Abstract:
A patch antenna having a single patch fed with multiple signals is provided. The patch antenna includes: a first patch; a first feeder and a second feeder which are connected to the first patch; and a second patch which is parallel to the first patch. Accordingly, since multiple signals can be fed into a single patch, a MIMO antenna can be embodied by using a patch antenna which has high isolation between feeders without increasing its size.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Korean Patent Application No. 10-2012-0153117, filed on Dec. 26, 2012 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Methods and apparatuses consistent with exemplary embodiments relate to a patch antenna, and more particularly, to a patch antenna which is fed with signals through a power divider. 
         [0004]    2. Description of the Related Art 
         [0005]    If a multiple input multiple output (MIMO) antenna is implemented in a related-art antenna implementing method, isolation between feeders is not high and thus the feeders affect each other&#39;s signals, thereby attenuating advantages of the MIMO antenna. 
         [0006]    On the other hand, there is a disadvantage of having to increase the size of the antenna several times greater than that of a single antenna to have high isolation. 
         [0007]    Therefore, there is a demand for a method for designing an antenna that is configured to improve performance by increasing isolation between feeders without increasing a size of the antenna. 
       SUMMARY 
       [0008]    One or more exemplary embodiments may overcome the above disadvantages and other disadvantages not described above. However, it is understood that one or more exemplary embodiment are not required to overcome the disadvantages described above, and may not overcome any of the problems described above. 
         [0009]    One or more exemplary embodiments provide a patch antenna which can have high isolation between feeders without increasing its size when a MIMO antenna is designed. 
         [0010]    According to an aspect of an exemplary embodiment, there is provided a patch antenna including: a first patch; a first feeder which is connected to the first patch; a second feeder which is connected to the first patch; and a second patch which is parallel to the first patch. 
         [0011]    The first feeder and the second feeder may be connected to two adjacent sides of the first patch, respectively. 
         [0012]    The first feeder may be fed with power through a first power divider, and the second feeder may be fed with power through a second power divider. 
         [0013]    The patch antenna may further include metal sidewalls which are disposed between a first substrate in which the first patch is provided and a second substrate in which the second patch is provided. 
         [0014]    The metal sidewalls may be formed in a cavity-back structure. 
         [0015]    The first feeder may receive a first common signal or a first differential signal, and the second feeder may receive a second common signal or a second differential signal. 
         [0016]    The first patch and the second patch may transmit and receive linearly polarized waves or circularly polarized waves. 
         [0017]    According to the exemplary embodiment as described above, since multiple signals can be fed into a single patch, a MIMO antenna can be embodied by using a patch antenna which has high isolation between feeders without increasing its size. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0018]    The above and/or other aspects will be more apparent by describing in detail exemplary embodiments, with reference to the accompanying drawings, in which: 
           [0019]      FIG. 1  is a perspective view illustrating a patch antenna according to an exemplary embodiment; 
           [0020]      FIG. 2  is a bottom view of an upper substrate of  FIG. 1  viewed from the bottom; 
           [0021]      FIG. 3  is a perspective view illustrating a frame which is separated from the patch antenna of  FIG. 1 ; 
           [0022]      FIG. 4  is a side view of the frame of  FIG. 3  viewed from the side; 
           [0023]      FIG. 5  is a top view illustrating a lower substrate which is separated from the patch antenna of  FIG. 1 , and viewed from the top; 
           [0024]      FIG. 6  is a top view illustrating a lower substrate in which feeders are replaced with feeders for differential signals; 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0025]    Hereinafter, exemplary embodiments will be described in greater detail with reference to the accompanying drawings. 
         [0026]    In the following description, same reference numerals are used for the same elements when they are depicted in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of exemplary embodiments. Thus, it is apparent that exemplary embodiments can be carried out without those specifically defined matters. Also, functions or elements known in the related art are not described in detail since they would obscure the exemplary embodiments with unnecessary detail. 
         [0027]      FIG. 1  is a perspective view illustrating a patch antenna according to an exemplary embodiment. As shown in  FIG. 1 , a patch antenna  100  according to an exemplary embodiment includes an upper substrate  110 , a frame  120 , and a lower substrate  130 . 
         [0028]    Specifically, the patch antenna  100  according to an exemplary embodiment is configured to have the lower substrate  130  disposed in the frame  120  and the upper substrate  110  covering an upper portion of the frame  120 . 
