Abstract:
A broadband antenna configured to receive and transmit at least one wireless signal includes a first metal radiation portion having a first triangular metal plate and a second triangular metal plate; a metal reflective module, having a plurality of metal reflective elements, wherein the plurality of metal reflective elements are able to be assembled to make the metal reflective module a shape substantially conforming to a cavity structure and to surround the first metal radiation portion, and the metal reflective module is configured to reflect the at least one wireless signal and to enhance gain of the broadband antenna; and a supporting element, configured to fix the first triangular metal plate in opposition to the second triangular metal plate, to attach the first metal radiation portion to the cavity structure of the metal reflective module, and to electrically isolate the metal reflective module from the first metal radiation portion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a broadband antenna, and more particularly, a broadband antenna providing high gain, wide operating frequency bandwidth and convenience of storage and transportation. 
         [0003]    2. Description of the Prior Art 
         [0004]    Electronic products with wireless communication functionalities utilize antennas to emit or receive radio waves, to transmit or exchange radio signals, so as to access a wireless communication network. Therefore, to facilitate a user&#39;s access to the wireless communication network, an ideal antenna should maximize both its operating frequency bandwidth and gain. 
         [0005]    In order to increase the gain, the prior art has already provided a variety of additional structures to enhance reflectivity of an antenna; nevertheless, physical dimensions of the antenna will also grow, such that the antenna costs become more and inconveniences increase during installation. Consequently, it is a common goal in the industry to design a broadband antenna with a simple structure to reduce the manufacture and transportation cost. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore one of the objectives of the present invention to provide a broadband antenna, which ensures high gain, wide operating frequency bandwidth and convenience of storage or transportation. 
         [0007]    An embodiment of the invention provides a broadband antenna, configured to receive and transmit at least one wireless signal, comprising a first metal radiation portion, comprising a first triangular metal plate and a second triangular metal plate; a metal reflective module, comprising a plurality of metal reflective elements, wherein the plurality of metal reflective elements are able to be assembled to make the metal reflective module a shape substantially conforming to a cavity structure and to surround the first metal radiation portion, and the metal reflective module is configured to reflect the at least one wireless signal and to enhance gain of the broadband antenna; and a supporting element, configured to fix the first triangular metal plate in opposition to the second triangular metal plate, to attach the first metal radiation portion within the cavity structure of the metal reflective module, and to electrically isolate the metal reflective module from the first metal radiation portion. 
         [0008]    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 
         [0009]      FIG. 1A  is a schematic diagram illustrating an exploded view of a broadband antenna according to an embodiment of the present invention. 
           [0010]      FIG. 1B  is a schematic diagram illustrating a perspective view of the broadband antenna shown in  FIG. 1A  after assembly. 
           [0011]      FIG. 1C  is a schematic diagram illustrating a top view of the broadband antenna shown in  FIG. 1A  after assembly. 
           [0012]      FIG. 1D  is a cross-sectional view diagram taken along a cross-sectional line A-A′ in  FIG. 1C . 
           [0013]      FIG. 1E  is a schematic diagram illustrating antenna resonance simulation results of the assembled broadband antenna shown in  FIG. 1A . 
           [0014]      FIG. 2A  is a schematic diagram illustrating an exploded view of a broadband antenna according to an embodiment of the present invention. 
           [0015]      FIG. 2B  is a schematic diagram illustrating a perspective view of the broadband antenna shown in  FIG. 2A  after assembly. 
