Abstract:
A multi-band antenna includes a grounding element having a side edge, a connecting element, and a radiating element. The radiating element is electrically connected to the grounding element via the connecting element, and includes a first radiating portion and a second radiating portion respectively extending from the connecting element. The connecting element includes a folded connecting arm extending along three dimensions. A slot is formed between the connecting arm and the grounding element.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to an antenna, specially, that the antenna is used in an electric device. 
         [0003]    2. Description of the Prior Art 
         [0004]    A planar inverted-F antenna is always used inside an electric device. For the electric device trending to be small and thin, the antenna inside the electric device should have the feature of small volume. TW Patent No. TW 12040450, issued to Cheng on May 1, 2005, discloses a planar inverted-F antenna. Referencing to  FIG. 1  of the patent, the antenna includes a grounding element, a radiating element apart from the grounding element, and a connecting element serving to connect a radiating element and a grounding element. The connecting element includes a plurality of segments. The radiating element includes a plurality of radiating arms. However, all the segments of the connecting element and the radiating arms of the radiating element are arranged on the same plane so as to the antenna is too long. 
         [0005]    Hence, in this art, an improved antenna to overcome the above-mentioned disadvantages of the prior art should be provided. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    A primary object, therefore, of the present invention is to provide a low-profile antenna with a three-dimensional connecting element. 
         [0007]    In order to implement the above object, the multi-band antenna comprises a grounding element having a side edge, a connecting element, and a radiating element. The radiating element is electrically connected to the grounding element via the connecting element, and comprises a first radiating portion and a second radiating portion respectively extending from the connecting element. The connecting element comprises a folded connecting arm extending along three dimensions. A slot is formed between the connecting arm and the grounding element. 
         [0008]    Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view illustrating an antenna assembly and a complementary connector according to a preferred embodiment of the present invention; 
           [0010]      FIG. 2  is a perspective view similar to  FIG. 1 , but viewed from another angle; 
           [0011]      FIG. 3  is an exploded, perspective view of  FIG. 2  without an feeding line; and 
           [0012]      FIG. 4  is a test chart recording for an antenna of the antenna assembly of  FIG. 1 , showing Voltage Standing Wave Ratio (VSWR) as a function of UWB frequency. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Reference will now be made in detail to a preferred embodiment of the present invention. 
         [0014]    Reference to  FIGS. 1 to 3 , an antenna assembly  1  comprises a supporting portion  10 , an antenna  20  and a feeding line  30 . 
         [0015]    The supporting portion  10  is made from insulating material and porose structure. The supporting portion  10  has eight surfaces. 
         [0016]    The antenna  20  is an inverted-F antenna and made from an integrated metal plate. The antenna  20  is attached on the five surfaces of the supporting portion  10 , and comprises a grounding element  21  attached on a lower surface thereof, a connecting element  22  extending upward from the grounding element  21 , and a radiating element  23  extending from the connecting element  22 . 
         [0017]    The grounding element  21  extends along a horizontal panel and comprises a first side edge  210  and a second side edge  212 . A metal foil (not shown) is attached on an lower surface of the grounding element  21  so as to make the performance of the antenna  20  better. In other embodiment, the metal foil should be attached on an metal plane inside the electric device. 
         [0018]    The connecting element  22  extends from the first side edge  210  of the grounding element  21  and is bent more than two times to form a three-dimensional structure. The connecting element  22  has a first end connected to the grounding element  21  and a second end apart from the grounding element  21 . The connecting element  22  comprises a first arm  220  extending from the first side edge  210  of the grounding element  21 , an inflectional second arm  222  extending from the first arm  220 . The second arm  222  extends in three dimensions and forms U-shaped configuration. The second arm  222  comprises a first segment  2220 , a second segment  2222  and a third segment  2224  defining a beginning portion  22242  connected to the second segment  2222  and an end portion  22240  opposite to the beginning portion  22242 . The connecting element  22  has a length and a width along a horizontal plane which are respectively no more than a length and a width of the grounding element  21 . A slot  24  is formed between the second arm  222  of the connecting element  22  and the grounding element  21 . The slot  24  is of U-shaped configuration for adjust the impedance of the antenna  20 . 
         [0019]    The radiating element  23  comprises a first radiating portion  230  extending upwardly from the end portion  22240  of the third segment  2224  of the connecting element  22  to form a free end  2306 , and a second radiating portion  232  extending upwardly from the beginning portion  22242  of the connecting element  22  to form a free end  2326 . In this embodiment, the two free ends of the first radiating portion  230  and the second radiating portion  232  extend along the same direction. And in other embodiment, the two ends can also respectively extend along different directions. The first radiating portion  230  is located on the same plane with the third segment  2224  and of L-shaped configuration. The second radiating portion  232  is of tridimensional L-shaped configuration and comprises a first radiating arm  2320  located on the same plane with the third sided arm  2224  of the connecting element  22 , and a second radiating arm  2322  extending from the first radiating arm  2320  along a direction perpendicular to the grounding element  21 . The first radiating arm  230  is shorter than and below the second radiating portion  232 . The first radiating arm  230  is between the second radiating portion  232  and the grounding element  21 . The grounding element  21  has substantially a length equal to the second radiating arm  2232 . In this embodiment, the first radiating portion  230  is used to receive and send higher frequency band signals, the second radiating portion works on lower frequency band. Referencing to  FIG. 4 , the antenna  20  operates at 2.3-2.7 GHz and 5.0-6.0 GHz. 
         [0020]    The feeding line  30  comprises an inner conductor  31  and an outer conductor  32 . The inner conductor  31  is connected to the end portion  22240  of the third segment  2224  of the connecting element  22  to form a feeding point  214 . The outer conductor  32  is connected to the grounding element  21  to form a grounding point  216 . In other embodiment, the feeding point  214  can be moved to other positions to match the impedance of the antenna  20  and driving point impedance. 
         [0021]    The supporting portion  10  is designed according to the antenna  20  so that the antenna  20  can be attached on the supporting portion  10 . In this embodiment, the grounding element  21  is attached on a lower surface of the supporting portion  10  and the second radiating arm  2322  of the second radiating portion  232  is attached on an upper surface of the supporting portion  10 . 
         [0022]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.