Patent Publication Number: US-7911398-B2

Title: Antenna structure and wireless communication apparatus thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an antenna structure and related wireless communication apparatus, and more particularly, to an antenna structure and related wireless communication apparatus further disposing a grounding element with an L shape to reduce coupling effects resulting from a metal plane with a large area. 
     2. Description of the Prior Art 
     As wireless telecommunication develops with the trend of micro-sized mobile communications products, the location and the space arranged for antennas become increasingly limited. Therefore, built-in micro antennas have been developed. Some micro antennas such as chip antennas and planar antennas, are commonly used and occupy very small volume. 
     The planar antenna has the advantages of small size, light weight, ease of manufacturing, low cost, high reliability, and can also be attached to the surface of any object. Therefore, micro-strip antennas and printed antennas are widely used in wireless communication systems. For example, monopole antennas or dipole antennas are suited for use in 3G transceivers. These antennas are widespread, being applied to GSM, DCS, UMTS, WLAN, Bluetooth, etc. 
     The housings of mobile communication products (for example, notebook computers) are now commonly constructed with metallic materials, such as Al—Mg alloys. However, a metal plane with a large area will affect the transmitting and receiving qualities of the monopole antenna, which makes the antennas difficult to match impedance to. Therefore, how to reduce sizes of the antennas, improve antenna efficiency, improve radiation patterns, and increase bandwidths of the antennas becomes important topics in this field. 
     SUMMARY OF THE INVENTION 
     It is one of the objectives of the present invention to provide an antenna structure and related wireless communication apparatus to solve the above-mentioned problems. 
     The present invention discloses an antenna structure. The antenna structure includes a radiation element, a grounding element, and a feeding point. The radiation element has a first section and a second section coupled to the first section. The grounding element has a third section and a fourth section coupled to the third section, wherein the third section is substantially parallel to the first section. The feeding point is coupled between the second section of the radiation element and the fourth section of the grounding element. 
     In one embodiment, the first section of the radiation element and the third section of the grounding element extend in an identical direction. 
     In one embodiment, the first section of the radiation element and the third section of the grounding element extend in different directions. 
     In one embodiment, a joint point of the third section and the fourth section of the grounding element forms a right angle, an oblique angle, or an arc angle. 
     The present invention discloses a wireless communication apparatus. The wireless communication apparatus includes a housing and an antenna structure. The antenna structure includes a radiation element, a grounding element, and a feeding point. The radiation element has a first section and a second section coupled to the first section. The grounding element has a third section and a fourth section coupled to the third section, wherein the third section is substantially parallel to the first section. The feeding point is coupled between the second section of the radiation element and the fourth section of the grounding element. 
     In one embodiment, the wireless communication apparatus is a notebook computer. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an antenna structure according to a first embodiment of the present invention. 
         FIG. 2  is a diagram of an antenna structure according to a second embodiment of the present invention. 
         FIG. 3  is a diagram of an antenna structure according to a third embodiment of the present invention. 
         FIG. 4  is a diagram of an antenna structure according to a fourth embodiment of the present invention. 
         FIG. 5  is a diagram of an antenna structure according to a fifth embodiment of the present invention. 
         FIG. 6  is a diagram illustrating the VSWR of the antenna structure shown in  FIG. 1 . 
         FIG. 7  is a diagram illustrating the VSWR of the antenna structure shown in  FIG. 4 . 
         FIG. 8  is a diagram of a wireless communication apparatus according to an embodiment of the present invention. 
         FIG. 9  is a diagram illustrating a first radiation pattern of the antenna of the wireless communication apparatus in  FIG. 8 . 
         FIG. 10  is a diagram illustrating a second radiation pattern of the antenna of the wireless communication apparatus in  FIG. 8 . 
