Patent Publication Number: US-7907099-B2

Title: Antenna

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application is the continuation of U.S. patent application Ser. No. 12/172,879 filed on Jul. 14, 2008, which claims priority of Taiwan Patent Application No. 97202097, filed on Jan. 31, 2008, the entirety of which are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an antenna, and more particularly to an antenna with increased bandwidth. 
     2. Description of the Related Art 
     U.S. Pat. Nos. 6,812,892, 7,161,543 and 6,891,504 disclose three conventional antennas, wherein the conventional antennas have narrow bandwidths, and cannot satisfy present transmission requirements. For example,  FIG. 1   a  shows a conventional antenna  1  disclosed in U.S. Pat. No. 6,812,892, which has a ground element  10 , a conductive element  20  and a radiator  30 . The conductive element  20  is connected to the ground element  10 . The radiator  30  is connected to the conductive element  20 . A coaxial cable  40  is electrically connected to the ground element  10  and the conductive element  20 . The radiator  30  has a first section  31  and a second section  32 . The first section  31  transmits a high frequency signal, and the second section  32  transmits a low frequency signal. 
       FIG. 1   b  shows signal transmission of the conventional antenna  1 , wherein the bandwidth of the antenna  1  (bandwidth is defined as signals having voltage standing wave ratio less than 2) is between about 2.39 GHz to 2.53 GHz and between 4.84 GHz to 5.80 GHz. The conventional antennas have narrow bandwidth, and cannot satisfy present transmission requirements. 
     BRIEF SUMMARY OF THE INVENTION 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     An antenna is provided. The antenna has a ground element, a radiator and a conductive element. The radiator has a body, wherein the body has a first edge, a second edge, a third edge and a fourth edge, the first edge is parallel to the third edge, a length of the first edge is shorter than a length of the third edge, the first edge is close to the ground element, the second edge connects the first edge and the third edge, a fourth edge connects the first edge and the third edge, and a first slot is formed on the radiator. The second edge and the fourth edge extend separately from the first edge to the third edge. The conductive element connects the ground element and the radiator. 
     The antennas of the embodiments of the invention provide wider bandwidth and improved transmission with decreased antenna dimension. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1   a  shows a conventional antenna disclosed in U.S. Pat. No. 6,812,892; 
         FIG. 1   b  shows signal transmission of the conventional antenna in  FIG. 1   a;    
         FIG. 2   a  is a perspective view of an antenna of a first embodiment of the invention; 
         FIG. 2   b  is a front view of the antenna of the first embodiment of the invention; 
         FIG. 3  shows signal transmission of the antenna of the first embodiment of the invention; 
         FIG. 4   a  shows signal transmission path of a first wireless signal (2.55 GHz); 
         FIG. 4   b  shows signal transmission path of a second wireless signal (4 GHz); 
         FIG. 4   c  shows signal transmission path of a third wireless signal (5.05 GHz); 
         FIG. 4   d  shows signal transmission path of a first wireless signal (6.75 GHz); 
         FIG. 5  shows an antenna of a second embodiment of the invention; 
         FIG. 6  shows an antenna of a third embodiment of the invention; 
         FIG. 7   a  shows an antenna of a fourth embodiment of the invention; 
         FIG. 7   b  shows an antenna of a modified example of the fourth embodiment of the invention; and 
         FIG. 8  shows an antenna of a fifth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIG. 2   a  is a perspective view of an antenna  100  of a first embodiment of the invention, and  FIG. 2   b  is a front view of the antenna  100  of the first embodiment of the invention. With reference to  FIGS. 2   a  and  2   b,  the antenna  100  has a ground element  110 , a conductive element  120  and a radiator  160 . The conductive element  120  is connected to the ground element  110  and the radiator  160 . The radiator  160  has a body  130 , a first slot  141 , a second slot  142  and an extending portion  150 . The body  130  has a first edge  131 , a second edge  132 , a third edge  133  and a fourth edge  134 . The first edge  131  is parallel to the third edge  133 . The length of the first edge  131  is shorter than the length of the third edge  133 . The first edge  131  is close to the ground element  110 . The second edge  132  connects the first edge  131  and the third edge  133 . The fourth edge  134  connects the first edge  131  and the third edge  133 . The second edge  132  and the fourth edge  134  extend separately from the first edge  131  to the third edge  133 . 
