Abstract:
A multi-band antenna includes a first antenna operating at wireless wide area network and having a first radiating arm, a second antenna operating at wireless local area network and a grounding portion employed by the first antenna and the second antenna. Wherein the first radiating arm of the first antenna further includes a metallic sheet, an insulative member affixed to the metallic sheet and a metal foil affixed to the insulative member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to an antenna, and more particularly to a multi-band antenna used for electronic devices, such as notebook. 
   2. Description of Prior Art 
   With the high-speed development of the mobile communication, people more and more expect to use a computer or other portable terminals to optionally connect to Internet. GPRS (General Packer Radio Service) and WLAN (Wireless Local Area Network) allow users to access data wirelessly over both cellular networks and 802.11b WLAN system. When operating in GPRS, the data transmitting speed is up to 30 Kbps˜50 Kbps, while when connected to a WLAN access point, the data transmitting speed is up to 11 Mbps. People can select different PC cards and cooperate with the portable terminals such as the notebook computer or the like. to optionally connect to Internet. Since WLAN has a higher transmitting speed, WLAN is usually used to provide public WLAN high-speed data services in some hot areas (for example, hotel, airport, coffee bar, commerce heartland, conference heartland and etc.). When leaving from these hot areas, network connection is automatically switched to GPRS. 
   As it is known to all, an antenna plays an important role in wireless communication. As a result, the PC card may choose individual antennas to respectively operate at WWAN (Wireless Wide Area Network), namely GPRS, and WLAN. It arises a hot problem to integrate two individual antennas in a limited space to go along with the miniaturization of portal devices. Please refer to  FIG. 1 , a multi-band antenna  10 ′ comprises a first type of antenna which is used in WWAN and has first and second antennas  1 ′,  2 ′ and a second type of antenna which is used in WLAN and has third and fourth antennas  3 ′,  4 ′. The multi-band antenna  10 ′ is integrally made from a metal sheet and integrates the first type of antenna for WWAN and the second type antenna for WLAN together. However, with the two types of antennas integration, the interference therebetween will become greater, and owing to this structure, the antenna  1 ′ can not achieve enough bandwidth. Hence, it is necessary to be concerned by researchers skilled in the art how to incorporate two antennas respectively operating at WWAN and WLAN into a single antenna while keeping enough bandwidth and low interference. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a multi-band antenna which integrate the antenna for WWAN and the antenna for WLAN together with merits of mini-structure, easy manufacturing, and low cost. 
   Another object of the present invention is to provide an antenna with reduced installation space and excellent performance. 
   To achieve the aforementioned object, a multi-band antenna comprises a first antenna operating at wireless wide area network and having a first radiating arm, a second antenna operating at wireless local area network and a grounding portion employed by the first antenna and the second antenna. Wherein the first radiating arm of the first antenna further comprises a metallic sheet, an insulative member affixed to the metallic sheet and a metal foil affixed to the insulative member. 
   Additional novel features and advantages of the present invention will become apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a conventional multi-band antenna; 
       FIG. 2  is a perspective view of a multi-band antenna in accordance with a preferred embodiment of the present invention; 
       FIG. 3  is a view similar to  FIG. 2 , but taken from a different aspect; 
       FIG. 4  is a perspective view of an antenna body of the present invention; 
       FIG. 5  is a view similar to  FIG. 2 , but taken from another different aspect; and 
       FIG. 6  is a view similar to  FIG. 2 , but taken from a further different aspect. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the preferred embodiment of the present invention. 
   Referring to  FIGS. 2-6 , a multi-band antenna  1  in accordance with a preferred embodiment of the present invention consists of an antenna body  100 , an insulative member  112  affixed to the antenna body  100  and a metal foil  113 . The multi-band antenna  1  comprises a first antenna  2  used in WWAN, a second antenna  3  used in WLAN and a grounding portion  6  employed in each antenna  2 ,  3 . The grounding portion  6  comprises a first grounding portion  61  and a bending portion  62  perpendicularly extending from the first grounding portion  61 . The multi-band antenna  1  is integrally made from a metal sheet and integrates the first type of antenna for WWAN and the second type of antenna for WLAN together. 