           [0016]      FIG. 2C  is a schematic diagram illustrating antenna resonance simulation results of the broadband antenna shown in  FIG. 2A . 
           [0017]      FIG. 3A  is a schematic diagram illustrating an exploded view of a broadband antenna according to an embodiment of the present invention. 
           [0018]      FIG. 3B  is a schematic diagram illustrating a perspective view of the broadband antenna shown in  FIG. 3A  after assembly. 
           [0019]      FIG. 3C  is a schematic diagram illustrating antenna resonance simulation results of the broadband antenna shown in  FIG. 3A . 
           [0020]      FIG. 4A  is a schematic diagram illustrating a perspective view of the broadband antenna  40  after assembly according to an embodiment of the present invention. 
           [0021]      FIG. 4B  is a schematic diagram illustrating antenna resonance simulation results of the broadband antenna shown in  FIG. 4A . 
           [0022]      FIG. 4C  is a schematic diagram illustrating antenna radiation gain pattern versus space angle relationship for the broadband antenna shown in  FIG. 4A  operated at 500 MHz. 
           [0023]      FIG. 4D  is a schematic diagram illustrating antenna radiation gain pattern versus space angle relationship for the broadband antenna shown in  FIG. 4A  operated at 800 MHz. 
           [0024]      FIG. 5  is a schematic diagram illustrating a locally enlarged view of a broadband antenna according to an embodiment of the present invention. 
           [0025]      FIG. 6  is a schematic diagram illustrating a locally enlarged view of a broadband antenna according to an embodiment of the present invention. 
           [0026]      FIG. 7  is a schematic diagram illustrating a locally enlarged view of a broadband antenna according to an embodiment of the present invention. 
           [0027]      FIG. 8  is a schematic diagram illustrating a locally enlarged view of a broadband antenna according to an embodiment of the present invention. 
           [0028]      FIG. 9  is a schematic diagram illustrating a broadband antenna according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Please refer to  FIGS. 1A-1D .  FIG. 1A  is a schematic diagram illustrating an exploded view of a broadband antenna  10  according to an embodiment of the present invention.  FIG. 1B  is a schematic diagram illustrating a perspective view of the broadband antenna  10  after assembly.  FIG. 1C  is a schematic diagram illustrating a top view of the broadband antenna  10  after assembly.  FIG. 1D  is a cross-sectional view diagram taken along a cross-sectional line A-A′ in  FIG. 1C . As shown in  FIG. 1A , the broadband antenna  10  comprises a metal radiation portion  100 , a metal reflective module  110  and a supporting element  120 . The metal radiation portion  100  comprises triangular metal plates  102  and  104 . In this embodiment, the triangular metal plates  102  and  104  are isosceles triangular metal plates, but not limited thereto. A central conductor of a transmission line for feeding the broadband antenna  10  can be connected to a triangular metal plate of the metal radiation portion  100  (e.g., the triangular metal plate  102 ), while a mesh conductor of the transmission line can be connected to another triangular metal plate of the metal radiation portion  100  (e.g., the triangular metal plate  104 ). The central conductor can be electrically connected to the metal reflective module  110 , but not limited thereto. The supporting element  120  is utilized to fix the triangular metal plates  102  and  104  positioned relative to each other, such that the base of the triangular metal plate  102  is parallel to the base of the triangular metal plate  104 , forming the metal radiation portion  100  into a rhombus. The supporting element  120  makes the metal radiation portion  100  fixed in a cavity of the assembled metal reflective module  110 , and the supporting element  120  separates the metal reflective module  110  from the metal radiation portion  100  by a gap G1 so that the metal reflective module  110  and the metal radiation portion  100  are electrically isolated as shown in  FIG. 1D   
