Patent Publication Number: US-7589679-B2

Title: Antenna device

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to antenna devices, and particularly to an antenna device in a wireless local area network (WLAN) device. 
   2. Description of Related Art 
   Nowadays, wireless communication devices, such as mobile phone handsets and portable computers, are becoming more and more popular. In order to communicate with one or more base stations, the wireless devices usually have to be equipped with an antenna. The characteristics of the antenna, such as radiation efficiency, orientation, and impedance bandwidth, bring influence on performance of the wireless device. Recently, wireless communication devices are becoming more compact and lightweight. Consequently, antennas, as key elements of wireless communication devices, are desired to be made ever smaller and space-saving. Therefore, a need exists in the industry. 
   SUMMARY OF THE INVENTION 
   In one aspect of the invention, an antenna device is disposed on a substrate, and includes a feed part, a holder, a body part, at least one ground plane, and a matching part. The feed part is for feeding electromagnetic signals. The body part for radiating and receiving the electromagnetic signals is electronically connected to the feed part. The body part includes at least two radiation parts electronically connected in sequence and surrounds at least two adjacent surfaces of the holder. The at least one ground plane for grounding is disposed on one side of the substrate. The matching part for impendence matching includes one end electronically connected to the body part and another end electronically connected to the ground plane. The ground plane surrounds two adjacent sides of the matching part. 
   Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of an antenna device according to an exemplary embodiment of the present invention; 
       FIG. 2  is a schematic view of the antenna device of  FIG. 1  disposed on a holder; 
       FIG. 3  is a schematic view of part elements of the antenna device of  FIG. 1 ; 
       FIG. 4  is a graph of simulated test results showing reflection coefficient of the antenna device of  FIG. 1 ; and 
       FIGS. 5-7  are graphs of simulated test results showing radiation patterns when the antenna device of  FIG. 1  is operated at 2.44 GHz. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , an antenna device  10  according to an exemplary embodiment of the present invention is shown. Referring also to  FIG. 2 , the antenna device  10  of  FIG. 1  is supported by surfaces of a hexahedron or a hexahedral holder  20 . The antenna device  10  includes a first ground plane  11 , a second ground plane  12 , a feed part  14 , a matching part  16 , and a body part  18 . 
   The feed part  14  for feeding electromagnetic signals and the matching part  16  for impedance matching are also disposed on a substrate  30 . In the exemplary embodiment, a characteristic impedance of the feed part  14  is 50 ohms. The first ground plane  11  and the second ground plane  12  are disposed on two opposite surfaces of the substrate  30 , and are used for grounding. The first ground plane  11  includes a first part  110 , a second part  112 , and a third part  114 . In the exemplary embodiment, the first part  110 , the second part  112 , and the third part  114  are all substantially rectangular shaped. The first part  110  and the second part  112  are disposed at two opposite sides of the feed part  14 . The third part  114  extends from the second part  112  to form an L-shaped ground plane, surrounding two adjacent sides of the matching part  16 . 
   The body part  18  for radiating and receiving the electromagnetic signals, surrounds on at least two adjacent surfaces of the holder  20 . In the exemplary embodiment, the holder  20  is substantially cubical shaped, includes six surfaces  21 ,  22 ,  23 ,  24 ,  25 ,  26 , and the body part  18  surrounds on the six surfaces  21 ,  22 ,  23 ,  24 ,  25 ,  26 . The sixth surface  26  covers at least one part of the matching part  16 . 
   The body part  18  includes a first radiation part  1800 , a second radiation part  1802 , a third radiation part  1804 , a fourth radiation part  1806 , a fifth radiation part  1808 , a sixth radiation part  1810 , a seventh radiation part  1812 , an eighth radiation part  1814 , a ninth radiation part  1816 , a tenth radiation part  1818 , an eleventh radiation part  1820 , a twelfth radiation part  1822 , and a thirteenth radiation part  1824  electronically connected in sequence. In the exemplary embodiment, the above-mentioned radiation parts are all substantially rectangular strip shaped. The two adjacent radiation parts of the above-mentioned radiation parts  1800 ,  1802 ,  1804 ,  1806 ,  1808 ,  1810 ,  1812 ,  1814 ,  1816 ,  1818 ,  1820 ,  1822 ,  1824  are perpendicular to each other. Note that other embodiments do not limit the number of radiation parts, as long as at least two radiation parts are electronically connected in sequence and surrounding at least two adjacent surfaces of the holder  20 . 
   The second radiation part  1802 , the third radiation part  1804 , and the eleventh radiation part  1820  are disposed on the first surface  21  of the holder  20 . The second radiation part  1802  is electronically connected to and perpendicular to the third radiation part  1804 , and the third radiation part  1804  is parallel to the eleventh radiation part  1820 . The fourth radiation part  1806  is disposed on the second surface  22  of the holder  20 . 
   The fifth radiation part  1808 , the ninth radiation part  1816 , and the thirteenth radiation part  1824  are disposed on the third surface  23  of the holder  20 . The ninth radiation part  1816  and the thirteenth radiation part  1824  are respectively parallel to the fifth radiation part  1808 , and the thirteenth radiation part  1824  has an open end. The sixth radiation part  1810 , the seventh radiation part  1812 , and the eighth radiation part  1814  are disposed on the fourth surface  24  of the holder  20 . The seventh radiation part  1812  is electronically connected to and perpendicular to the sixth radiation part  1810  and the eighth radiation part  1814 . The tenth radiation part  1818  and the twelfth radiation part  1822  are disposed on the fifth surface  25  of the holder  20 . The tenth radiation part  1818  is parallel to the twelfth radiation part  1822 . 
