Patent Publication Number: US-7719479-B2

Title: Antenna array

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority benefit of Taiwan application serial no. 96122770, filed on Jun. 23, 2007. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention generally relates to an antenna array, and more particularly to an antenna array with a simple production process and lower side lobe energy dissipation of its radiation pattern. 
   2. Description of Prior Art 
   Currently, the conventional antenna array includes a grounding plate, radiation conductors, a signal transmission part, and a signal feed cable. Wherein, the radiation parts are set on the top side of the grounding plate, and the signal transmission part is connected between the radiation conductors. The signal feed cable includes a central conductor connected to the signal transmission part and an outer conductor connected to the grounding plate. The signal feed cable is used to feed the high frequency signal into the conventional antenna array. 
   The high frequency signal may leak its energy when transmitting in the signal transmission part, and thus an energy loss occurs. Further, because the signal transmission part and the radiation conductors of the conventional antenna array are sited at the same side of the grounding plate, the radiation pattern of the conventional antenna array may be interfered by the leaking energy. Thus, the energy of the side lobe in the radiation pattern of the conventional array may increase, and according to the law of the energy conservation, the increasing of the energy of the side lobe decreases the signal level of the main lobe of the conventional antenna array. Furthermore, when the distance between the signal transmission part and the grounding plate is large, the input impendence of the conventional antenna array may be large too, and thus the impendence match of the conventional antenna is hard to be achieved. Accordingly, the signal transmission part of the conventional antenna array may be bent to approach the grounding plate. Thus, the transmission impendence of the signal transmission part may be lowered, and the impendence match may be achieved. 
   Contrary to the design of making the signal transmission part approach to the grounding plate, the efficiency of the radiated signal of the conventional antenna array may increase when the distance between the radiation conductors and the grounding plate increases. That is, the gain of the whole radiated signal may be enhanced when the distance between the radiation conductors and the grounding plate is large. 
   The radiation conductors and the signal transmission part are connected to each other, but the design of the distance between the radiation conductors and the grounding plate and the design of the distance between the signal transmission part and the grounding plate are opposite to each other. Therefore, the radiation conductors and the signal transmission part must be sited on the different heights, and the difficulty of producing the conventional antenna array may increase. Thus the impendence of the conventional antenna array may be hard to adjust and match, the stability of conventional antenna array may decrease, and the production cost of the conventional antenna array may increase. In addition, for the conventional antenna array, the isolation level of the radiation conductors may decrease when the distance between the radiation conductors is too short. That is, the interference thereof may occur, and the radiation pattern of the conventional antenna array is affected. 
   In order to solve these and other problems as stated above, the exemplary embodiment of the present invention provides an antenna array with a simple production process and lower side lobe energy dissipation of its radiation pattern. 
   SUMMARY OF THE INVENTION 
   Accordingly, the exemplary embodiment of present invention is directed to an antenna array. The antenna array lowers the leaking energy of its signal transmission part, and thus the interference to the radiation pattern of the antenna array is decreased. Therefore, the energy dissipation of the side lobe of the antenna array is decreased, and the radiated signal level is enhanced. 
   The antenna array provided by the exemplary embodiment of the present invention has a simple producing process and flexibility for adjusting the impendence of the antenna array. Therefore, the stability of the antenna array is increased, and the producing cost thereof is decreased. 
   Further, for the antenna array provided by the exemplary embodiment of the present invention, the distance between its radiation conductors is increased, and thus the interference between the radiation conductors is decreased. Therefore, the energy of the main lobe in the radiation pattern is increased. 