         [0030]    Specifically, the metal reflective module  110  comprises metal reflective elements  111 ,  112 ,  113 ,  114 , and  115 . The metal reflective elements  111 ,  112 ,  113  and  114  have a shape substantially conforming to a rectangle, and an assembly element is provided around each of the four vertices marked as  1111 - 1114 ,  1121 - 1124 ,  1131 - 1134 , and  1141 - 1144  respectively. The metal reflective element  115  has a shape substantially conforming to a square, and an assembly element is provided around each of the four vertices, marked as  1151 - 1154 . As shown in  FIGS. 1A and 1B , when the metal reflective elements  111 - 115  are completely assembled, the adjacent vertices of the assembly elements correspond to each other—that is to say, the assembly element  1111  corresponds to the assembly elements  1121  and  1151 , by the same token the assembly element  1112  corresponds to the assembly element  1124 , and so forth. As a result, by means of fixing the assembly element  1111  to the assembly elements  1121  and  1151 , fixing the assembly element  1112  to the assembly element  1124 , fixing the assembly element  1122  to the assembly elements  1132  and  1152 , fixing the assembly element  1123  to the assembly element  1131 , fixing the assembly element  1133  to the assembly elements  1143  and  1153 , fixing the assembly element  1134  to the assembly element  1142 , fixing the assembly element  1144  to the assembly elements  1114  and  1154 , fixing the assembly element  1141  to the assembly element  1113 , the metal reflective elements  111 - 115  are electrically connected one another, and hence the metal radiation portion  100  is surrounded by the metal reflective module  110 . In other words, the metal reflective elements  111 - 115  form a cavity with the assembly elements  1111 - 1154  to reflect wireless signals from or toward the metal radiation portion  100 , and to enhance gain of the broadband antenna  10 . It is worth noting that each two adjacent metal reflective elements  111 - 115  shown in  FIGS. 1B-1D  are separated by a distance D1, and the distance D1 can be 0 to enhance reflection effect. Simultaneously, since the metal radiation portion  100  and the metal reflective elements  111 - 115  of the metal reflective module  110  substantially have a plate-like structure, it is simple to manufacture and convenient for storage and transportation after dismantled. Please note that the assembly elements  1111 - 1154  are exemplary embodiments of the present invention, but the present invention is not limited thereto and the number of the assembly elements can be adjusted according to different design requirements. For example, only the assembly elements  1111 ,  1113  and  1114  are disposed respectively around three vertices of the metal reflective element  111 , and the assembly element  1124  of the metal reflective element  112  is fixed to the last vertex of the metal reflective element  111  without an assembly element. Alternatively, apart from the assembly elements  1111 - 1114 , the metal reflective element  111  further comprises other assembly elements in order to enhance the connection among the metal reflective element  111  and the metal reflective elements  112 ,  114  and  115 . 
         [0031]    Briefly, the embodiment of the present invention receives and transmits wireless signals through the metal radiation portion  100 . The triangular shape of the triangular metal plates  102  and  104  provides wider bandwidth, and the cavity structure of the metal reflective module  110  surrounding the metal radiation portion  100  effectively benefits reflection of wireless signals, thereby enhancing the gain of the broadband antenna  10 . The metal reflective module  110  substantially comprises the metal reflective elements  111 - 115  which are flat-structured ones. Therefore, it is simple to manufacture and convenient for storage and transportation after disassembled. 
         [0032]    Simulation and measurement may be employed to determine whether the broadband antenna  10  meets system requirements. For example,  FIG. 1E  is a schematic diagram illustrating antenna resonance simulation results of the assembled broadband antenna  10 , wherein length and width of the assembled broadband antenna  10  are both set to be 500 mm, height is set to be 163 mm, and distance D1 between the metal reflective elements  111 - 115  is set to be 0.5 mm. As can be seen from  FIG. 1E , the resonance bandwidth of the broadband antenna  10  covers ultra high frequency (UHF) band by using −10 dB as a threshold. On the other hand, Table 1 is an antenna characteristic table for the broadband antenna  10 . According to Table 1, the broadband antenna  10  has a high directivity. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 3 dB 
                   
