antenna according to this embodiment. An upper half of  FIG. 3  is an elevational view of the slot antenna, and a lower half of  FIG. 1  is a side view of the slot antenna. As shown in  FIG. 3 , the slot antenna may include: a printed circuit board  310  having a slot  312 , a first capacitor  320 , a radio frequency signal source  330 , a transmission line  340 , a ground cable  350 , and an open radiation branch  380 . 
     The printed circuit board  310  is grounded. One end of the slot  312  is open, and the other end is closed. The open radiation branch  380  is disposed in the slot  312 ; and the open radiation branch  380  is not in contact with the printed circuit board  310 . 
     The ground cable  350  is disposed on the printed circuit board  310 . The first capacitor  320  is disposed on the open radiation branch  380 , and the first capacitor  320  is located on the open end of the slot  312 . 
     The first capacitor  320  is connected to the radio frequency signal source  330  by using the transmission line  340 , and the radio frequency signal source  330  connects the transmission line  340  to the ground cable  350 . The radio frequency signal source  330  is configured to: stimulate a feeding signal, and feed the feeding signal to the open end of the slot  312  by using the first capacitor  320 . 
     To sum up, in the slot antenna provided in this embodiment disclosure, a signal is fed to an open end of a slot by using a capacitor, and impedance matching can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by the slot antenna can be reduced. Furthermore, an open radiation branch is disposed in the slot, and a capacitor is disposed on the open radiation branch, to implement dual-band resonance of the slot antenna, so that the slot antenna can have two resonance frequencies at the same time. 
     Based on the foregoing slot antenna shown in  FIG. 3 ,  FIG. 4A  is a structural diagram of a slot antenna according to another embodiment of the present. An upper half of  FIG. 4A  is an elevational view of the slot antenna, and a lower half of  FIG. 2A  is a side view of the slot antenna. As shown in  FIG. 4A , the slot antenna may include: a printed circuit board  310  having a slot  312 , a first capacitor  320 , a radio frequency signal source  330 , a transmission line  340 , a ground cable  350 , and an open radiation branch  380 . 
     For positions and connection structures of the foregoing components, refer to  FIG. 1 , and details are not described herein again. 
     Optionally, the first capacitor  320  may be disposed on a position that enables a largest electric field of the slot antenna. The transmission line  340  is not in contact with the printed circuit board  310 , and a distance between the transmission line  340  and the printed circuit board  310  is set to a thickness of the printed circuit board. 
     The first capacitor  320 , the radio frequency signal source  330 , the transmission line  340 , and the ground cable  350  constitute a feeding unit of the slot antenna. The feeding unit is configured to: generate a feeding signal and feed the feeding signal to the slot of the antenna. 
     It should be noted that, the structural diagrams of the slot antennas shown in  FIG. 3  and  FIG. 4A  are used to describe connection and position relationships between the components, and do not limit actual shapes and sizes of the components and distances between the components. 
     In this embodiment, impedance matching of the slot antenna can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by the slot antenna can be reduced. Furthermore, an open radiation branch is disposed in a slot, and a capacitor is disposed on an open radiation branch, to implement dual-band resonance of the slot antenna, so that the slot antenna can have two resonance frequencies at the same time. 
     Optionally, the first capacitor  320  may be a variable capacitor. 
     Optionally, the slot antenna further includes: a second capacitor  360 . 
     The second capacitor  360  is disposed on a middle part of the slot  312 , and the second capacitor  360  connects one side of the slot  312  and the open radiation branch  380 . 
     In this embodiment, a capacitor that connects one side of the slot and an open radiation branch may be disposed on a middle part of the slot of the slot antenna, so as to reduce a length of the slot, and reduce a size of the slot antenna. 
     Optionally, the second capacitor  360  may be a variable capacitor. 
     In this embodiment, the first capacitor and the second capacitor may be variable capacitors. A reflection coefficient and efficiency of the slot antenna are adjusted by separately or simultaneously adjusting capacitances of the two capacitors, so as to implement independent double resonance adjustment, thereby improving efficiency and a bandwidth of performance of the slot antenna. 
     Specifically, it is assumed that the first capacitor  320  in  FIG. 4A  is a variable capacitor C 1 . Referring to  FIG. 4B ,  FIG. 4C , and  FIG. 4D ,  FIG. 4B  is a curve chart of a relationship between a working frequency and a reflection coefficient for different C 1 ,  FIG. 4C  is a curve chart of a relationship between a working frequency and a reflection coefficient for different C 2 , and  FIG. 4D  is a curve chart of a relationship between a working frequency and antenna efficiency for different C 2 . 
     It can be seen from  FIG. 4B ,  FIG. 4C , and  FIG. 4D  that a resonance frequency of the slot antenna shown in  FIG. 4A  may be adjusted by using either of the first capacitor and the second capacitor. 
     Optionally, the slot  312  is filled with a dielectric material  370 . 
     In this embodiment, the slot of the slot antenna may further be filled with a dielectric material, to improve the working efficiency of the slot antenna in a low frequency, thereby achieving an effect of expanding a use frequency of the slot antenna. 