         FIG. 11  is a diagram illustrating a third radiation pattern of the antenna of the wireless communication apparatus in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1 .  FIG. 1  is a diagram of an antenna structure  100  according to a first embodiment of the present invention. The antenna structure  100  includes a radiation element  110 , a grounding element  120 , and a feeding point  140 . The radiation element  110  has a first section  112  and a second section  114  coupled to the first section  112 . The first section  112  is not parallel to the second section  114 , and there is an angle θ 1  included between the first section  112  and the second section  114 . The grounding element  120  has a third section  122  and a fourth section  124  coupled to the third section  122 . The third section  122  is not parallel to the fourth section  124 , and there is an angle θ 2  included between the third section  122  and the fourth section  124 . The third section  122  of the grounding element  120  is substantially parallel to the first section  112  of the radiation element  110 . In addition, the feeding point  140  is coupled between the second section  114  of the radiation element  110  and the fourth section  124  of the grounding element  120 . 
     Please keep referring to  FIG. 1 . The radiation element  100  assumes an L shape, wherein the first section  112  and the second section  114  are each slender rectangles and a current I 1  flows through the first section  112  in the direction of the arrow shown in  FIG. 1 . Similarly, the grounding element  120  has an L shape, wherein the third section  122  and the fourth section  124  are each slender rectangles and a current I 2  flows through the third section  122  in the direction of the arrow shown in  FIG. 1 . Because the third section  122  of the grounding element  120  is substantially parallel to the first section  112  of the radiation element  110 , the direction of the current I 2  can be adjusted to be substantially parallel to the direction of current I 1 . Therefore, an impedance matching and radiation patterns of the antenna structure  100  can be changed to achieve a goal of adjusting energy upward (i.e., +Z axis) without being affected by a nearby metal plane with a large area. The antenna structure  100  is usually disposed on a housing of a wireless communication apparatus (for example, a notebook computer). Assuming that the housing of the notebook computer is constructed of metallic material, such as Al—Mg alloy, the efficiency of the antenna structure  100  will be affected by the housing. The third section  122  of the grounding element  120  being designed as a slender rectangle in the present invention reduces the decrease in efficiency caused by the housing on the antenna structure  100 . Furthermore, a length L 3  of the third section  122  of the grounding element  120  should be determined depending on the effect to the radiation element  110  caused from the housing. The length L 3  of the third section  122  of the grounding element  120  can be designed to be greater than a length L 1  of the first section  112  of the radiation element  110 , which means L 3 &gt;L 1 . 
     In this embodiment, the first section  112  of the radiation element  110  and the third section  122  of the grounding element  120  extend in an identical direction (i.e., the +Y axis shown in  FIG. 1 ), but is not a limitation of the present invention. In addition, the radiation element  100  resonates at an operating frequency band of a 3G wireless communication system, for example, at the operating frequency band 1570 MHz-1580 MHz of GPS, but this is not a limitation of the present invention and can be applied to wireless communication systems of other types. The length L 1  is approximately one-fourth of a wavelength (λ/4) of a resonance mode generated by the antenna structure  100 . 
     Please note that, as mentioned above, the radiation element  100  has an L shape and the first section  112  and the second section  114  are each a slender rectangle, but this is not a limitation of the present invention. Those skilled in the art should appreciate that various modifications of the radiation element  110  may be made. For example, the shape of the antenna structure  110  may be modified appropriately without departing the design spirit of the antenna structure disclosed in the present invention. Please also note that, the angles θ 1  and θ 2  are each a right angle (i.e., θ 1 =θ 2 =90°) in this embodiment. Of course, the antenna structure  100  shown in  FIG. 1  is merely an embodiment of the present invention, and, as is well known by persons of ordinary skill in the art, suitable variations can be applied to the antenna structure  100 . In the following, several embodiments illustrate various modifications of the antenna structure  100 . 
     Please refer to  FIG. 2 .  FIG. 2  is a diagram of an antenna structure  200  according to a second embodiment of the present invention, which is a varied embodiment of the antenna structure  100  shown in  FIG. 1 . In  FIG. 2 , the architecture of the antenna structure  200  is similar to that of the antenna structure  100 , and the difference between them is that a joint point of a third section  222  and a fourth section  224  of a grounding element  220  included by antenna structure  200  forms an oblique angle; that is, the angle θ 3  is not 90° (in this embodiment, θ 3 &lt;90°). 