     The first slot  141  is formed on the second edge  132 . The first slot  141  extends parallel to the first edge  131 . The antenna  100  further has a first datum line  101 . The first datum line  101  extends from the second edge  132  to the fourth edge  134 . The first datum line  101  is parallel to the first edge  131 . The first slot  141  extends along the first datum line  101 . The length of the first slot  141  is not longer than half the length d 2  of the first datum line  101 . 
     The second slot  142  is formed on the fourth edge  134 . The second slot  142  extends parallel to the first edge  131 . The antenna  100  further has a second datum line  102 . The second datum line  102  extends from the second edge  132  to the fourth edge  134 . The second datum line  102  is parallel to the first edge  131 . The second slot  142  extends along the second datum line  102 . The length of the second slot  142  is not longer than half the length d 1  of the second datum line  102 . 
     The conductive element  120  is connected to the fourth edge  134 . The antenna  100  further has a feed point  170 . The feed point  170  is located on the first edge  131 . A coaxial cable  180  feeds the radiator  160  at the feed point  170 . The distance between the feed point  170  and the second edge  132  is not longer than half the length d 3  of the first edge  131 . 
     With reference to  FIGS. 2   a  and  2   b,  the extending portion  150  is connected to the third edge  133 . The extending portion  150  has a first section  151  and a second section  152 . The first section  151  is perpendicular to the second section  152 . The first section  151  is connected to the body  130  and perpendicular thereto. The second section  152  is connected to the first section  151  and parallel to the body  130 . 
     In the first embodiment, a width of the first slot  141  is about 1.5 mm, and a width of the second slot  142  is about 1 mm. However, the dimensional description does not limit the scope of the invention. 
       FIG. 3  shows signal transmission of the antenna  100  of the first embodiment of the invention, wherein the bandwidth of the antenna  100  (bandwidth is defined as signals having voltage standing wave ratio less than 2) is between 2.45 GHz to 7 GHz. Therefore, the antenna  100  of the embodiment provides wider bandwidth and improved transmission with decreased antenna dimension. 
       FIGS. 4   a  to  4   d  shows signal transmission path in the first embodiment of the invention.  FIG. 4   a  shows signal transmission path of a first wireless signal (2.55 GHz).  FIG. 4   b  shows signal transmission path of a second wireless signal (4 GHz).  FIG. 4   c  shows signal transmission path of a third wireless signal (5.05 GHz).  FIG. 4   d  shows signal transmission path of a first wireless signal (6.75 GHz). 
       FIG. 5  shows an antenna  201  of a second embodiment of the invention, wherein the second slot further has an L-shaped section  1421  and a straight section  1422 . The L-shaped section  1421  is connected to the straight section  1422 . In a modified example, the first slot can further have an L-shaped section and a straight section, and the L-shaped section is connected to the straight section. 
       FIG. 6  shows an antenna  202  of a third embodiment of the invention, wherein the extending portion is omitted, and the radiator  202  transmits wireless signals simply via the body  130 . 
       FIG. 7   a  shows an antenna  203  of a fourth embodiment of the invention, wherein a notch  211  is formed on the radiator. The notch  211  is located on the second edge  132 , and connected to the first slot  141 . The notch  211  is substantially triangular shaped.  FIG. 7   b  shows an antenna  203 ′ of a modified example of the fourth embodiment of the invention, wherein a notch  212  and a notch  213  are formed on the radiator. The notch  212  is trapezoid and connected to the first slot  141 . The notch  213  is parallelogram shaped and connected to the second slot  142 . In the embodiments of the invention, the shape of the notches can be modified. 
       FIG. 8  shows an antenna  204  of a fifth embodiment of the invention, wherein locations of the first groove  141  and the second groove  142  can be modified to satisfy various signal transmission requirements. 
     In the embodiments of the invention, the second edge  132  is perpendicular to the first edge  131 . However, the invention is not limited thereby. Additionally, the body can be various polygon shapes, and is not limited to be a trapezoid shape. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.