Abstract:
A multi-band antenna includes a radiating element, a connecting element and a grounding element; the radiating element is made from a metal plate, and includes a first radiating portion and a second radiating portion having an end connect to one end of the first radiating portion. The first radiating portion, the second radiating portion and the connecting element is on the same planar, and the first radiating portion and the second radiating portion surround a rectangle rim.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to a multi-band antenna, and more particularly to a multi-band antenna used for electronic devices, such as notebook.  
         [0003]     2. Description of the Prior Art  
         [0004]     As communication technology is increasingly improved, the weight, volume, cost, performance, and complexity of a communication system also become more important, so antennas that transmit and receive signals in a wireless communication system especially draw designers attention. At present the wireless local area network (WLAN) and General Packer Radio Service (GPRS), because the space for setting up an antenna is limited and the antenna should transmit a large amount of data, the antenna should be carefully designed.  
         [0005]     Planar Inverted-F Antenna (PIFA) is a kind of small size antennas used for mobile communication terminal. The antenna has light weight, good impedance, compact size, reduced manufacture cost and perform a double-band or a multi-band antenna easily. CN pat. No. 2593384 discloses a Planar Inverted-F Antenna, it comprises two radiating elements each of which respectively extends along different directions, a grounding element, and a connecting element connecting the radiating elements and the grounding element. This antenna can performs multi-band frequency, but the whole length of the connecting element is so long that this antenna takes up big space in the notebooks or the carry-home electric devices. So, this kind antenna is not propitious to the smaller-device trend.  
         [0006]     Hence, an improved antenna is desired to overcome the above-mentioned shortcomings of the existing antennas.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     A primary object, therefore, of the present invention is to provide a multi-band antenna having low profile with simple structure, and reduced size.  
         [0008]     In order to implement the above object and overcomes the above-identified deficiencies in the prior art, the multi-band antenna comprises a radiating element, a connecting element and a grounding element; the radiating element is made from metal plate, and comprises a first radiating portion and a second radiating portion having an end connect to one end of the first radiating portion. The first radiating portion, the second radiating portion and the connecting element is on the same planar, and the first radiating portion and the second radiating portion surround a rectangle rim. 
     
    
       [0009]     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  
       [0010]      FIG. 1  is a perspective view of a multi-band antenna according to a preferred embodiment of the present invention; and  
         [0011]      FIG. 2  is a perspective view of a multi-band antenna according to another preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]     Reference will now be made in detail to a preferred embodiment  
         [0013]     Reference to  FIG. 1  in one embodiment of the present invention, the multi-band antenna  10  comprises a radiating element  11 , a grounding element  13 , a connecting element  12  connecting the radiating element  11  and the grounding element  13 , a feeding point  4 , a feeding line  5  and two setting elements  15 .  
         [0014]     The radiating element  11  comprises a first radiating portion  16  and a second radiating portion  17 . The first radiating portion  16  is a high-frequency radiating portion which is worked at 5 GHz, and the second portion  17  is low-frequency radiating portion which is worked at 2.4 GHz. The radiating portion  17  comprises a horizontal first radiating arm  171 , a second radiating arm  172  extending from left end of the first radiating arm  171  and perpendicular to the first radiating arm  171 , and a horizontal third radiating arm  173  extending from the second radiating arm  172  in the neighborhood of the first radiating arm  171  and perpendicular to the second radiating arm  172 , and a fourth radiating arm  174  extending downwardly from the right end of the third radiating arm  173  in the neighborhood of the first radiating arm  171  and perpendicular to the third radiating arm  173 . The first radiating portion  16  extends from the right end of the first radiating arm  171  of the second radiating portion  17  opposite to the left end of the first radiating arm  171  connecting the second radiating arm  172 . The first radiating portion  16  and the second radiating portion  17  form a rectangle frame with formed between the first radiating portion  16  and the fourth radiating arm  174 , so that the total length of the multi-band antenna  10  is reduced. The radiating element  11  and the connecting element  12  are in the same plane, and the first radiating portion  16  and the fourth radiating arm  174  of the radiating element  11  are located at the same of the connecting element  12 , so that the total height of the multi-band antenna  10  could be reduced.  
         [0015]     The grounding element  13  comprises a first grounding portion  131  and a second grounding portion  132  perpendicular to the first grounding portion  131 . The first grounding portion  131  is perpendicular to the second grounding portion  132 .  
         [0016]     The connecting element  12  is Z shape, and the radiating element  11  and the first grounding portion  131  are all in the same plane. The connecting portion  12  comprises a first section  121 , a third section  123  connecting the joint of the second radiating arm  171  of the second radiating portion  17  and the third radiating arm  173 , and a vertical second portion  122  connecting the first portion  121  and the third portion  123 .  
         [0017]     The feeding point  4  is located at the joint of the first radiating portion  16  and the second radiating portion  17 . The feeding line  5  comprises an inner conductor  51  soldered on the feeding point  4 , an inner isolator  52  covering the inner conductor  51 , an outer conductor layer  53  soldered on the second grounding portion  132  and an outer isolator  54  encircling the outer conductor  53 . The two setting elements  15  respectively extend from opposite ends of the grounding element  13  and each of them respectively has a circular aperture to assemble the multi-band antenna  10  to the electric device. The radiating element  11  and the pair of the setting elements are in the same plane which is perpendicular to the plane on which the second grounding portion is located. And the height of the radiating element is lower than the height of the setting element.  
         [0018]     Reference to  FIG. 2  in another embodiment of the present invention, the multi-band antenna  10 ′ comprises a radiating element  11 ′, a grounding element  13  ′, a connecting element  12 ′ connecting the radiating element  11 ′ and the grounding element  13 ′, a feeding point  4 ′, a feeding line  5 ′, and two setting elements  15 ′. In this embodiment, the feeding point  4 ′, and the feeding line  5 ′ are the same as the structures of the first embodiment.  
         [0019]     The radiating element  11 ′ comprises a first radiating portion  16 ′ and a second radiating portion  17 ′. The second radiating portion  16 ′ comprises a horizontal first radiating arm  171 ′, a second radiating arm  172 ′ extending from left end of the first radiating arm  171 ′ in the vertical direction, a third horizontal radiating arm  173  ′ extending from one end of the second radiating arm  172 ′ in the neighborhood of the first radiating arm  171 ′ in the perpendicular direction to the second radiating arm  172 ′, and a fourth radiating arm  174 ′ extending from the third radiating arm  173 ′ in the neighborhood of right end of the first radiating arm  171 ′ and in the vertical direction to the third radiating arm  173 ′. The grounding element  13 ′ comprises a first grounding section  131 ′ and a second grounding section  132 ′. A protrude  141 ′ extends from the second grounding section  132  located between the two setting elements  15 ′ and one end of the connecting element  12 ′ to fasten the feed line. The connecting element  12 ′ extends from one end of the second radiating arm  172 ′ and aligned with the second radiating arm  172 ′ in the vertical direction. The length of the connecting element  12 ′ in the vertical direction is the same as the length of the least distance between the radiating element  11 ′ and the grounding element  13 ′. The connecting element  12 ′and the radiating element  11 ′ are in the same plane and connect with the grounding element  13 ′ in another end thereof.  
         [0020]     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.