     Please refer to  FIG. 3 .  FIG. 3  is a diagram of an antenna structure  300  according to a third embodiment of the present invention, which is a varied embodiment of the antenna structure  100  shown in  FIG. 1 . In  FIG. 3 , the architecture of the antenna structure  300  is similar to that of the antenna structure  100 , the difference between them being that a joint point of a third section  322  and a fourth section  324  of a grounding element  320  included by antenna structure  300  forms an arc. In other words, the angle θ 4  is an arc angle. 
     Please refer to  FIG. 4 .  FIG. 4  is a diagram of an antenna structure  400  according to a fourth embodiment of the present invention. In  FIG. 4 , the architecture of the antenna structure  400  is also similar to that of the antenna structure  100 . The difference between them is that a third section  422  of a grounding element  420  and the first section  112  of the radiation element  110  included by the antenna structure  400  extend in different directions. The third section  422  of the grounding element  420  extends in the −Y direction of the Y axis, and the first section  112  of the radiation element  110  extends in the +Y direction. In addition, a current I 11  of the radiation element  110  flowing through the first section  112  and a current I 22  of the grounding element  420  flowing through the third section  422  are represented by the arrows shown in  FIG. 4 . As can be seen from  FIG. 4 , because the third section  422  of the grounding element  420  is substantially parallel to the first section  112  of the radiation element  110 , the directions of the currents I 11  and I 22  are substantially parallel to each other. 
     Please refer to  FIG. 5 .  FIG. 5  is a diagram of an antenna structure  500  according to a fifth embodiment of the present invention. In  FIG. 5 , the architecture of the antenna structure  500  is similar to that of antenna structure  100 , but the antenna structure  500  further includes an active component  530  disposed between the second section  114  of the radiation element  110  and the feeding point  140 . In one embodiment, the active component  530  can be a low-noise amplifier (LNA) or a matching circuit, but is not meant as a limitation of the present invention. Those skilled in the art should appreciate that active components of other types can also be disposed between the second section  114  of the radiation element  110  and the feeding point  140  without departing from the spirit of the present invention, which should also belong to the scope of the present invention. 
     Those skilled in the art should appreciate that various modifications of the antenna structures in  FIG. 1-FIG .  5  may be made without departing from the spirit of the present invention. For example, the antenna structures in  FIG. 1-FIG .  5  can be arranged or combined randomly into a new varied embodiment. The abovementioned embodiments are presented merely for illustrating practicable designs of the present invention, and should not be limitations of the present invention. 
     Please refer to  FIG. 6  to  FIG. 7 .  FIG. 6  is a diagram illustrating the VSWR of the antenna structure shown in  FIG. 1 , and  FIG. 7  is a diagram illustrating the VSWR of the antenna structure shown in  FIG. 4 . The horizontal axis represents frequency (Hz), between 700 MHz and 2.5 GHz, and the vertical axis represents the VSWR. As shown in  FIG. 6 , the frequency 1.575 GHz and the VSWR 1.677 of a sign Mkr_ 1  are marked. As shown in  FIG. 7 , the frequency 1.575 GHz and the VSWR 1.671 of a sign Mkr_ 2  are marked. As is known from  FIG. 6  and  FIG. 7 , the VSWR falls below 2 for frequencies adjacent to 1570-1580 MHz, which can satisfy demands of the wireless communication system (for example, the GPS application). In other words, regardless of whether the first section of the radiation element and the third section of the grounding element extend in the same direction, all belong to the scope of the present invention. 