   The exemplary embodiment of the present invention provides an antenna array. The antenna array comprises a plurality of grounding plates, a signal transmission part, a first radiation conductor, a second radiation conductor, and a signal feed cable. Wherein, the plurality of grounding plates comprises a first, second, third, fourth, and fifth grounding plates. A first hole (or groove) and a second hole (or groove) are sited on the second and fourth grounding plates respectively. The first and fifth grounding plates are located at a same plane. The second and fourth grounding plates are connected to the first and fifth grounding plates respectively, and substantially perpendicular with the first and fifth grounding plates respectively. The second and fourth grounding plates substantially extend with a same direction. The third grounding plate is connected the between the second and fourth grounding plates and substantially perpendicular with the second and fourth grounding plates. The signal transmission part has a first and second ends and passes through the first and second holes (or grooves), and a direction from the first end to the second end is substantially perpendicular with the second and fourth grounding plates. The first radiation conductor is connected to the first end and substantially parallel with the first grounding plate. The second radiation conductor is connected to the second end and substantially parallel with the fifth grounding plate. The signal feed cable comprises a central conductor connected to the signal transmission part and an outer conductor connected to the third grounding plate. 
   According to an exemplary embodiment of the present invention, the antenna array further comprises at least a first supporting pillar and at least a second supporting pillar. Wherein, the first supporting pillar set between the first radiation conductor and the first grounding plate is adapted for supporting the first radiation conductor. The second supporting pillar set between the second radiation conductor and the fifth grounding plate is adapted for supporting the second radiation conductor. 
   According to an exemplary embodiment of the present invention, the antenna array further comprises a sixth and seventh grounding plates. Wherein, the sixth grounding plate connected to the first grounding plate is substantially perpendicular with the first grounding plate. The seventh grounding plate connected to the fifth grounding plate is substantially perpendicular with the fifth grounding plate. The sixth and seventh grounding plates are substantially parallel with the second and fourth grounding plates, and a direction which the sixth grounding plate extends is substantially same as a direction which the seventh grounding plate extends. 
   According to an exemplary embodiment of the present invention, an opening direction of the first groove is substantially same as or opposite to an opening direction of the second groove. 
   Accordingly, since the signal transmission part passes through the first and second holes (or grooves) to connect with the first and second radiation conductors, the signal transmission part is surrounded by the second, third, and fourth grounding plates. Consequently, the leaking energy of the signal transmission part is substantially blocked by the second, third, and fourth grounding plates, and the leaking energy of the signal transmission part affects the radiation pattern less. Furthermore, the leaking energy of the side lobe is decreased, and the gain of the radiated signal is enhanced. When the first and second radiation is distant from the first and fifth grounding plates, the signal transmission part is near the third grounding plate, so as to achieve the better radiation efficiency of the antenna array and flexibility for adjusting the impendence of the antenna array. 
   Further, the first and second radiation conductors are respectively connected to the first and second ends of the signal transmission part. Thus, the first and second radiation conductors are isolated by the second, third, and fourth grounding plates, and the interference between the he first and second radiation conductors is decreased by this arrangement. 
   The first and second supporting pillars are made by insulating materials. If the signal transmission touches the second and fourth grounding plates, the part the performance of the antenna array will perform badly. Thus, using the first and second supporting pillars can prevent the signal transmission part from touching the second and fourth grounding plates, so as to achieve the better performance of the antenna array. 
   The first radiation conductor is surrounded by the second and sixth grounding plates, and the second radiation conductor is surrounded by the fourth and seventh grounding plates, hence the radiations of the first and second radiation conductors are more focusing and not dispersing divergently. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is a solid schematic diagram showing an antenna array  100  provided by one exemplary embodiment of the present invention. 
       FIG. 2A  is an explosive schematic diagram showing the decomposition of the antenna array  100  provided by one exemplary embodiment of the present invention. 
       FIG. 2B  is a solid schematic diagram showing the signal feed cable  4  of the antenna array  100  provided by one exemplary embodiment of the present invention. 
       FIG. 2C  is sectional schematic diagram showing the signal feed cable  4  of the antenna array  100  provided by one exemplary embodiment of the present invention. 
       FIG. 3  is a solid schematic diagram showing an antenna array  300  provided by one exemplary embodiment of the present invention, wherein the antenna array  300  further comprises a plurality of supporting pillars  51  and  52 . 
       FIG. 4  is a solid schematic diagram showing an antenna array  400  provided by one exemplary embodiment of the present invention, wherein the antenna array  400  further comprises a plurality of grounding plates  16  and  17 . 
