Patent Publication Number: US-8531340-B2

Title: Multi-band antenna module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Application No. 099143470, filed on, Dec. 13, 2010. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a multi-band antenna module, more particularly to a multi-band antenna module to be disposed in a notebook computer. 
     2. Description of the Related Art 
     Conventional antennas for notebook computers are usually mounted in spaces provided inside frame parts of displays of the notebook computers. In order to avoid radiation interference of the conventional antennas, frame parts of the displays are usually made of an insulating material. 
     However, frame parts of some notebook computers are nowadays made of metal, and as a consequence, the conventional antennas employed in the notebook computers having metal frame portions have a relatively low efficiency. Therefore, it is desirable to have antennas suitable for notebook computers having metal frame parts. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a multi-band antenna module capable of operating at various frequency bands, and applicable to a notebook computer with a metal frame part. 
     Accordingly, a multi-band antenna module of this invention is adapted to be disposed in a housing of an electronic device. The housing has a grounding plane disposed therein and includes a metal frame part having two ends electrically connected to two opposite side edges of the grounding plane. The multi-band antenna module comprises a conductor, a substrate, a grounding section, and a first radiator section. The conductor is to be coupled across the metal frame part and the grounding plane so as to cooperate with the grounding plane and a portion of the metal frame part to form a closed loop thereamong. The substrate is to be disposed in the closed loop. The grounding section is disposed on the substrate, is to be coupled electrically to the grounding plane, and has a grounding point. The first radiator section is disposed on the substrate, is spaced apart from the grounding section, and has a feed-in end for feeding of radio frequency signals. A portion of the first radiator section is parallel to a portion of the closed loop and cooperates with the closed loop to resonate in a first frequency band. Another portion of the first radiator section is parallel to and cooperates with the grounding section to resonate in a second frequency band. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a perspective view of a notebook computer provided with a preferred embodiment of a multi-band antenna module according to the present invention; 
         FIG. 2  is a fragmentary schematic diagram of the preferred embodiment; 
         FIG. 3  is a fragmentary schematic diagram illustrating dimensions of the preferred embodiment; 
         FIG. 4  is a Voltage Standing Wave Ratio (VSWR) plot showing VSWR values of the preferred embodiment; 
         FIG. 5  illustrates radiation patterns of the preferred embodiment operating at 824 MHz; 
         FIG. 6  illustrates radiation patterns of the preferred embodiment operating at 960 MHz; 
         FIG. 7  illustrates radiation patterns of the preferred embodiment operating at 1710 MHz; and 
         FIG. 8  illustrates radiation patterns of the preferred embodiment operating at 2170 MHz. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 and 2 , a preferred embodiment of a multi-band antenna module of the present invention is adapted to be disposed in a housing  12  of an electronic device  1 . The electronic device  1  is a notebook computer and includes a display  11  having the housing  12 . The housing  12  has a grounding plane  13  disposed therein and includes an inverted U-shaped metal frame part  121  having two ends electrically connected to two opposite side edges of the grounding plane  13 . In this embodiment, the grounding plane  13  is an aluminum foil. The multi-band antenna module comprises a conductor  21 , a substrate  3 , a grounding section  4 , a first radiator section  5 , a second radiator section  6 , and a coaxial transmission cable  7 . 
     The conductor  21  is to be coupled across the metal frame part  121  and the grounding plane  13 . In this embodiment, the grounding plane  13  has a rectangular main portion  131  and a protruding portion  132  extending from an upper end of the main portion  131 . The conductor  21  is coupled across the metal frame part  121  and the protruding portion  132 . Further, the metal frame part  121  has an L-shaped first segment  122  extending from a junction between the metal frame part  121  and the conductor  21  in a first direction and an L-shaped second segment  123  extending from the j unction between the metal frame part  121  and the conductor  21  in a second direction different from the first direction. The conductor  21  cooperates with the main portion  131  and the protruding portion  132  of the grounding plane  13 , and the first segment  122  of the metal frame part  121  to form a closed loop  20  thereamong. 
     The substrate  3  is to be disposed in the closed loop  20 . The grounding section  4  is disposed on the substrate  3 , is to be coupled electrically to the grounding plane  13 , and has a grounding point  41 . In this embodiment, the grounding section  4  extends along a straight line, is disposed at a lower end of the substrate  3 , and is coupled electrically to the grounding plane  13  via a conductor  22 . 
     The first radiator section  5  is disposed on the substrate  3 , is spaced apart from the grounding section  4 , and has a feed-in end  50  for feeding of radio frequency signals. A portion of the first radiator section  5  is parallel to a portion of the closed loop  20  and is mutually coupled to the closed loop  20  so as to cooperate with the closed loop  20  to resonate in a first frequency band, and another portion of the first radiator section  5  is parallel to and is mutually coupled to the grounding section  4  so as to cooperate the grounding section  4  to resonate in a second frequency band. 
     In this embodiment, the first radiator section  5  includes a first radiator portion  51  extending from the feed-in end  50  in the second direction, i.e., a right-to-left direction in the drawings, and a second radiator portion  52  extending from the feed-in end  50  in the first direction, i.e., a left-to-right direction in the drawings. 
     The first radiator portion  51  of the first radiator section  5  is disposed such that the portion of the closed loop  20  is parallel to, is adjacent to, and is mutually coupled to the first radiator portion  51  to resonate in the first frequency band. The second radiator portion  52  of the first radiator section  5  is disposed such that the grounding section  4  is parallel to, is adjacent to, and is mutually coupled to the second radiator portion  52  to resonate in the second frequency band. In this embodiment, the second radiator portion  52  has a length shorter than that of the first radiator portion  51 . 
     More specifically, the first radiator portion  51  of the first radiator section  5  is disposed parallel to and to form a first clearance (G 1 ) with the first segment  122 , such that the first radiator portion  51  cooperates with the first segment  122  to resonate in the first frequency band. The second radiator portion  52  of the first radiator section  5  is disposed to form a second clearance (G 2 ) with the grounding section  4 , such that the second radiator portion  52  cooperates with the grounding section  4  to resonate in the second frequency band. 
     The second radiator section  6  is substantially parallel to the first radiator portion  51  and is to be electrically coupled to the grounding plane  13 . In this embodiment, the second radiator section  6  extends along a straight line in the first direction, and is coupled electrically to the protruding portion  132  of the grounding plane  13  via a conductor  23 . The second radiator section  6  is disposed to form a third clearance (G 3 ) with the first radiator portion  51  of the first radiator section  5  and is mutually coupled to the first radiator portion  51  so as to cooperate with the first radiator portion  51  to resonate in a third frequency band. 
     The coaxial transmission cable  7  has a first signal line  71  electrically connected to the feed-in end  50  and a second signal line  72  electrically connected to the grounding point  41 . In this embodiment, the first signal line  71  is a positive signal line, and the second signal line  72  is a negative signal line. 
     It should be noted that the conductors  21 ,  22 ,  23  are conductive cooper foils in this embodiment. 
     Further referring to  FIG. 3 , the detailed dimensions (in mm) of the multi-band antenna module of the preferred embodiment are shown. The housing  12  of the electronic device  1  has a dimension of length L=275 mm, and a dimension from a top edge of the metal frame part  121  to a bottom edge of the grounding plane  13  is width W=195 mm. The multi-band antenna module has dimensions of the first clearance (G 1 )=3.2 mm, the second clearance (G 2 )=1 mm, the third clearance (G 3 )=5 mm, and a thickness of the substrate  3  is equal to 0.6 mm (not shown). 
     With the dimensions shown in  FIG. 3 , the first frequency band ranges from 824 MHz˜960 MHz, the second frequency band ranges from 1710 MHz˜1880 MHz, and the third frequency band ranges from 1850 MHz˜2170 MHz. Accordingly, the preferred embodiment can operate in frequency bands GSM850, GSM 900, DCS1800, PCS1900, and UMTS within the Wireless Wide Area Network (WWAN) communication protocol. 
       FIG. 4  shows VSWR values of the multi-band antenna module of this embodiment applied to the notebook computer  1 . It is apparent from this figure that the measured VSWR values of the multi-band antenna module at frequencies within the first, second, and third frequency bands do not exceed 3. 
     According to Table 1 below, the overall radiation efficiency of the multi-band antenna module of this embodiment applied to the notebook computer  1  at frequencies within the first, second, and third frequency bands is &gt;−5.2dB (&gt;30.1%). 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Frequency 
                 Efficiency 
                 Efficiency 
               