                 common polarization 
               
               
                   
                 maximum 
                 beam- 
                 front-to-back 
                 to cross polarization 
               
               
                 frequency 
                 gain 
                 width 
                 (F/B) ratio 
                 (Co/Cx) ratio 
               
               
                   
               
             
             
               
                 470 MHz 
                  8.7 dBi 
                 72 deg 
                 25.6 dB 
                 48.5 dB 
               
               
                 500 MHz 
                  9.0 dBi 
                 70 deg 
                 27.5 dB 
                 44.7 dB 
               
               
                 600 MHz 
                 10.0 dBi 
                 60 deg 
                 42.3 dB 
                 45.5 dB 
               
               
                 700 MHz 
                 11.4 dBi 
                 49 deg 
                 18.3 dB 
                 47.6 dB 
               
               
                 800 MHz 
                 11.4 dBi 
                 43 deg 
                 20.3 dB 
                 51.5 dB 
               
               
                 862 MHz 
                 12.0 dBi 
                 38 deg 
                 23.6 dB 
                 36.6 dB 
               
               
                   
               
             
          
         
       
     
         [0033]    In order to further reduce the maximum area, length and width of single plate of the disassembled broadband antenna  10 , please refer to  FIGS. 2A-2C .  FIG. 2A  is a schematic diagram illustrating an exploded view of a broadband antenna  20  according to an embodiment of the present invention.  FIG. 2B  is a schematic diagram illustrating a perspective view of the broadband antenna  20  after assembly. As shown in  FIG. 2A , structures of the broadband antenna  20  and the broadband antenna  10  are substantially similar. However, unlike the broadband antenna  10 , a metal reflective element  215  of a metal reflective module  210  of the broadband antenna  20  comprises metal reflective plates  215   a - 215   d . Moreover, the metal reflective plates  215   a - 215   d  can be assembled to form the metal reflective element  215  by fixing assembly elements  2151   c ,  2152   d ,  2153   a  and  2154   b  of the metal reflective plates  215   a - 215   d  together, by fixing assembly elements  2152   a  and  2154   a  of the metal reflective plate  215   a  respectively to an assembly element  2151   b  of the metal reflective plate  215   b  and an assembly element  2151   d  of the metal reflective plate  215   d , and by fixing assembly elements  2152   c  and  2154   c  of the metal reflective plate  215   c  to an assembly element  2153   b  of the metal reflective plate  215   b  and an assembly element  2153   d  of the metal reflective plate  215   d . Besides, assembly elements  2151   a ,  2154   a ,  2151   d  and  2154   d  of the metal reflective element  215  can be fixed to assembly elements  2111 ,  2115  and  2114  of the metal reflective element  211 ; assembly elements  2151   a ,  2152   a ,  2151   b  and  2152   b  can be fixed to assembly elements  2121 ,  2125  and  2122  of the metal reflective element  212 ; assembly elements  2152   b ,  2153   b ,  2152   c  and  2153   c  can be fixed to assembly elements  2132 ,  2135  and  2133  of the metal reflective element  213 ; assembly elements  2153   c ,  2154   c ,  2153   d  and  2154   d  can be fixed to assembly elements  2143 ,  2145  and  2144  of the metal reflective element  214 .  FIG. 2C  is a schematic diagram illustrating antenna resonance simulation results of the broadband antenna  20 , wherein length and width of the broadband antenna  20  are set to be 500 mm, height is set to be 163 mm; the distance D1 between the metal reflective elements  211 - 214  and the metal reflective plates  215   a - 215   d  is set to be 0.5 mm. As can be seen from  FIG. 2C , the resonance bandwidth of the broadband antenna  20  covers ultra high frequency by using −10 dB as a threshold. On the other hand, Table 2 is an antenna characteristic table for of the broadband antenna  20 . According to Table 2, the broadband antenna  20  has a high directivity. Furthermore, since the metal reflective element  215  is formed from four smaller metal reflective plates assembled together, the maximum area, length and width of one single dismantled metal reflective plate can be minimized to facilitate storage and transportation. Please note that the metal reflective element  215  may be formed from two or more pieces of metal reflective plates to make storage and transportation easier. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 3 dB 
                   
                 common polarization 
               
               
                   
                 maximum 
                 beam- 
                 front-to-back 
                 to cross polarization 
               
               
                 frequency 
                 gain 
                 width 
                 ratio 
                 ratio 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 470 MHz 
                 8.7 
                 dBi 
                  7l deg 
                 17.2 dB 
                 31.3 dB 
               
               
                 500 MHz 
                 9.l 
                 dBi 
                 68 deg 
                 16.4 dB 
                 25.8 dB 
               
               
                 600 MHz 
                 9.l 
                 dBi 
                 59 deg 
                 10.1 dB 
                 17.3 dB 
               
               
                 700 MHz 
                 10.7 
                 dBi 
                 53 deg 
                 15.5 dB 
                 28.7 dB 
               
               
                 800 MHz 
                 11.4 
                 dBi 
                 43 deg 
                 14.6 dB 
                 42.6 dB 
               
               
                 862 MHz 
                 12.2 
                 dBi 
                 38 deg 
                 19.4 dB 
                 44.3 dB 
               
               
                   
               
             
          
         
       
     