       FIG. 5  is a curve diagram showing the relation of the return loss and the frequency of the antenna array  400  provided by one exemplary embodiment of the present invention. 
       FIG. 6  is curve diagram showing the radiation pattern of the antenna array  400  provided by one exemplary embodiment of the present invention. 
       FIG. 7A  is a solid schematic diagram showing an antenna array  700  provided by one exemplary embodiment of the present invention, wherein the opening directions of the grooves  122  and  142  are the same. 
       FIG. 7B  is a solid schematic diagram showing an antenna array  701  provided by one exemplary embodiment of the present invention, wherein the opening directions of the grooves  122  and  143  are opposite to each other. 
       FIG. 8  is a solid schematic diagram showing an antenna array  800  provided by one exemplary embodiment of the present invention, wherein the antenna array  800  further comprises a plurality of supporting pillars  51  and  52 . 
       FIG. 9  is a solid schematic diagram showing an antenna array  900  provided by one exemplary embodiment of the present invention, wherein the antenna array  900  further comprises a plurality of grounding plates  16  and  17 . 
   

   DESCRIPTION OF THE EMBODIMENTS 
   Reference will now be made in detail to the present preferred embodiment of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
   Referring to  FIGS. 1 and 2A ,  FIG. 1  is a solid schematic diagram showing an antenna array  100  provided by one exemplary embodiment of the present invention, and  FIG. 2A  is an explosive schematic diagram showing the decomposition of the antenna array  100  provided by one exemplary embodiment of the present invention. The antenna array  100  comprises a plurality of grounding plates  1 , a signal transmission part  2 , two radiation conductors  3 , and signal feed cable  4 . 
   Wherein, the antenna array the plurality of grounding plates  1  comprise a first grounding plate  11 , a second grounding plate  12 , a third grounding plate  13 , a fourth grounding plate  14 , and a fifth grounding plate  15 . Two holes  121 ,  141  are sited on the second grounding plate  12  and the fourth grounding plate  14  respectively. The first grounding plate  11  and the fifth grounding plate  15  are located at the same plane. The second and fourth grounding plates  12 ,  14  are connected to the first and fifth grounding plates  11 ,  15  respectively, and substantially perpendicular with the first and fifth grounding plates  11 ,  15  respectively. The second and fourth grounding plates  12 ,  14  substantially extend with a same direction. The two sides of third grounding plate  13  are connected with the second and fourth grounding plates  12 ,  14  and substantially perpendicular with the second and fourth grounding plates  12 ,  14 . In the practical producing process, the plurality of grounding plates can be made by a single metal sheet member, and then the single metal sheet member is bent to form the first, second, third, fourth, and fifth grounding plates  11 ,  12 ,  13 ,  14 ,  15  in order. 
   The signal transmission part  2  is can be a rectangular member passing through the two holes  121 ,  141 , and a direction from the end  21  of the signal transmission part  2  to the end  22  of the signal transmission part  2  is substantially perpendicular with the second and fourth grounding plates  12 ,  14 . 
   The two radiation conductors  2  comprise two radiation conductors  31  and  32 . The radiation conductor  31  is connected to the end  21  and substantially parallel with the first grounding plate  11 . The radiation conductor  32  is connected to the end  22  and substantially parallel with the fifth grounding plate  15 . In this embodiment, the radiation conductors  31  and  32  are rectangular radiation conductors, however the implementation of the radiation conductors  31  and  32  is not intended to limit the scope of the present invention. 
   Please see  FIGS. 1 ,  2 B and  2 C,  FIG. 2B  is a solid schematic diagram showing the signal feed cable  4  of the antenna array  100  provided by one exemplary embodiment of the present invention, and  FIG. 2C  is sectional schematic diagram showing the signal feed cable  4  of the antenna array  100  provided by one exemplary embodiment of the present invention. From inner to outer, the signal feed cable  4  comprises a central conductor  41 , a first isolation layer  42 , an outer conductor  43 , and a second isolation layer  44 . Wherein, the central conductor  41  is connected to the signal transmission part  2 , and the outer conductor  43  is connected to the third grounding plate  13 . In this embodiment, the position where the central conductor  41  is connected to the signal transmission part  2  is between the second and fourth grounding plates  12 ,  14 . 