         [0029]    The upper substrate  110  and the lower substrate  130  of the patch antenna  100  are arranged in parallel with each other due to the presence of the frame  120 . Also, the frame  120  of the patch antenna  100  has a side surface formed in a cavity-back structure. 
         [0030]      FIG. 2  is a bottom view of the upper substrate  110  of  FIG. 1  viewed from the bottom. As shown in  FIG. 2 , the upper substrate  110  is provided with an upper patch  115 . 
         [0031]    The upper patch  115  of the patch antenna  100  according to the exemplary embodiment is implemented in a square shape. However, this is merely an example. The upper patch  115  may be implemented in a shape other than the square shape. 
         [0032]      FIG. 3  is a perspective view illustrating the frame  120  which is separated from the patch antenna  100  of  FIG. 1 .  FIG. 4  is a side view of the frame  120  of  FIG. 3  viewed from the side. 
         [0033]    As shown in  FIGS. 3 and 4 , metal sidewalls  125  are formed on four sides of the frame  120  except corners. The metal sidewall  125  is implemented in a cavity-back structure and prevents electromagnetic waves from being discharged through a rear surface of the patch antenna  100 , thereby collecting the electromagnetic waves on a front side of the patch antenna  100 . 
         [0034]    The metal sidewall  125  of the cavity-back structure may increase a front-back ratio of the patch antenna  100  and simultaneously may prevent a size of the patch antenna  100  from being increased. 
         [0035]      FIG. 5  is a top view illustrating the lower substrate  130  which is separated from the patch antenna  100  of  FIG. 1 , and viewed from the top. As shown in  FIG. 5 , a lower patch  135  is provided on a center of the lower substrate  130 . 
         [0036]    The lower patch  135  of the patch antenna  100  according to the exemplary embodiment is implemented in a square shape. However, this is merely an example. The lower patch  135  may be implemented in a shape other than the square shape. 
         [0037]    The lower patch  135  is provided with two feeders  131  and  132 . The feeders  131  and  132  provided in the lower patch  135  are fed with power through different power dividers. 
         [0038]    Specifically, the feeder-1  131  is fed with power through a power divider-1 (not shown), and the feeder-2  132  is fed with power through a power divider-2 (not shown). Accordingly, different signals flow into the feeder-1  131  and the feeder-2  132 . 
         [0039]    When signals are fed into the feeders  131  and  132  and transmitted to the lower patch  135 , the signals are coupled with the upper patch  115  such that electromagnetic waves are discharged from the patch antenna  100 . 
         [0040]    As shown in  FIG. 5 , a side (left side) of the lower patch  135  to which the feeder-1  131  is connected and a side (lower side) of the lower patch  135  to which the feeder-2  132  is connected are adjacent to each other (meet each other). 
         [0041]    If a condition that the sides of the lower patch  135  to which the feeders  131  and  132  are connected are adjacent to each other is satisfied, the feeders  131  and  132  may be connected to other sides of the lower patch  135  unlike in  FIG. 5 . 
         [0042]    For example, the feeder-1  131  may be connected to an upper side of the lower patch  135  and the feeder-2  132  may be connected to the left side of the lower patch  135 , the feeder-1  131  may be connected to a right side of the lower patch  135  and the feeder-2  132  may be connected to the upper side of the lower patch  135 , or the feeder-1  131  may be connected to the lower side of the lower patch  135  and the feeder-2  132  may be connected to the right side of the lower patch  135 . 
         [0043]    The feeders  131  and  132  shown in  FIG. 5  are to transmit common signals to the lower patch  135 . The feeders  131  and  132  may be replaced with feeders  133  and  134  to transmit differential signals to the lower patch  135  as shown in  FIG. 6 . 
         [0044]    In this case, if a condition that the sides of the lower patch  135  to which the feeders  133  and  134  are connected are adjacent to each other is satisfied, the feeders  133  and  134  may be connected to other sides of the lower patch  135  unlike in  FIG. 6 . 
         [0045]    Up to now, the patch antenna having a single patch fed with multiple signals according to exemplary embodiments has been described. 
         [0046]    The patch antenna proposed in the above-described exemplary embodiments may be embodied by an antenna that can transmit and receive circularly polarized waves as well as linearly polarized waves. 
         [0047]    The foregoing exemplary embodiments and advantages are merely exemplary and are not to be construed as limiting the present inventive concept. The exemplary embodiments can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.