Abstract:
A multi-band antenna ( 1 ) used in wireless communications includes a radiating portion ( 2 ), a grounding portion ( 4 ), and a connecting portion ( 3 ). The radiating portion ( 2 ) includes a first radiating element ( 21 ) operating at 900 MHz frequency band and a second radiating element ( 22 ) operating at 1800 MHz frequency band. The connecting portion ( 3 ) connects the radiating portion ( 2 ) and the grounding portion ( 4 ). The grounding portion ( 4 ), the radiating portion ( 2 ), and the connecting portion ( 3 ) locate in the same plane.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to an antenna, and more particularly to a planar inverted-F antenna (PIFA) used in a portable electronic device. 
   2. Description of the Prior Art 
   With the development of wireless communication, more and more portable electronic devices, for example note book, install an antenna system for working in a Wireless Local-area Network (WLAN). Transmitting and receiving signals plays an important role in wireless communication process. In recent years, a majority of WLAN bases on Bluetooth technical standard or 802.11 technical standard. Antenna in Bluetooth technical standard bases on 2.4 GHz frequency band, and in 802.11 technical standard bases on 2.4 GHz and 5 GHz. So, antenna in notebook mostly works in the above frequency bands at the present time. 
   However, user would not satisfy a portable wireless communication devices only working in WLAN in the future. It&#39;s desired to make portable wireless communication device working in Wireless Wide-area Network (WWAN). The portable wireless communication device working in WWAN can work and entertain in more broad area. WWAN adopts two techniques, GSM and CDMA at present. However, a portable wireless communication device can work in GSM unless it has an antenna working in the frequency band of GSM. Antennas in notebook and other portable wireless communication device mostly work in 2.4 GHz frequency and 5 GHz frequency now. However, antennas of the mobile phone working in GSM mostly cannot be set in notebook or other portable wireless communication device because of size or power. 
   For example, China Patent No. 2689482Y discloses a PIFA capable of working on three frequency bands. The antenna includes three radiating elements, respectively operating at 1800 GHz, 900 MHz, and 2450 MHz. So, the antenna can be set in notebook or other portable wireless communication device for working in GSM. However, this antenna adopts solid structure, that is, the radiating elements, connection element, and grounding element respectively locate in different planes. Complex configuration and taking up more space result in the antenna going against industrialization manufacture, wasting cost and breaching trend of miniaturization development of antenna. 
   Hence, in this art, a planar inverted-F 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 planar inverted-F antenna with simplified structure and reduced size. 
   A second object, therefore, of the present invention is to provide a method of manufacturing the antenna above. 
   In order to implement the above object and overcomes the above-identified deficiencies in the prior art, the planar inverted F antenna forming in a metal patch, comprises a first radiating element and extending in a first direction, a second radiating element and extending in a second direction different from the first direction, a grounding portion and spacing with the first radiating element and the second radiating element, an connecting portion connecting the first and the second radiating elements and the grounding portion, and a feeder line comprising a inner conductor for attaching to the connecting portion and a outer conductor for attaching to the grounding portion. The first radiating element has a first radiating portion and a second radiating portion being perpendicular to the first radiating portion. The connecting portion comprises a first portion, a second portion paralleling the first portion and s third portion connecting the first portion and the second portion. 
   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 top elevation view of a planar inverted-F antenna in accordance with the present invention; 
       FIG. 2  is a horizontally polarized principle plane radiation pattern of the antenna operating at the resonant frequency of 900 MHz; 
       FIG. 3  is a vertically polarized principle plane radiation pattern of the antenna operating at the resonant frequency of 900 MHz; 
       FIG. 4  is a horizontally polarized principle plane radiation pattern of the antenna operating at the resonant frequency of 1800 MHz; 
       FIG. 5  is a vertically polarized principle plane radiation pattern of the antenna operating at the resonant frequency of 5.1800 MHz; and 
       FIG. 6  is a test chart recording of Voltage Standing Wave Ratio (VSWR) of the inverted-F antenna as a function of frequency. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to a preferred embodiment of the present invention. 