   In the embodiment, when the radiation conductors  3  is far away from the first grounding plate  11 , the distance between the radiation conductors  3  and the first grounding plate  11  increases, so as to letting the signal transmission part  2  close to the third grounding plate  13 . Thus, the radiation efficiency of the antenna array  100  performs well, and the impendence matching of the antenna array  100  is easy to be adjusted. In addition, the signal transmission part  2  is surrounded by the second, third, and fourth grounding plates  12 ,  13 ,  14 , and thus the leaking energy of the signal transmission part  2  is blocked by the second, third, and fourth grounding plates  12 ,  13 ,  14 . Therefore, the effect of the leaking energy of the signal transmission part  2  on the radiation pattern of the radiation conductors  3  is reduced, the leaking energy of the side lobe is reduced, and the gain of the radiated signal is enhanced. 
   Furthermore, the radiation conductors  31  and  32  are connected to the ends  21  and  22  of the signal transmission part  2 , and are isolated by the second, third, fourth grounding plates  12 ,  13 ,  14 . Thus the interference between the radiation conductors  31  and  32  is reduced. 
   Please see  FIG. 3 ,  FIG. 3  is a solid schematic diagram showing an antenna array  300  provided by one exemplary embodiment of the present invention, wherein the antenna array  300  further comprises a plurality of supporting pillars  51  and  52 . The supporting pillars  51  and  52  are made of insulating materials. The supporting pillar  51  is set between the radiation conductor  31  and the first grounding plate  11 , which is used for supporting the radiation conductor  31 . The supporting pillar  52  is set between the radiation conductor  32  and the fifth grounding plate  15 , which is used for supporting the radiation conductor  32 . Thus, the signal transmission part  2  connected to the radiation conductors  3  do not touch the second and fourth grounding plates  12 ,  14 , and the destruction of the performance of the antenna array  300  is prevented. 
   Please see  FIG. 4 ,  FIG. 4  is a solid schematic diagram showing an antenna array  400  provided by one exemplary embodiment of the present invention, wherein the antenna array  400  further comprises a plurality of grounding plates  16  and  17 . The sixth grounding plate  16  is connected to the first grounding plate  11  and substantially perpendicular with the first grounding plate  11 . The seventh grounding plate  17  is connected to the fifth grounding plate  15  and substantially perpendicular with the fifth grounding plate  15 . The sixth and seventh grounding plates  16 ,  17  are substantially parallel with the second and fourth grounding plates  12 ,  14 , and a direction which the sixth grounding plate  16  extends is substantially same as a direction which the seventh grounding plate  17  extends. The radiation conductor  31  is surrounded by the second and sixth grounding plates  12 ,  16 , and the radiation conductor  32  is surrounded by the fourth and seventh grounding plates  14 ,  17 . Hence, the radiations of the radiation conductors  3  are more focusing and not dispersing divergently. Therefore, the radiation gain of the antenna array  400  is enhanced greatly. 
   In this embodiment, the first, third, and fifth grounding plates  11 ,  13 ,  15  are rectangular metal sheets which lengths and widths are about 5 centimeters. The second and fourth grounding plates  12 ,  14  are rectangular metal sheets which lengths and heights are about 5 centimeters and about 1 centimeter respectively. The sixth and seventh grounding plates  16 ,  17  are rectangular metal sheets which sizes are same as that of the second grounding plate  12 . The signal transmission part  2  is a rectangular metal sheet which length and width are about 4.5 and 0.5 centimeters, and the radiation conductors  3  are rectangular metal sheets which lengths and widths are about 4.5 and 3.5 centimeters. Please see  FIG. 5 ,  FIG. 5  is a curve diagram showing the relation of the return loss and the frequency of the antenna array  400  provided by one exemplary embodiment of the present invention. By the arrangement stated above, the return loss is shown in  FIG. 5 . In the definition of VSWR (Voltage Standing Wave Ratio) being 2:1, the bandwidth of the antenna array  400  is approaching to 1050 megahertz (3300˜4350 megahertz), and the bandwidth of the antenna array  400  covers the bandwidth of the WiMax system (3300˜3800 megahertz). 