         [0034]    In order to further reduce the maximum area, length and width of the single plate of the disassembled broadband antenna  20 , please refer to  FIGS. 3A-3C .  FIG. 3A  is a schematic diagram illustrating an exploded view of a broadband antenna  30  according to an embodiment of the present invention.  FIG. 3B  is a schematic diagram illustrating a perspective view of the broadband antenna  30  after assembly.  FIG. 3C  is a schematic diagram illustrating antenna resonance simulation results of the broadband antenna  30 . As shown in  FIG. 3A , structures of the broadband antenna  30  and the broadband antenna  20  are substantially similar. However, unlike the broadband antenna  20 , a metal reflective element  311  of a metal reflective module  310  of the broadband antenna  30  comprises metal reflective plates  311   a  and  311   b , a metal reflective element  312  comprises metal reflective plates  312   a  and  312   b , a metal reflective element  313  comprises metal reflective plates  313   a  and  313   b , and a metal reflective element  314  comprises metal reflective plates  314   a  and  314   b . Moreover, the metal reflective plates  311   a ,  311   b  can be assembled to form the metal reflective element  311  by fixing assembly elements  3111   a  and  3112   a  of the metal reflective plate  311   a  to assembly element  3114   b  and  3113   b  of the metal reflective plate  311   b  together. The metal reflective plates  312   a  and  312   b  can be assembled to form the metal reflective element  312  by fixing assembly element  3122   a  and  3123   a  of the metal reflective plate  312   a  to assembly elements  3121   b  and  3124   b  of the metal reflective plates  312   b  together, The metal reflective plate  313   a  and  313   b  can be assembled to form the metal reflective element  313  by fixing assembly elements  3133   a  and  3134   a  of the metal reflective plate  313   a  to assembly elements  3132   b  and  3131   b  of the metal reflective plate  313   b  together. The metal reflective plates  314   a  and  314   b  can be assembled to form the metal reflective element  314  by fixing assembly elements  3141   a  and  3144   a  of the metal reflective plate  314   a  to assembly elements  3142   b  and  3143   b  of the metal reflective plate  314   b  together.  FIG. 3C  shows the antenna simulation resonant results of the broadband antenna  30 , wherein length and width of the assembled broadband antenna  30 , are set to be 500 mm, height is set to be 163 mm, and the distance D1 between the metal reflective plates  311   a - 314   b  and  215   a - 215   d  is set to be 0.5 mm. As can be seen from  FIG. 3C , the resonance bandwidth of the broadband antenna  30  covers ultra high frequency band by using −10 dB as a threshold. On the other hand, Table 3 is an antenna characteristic table for the broadband antenna  30 . According to table 3, the broadband antenna  30  has a high directivity. Since the metal reflective elements  311 - 314  are formed from two smaller metal reflective plates assembled together, the maximum area, length and width of one single dismantled metal reflective can be minimized to facilitate storage and transportation. It is worth to note that the metal reflective elements  311 - 314  can be respectively formed from more pieces of the metal reflective plates to further increase convenience of storage and transportation. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 3 dB 
                   
                 common polarization 
               
               
                   
                 maximum 
                 beam- 
                 front-to-back 
                 to cross polarization 
               
               
                 frequency 
                 gain 
                 width 
                 ratio 
                 ratio 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 470 MHz 
                 8.8 
                 dBi 
                 70 deg 
                 17.2 dB 
                 40.2 dB 
               
               
                 500 MHz 
                 9.l 
                 dBi 
                 68 deg 
                 17.3 dB 
                 47.2 dB 
               
               
                 600 MHz 
                 8.8 
                 dBi 
                 57 deg 
                  8.1 dB 
                 17.5 dB 
               
               
                 700 MHz 
                 10.7 
                 dBi 
                 53 deg 
                 15.8 dB 
                 32.4 dB 
               
               
                 800 MHz 
                 11.4 
                 dBi 
                 44 deg 
                 14.4 dB 
                 42.7 dB 
               
               
                 862 MHz 
                 12.l 
                 dBi 
                 38 deg 
                 19.5 dB 
                 40.4 dB 
               
               
                   
               
             
          
         
       
     
