Abstract:
An antenna has a plurality of metallic patches and a feed network both being spaced apart from a ground plate at different levels to obtain better radiation pattern and gain effects. Each of the metallic patches has a body with an outer edge from which an inclined wing extends upwardly and outwardly. Furthermore, the metallic patches and the feed network are integrally formed by bending a single piece of metal plate, thus the antenna improves the design flexibility and also simplifies the production process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation-in-part application of the copending U.S. patent application Ser. No. 11/470,592, which was filed on Sep. 6, 2006. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an antenna having patch arrays, and more particularly to an antenna having patch arrays integrally formed with a network thereof. 
         [0004]    2. Description of Related Art 
         [0005]    With the fast development of the wireless communication, the demands for various antennas with different properties or features are increasing. The conventional microstrip antenna is formed by mounting thin metallic patches on a substrate with a ground plate on an opposite side thereof, usually using a feed network cable or a coaxial probe to feed signals. The above metallic patches are usually thin foils with regular shapes, which maybe in shapes of a rectangle, a circle or an ellipse etc. The microstrip antenna can also utilize the metallic patches to form an array structure according to a certain regular arrangement. The pattern of a single metallic patch is difficult to control, and the gain is not high. Therefore array style is used to meet the required conditions. The technique principles of antennas are well known to the industry, so they are not described here any more. 
         [0006]    At the present market, the microstrip antenna generally comprises a ground plate, an SIMO (single in multiple out) feed network and at least a pair of metallic patches. The feed network may be composed of multiple paths with different lengths being connected electrically with the metallic patches respectively along different transmitting directions. When electromagnetic signals are input from a signal recourse, the electromagnetic signals will be feed to each of the metallic patches through the feed network. Since the paths of the feed network have different lengths and transmitting directions, it would result in phase differences and also produce interference. The signals can be radiated out to achieve the objects and effects needed by the antenna. 
         [0007]    Based on the fabricating and assembling techniques, the conventional array antennas may be categorized to three types. 
         [0008]    Type A: The feed network and the metallic patches are individually manufactured and then respectively mounted on the opposite surfaces of the ground plate. 
         [0009]    Type B: The feed network and the metallic patches are individually manufactured, mounted on the same surface of the ground plate and located at different altitudes. 
         [0010]    Type C: The metallic patches and the feed network in the form of microstrip cable are individually manufactured and integrated on a PCB. 
         [0011]    Since the feed network and the metallic patches are individually produced, assembling them to the ground plate respectively would result in higher complexity and obvious interference. Further, the foregoing type C also makes the microstrip increases partial loss, and deteriorates the radiation properties including the gain and the sidelobe level. 
         [0012]    With reference to U.S. Pat. No. 6,326,920, Barnett discloses an antenna comprising a ground plate, a feed network and multiple metallic patches in pairs integrally connected to the feed network. However, the flat configuration of each metallic patch may cause the sidelobe and energy dissipation problem. 
       SUMMARY OF THE INVENTION 
       [0013]    The primary object of the present invention is to provide an antenna, in which metallic patches and a feed network are integrally formed to simplify the production of the antenna, and each of the metallic patches extends an inclined wing to mitigate the sidelobe problem. 
         [0014]    The antenna of the present invention comprises a plurality of metallic patches and a feed network both being spaced apart from a ground plate at different levels to obtain better radiation pattern and gain effects. Each of the metallic patches has a body with an outer edge from which an inclined wing extends upwardly and outwardly. Furthermore, the metallic patches and the feed network are integrally formed by bending a single piece of metal plate, thus the antenna improves the design flexibility and also simplifies the production process. 
         [0015]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a top view of an antenna in accordance with the present invention; 
           [0017]      FIG. 2  is a perspective view of the antenna of  FIG. 1 ; 
           [0018]      FIG. 3  is a side view of the antenna of  FIG. 1 ; 
           [0019]      FIG. 4  shows the return loss of the antenna in accordance with the present invention; and 
           [0020]      FIGS. 5A-5F  show the radiation patterns of the antenna being operated at different frequencies in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    With reference to  FIGS. 1 and 2 , an antenna according to a preferred embodiment of the present invention is proposed. The antenna comprises a ground plate  10 , a feed network  20 , a plurality of metallic patches  30 , multiple conductive screws  40 , conductive fixing posts  50 , insulated supporting posts  60  and a feed coaxial cable  70 . 
         [0022]    The ground plate  10  is made of conductive material and has a top surface  11 , a bottom surface  12  and two opposite edges  13 ,  14 . 