               
                 (MHz) 
                 (dB) 
                 (%) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 824 
                 −3.5 
                 44.2 
               
               
                 836.6 
                 −3.2 
                 47.7 
               
               
                 849 
                 −2.8 
                 52.0 
               
               
                 869 
                 −2.5 
                 56.7 
               
               
                 881.6 
                 −2.4 
                 57.5 
               
               
                 880 
                 −2.4 
                 56.9 
               
               
                 894 
                 −2.5 
                 56.3 
               
               
                 897.4 
                 −2.5 
                 55.9 
               
               
                 915 
                 −2.8 
                 53.1 
               
               
                 925 
                 −2.8 
                 52.7 
               
               
                 942.4 
                 −2.7 
                 53.6 
               
               
                 960 
                 −2.8 
                 53.1 
               
               
                 1710 
                 −2.0 
                 62.7 
               
               
                 1747.8 
                 −1.5 
                 70.9 
               
               
                 1785 
                 −1.8 
                 65.6 
               
               
                 1805 
                 −2.0 
                 62.8 
               
               
                 1842.8 
                 −2.1 
                 62.1 
               
               
                 1850 
                 −2.0 
                 63.0 
               
               
                 1880 
                 −1.7 
                 67.0 
               
               
                 1910 
                 −1.5 
                 70.8 
               
               
                 1920 
                 −1.5 
                 70.1 
               
               
                 1930 
                 −1.5 
                 70.0 
               
               
                 1950 
                 −1.7 
                 67.8 
               
               
                 1960 
                 −1.8 
                 65.8 
               
               
                 1980 
                 −2.1 
                 61.1 
               
               
                 1990 
                 −2.3 
                 59.1 
               
               
                 2110 
                 −4.3 
                 36.7 
               
               
                 2140 
                 −4.8 
                 33.2 
               
               
                 2170 
                 −5.2 
                 30.1 
               
               
                   
               
            
           
         
       
     
       FIGS. 5 to 8  illustrate radiation patterns of the multi-band antenna module of this embodiment. It is evident from these figures that the radiation patterns of the multi-band antenna module have relatively good omni-directionality. 
     To sum up, the conductor  21  forms the closed loop  20  with the grounding plane  13  and the metal frame part  121 , and the closed loop  20  is coupled to and cooperates with the first radiator portion  51  of the first radiator section  5  to resonate in the first frequency band. Consequently, the metal frame portion  121  can serve as a component for transmitting and receiving signals. Additionally, the second radiator portion  52  of the first radiator section  5  is coupled to the grounding section  4  to resonate in the second frequency band, and the first radiator portion  51  of the first radiator section  5  is coupled to the second radiator section  6  for resonation and for transmitting and receiving signals in the third frequency band. Therefore, the multi-band antenna module of this invention can operate in multiple frequency bands within the WWAN communication protocol. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.