         [0035]    As set forth above, the metal reflective elements in the embodiment of the present invention can be formed with a plurality of metal reflective plates, and two adjacent metal reflective elements can be electrically connected by assembly elements, such that the metal reflective module can provide a cavity structure to effectively reflect wireless radio signals and to increase gain of the broadband antenna. However, when the size of the metal reflective module is enlarged, not only the gain of the broadband antenna can increase but weight of the broadband antenna or air resistance (sometimes called drag) of the broadband antenna, when installed outdoors, will also grow. Therefore, geometrical structure of the metal reflective module can be properly adjusted according to system requirements. Please refer to  FIG. 4A .  FIG. 4A  is a schematic diagram illustrating a perspective view of the broadband antenna  40  after assembly according to an embodiment of the present invention. As shown in  FIG. 4A , structures of the broadband antenna  40  and the broadband antenna  10  are substantially similar. However, metal reflective elements  411 - 415  of the broadband antenna  40  comprise a plurality of grids.  FIG. 4B  is a schematic diagram illustrating antenna resonance simulation results of the broadband antenna  40 .  FIG. 4C  is a schematic diagram illustrating antenna gain versus radiation pattern angle relationship for the broadband antenna  40  operated at 500 MHz .  FIG. 4D  is a schematic diagram illustrating antenna gain versus radiation pattern angle relationship for the broadband antenna  40  operated at 800 MHz. In  FIGS. 4C and 4D , length and width of the assembled broadband antenna  40  are set to be 500 mm, height is set to be 163 mm, the distance D1 between the metal reflective elements  411 - 415  is set to be 0.5 mm, the metal reflective elements  411 - 414  are respectively woven from 6 transverse metal wires and 16 longitudinal metal wires (i.e., 6 rows of metal wires woven over and under 16 columns of metal wires), and the metal reflective element  415  is woven from 16 transverse metal wires and 16 longitudinal metal wires. As can be seen from  FIG. 4B , the resonance bandwidth of the broadband antenna  40  covers ultra high frequency band by using −10 dB as a threshold. On the other hand, Table 4 is an antenna characteristic for the broadband antenna  40 . According to Table 4, the broadband antenna  40  has a high directivity. Since the metal reflective elements  411 - 415  respectively have a plurality of grids, both the weight and air resistance of the broadband antenna  40  can be further minimized. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                 3 dB 
                   
                 common polarization 
               
               
                   
                 maximum 
                 beam- 
                 front-to-back 
                 to cross polarization 
               
               
                 frequency 
                 gain 
                 width 
                 ratio 
                 ratio 
               
               
                   
               
             
             
               
                 470 MHz 
                  8.6 dBi 
                 73 deg 
                 31.0 dB 
                 44.6 dB 
               
               
                 500 MHz 
                  8.8 dBi 
                 72 deg 
                 33.5 dB 
                 43.2 dB 
               
               
                 600 MHz 
                 10.0 dBi 
                 60 deg 
                 35.9 dB 
                 41.5 dB 
               
               
                 700 MHz 
                 11.0 dBi 
                 50 deg 
                 18.6 dB 
                 48.0 dB 
               
               
                 800 MHz 
                 11.0 dBi 
                 44 deg 
                 20.9 dB 
                 45.9 dB 
               
               
                 862 MHz 
                 11.2 dBi 
                 42 deg 
                 21.0 dB 
                 34.6 dB 
               
               
                   
               
             
          
         
       
     