   Please see  FIG. 6 ,  FIG. 6  is curve diagram showing the radiation pattern of the antenna array  400  provided by one exemplary embodiment of the present invention. In  FIG. 6 , the maximum gain of the main lobe of the radiation can be about 11.5 dBi (defined in 0°), and the maximum gain of the side lobe can be about −2.5 dBi. Hence, the maximum gains of the antenna array  400  are larger than those of the conventional 1×2 antenna array (about 10 dBi). That is, antenna array  400  has high gains. Furthermore, the side-lobe level of the antenna array  400  can be approaching to 14 dB, and the side-lobe level of the antenna array  400  is also higher than that of the conventional 1×2 antenna array (about 10 dB). 
   Please see  FIGS. 7A and 7B ,  FIG. 7A  is a solid schematic diagram showing an antenna array  700  provided by one exemplary embodiment of the present invention, wherein the opening directions of the grooves  122  and  142  are the same.  FIG. 7B  is a solid schematic diagram showing an antenna array  701  provided by one exemplary embodiment of the present invention, wherein the opening directions of the grooves  122  and  143  are opposite to each other. The difference between antenna array  700  and antenna array  100  is that the holes  121 ,  141  are changed to the grooves  122 ,  142 . The difference between antenna array  701  and antenna array  100  is that the holes  121 ,  141  are changed to the grooves  122 ,  143 . By the design concept stated above, the grounding plates  1  can be produced by a single metal sheet, and the signal transmission part  2  and the radiation conductors  3  can be produced by a single metal sheet, too. Therefore, the producing process is simplified, the impendence of the antenna array  700  or  701  is easy to be adjusted, the stability of the product is enhanced, and the producing cost is lowered. As stated above, the opening directions of the grooves  122 ,  142  are same as each other, and the opening directions of the grooves  122 ,  143  are opposite to each other. However, these implementations of the grooves  122 ,  142 ,  143  are not intended to limit the scope of the present invention. Furthermore, the opening directions of the grooves  122 ,  142 ,  143  are substantially parallel with the third grounding plate  13 . 
   Referring to  FIG. 8 ,  FIG. 8  is a solid schematic diagram showing an antenna array  800  provided by one exemplary embodiment of the present invention, wherein the antenna array  800  further comprises a plurality of supporting pillars  51  and  52 . The supporting pillar  51  is set between the radiation conductor  31  and the first grounding plate  11 , which is used for supporting the radiation conductor  31 . The supporting pillar  52  is set between the radiation conductor  32  and the fifth grounding plate  15 , which is used for supporting the radiation conductor  32 . Thus, the signal transmission part  2  connected to the radiation conductors  3  do not touch the second and fourth grounding plates  12 ,  14 , and the destruction of the performance of the antenna array  300  is prevented. 
   Referring to  FIG. 9 ,  FIG. 9  is a solid schematic diagram showing an antenna array  900  provided by one exemplary embodiment of the present invention, wherein the antenna array  900  further comprises a plurality of grounding plates  16  and  17 . The sixth grounding plate  16  is connected to the first grounding plate  11  and substantially perpendicular with the first grounding plate  11 . The seventh grounding plate  17  is connected to the fifth grounding plate  15  and substantially perpendicular with the fifth grounding plate  15 . The sixth and seventh grounding plates  16 ,  17  are substantially parallel with the second and fourth grounding plates  12 ,  14 , and a direction which the sixth grounding plate  16  extends is substantially same as a direction which the seventh grounding plate  17  extends. The radiation conductor  31  is surrounded by the second and sixth grounding plates  12 ,  16 , and the radiation conductor  32  is surrounded by the fourth and seventh grounding plates  14 ,  17 . Hence, the radiations of the radiation conductors  3  are more focusing and not dispersing divergently. Therefore, the radiation gain of the antenna array  400  is enhanced greatly. 
   It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing descriptions, it is intended that the present invention covers modifications and variations of this invention if they fall within the scope of the following claims and their equivalents.