   The first antenna  2  comprises a first radiating member  10 , a first connecting portion  20  and the grounding portion  6 . The first radiating member  10  comprises a first radiating portion  11  and a second radiating portion  12  arranged in a line with the first radiating portion  11 . The first radiating portion  11  comprises a first radiating arm  101  and a second radiating arm  102  perpendicular to the first radiating arm  101 . The second radiating portion  12  comprises a second radiating arm  102 , a third radiating arm  103  perpendicular to the second radiating arm  102  and a fourth radiating arm  104  extending downwardly and perpendicularly from the third radiating arm  103 . The first radiating arm  101  comprises a metal sheet  111 , an insulative member  112  affixed to the metal sheet  111  and a metal foil  113  affixed to the metal sheet  111  and the insulative member  112 . The metal foil  113  can be many kinds of metallic materials, and in preferred embodiment, the metal foil is AL foil. The metal sheet  111  is L-shaped and comprises a wider portion  111   a  and a narrower portion  111   b  extending vertically from the wider portion  111   a . One side surface of the insulative member  112  affixes to the surface of the metal sheet  111  facing to the first grounding portion  61 , another side surface of the insulative member  112  affixes to the second antenna  3  and one surface of the insulative member  112  facing to the first grounding portion  61  is designated as a lower wall. The insulative member  112  is substantially cuboid shaped to adapt to the L-shaped metal sheet  111 , and has a protruding rib  112 ′ engaging with the narrower portion  111   b  to make sure the distal end of the protruding rib  112 ′ and the distal end of the metal sheet  111  are coplanar. 
   The metal foil  113  is featured with inverted-U shape and comprises a top wall  113   a , a bottom wall  113   c  and a side wall  113   b  connecting with the top wall  113   a  and the bottom wall  113   c . The side wall  113   b , the top wall  113   a  and the bottom wall  113   c  all affix to the insulative member  112 , and the top wall  113   a  further electrically connects to the metal sheet  111 . The top wall  113   a  is narrower than the wall of the insulative member  112  affixed by the top wall  113   a  in order to avoid electrically contacting with the second antenna  3 . The first radiating arm  101  has a lateral wall  11   a  connecting with the second radiating arm  102 . The third radiating arm  103  and the first radiating arm  101  of the second radiating portion  12  together form a first metallic arm  7 . The fourth radiating arm  104  extends perpendicularly from the distal end of the third radiating arm  103  along the vertical direction. The third radiating arm  103  defines a lateral wall  12   b  opposite to the second radiating arm  102  and defines a triangular notch  120  to improve the impedance matching. The first radiating portion  11  of the first antenna  2  is used to receive/transmit low frequency, whereas the second radiating portion  12  of the first antenna  2  is used to receive/transmit high frequency. 
   The first connecting portion  20  comprises a first connecting arm  21  extending perpendicularly from the second radiating arm  102  and a second connecting arm  22  extending perpendicularly from the first connecting arm  21 . The second radiating arm  102  and the first connecting portion  20  are coplanar in the same plane which is perpendicular to the first metallic arm  7  and the fourth radiating arm  104 . The junction of the first connecting arm  21  and the second radiating arm  102  has a heave  30  which is perpendicular to the first connecting portion  20  and parallel to the first metallic arm  7 . The heave  30  is used to connect with a feeding line (not shown). In alternative embodiment, the heave  30  can be located in alternative places to change the radiating frequency of the radiating portion. 
