Abstract:
A monopole antenna comprises a planar substrate, a radiating element arranged on the planar substrate and of long-guide trapezium-shape and comprises a trapezium notch in the middle thereof, a grounding element assembled with said planar base with a predetermined angle.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a monopole antenna, and more particularly to a monopole antenna being used in an electronic device. 
   2. Description of the Prior Art 
   With the development of wireless communication, compact structure antennas are popular to be used in electronic devices. Several conventional compact structure antennas include multiple parts, usually occupying rekatively space, while the electronic device has compact structure. Thus, reducing the number of parts of antenna can significantly reduce the cost and suitable for used in the electronic device. TW Pat. No. 239677 describes a wide band monopole antenna. The monopole antenna comprises a grouding portion, a radiating portion located above the grouding portion and a feeder line. The grouding portion is rectangular and includes an up edge, a low edge, a grouding point and a short point. The radiating portion includes a first metal patch, a second metal patch and a short metal arm. The feeder line includes a center conductor and an external conductor. But the occupied space of the monopole antenna is too large to be assembled in an interior space of the electronic devices with compact structure. 
   Referring now to  FIG. 1 , a muti-band antenna  1 ′ is shown and includes an insulative substrate  10 ′, a first ground portion  20 ′, a second ground portion  50 ′, a low-frequency radiating portion  20 ′, a high-frequency radiating portion  30 ′, and a signal feeder cable  70 ′. The first ground portion  40 ′, the low-frequency radiating portion  40 ′, and the high-frequency radiating portion  30 ′ are made of sheet metal and are arranged on an upper surface of the insulative substrate  10 ′. The second ground portion  50 ′ is arranged on a lower surface of the insulative substrate  10 ′ opposite to the first ground portion  40 ′. The signal feeder cable  70 ′ comprises an inner core wire  71 ′ and a metal braiding layer  72 ′ respectively soldered onto the high-frequency radiating portion  30 ′ and the first ground portion  40 ′. The high-frequency radiating portion  30 ′ and the first ground portion  40 ′ are configured to cooperately define a resonating space  60 ′ therebetween. The low-frequency portion  20 ′ of the muti-band antenna  1 ′ is of trapezium shape and has difficulty to match impedance. The antenna with smaller size needs some special shape to achieve its impedance. 
   Hence, an improved antenna is desired to overcome the above-mentioned shortcomings of the existing antennas. 
   BRIEF SUMMARY OF THE INVENTION 
   A primary object, therefore, of the present invention is to provide a monopole antenna with smaller size and wide bandwidth. 
   In order to implement the above object and overcomes the above-identified deficiencies in the prior art, the monopole antenna comprising: a planar base; a radiating element is long-guide trapezium-shaped and includes notch in the middle thereof; a grounding element locates on said planar base with a determined angle; a feeder line includes a center conductor connecting with said radiating element and a external conductor connecting with said grounding 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 an assembled perspective view of a conventional multi-band antenna. 
       FIG. 2  is an assembled perspective view of a monopole antenna in accordance with the present invention. 
       FIG. 3  is a view similar to  FIG. 2  but take from a different aspect. 
       FIG. 4  is another view similar to  FIG. 2  but take from another different aspect. 
       FIG. 5  is an enlarged view of the circled area of  FIG. 2 ; 
       FIG. 6  is an enlarged view of the circled area of  FIG. 3 ; 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to a preferred embodiment of the present invention. 
   Referring to  FIG. 2  to  FIG. 6 , a monopole antenna  1  according to the present invention is shown. The monopole antenna  1  comprises a planar substrate  10 , a radiating element  20 , a grounding element  30 , and a feeder line  40 . The radiating element  20  and the grounding element  30  are made of metal sheet and the radiating element  20  locates on the upper surface of the planar substrate  10 . 
   The radiating element  20  of long-guide trapezium-shape comprises a trapezium-shaped notch  21  in the middle of the metal sheet which divides the antenna  1  into a first radiating arm  201  and a second radiating arm  202 . Referring to  FIG. 6 ,  8 the narrower end adjacent to grounding element  30  of the radiating element  20  comprises a U-shaped slot  22 , resulting in the narrower end of the radiating element  20  forming a first rectangular arm  24   a , a second rectangular arm  24   b  and a protruding portion  23 . the radiating element  20  is plastered on the planar substrate  10 . 
   The grouding element  30  of rectangle-shaped is arranged substantially perpendicular to the planar substrate  10  and comprises a cutout  32  forming symmetrical rectangle-shaped grooves  31   a ,  31   b  on the both sides of the cutout in the middle thereof. 
   The feeder line  40  is a coaxial cable, and includes an inner conductor  41 , an inner insulator  42  surrounding the inner conductor  41 , a braid layer  43  surrounding the inner insulator  42 , and an outer insulator  44  surrounding the braid layer  43 . A front end of the inner insulator  42  is stripped to expose front end of the inner conductor  41 . The inner conductor  41  is connected with the protruding portion  23  and the braid layer  43  extends through the cutout  32  to be connected with the grounding element  30 . 
   The planar substrate  10  forms a pair of heaves  11   a ,  11   b  extending from the underside thereof. In assembly the heaves  11   a ,  11   b  respectively extend through the grooves  31   a ,  31   b , so as to attach itself on the grouding element  30  firmly. 
   The data of the experiment of the monopole antenna  1  achieves enough band width. The monopole antenna  1  uses the special figure of trapezium with the notch  21  to improve its impedance matching. The monopole antenna  1  can gain enough band with. 
   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.