   In other exemplary embodiments, the body part  18  can include a plurality of radiation parts. For instance, when the holder  20  is substantially orbicular, the body part  18  is also substantially orbicular, and the radiation parts of the body part  18  are numerous. 
     FIG. 3  is a schematic view of elements of the antenna device  10  of  FIG. 1 . The first radiation part  1800  is disposed on the substrate  30 , and the sixth surface  26  of the holder  20  (shown in  FIG. 2 ) covers the first radiation part  1800 . The first radiation part  1800  has one end electronically connected to the feed part  14  and the other end electronically connected to the matching part  16 . In the exemplary embodiment, the first radiation part  1800  and the matching part  16  are designed as printed elements, and the other radiation parts are made of metallic sheets. 
   One end of the matching part  16  is electronically connected to the first radiation part  1800  of the body part  18 , and the other end of the matching part  16  is electronically connected to the first ground plane  11 . The matching part  16  includes a first matching segment  161 , a second matching segment  162 , a third matching segment  163 , a fourth matching segment  164 , a fifth matching segment  165 , and a sixth matching segment  166  electronically connected in sequence. In the exemplary embodiment, the above-mentioned matching segments are all substantially in rectangular strip shape. The two adjacent matching segments of the above-mentioned matching segments  161 ,  162 ,  163 ,  164 ,  165 ,  166  are perpendicular to each other. 
   The first matching segment  161  is electronically connected to and perpendicular to the first radiation part  1800  of the body part  18 . The sixth matching segment  166  is electronically connected to the first ground plane  11 . In the exemplary embodiment, the first matching segment  161  and the fifth matching segment  165  are configured in one line, and parallel to the third matching segment  163 . The second matching segment  162  and the fourth matching segment  164  are parallel to the sixth matching segment  166 . In the exemplary embodiment, the matching part  16  is designed as a printed element, which is electronically connected to the body part  18  made of metallic sheets. 
   At least one surface of the holder  20  covers at least one part of the matching part  16 ; that is, the body part  18  projects on a plane where the matching part  16  is located. In the exemplary embodiment, the sixth surface  26  of the holder  20  covers the first matching segment  161 , the second matching segment  162 , the third matching segment  163 , the fourth matching segment  164 , and the fifth matching segment  165 . 
   In the exemplary embodiment, a length and a width of the first radiation part  1800  are respectively about 4 millimeters (mm) and 1 mm. A length and a width of the second radiation part  1802  are respectively about 1.5 mm and 1 mm. A length and a width of the third radiation part  1804  are respectively about 6 mm and 1 mm. A length and a width of the fourth radiation part  1806  are respectively about 4 mm and 1 mm. A length and a width of the fifth radiation part  1808  are respectively about 6 mm and 1 mm. A length and a width of the sixth radiation part  1810  are respectively about 3 mm and 1 mm. A length and a width of the seventh radiation part  1812  are respectively about 1.5 mm and 1 mm. A length and a width of the eighth radiation part  1814  are respectively about 2 mm and 1 mm. A length and a width of the ninth radiation part  1816  are respectively about 2 mm and 2 mm. A length and a width of the tenth radiation part  1818  are respectively about 4 mm and 2 mm. A length and a width of the eleventh radiation part  1820  are respectively about 6 mm and 1.5 mm. A length and a width of the twelfth radiation part  1822  are respectively about 4 mm and 3 mm. A length and a width of the thirteenth radiation part  1824  are respectively about 0.2 mm and 3 mm. 
   A length and a width of the first matching segment  161  are respectively about 2 mm and 1 mm. A length and a width of the second matching segment  162  are respectively about 3 mm and 1 mm. A length and a width of the third matching segment  163  are respectively about 2 mm and 1 mm. A length and a width of the fourth matching segment  164  are respectively about 3 mm and 1 mm. A length and a width of the fifth matching segment  165  are respectively about 1 mm and 1 mm. A length and a width of the sixth matching segment  166  are respectively about 4.5 mm and 1 mm. In other exemplary embodiments, the above lengths and widths of elements of the antenna device  10  can be changed. 
     FIG. 4  is a graph of simulated test results showing reflection coefficient of the antenna device of  FIG. 1 . As shown, when the antenna device  10  operates at working frequency bands of 2.4˜2.5 GHz, its reflection coefficient is less than −6 dB, which is capable of meeting operating standards set forth in IEEE 802.11b. 
     FIGS. 5-7  are graphs of simulated test results showing radiation patterns in horizontal and vertical planes when the antenna device  10  of  FIG. 1  is operated at 2.44 GHz. It is to be noted that the radiation pattern is close to an omni-directional radiation pattern at X-Z plane when the antenna device  10  of the present invention is operated at 2.44 GHz. 
   While exemplary embodiments have been described above, it should be understood that they have been presented by way of example only and not by way of limitation. Thus the breadth and scope of the present invention should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.