         [0036]    In short, the metal reflective module  410  with grids is substantially composed of the metal reflective elements  411 - 415 , which substantially have a plate-like structure respectively. Therefore, it is not only simple to manufacture but also easier for storage and transportation after dismantled. Furthermore, because there are a plurality of grids in the metal reflective elements  411 - 415  respectively, it can effectively minimize the weight and air resistance of the broadband antenna. 
         [0037]    Please note that the broadband antennas  10 - 40  are exemplary embodiments of the present invention. Those skilled in the art can make modifications or alterations accordingly. For example, the gap G1 is related to operating frequency of the broadband antenna. In general, when the gap G1 is substantially equal to a quarter of a wavelength of wireless signals, the broadband antenna can provide a maximum gain. As long as the metal radiation portion  100  and the metal reflective module are not electrically connected to each other, the supporting element  120  can be made of isolating materials, such as wood, glass, rubber etc., but is not limited thereto. On the other hand, size of the grids within the metal reflective elements can be properly adjusted according to system requirements, and each of the metal reflective elements may have different grid sizes. As shown in  FIG. 4A , the grids of the metal reflective elements  411 - 414  have a shape substantially conforming to a square; however, the present invention is not limited thereto, and the grids may have other shapes such as a triangle, a rectangle, a diamond, a hexagon or other proper shapes. Lengths of the metal reflective elements can be adjusted according to system requirements and thus may not be a constant. The metal reflective module is not limited to have a shape conforming to cuboid, and it maybe assembled to form a cavity structure of other shapes, for example, a sphere, a polyhedron or an irregular three-dimensional structure, which facilitates storage and transportation after the metal reflective module is properly folded or dismantled. 
         [0038]    The assembly elements of the broadband antennas can be electrically connected by soldering; for example, the metal reflective element  215  can be formed by soldering the metal reflective plates  215   a - 215   d  shown in  FIGS. 2A-2C . However, according to ways to dismantle or fold the metal reflective module, fixation of the supporting element and the metal reflective module as well as structure of the assembly element can be properly designed. For example, please refer to  FIG. 5 .  FIG. 5  is a schematic diagram illustrating a locally enlarged view of a broadband antenna  50  according to an embodiment of the present invention. Structures of the broadband antenna  50  and the broadband antenna  40  are substantially similar. In the broadband antenna  50 , the assembly elements (e.g., the assembly elements  1131 ,  1123 ) at the adjacent vertices of the metal reflective elements may have an opening respectively, and can be fixed with corresponding locking elements (e.g., locking elements  550   a ,  550   b ) of the assembly elements, such that the metal reflective module can be assembled to form a cavity structure, electrical connection among the metal reflective elements can be ensured, and the broadband antenna  50  may be dismantled for easier storage or transportation. Please note that the locking elements (e.g., the locking element  550   b ) can be fixed to the corresponding assembly elements (e.g., the assembly element  1131 ) of the metal reflective elements (e.g., the metal reflective element  413 ), and, alternatively, the locking elements (e.g.,  550   a ) can be semi-fixed to the corresponding assembly elements (e.g.,  1123 ) of the metal reflective elements (e.g.,  412 ) to ensure relative rotation. Besides, please refer to  FIG. 6 .  FIG. 6  is a schematic diagram illustrating a locally enlarged view of a broadband antenna  60  according to an embodiment of the present invention. Structures of the broadband antenna  60  and the broadband antenna  40  are substantially similar. In the broadband antenna  60 , the assembly elements (e.g.,  1131 ,  1123 ) at the adjacent vertices of the metal reflective elements may have a shaft hole respectively, and can be fixed with corresponding shaft elements (e.g., a shaft element  650 ) of the assembly elements serving as a pivot, such that the metal reflective module can be assembled to form a cavity structure, electrical connection among the metal reflective elements can be ensured, and the broadband antenna  60  may be dismantled for easier storage or transportation. Please note that the shaft elements (e.g., the shaft element  650 ) can be semi-fixed to the corresponding assembly elements (e.g.,  1131 ) of the metal reflective elements (e.g.,  413 ) or assembly elements (e.g.,  1123 ) of metal reflective elements (e.g.  412 ) to ensure relative rotation. Please refer to  FIG. 7 .  FIG. 7  is a schematic diagram illustrating a locally enlarged view of a broadband antenna  70  according to an embodiment of the present invention. Structures of the broadband antenna  70  and the broadband antenna  40  are substantially similar. In the broadband antenna  70 , the assembly elements (e.g.,  1131 ,  1123 ) at the adjacent vertices of the metal reflective elements may respectively be a sliding slot and a sliding pin structure with sizes corresponding to each other. In this case, the sliding pin structure can be pushed onto the sliding slot to lock metal reflective elements, such that the metal reflective module can be assembled to form a cavity structure, electrical connection among the metal reflective elements can be ensured, and the broadband antenna  70  may be dismantled for easier storage or transportation. 