     To sum up, in the slot antenna provided in this embodiment, a signal is fed to an open end of a slot by using a capacitor, and impedance matching can be implemented as long as a capacitor having a fixed capacitance is selected, so that a requirement on a manufacturing process is relatively low. In addition, a volume of a capacitor is relatively small, so that space occupied by the slot antenna can be reduced. Furthermore, an open radiation branch is disposed in the slot, and a capacitor is disposed on the open radiation branch, to implement dual-band resonance of the slot antenna, so that the slot antenna can have two resonance frequencies at the same time. In addition, another capacitor is disposed on a middle part of the slot, to reduce a size of the slot antenna. In addition, the two capacitors are both set to variable capacitors, to implement double resonance adjustment of the slot antenna, and improve performance and efficiency of the antenna. In addition, the slot may further be filled with a dielectric material, to achieve an effect of expanding a use frequency of the slot antenna. 
     The slot antenna shown in the foregoing embodiment further has an advantage of relatively high isolation between a high frequency and a low frequency, and it is easy to implement multiple-antenna design in a same electronic device. Specifically, the present disclosure further provides an electronic device. The electronic device may include: at least one slot antenna shown in  FIG. 1  or  FIG. 2A , and/or, at least one slot antenna shown in  FIG. 3  or  FIG. 4A . 
     Optionally, when the electronic device includes two or more slot antennas, printed circuit boards of the two or more slot antennas are a same printed circuit board. 
     Optionally, a printed circuit board of the at least one slot antenna is a housing of the electronic device or a part of a housing of the electronic device. 
     Specifically, referring to  FIG. 5A ,  FIG. 5A  is a device composition diagram of an electronic device according to the present disclosure. As shown in  FIG. 5A , an electronic device  500  includes: a first slot antenna  510  having a low working frequency and a second slot antenna  520  having a high working frequency. 
     The first slot antenna  510  and the second slot antenna  520  share one printed circuit board  530 . A slot of the first slot antenna  510  and a slot of the second slot antenna  520  are in a linear shape and are respectively disposed on two sides of the printed circuit board  530 , and there is a particular distance between the two slots. 
     The first slot antenna  510  may be implemented as the foregoing slot antenna shown in  FIG. 2A . For position and connection relationships of components included in the slot antenna, refer to  FIG. 2A , and details are not described herein again. 
     The second slot antenna  520  may be implemented as the foregoing slot antenna shown in  FIG. 4A . For position and connection relationships of components included in the slot antenna, refer to  FIG. 4A , and details are not described herein again. 
     Using that the first slot antenna  510  includes a first capacitor (a capacitance is C 1 ) and a second capacitor (a capacitance is C 2 ), the second slot antenna  520  includes only a first capacitor (a capacitance is C 3 ), C 1 =0.8 pF, C 3 =1.6 pF, and C 2  is adjustable as an example, and referring to  FIG. 5B ,  FIG. 5C ,  FIG. 5D , and  FIG. 5E ,  FIG. 5B  is a curve chart of a relationship between a working frequency and an input reflection coefficient of the first slot antenna for different C 2 , FIG.  5 C is a curve chart of a relationship between a working frequency and an output reflection coefficient of the second slot antenna for different C 2 ,  FIG. 5D  is a curve chart of a relationship between a working frequency and antenna efficiency of the first slot antenna for different C 2 , and  FIG. 5E  is a curve chart of a relationship between a working frequency and antenna efficiency of the second slot antenna for different C 2 . 
     It can be seen from  FIG. 5B  to  FIG. 5E  that resonance frequencies of the first slot antenna and the second slot antenna shown in  FIG. 5A  may be adjusted by using the second capacitor of the first slot antenna. That is, the double-feeding antenna shown in this embodiment implements a solution of independent high and low frequency adjustment, so that use of Diplexer components (diplexer) can be reduced, and a difference loss is reduced. 
     In addition, referring to  FIG. 5F ,  FIG. 5F  is a curve chart of a relationship between a working frequency and antenna efficiency of the first slot antenna, and a relationship between a working frequency and antenna efficiency of the second slot antenna for different C 2 . As can be seen from  FIG. 5F , the first slot antenna and the second slot antenna shown in  FIG. 5A  has relatively good isolation between a high frequency and a low frequency, and are applicable to an antenna solution of carrier aggregation (CA). 
     In the electronic device provided in this embodiment, a dielectric material may be filled between the first slot antenna  510  and the second slot antenna  520 . Specifically, using that C 1 =0.8 pF, C 2 =2.5 pF, and C 3 =1.6 pF as an example, referring to  FIG. 5G  and  FIG. 5H ,  FIG. 5G  is a curve chart of a relationship between an input reflection coefficient and a working frequency of the first slot antenna  510  for different dielectric coefficients of a dielectric material, and  FIG. 5H  is a curve chart of a relationship between antenna efficiency and a working frequency of the first slot antenna  510  for different dielectric coefficients of a dielectric material. It can be seen that when the slot is filled with a dielectric material and the first slot antenna works at a super low frequency (650-800 MHz), a relatively good input reflection coefficient and relatively good antenna efficiency can also be obtained. 
     A person of ordinary skill in the art may understand that all or some of the steps of the embodiments may be implemented by hardware or a program instructing related hardware. The program may be stored in a computer-readable storage medium. The storage medium may include: a read-only memory, a magnetic disk, or an optical disc. 
     The foregoing descriptions are merely example embodiments of the present disclosure, but are not intended to limit the present disclosure. Any modification, equivalent replacement, and improvement made without departing from the spirit and principle of the present disclosure shall fall within the protection scope of the present disclosure.