     Please refer to  FIG. 8 .  FIG. 8  is a diagram of a wireless communication apparatus  800  according to an embodiment of the present invention. In this embodiment, the wireless communication apparatus  800  is a notebook computer, but is not a limitation of the present invention and can be a wireless communication apparatus of other types. As shown in  8 A, the wireless communication apparatus  800  includes a housing  810  and an antenna  830 , wherein the antenna  830  is disposed inside the housing  810  and is parallel to a first plane  820  of the housing  810 . When a user starts using the wireless communication apparatus  800 , the first plane  820  of the housing  810  is located at a Y-Z plane and the antenna  830  is disposed on locations A 1  or A 2  of the first plane  820 . The housing  810  is constructed of a conductive material, such as an Al—Mg alloy, but is not limited to this only. As shown in  8 B, the antenna  830  can be implemented by the antenna structure  100  shown in  FIG. 1 . Of course, the antenna  830  can also be implemented by changed forms of the antenna structure  100 , such as the antenna structures  200 - 500  or any combinations of them in  FIG. 2-FIG .  5 . 
     Please note that when the user starts using the wireless communication apparatus  800 , the first plane  820  of the housing  810  and the antenna  830  are located on the Y-Z plane. As can be seen from the antenna structure  100  in  FIG. 1 , because the third section  122  of the grounding element  120  is substantially parallel to the first section  112  of the radiation element  110 , the direction of the current I 2  can be adjusted to be substantially parallel to the direction of the current I 1 . Thus, the impedance matching and radiation patterns of the antenna structure can be changed to center the radiation patterns and energy of the antenna  830  onto the +Z axis. 
     Please refer to  FIG. 9-FIG .  11 .  FIG. 9-FIG .  11  are each a diagram illustrating a radiation pattern of the antenna  830  of the wireless communication apparatus  800  in  FIG. 8 .  FIG. 9  shows measurement results of the antenna  830  in XZ plane.  FIG. 10  shows measurement results of the antenna  830  in YZ plane.  FIG. 11  shows measurement results of the antenna  830  in XY plane. As can be seen, although the antenna  830  is disposed on the first plane  820  of the housing  810  constructed of a metallic material, the radiation patterns and the efficiency of the antenna  830  are not affected by the material of the housing  810 . 
     In addition, let&#39;s compare the antenna structure disclosed in the present invention with a conventional monopole antenna to further expand advantages of the antenna structure disclosed in the present invention. The conventional monopole antenna mentioned herein means an antenna having a single radiation object and a grounding plane with a large area: for example, a combination formed by the radiation element  110 , the feeding point  140 , and a grounding plane with a large area. That is, a grounding plane with a large area is used for replacing the grounding element  120 . Let&#39;s now assume that the antenna structure disclosed in the present invention and the conventional monopole antenna are both disposed at the locations A 1  or A 2  of the wireless communication apparatus  800 . The signal-to-noise ratio (C/No) of the antenna structure disclosed in the present invention is  46 , and the C/No of the conventional monopole antenna is  42 . As can be seen, inside the wireless communication apparatus  800  such as the notebook computer, the coupling effect caused from the housing  810  will seriously affect the conventional monopole antenna, for which it is hard to match impedance. However, the antenna structure in the present invention can substantially reduce such an effect. 
     From the above descriptions, the present invention provides the antenna structures  100 - 500  and related wireless communication apparatus  800 . Through additionally disposing the grounding element with an L shape, the direction of the current I 2  can be adjusted and the coupling effect of the metal plane with a large area can be reduced. As can be seen from  FIG. 1  and  FIG. 8 , when the user starts using the wireless communication apparatus  800 , the first plane  820  of the housing  810  is located on the Y-Z plane and the antenna structure  830 , implemented by the antenna structure  100 , is also located on the Y-Z plane. At this time, the impedance matching and radiation patterns of the antenna structure can be changed by the third section  122  of the grounding element  120 , therefore achieving the goal of adjusting energy upward (i.e., +Z axis) without being affected by the metal plane with a large area. Compared with the conventional monopole antenna, the radiation patterns of the antenna structures disclosed in the present invention can be centered upwards and have better C/No values. Hence, the antenna structures disclosed in the present invention are suitably applied to wireless communication systems like GPS. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.