         [0039]    In addition, the assembly elements  1111 - 3144   b  of the broadband antennas  10 - 70  are exemplary embodiments of the present invention, but the present invention is not limited thereto and may be adjusted by adding or reducing the number of the assembly elements according to different design requirements such as the structure of the assembly elements. Please refer to  FIG. 8 .  FIG. 8  is a schematic diagram illustrating a locally enlarged view of a broadband antenna  80  according to an embodiment of the present invention. Structures of the broadband antenna  80  and the broadband antenna  40  are substantially similar. In the broadband antenna  80 , the assembly elements (e.g. ,  1123 ) of the metal reflective elements may be a hook, and can be fixed to a longitudinal metal wire (e.g., WIRE 1 ) at the edge of the adjacent vertex, such that the metal reflective module can be assembled to form a cavity structure, electrical connection among the metal reflective elements can be ensured, and the broadband antenna  80  may be dismantled for easier storage or transportation. In other words, assembly elements may be disposed merely around a portion of the vertices of the metal reflective elements (e.g. ,  413 ), while no assembly element is provided around the other vertices (e.g., the vertex around the longitudinal metal wire WIRE 1 ) of the metal reflective elements (i.e.,  413 ). In such a situation, an assembly element (e.g. ,  1123 ) is fixed to the corresponding vertex (e.g., the vertex around the longitudinal metal wire WIRE 1 ) of the adjacent metal reflective elements without an assembly element so as to assemble the metal reflective module to form a cavity structure. 
         [0040]    On the other hand, the broadband antenna of the present invention may be a broadband dual polarization antenna. Please refer to  FIG. 9 .  FIG. 9  is a schematic diagram illustrating a broadband antenna  90  according to an embodiment of the present invention. Structures of the broadband antenna  90  and the broadband antenna  40  are substantially similar. Unlike the broadband antenna  40 , the broadband antenna  90  further comprises a metal radiation portion  900  disposed on the metal radiation portion  100 . The supporting element  120  separates the metal radiation portion  900  from the metal radiation portion  100  by a gap so that the metal radiation portion  900  is electrically isolated from the metal radiation portion  100  to enhance isolation of the metal radiation portions  100  and  900 . The metal radiation portion  900  comprises triangular metal plates  902  and  904 . The base of the triangular metal plate  102  is in parallel to the base of the triangular metal plate  104 , forming the metal radiation portion  900  into a rhombus. A midline of the metal radiation portion  100  is substantially perpendicular to a midline of the metal radiation portion  900 . 
         [0041]    Please note that the metal radiation portions  100  and  900  of the broadband antenna  90  shown in  FIG. 9  are parallel to each other, but not limited hereto. The metal radiation portion  900  of the broadband antenna  90  of the embodiment of the present invention can be leaned out from the supporting element  120  upwardly. Alternatively, the metal radiation portion  100  can be leaned out from the central supporting element  120  toward the metal reflective element  415 . In other words, the metal radiation portion  100  of the present invention may not be completely parallel to the metal radiation portion  900 . On the other hand, the metal radiation portion  100  of present invention of the broadband antenna  90  can be bent upward with a specific curvature to lower down radiation pattern, thereby balancing the radiation pattern. Alternatively, the metal radiation portion  900  of the broadband antenna  90  of the embodiment of the present invention can be bent toward the metal reflective element  415  with a specific curvature in order to shorten the distance between the metal radiation portion  900  and the metal reflective element  415 , thereby rising radiation pattern of the metal radiation portion  900 . 
         [0042]    In summary, the triangular metal plates of the metal radiation portions in the embodiment of the present invention increase bandwidth. After assembly, the metal radiation portion is enveloped by the metal reflective module of a cavity structure to effectively reflect wireless signals and to enhance the gain of the broadband antenna. After dismantling, the elements of the broadband antenna can be accommodated separately. Because the metal reflective module is substantially composed of the metal reflective elements of a plate-like structure, it is simple to manufacture and easier for storage and transportation. Besides, the metal reflective elements may have a plurality of grids respectively to minimize both weight and air resistance of the broadband antenna. 
         [0043]    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. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.