Abstract:
An antenna switching system includes a first antenna, a second antenna, a first sensing unit, a second sensing unit, a controlling unit, and a switching unit. The first sensing unit detects a distance between an object and the first antenna. The second sensing unit detects a distance between the object and the second antenna. The controlling unit is electronically connected to the first sensing unit and the second sensing unit. The switching unit is electronically connected to the controlling unit, the first antenna, and the second antenna. The controlling unit is configured to activate and deactivate the first antenna and the second antenna via the switching unit based on detections of the first sensing unit and the second sensing unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 201310749264.2 filed on Dec. 31, 2013, the contents of which are incorporated by reference herein. 
     FIELD 
     The disclosure generally relates to an antenna switching system and a wireless communication device using the antenna switching system. 
     BACKGROUND 
     Antennas are important elements of wireless communication devices, such as mobile phones, or personal digital assistants. Generally, a position of the antenna in the wireless communication device is fixed. Thus, a radiating efficiency of the antenna will be affected when the wireless communication device is hold by a user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is an isometric view of an embodiment of a wireless communication device employing an antenna switching system. 
         FIG. 2  is a block diagram of the antenna switching system of  FIG. 1 . 
         FIG. 3  is an isometric view of the wireless communication device, when the wireless communication device is at a first holding mode. 
         FIG. 4  is similar to  FIG. 3 , but showing the wireless communication device is at a second holding mode. 
         FIG. 5  is similar to  FIG. 3 , but showing the wireless communication device is at a third holding mode. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     The term “comprising” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. 
       FIG. 1  illustrates an embodiment of a wireless communication device  200 . The wireless communication device  200  may be a mobile phone or a personal digital assistant, for example. The wireless communication device  200  includes a base board  210 , a first metal member  221 , a second metal member  222 , and an antenna switching system  100 . 
     In this embodiment, the base board  210  is a circuit board of the wireless communication device  200 . The base board  210  is substantially rectangular and includes a keep-out-zone  211 . In this embodiment, the keep-out-zone  211  is formed in a side of the base board  210 . The purpose of the keep-out-zone  211  is to prevent other electronic elements (such as a battery, a vibrator, a speaker, a Charge Coupled Device, etc.) from being placed in a predetermined area where it may interfere with antennas positioned in the wireless communication device  200 . The first metal member  221  and the second metal member  222  can both be a portion of a metal housing of the wireless communication device  200 . In this embodiment, the first metal member  221  is positioned at a first side of the base board  210 . The second metal member  222  is positioned at a second side of the base board  210  opposite to the first metal member  221 . 
     The antenna switching system  100  includes a first antenna  10 , a second antenna  20 , a first sensing unit  30 , and a second sensing unit  40 . The first antenna  10  is positioned in the keep-out-zone  211  adjacent to the first metal member  221 . In this embodiment, the first antenna  10  is a broadband antenna and can work at both a low-frequency band and a high-frequency band. In this embodiment, the low-frequency band has a frequency band of about 704-746 MHz (LTE Band 17) with a radiating efficiency of about 49-64%. The high-frequency band has a frequency band of about 1710-2170 MHz and 2500-2690 MHz (LTE Band 7) with a radiating efficiency of about 53-79%. 
     The second antenna  20  is positioned in the keep-out-zone  211  adjacent to the second metal member  222 . The second antenna  20  is a high-frequency antenna and can work at the high-frequency band of the first antenna  10 . That is, the second antenna  20  can work at the frequency band of about 1710-2170 MHz and 2500-2690 MHz (LTE Band 7) with a radiating efficiency of about 60-92%. 
     The first sensing unit  30  is positioned in the keep-out-zone  211  adjacent to the first antenna  10 . In this embodiment, the first sensing unit  30  is positioned between the first metal member  221  and the first antenna  10 . The first sensing unit  30  may be a proximity sensor. The first sensing unit  30  is configured to detect whether a distance between an object (for example, a palm of a user) and the first antenna  10  is in a predetermined range and output a corresponding sensing signal according to the detection. Generally, the first sensing unit  30  has a maximum sensing distance that the first sensing unit  30  can sense, for example, 3 mm. In this embodiment, the maximum sensing distance is equal to a distance between the palm of the user and the first antenna  10  when the user holds the right side of the wireless communication device  200 , and the predetermined range is from about 0 mm to the maximum sensing distance of the first sensing unit  30 . Thus, when a distance between the object and the first antenna  10  is in the predetermined range, the first sensing unit  30  outputs a first sensing signal (for example, a high level signal, logic 1). When the distance between the object and the first antenna  10  is out of the predetermined range, for example, the distance between the object and the first antenna  10  is about 4 mm, the first sensing unit  30  outputs a second sensing signal different from the first sensing signal (for example, a low level signal, logic 0). 
     The second sensing unit  40  is positioned in the keep-out-zone  211  adjacent to the second antenna  20 . In this embodiment, the second sensing unit  40  is positioned between the second metal member  222  and the second antenna  20 . The second sensing unit  40  may be a proximity sensor. The second sensing unit  40  is configured to detect whether a distance between the object and the second antenna  20  is in a predetermined range and output a corresponding sensing signal according to the detection. Generally, the second sensing unit  40  has a maximum sensing distance that the second sensing unit  40  can sense, for example, 3 mm. In this embodiment, the maximum sensing distance is equal to a distance between the palm of the user and the second antenna  20  when the user holds the left side of the wireless communication device  200 , and the predetermined range is from about 0 mm to the maximum sensing distance of the second sensing unit  40 . Thus, when a distance between the object and the second antenna  20  is in the predetermined range, the second sensing unit  40  outputs the first sensing signal. When the distance between the object and the second antenna  20  is out of the predetermined range, for example, the distance between the object and the second antenna  20  is about 4 mm, the second sensing unit  40  outputs the second sensing signal. 