   The second antenna  3  comprises a second radiating member  40 , a second connecting portion  50  and the grounding portion  6 . The second connecting portion  50  comprises a third connecting arm  51  and a fourth connecting arm  52  perpendicular to the third connecting arm  51 . The second radiating member  40  comprises a third radiating portion  43 , a fourth radiating portion  44  and a fifth radiating portion  45 . The third radiating portion  43  comprises a Z-shaped metallic arm  404  and a bending arm  406  extending perpendicularly from the metallic arm  404 . The fourth radiating portion  44  comprises a bending arm  406  and a fifth radiating arm  405 . The Z-shaped metallic arm  404  of the third radiating portion  43  comprises a first arm  431  connecting with the fifth radiating arm  405 , a second arm  432  extending perpendicularly and downwardly from the first arm  431  and a third arm  433  extending perpendicularly to the second arm  432  and parallel to the first arm  431 . The fifth radiating arm  405  and the first arm  431  together and electrically form a second elongated metallic arm  8 . The bending arm  406  extends from the junction of the fifth radiating arm  405  and the first arm  431  and perpendicular to the second elongated metallic arm  8 . The fifth radiating portion  45  is perpendicular to the bending arm  406  and extends along the direction parallel to the fifth radiating arm  405 . The fifth radiating portion  45  and the third connecting arm  51  together and electrically form a third elongated metallic arm  9 . The second elongated metallic arm  8  is parallel to and spaced from the third elongated metallic arm  9  a predetermined distance. The junction of the fifth radiating portion  45 , the bending arm  406  and the third connecting arm  51  forms a projection  70  projecting therefrom and perpendicular to the second connecting portion  50  and parallel to the first elongated metallic arm  7  to be used to connect a feeding line (not shown) of the second antenna  3 . In alternative embodiment, the location of the projection  70  can be changed for the purpose of shifting the radiating or receiving frequency. The third radiating portion  43  is used to radiate/receive the low-frequency, whereas the fourth radiating portion  44  is used to radiate/receive the high-frequency, and the fifth radiating portion  45  is used to amplify the band-volume of the fourth radiating portion  44 . 
   The grounding portion  6  is a metal plate, and comprises the first grounding portion  61 , a first mounting portion  4  and a second mounting portion  5  respectively located at two distal ends of the first grounding portion  61 . The first mounting portion  4  and the second mounting portion  5  together form a mounting plane. The first grounding portion  61  defines an L-shaped strip  63  at one side of the distal end thereof which is opposite to the first mounting portion  4 . The strip  63  comprises a main portion  631  extending perpendicularly and from the first grounding portion  61  and a parallel arm  632  parallel to the first grounding portion  61 . The two distal ends of the bending portion  62  respectively connect with the second connecting arm  22  of the first antenna  2  and the fourth connecting arm  52  of the second antenna  3 . 
   The second antenna  3 , the second radiating arm  102  and the first connecting portion  20  of the first antenna  2  and the bending portion  62  of the grounding portion  6  are in the same plane. The first elongated metallic arm  7  is parallel to the first grounding portion  61 . 
   In preferred embodiment, the insulative member  112  affixes to the metal sheet  111  of the first antenna  2 . Owing to the different dielectric constant between the metal sheet  111  and the insulative member  112 , the first radiating portion  11  of the first antenna  2  is capable of achieving the same frequency with shorter radiating length than that of first radiating portion  11  without the insulative member  112 , nevertheless accompanying with the defect of reducing the radiating energy. Then, the inverted-U shaped metal foil  113  affixed to the insulative member  112  is capable of enlarging the area of the first antenna  2 , namely enlarging the band-volume of the first antenna  2 , thus, the radiating energy of the first antenna  2  will be compensated. Therefore, the first antenna  2  is capable of being operated at the predetermined frequency, the enough band-volume and the radiating energy with small compact size. The third radiating portion  43  of the second antenna  3  is configured with Z-shape to decrease its relative length. Thus, the lengths of the first radiating portion  11  of the first antenna  2  and the third radiating portion  43  of the third antenna  3  are all decreased. In alternative embodiment, other metal foil, such as Cu foil, can replace the metal foil  113 . 
   While the foregoing description includes details which will enable those skilled in the art to practice the invention, it should be recognized that the description is illustrative in nature and that many modifications and variations thereof will be apparent to those skilled in the art having the benefit of these teachings. It is accordingly intended that the invention herein be defined solely by the claims appended hereto and that the claims be interpreted as broadly as permitted by the prior art.