         [0023]    The plurality of metallic patches  30  includes but not limited to three groups of symmetrical metallic patches  30 . The metallic patches  30  are named as a first metallic patch group  30   a , a second metallic patch group  30   b  and a third metallic patch group  30   c  respectively. These metallic patch groups  30   a ,  30   b  and  30   c  are arranged in array that is symmetrical in left and right. Each of the metallic patch  30  has a substantially rectangular body  31  with an outer edge from which an inclined wing  32  extend outwardly and upwardly toward the edge  13 ,  14  of the ground plate  10 . In other words, the two inclined wings  31  of the metallic patches  30  in pairs outwardly extend toward the opposite edges  13 ,  14  of the ground plate  10  respectively. Preferably, taking the ground plate  10  as a basis (0 degree), the angle between the inclined wing  32  and the ground plate  10  may be within a range from 45 to 90 degrees to ensure that the antenna has superior radiation characteristics. With these inclined wings  31 , the radiation energy of the metallic patches  30  can be more concentrated to avoid sidelobe problem and to increase the radiation gain of the antenna. 
         [0024]    The feed network  20  are located above the top surface  11  of the ground plate  10  and interconnected among the metallic patches  30 . The overlooking projection arrangements of the metallic patches  30  and the feed network  20 , the feed network  20  comprises multiple paths with different lengths widths that extend along different directions based on the characteristic requirements of the antenna. 
         [0025]    With further reference to  FIG. 3 , the metallic patches  30  and the feed network  20  of the present invention are located at different levels relative to the top surface of the ground plate  10 , and the metallic patches  30  and the feed network  20  are separated by a certain distance. 
         [0026]    The conductive fixing posts  50  and the insulated supporting posts  60  are disposed below the metallic patches  30  for separating the metallic patches  30  from the top surface  11  of the ground plate  10  by a certain gap. The conductive screws  40  pass through the metallic patches  30  and fasten the metallic patches  30  on the conductive fixing posts  50 . The material of the conductive fixing posts  50  is metal, by connecting the fixing posts  50  and the screws  40  with the metallic patches  30  to make the metallic patches  30  to achieve a ground effect. 
         [0027]    As to the screws  40 , they can be replaced by any other equivalent fastening elements. The insulated supporting posts  60  are plastic posts that can be engaged with each other up and down have a function of supporting the metallic patches  30 . 
         [0028]    Furthermore, the level of the metallic patches  30  relative to the ground plate  10  is higher than that of the feed network  20 . The relative distance between the metallic patches  30  and the feed network  20  can be adjusted according to the required conditions, and the relative distance between the metallic patches  30  and the ground plate  10  also can be adjusted according to the required conditions. 
         [0029]    Besides, in the present invention, the metallic patches  30  and the feed network  20  are stamped and bent from an integral piece of metal. Through a single piece of metal, the shapes of the metallic patches  30  and the feed work  20  are punched out, then vertical connecting portions  25  are formed by bending disposed between the metallic patches  30  and the feed network  20 . 
         [0030]    In a preferred embodiment of the present invention, the feed network  20  may be stamped in a form of H-shaped configuration and the paths thereof between the first metallic patch group  30   a  and the second metallic patch group  30   b  may be further formed with a U-shaped path  21  to increase the flexibility thereof. Since the two metallic patches  30  of the first metallic patch group  30   a  are arranged in symmetrical, their excited baseband-mode currents have opposite phases. The U-shaped paths  21  allow the phases of the two metallic patches  30  being different from each other by 180 degrees. Therefore, the baseband-mode currents of the two metallic patches  30  are accordingly adjusted to be the same phases by the U-shaped paths  21  to improve the gain of the antenna. 
         [0031]    Moreover, when the excited baseband-mode currents of the metallic patches  30  are adjusted to have the same phases, their intercross polarization currents are effectively restrained by each other. The reduction of the intercross polarization currents is also helpful to increase the gain of the antenna. 
         [0032]    The vertical connecting portions  25  along with the metallic patches  30  and the feed network  20  are belonging to a same piece of metal plate, therefore it can secure the electrical connection between the metallic patches  30  and the feed network  20 . 
         [0033]    The feed coaxial cable  70  is mounted on the bottom surface  12  of the ground plate  10  and electrically connected with the feed network  20  so as to feed the signals. 
         [0034]    With reference to  FIG. 1 , when the antenna in accordance with the present invention is operated at the bandwidth S 1  from 3.3 GHz to 3.8 GHz, the return loss is higher than 20 dB. The bandwidth S 1  can be applied to Wimax requiring the operating frequency of 3.5 GHz. 
         [0035]    With reference to  FIGS. 5A to 5F , the return loss characteristics of the antenna are measured when the antenna is operated at different frequencies from 3.3 GHz to 3.8 GHz. The peak gains at different operating frequencies are all higher than 15.0 dB and even reach 16.0 dB. With the antenna configuration of the present invention, the interference to the radiation patterns is effectively mitigated. 
         [0036]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.