   Referring to  FIG. 1 , a planar inverted-F antenna  1  according to the present invention is made of a metal sheet and comprises a radiating portion  2 , a grounding portion  4 , and a connecting portion  3  connecting the radiating portion  2  and the grounding portion  4 . 
   The radiating portion  2  comprises a first radiating element  21  operating at a lower frequency and a second radiating element  22  operating at a higher frequency and extending along a first direction. The first radiating element  21  is of L-shape and comprises a first part  210  extending along the first direction and parallel to the second radiating element  22  and a second part  211  extending along a second direction from left end of the first part  210  toward the grounding portion  4 . The L-shape design of the first radiating element  21  is capable of avoiding adding the lateral size of the planar inverted-F antenna  1 . The connecting portion  3  comprises a first side section  31  parallel to the second part  211  of the first radiating element  21  and connecting the first radiating element  21  and the second radiating element  22 , a second side section  32  extending along the first direction from a lower end of the first side section  31  toward the second part  211 , and a third side section  33  extending along the second direction from left end of the second side section  32  to terminate the second side section  32  with the grounding portion  4 , respectively. The grounding portion  4  is a rectangular piece connecting the third side section  33  and parallel to the second side section  32 . A feeding point  5  locates on the second side section  32  near the third side section  33 . A feeding line  6  extends from feeding point  5  and connects the grounding portion  4 . The feeding line  6  comprises an inner conductor  61  soldered to the feeding point  5 , an inner insulating layer  63  enclosing the inner conductor  61 , a metal braiding layer  62  soldered to the grounding portion  4  and an outer insolating layer (not labeled). 
   The second, third side sections  32 ,  33  of the connecting portion  3  and a longer edge of the grounding portion  4  together form a slot  7  with width equal to the length of the third side section  33 . High frequency of the second radiating portion  22  can arrive at a more wider frequency band and a more better radiation impression by changing the width of the slot  7  i.e. the length of the third side section  33  and location of the feeding point  5 . 
   The first radiating element  21 , the connecting portion  3 , and the grounding portion  4  together form a first planar inverted-F antenna receiving and transmitting lower frequency signal. The second radiating portion  22 , the connecting portion  3 , and the grounding portion  4  form a second planar inverted F antenna receiving and transmitting higher frequency signal. 
     FIGS. 2-5  show the horizontally polarized and vertically polarized principle plane radiation patterns of the antenna  1  operating at the resonant frequency of 900 MHz and 1800 GHz. Note that each radiation pattern of the planar inverted-F antenna  1  is close to corresponding optimal radiation pattern and there is no obvious radiating blind area, conforming to the practical use conditions of an antenna. 
   Referring to  FIG. 6 , sets forth a test chart recording of Voltage Standing Wave Ratio (VSWR) of the antenna  1  as a function of frequency. Note that VSWR drops below the desirable maximum value “2” in the 880 M-920 MHz frequency band and in the 1710-2180 MHz frequency band, indicating acceptable efficient operation in these two wide frequency bands, which cover more than the total bandwidth of GSM (low frequency band includes 880-960 MHz, high frequency band includes 1710-1880 MHz) and be provided with more wider frequency band of the operating at high frequency. 
   The method of making the same of the planar inverted-F antenna  1  of the present invention comprises following steps. Firstly, selecting a rectangle metal piece. Secondly, calculating a required length of the radiating portion  2  according to the bands of 900 MHz and 1800 MHz. Thirdly, calculating a length and shape of the connecting portion  3  according to required impendence matching. Fourth, achieving the radiating portion  2 , the connecting portion  3 , and the grounding portion  4  by digging slots in the rectangle metal piece according to the calculations. Fifth, calculating the location of the feeding point  5  and providing the feeding line  6  connecting to the feeding point  5  according to impendence matching. 
   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.