Patent Publication Number: US-8120535-B2

Title: Multi-band antenna with improved connecting portion

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a multi-band antenna, and more particularly to a multi-band antenna with single feeding point and multi radiating portions. 
     2. Description of the Prior Art 
     A present electric device always needs multi antennas for wireless communication. And in most designs, theses antennas are assembled in the inner space of the electric device. Thus, antennas used on different frequency bands are integrated together to reduce their volume. 
     U.S. Patent application Publication No. 2007/0040754 discloses an antenna structure integrating a first antenna of wireless wide area network (WWAN) and a second antenna of wireless local area network (WLAN), the same as U.S. Pat. No. 7,289,071, U.S. patent application Publication Nos. 2007/0060222, 2007/0096999, and so on. The two antennas respectively work as a single antenna but not influence to each other. However, some wireless communication criterions have common frequency band. For example, the center frequency under WLAN includes 2.4 GHz and 5 GHz and the frequency band under Worldwide Interoperability for Microwave Access (WiMax) includes 2.3-2.4 GHz, 2.5-2.7 GHz and 3.3-3.8 GHz, which overlaps the frequency bands under WLAN. Accordingly, an antenna integrated with a single WLAN antenna and a single WiMax antenna is not benefit for saving the inner space of the electric device. 
     Hence, in this art, a multi-band antenna to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment. 
     BRIEF SUMMARY OF THE INVENTION 
     A primary object, therefore, of the present invention is to provide a multi-band antenna adapt to at least two types of network criterions. 
     In order to implement the above object and overcomes the above-identified deficiencies in the prior art, the multi-band antenna comprises a grounding element located on a first plane, a connecting element extending from the grounding element to form a slot between the connecting element and the grounding element, a conductive portion extending from the connecting element, a first radiating portion, a second radiating portion, and a third radiating portion. The first radiating portion is narrower than the conductive portion and extends from an end of the conductive portion along a first direction. The second radiating portion is connected to the first radiating portion and extends along a second direction opposite to the first direction. The third radiating portion is narrower than the first radiating portion and extends from an end of the connecting element. 
     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 
         FIG. 1  is a perspective view illustrating a preferred embodiment of a multi-band antenna in according with the present invention; 
         FIG. 2  is a perspective view of  FIG. 1 , but viewed from a different angle; 
         FIG. 3  is a test chart recording for the multi-band antenna of  FIG. 1 , showing Voltage Standing Wave Ratio (VSWR). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to a preferred embodiment of the present invention. 
     Reference to  FIG. 1 and 2 , a multi-band antenna  1  in accordance with a preferable embodiment of the present invention is shown. The multi-band antenna  1  is assembled in a notebook (not shown) and comprises a grounding element  300 , a connecting element  200  extending from the grounding element  300 , a conductive portion  140  upward and perpendicularly extending from the connecting element  200 , a first radiating portion  110 , a second radiating portion  120  and a third radiating portion  130 . The first radiating portion  110  and the second radiating portion  120  respectively extend from the conductive portion  140 . The third radiating portion  130  extends from the connecting element  200 . 
     The grounding element  300  is located on a first plane. A first setting portion  400  and a second setting portion  500  respectively extends from the two ends of grounding element  300  to fix the multi-band antenna  1  in the notebook. The multi-band antenna  1  can be assembled on any side of display of the notebook. The grounding element  300  comprises a rectilineal first side  301 , a Z-shape second side  302  and a side arm  303  extending from the second side  302  to further fix the multi-band antenna  1 . 
     The connecting element  200  extends from the joint of the second side  302  and the side arm  303  to form a slot  600  between the connecting element  200  and the grounding element  300 . The connecting element  200  is also located on the first plane and comprises a first section  204  extending from the grounding element  300  to form an angle and a second section  202  extending from the first section  204  and parallel to the first side  301  to form a beginning portion and an end. 
     The conductive portion  140  is of rectangular configuration and upwardly and perpendicularly extends from the beginning portion of the second section  202  of the connecting element  200  to be located on a second plane. 
     The first radiating portion  110  is of rectangular configuration and located on the second plane. The first radiating portion  110  perpendicularly extends from a first side of the conductive portion  140  along a first direction. The second radiating portion  120  comprises a trapeziform first piece  122  extending from the upper surface of the first radiating portion and a second rectangular second piece  124  extending from the first piece  122  along a second direction opposite to the first direction. The second radiating element  120  is located on a third plane which is parallel to the first plane and perpendicular to the second plane. The third radiating portion  130 , which is on the free end of the second section  202 , is of plane L shape on the second plane. The third radiating portion  130  comprises a first radiating arm  132  upward perpendicularly extends from the first side of the second section  202  and a second radiating arm  134  perpendicularly extending from the first radiating arm  132  along the second direction. The third radiating portion  130  is lower than the second radiating portion  120 . 
     A feeding point F is formed on the free end of the radiating portion  130  to be connected to an inner conductor of a feeding line (not shown). A grounding point G is formed on the grounding element  300  to be connected to an outer conductor of the feeding line (not shown). 
     The conductive portion  140  is wider than the first radiating portion  110 . The third radiating portion  130  is narrower than both the first radiating portion  110  and the second radiating portion  120 . Because of the wide conductive portion  140 , the working band width both of the first radiating portion  110  and the second radiating portion  120  achieve 400 MHz.  FIG. 3  shows the VSWR view of the multi-band antenna  1 . The first radiating portion  110  is used to receive and send signals on a higher frequency band of 4.9-5.8 GHz, the second radiating portion  120  works at a lower frequency band of 2.3-2.7 GHz, and the third radiating portion resonates on a frequency band of 3.3-3.8 GHz. Thus, the multi-band antenna  1  is obviously adapted to the requests of WLAN and WiMax. 
     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.