       FIG. 2  shows the antenna switching system  100  further includes a controlling unit  50  and a switching unit  60 . The controlling unit  50  may be a central processing unit (CPU) of the wireless communication device  200  and is electronically connected to the first sensing unit  30  and the second sensing unit  40 . 
     The controlling unit  50  is configured to receive the sensing signals from the first sensing unit  30  and the second sensing unit  40  and determine a holding mode of the wireless communication device  200  according to the sensing signals. For example, when the controlling unit  50  receives the first sensing signal from the first sensing unit  30  and the second sensing signal from the second sensing unit  40 , the controlling unit  50  determines that the wireless communication device  200  is at a first holding mode which represents that the user holds the right side of the wireless communication device  200 . When the controlling unit  50  receives the second sensing signal from the first sensing unit  30  and the first sensing signal from the second sensing unit  40 , the controlling unit  50  determines that the wireless communication device  200  is at a second holding mode which represents that the user holds the left side of the wireless communication device  200 . When the controlling unit  50  receives the first sensing signals both from the first sensing unit  30  and the second sensing unit  40 , the controlling unit  50  determines that the wireless communication device  200  is at a third holding mode which represents that the user holds both the left side and the right side of the wireless communication device  200 . When the controlling unit  50  receives the second sensing signals both from the first sensing unit  30  and the second sensing unit  40 , the controlling unit  50  determines that the wireless communication device  200  is not hold by the user. 
     The switching unit  60  is electronically connected to the controlling unit  50 , the first antenna  10 , and the second antenna  20 . The controlling unit  50  switches working status of the first antenna  10  and the second antenna  20  through the switching unit  60 . For example, when the controlling unit  50  determines that the wireless communication device  200  is at the first holding mode (that is, the user holds the right side of the wireless communication device  200 ), the controlling unit  50  switches the switching unit  60  to a first mode that the second antenna  20  is selected and the first antenna  10  is selected to work at the low-frequency band. Then, the wireless communication device  200  receives and sends wireless signals through the first antenna  10  and the second antenna  20 . That is, the first antenna  10  works as a low-frequency antenna and the second antenna  20  works as a high-frequency antenna. 
     When the controlling unit  50  determines that the wireless communication device  200  is at the second holding mode (that is, the user holds the left side of the wireless communication device  200 ), the controlling unit  50  switches the switching unit  60  to a second mode that the first antenna  10  is selected and the second antenna  20  is turned off. Then, the wireless communication device  200  receives and sends wireless signals through the first antenna  10 . That is, the first antenna  10  works as both a low-frequency antenna and a high-frequency antenna. 
     When the controlling unit  50  determines that the wireless communication device  200  is at the third holding mode (that is, the user holds both the left side and the right side of the wireless communication device  200 ), the controlling unit  50  switches the switching unit  60  to a third mode that both the first antenna  10  and the second antenna  20  are selected. Then, the wireless communication device  200  receives and sends wireless signals through the first antenna  10  and the second antenna  20 . That is, the first antenna  10  works as a low-frequency antenna and a high-frequency antenna, and the second antenna  20  works as a high-frequency antenna to help the first antenna  10  to receive and send wireless signals in a high-frequency band. 
     In addition, when the controlling unit  50  determines that the wireless communication device  200  is not hold by the user, the controlling unit  50  switches the switching unit  60  to the second mode, that is, the first antenna  10  is selected and the second antenna  20  is turned off. The first antenna  10  can work at both the low-frequency band and the high-frequency band with a better radiating efficiency, which satisfies radiation requirements. 
       FIG. 3  shows the wireless communication device  200  is at the first holding mode, that is, the right side of the wireless communication device  200  is hold by the user. Then, the controlling unit  50  receives the first sensing signal from the first sensing unit  30  and the second sensing signal from the second sensing unit  40 , and determines that the wireless communication device  200  is at the first holding mode. The controlling unit  50  switches the switching unit  60  to the first mode that the second antenna  20  is selected and the first antenna  10  is selected to work at the low-frequency band. Thus, the wireless communication device  200  receives and sends wireless signals through the first antenna  10  and the second antenna  20 . 
       FIG. 4  shows the wireless communication device  200  is at the second holding mode, that is, the left side of the wireless communication device  200  is hold by the user. Then, the controlling unit  50  receives the second sensing signal from the first sensing unit  30  and the first sensing signal from the second sensing unit  40 , and determines that the wireless communication device  200  is at the second holding mode. The controlling unit  50  switches the switching unit  60  to the second mode that the first antenna  10  is selected and the second antenna  20  is turned off. Thus, the wireless communication device  200  receives and sends wireless signals through the first antenna  10 . 
       FIG. 5  shows the wireless communication device  200  is at the third holding mode, that is, both the left side and the right side of the wireless communication device  200  are hold by the user. Then, the controlling unit  50  receives the first sensing signals both from the first sensing unit  30  and the second sensing unit  40 , and determines that the wireless communication device  200  is at the third holding mode. The controlling unit  50  switches the switching unit  60  to the third mode that both the first antenna  10  and the second antenna  20  are selected. Thus, the wireless communication device  200  receives and sends wireless signals through the first antenna  10  and the second antenna  20 . 
     The embodiments shown and described above are only examples. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size and arrangement of the parts within the principles of the present disclosure up to, and including, the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.