Patent Publication Number: US-9905938-B2

Title: Dual polarized high gain and wideband complementary antenna

Description:
TECHNICAL FIELD 
     The subject disclosure generally relates to embodiments for a dual polarized high gain and wideband complementary antenna. 
     BACKGROUND 
     Conventional antenna technologies including magneto-electric dipole and linearly-polarized antennas are associated with high gain and wideband characteristics. However, such technologies have had some drawbacks, some of which may be noted with reference to the various embodiments described herein below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting embodiments of the subject disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified: 
         FIG. 1  illustrates a block diagram of electric dipoles of a dual-polarized antenna, in accordance with various embodiments; 
         FIG. 2  illustrates a block diagram of magnetic dipoles of a dual-polarized antenna, in accordance with various embodiments; 
         FIG. 3  illustrates a block diagram of top views of feeding mechanisms for a first port of a dual-polarized antenna and a second port of the dual-polarized antenna, in accordance with various embodiments; 
         FIG. 4  illustrates a block diagram of a side view of feeding mechanisms for a first port of a dual-polarized antenna and a second port of the dual-polarized antenna, in accordance with various embodiments; 
         FIG. 5  illustrates a block diagram of a top view of combined feeding mechanisms for a dual polarized antenna, in accordance with various embodiments; 
         FIG. 6  illustrates a block diagram of a side view of combined feeding mechanisms for a dual polarized antenna, in accordance with various embodiments; 
         FIG. 7  illustrates a block diagram of another side view of combined feeding mechanisms for a dual polarized antenna, in accordance with various embodiments; 
         FIG. 8  illustrates a block diagram of a perspective of a dual-polarized antenna, in accordance with various embodiments; 
         FIG. 9  illustrates a block diagram of a top view of a dual-polarized antenna, in accordance with various embodiments; 
         FIG. 10  illustrates a block diagram of a side view of a dual-polarized antenna, in accordance with various embodiments; 
         FIG. 11  illustrates a block diagram of a dual-polarized antenna array, in accordance with various embodiments; 
         FIGS. 12-13  illustrate measured and simulated SWR against frequency for a first port and a second port, respectively, of a dual-polarized antenna, in accordance with various embodiments; 
         FIG. 14  illustrates measured and simulated isolation between two ports of a dual-polarized antenna, in accordance with various embodiments; 
         FIGS. 15-16  illustrate measured and simulated gain against frequency for a first port and a second port of a dual-polarized antenna, in accordance with various embodiments; 
         FIGS. 17-21  illustrate measured and simulated radiation patterns for a first port of a dual-polarized antenna, in accordance with various embodiments; and 
         FIGS. 22-26  illustrate measured and simulated radiation patterns for a second port of a dual-polarized antenna, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the subject disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments. However, the subject disclosure may be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. 
     Conventional antenna technologies have had some drawbacks with respect to effectively coupling bandwidth and gain enhancements for dual-polarized antennas. Various embodiments disclosed herein provide for a dual-polarized high gain and wideband antenna associated with a low profile and efficient design utilizing a folded dipole and shorted patch antenna. 
     For example, an antenna, e.g., dual-polarized antenna, can comprise a ground plane, e.g., an electrically conductive surface, a folded dipole, e.g., half-wave dipole, portion electrically coupled to the ground plane, a shorted patch antenna portion comprising an open end that is electrically coupled to the folded dipole portion, and a metal plate located at a bottom portion, e.g., bottom, of the dual-polarized antenna. 
     In an embodiment, the ground plane can comprise two H-shaped ground planes, and the folded dipole portion can be electrically connected to the two H-shaped ground planes. In another embodiment, the folded dipole portion can comprise four folded dipoles. In yet another embodiment, the shorted patch antenna portion can comprise four open ends (e.g., comprising the open end) that are electrically coupled to the four folded dipoles. 
     In an embodiment, the dual-polarized antenna can further comprise two ports—each port comprising a pair of feeding sources. In this regard, each feeding source of the pair of feeding sources of each port can be configured to generate an electric dipole and a magnetic dipole. In one embodiment, the magnitudes of the electric dipoles can be equivalent. Further, the magnitudes of the magnetic dipoles can be equivalent. 
     In another embodiment, the metal plate can be configured to reduce back radiation. In yet another embodiment, the metal plate can comprise a reflector or another ground plane. In an embodiment, each feeding source of the pair of feeding sources can comprise a pair of microstrip lines, a stub with a shorting pin, and a pair of L-shaped strips, e.g., electrically connected to the pair of microstrip lines and the stub. 
     In an embodiment, the ground plane can comprise an H-shaped ground plane. Further, the pair of micro strip lines, the stub, and the pair of L-shaped strips of each feeding source of the pair of feeding sources can be printed, formed, etc. on a top layer of a substrate. Furthermore, the H-shaped ground plane can be printed, formed, etc. on a bottom layer of the substrate. 
     In one embodiment, the antenna can comprise a balun source, e.g., corresponding to open portions of the ground plane. In an example, each feeding source of the pair of feeding sources can form a Marchand balun source, e.g., which can provide 180° phase difference across a respective open slot of the ground plane. 
     In another embodiment, an array of antennas can comprise a ground plane, a set of dual-polarized antennas, and a metal plate located at a bottom portion, e.g., bottom, of the array of antennas. Further, a dual-polarized antenna of the set of dual-polarized antennas can comprise a folded dipole antenna portion electrically coupled to the ground plane and a shorted patch antenna portion comprising an open end that is electrically coupled, e.g., using the metal plate, to the folded dipole portion. 
     In yet another embodiment, adjacent dual-polarized antennas of the set of dual-polarized antennas can be separated by a defined spacing. In an embodiment, the metal plate can be located below the set of dual-polarized antennas. 
     In one embodiment, a dual-polarized antenna can comprise a ground plane, a folded dipole antenna electrically coupled to the ground plane, a shorted patch antenna comprising an open portion that is electrically coupled to the folded dipole antenna, and a metal plate located below the folded dipole antenna. In an embodiment, the ground plane can comprise H-shaped ground planes, e.g., electrically connected to the folded dipole antenna. In another embodiment, the folded dipole antenna can comprise four folded dipoles. 
     Reference throughout this specification to “one embodiment,” or “an embodiment,” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “in one embodiment,” or “in an embodiment,” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     To the extent that the terms “includes,” “has,” “contains,” and other similar words are used in either the detailed description or the appended claims, such terms are intended to be inclusive—in a manner similar to the term “comprising” as an open transition word—without precluding any additional or other elements. Moreover, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. 
     Further, the word “exemplary” and/or “demonstrative” is used herein to mean serving as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited by such examples. In addition, any aspect or design described herein as “exemplary” and/or “demonstrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs, nor is it meant to preclude equivalent exemplary structures and techniques known to those of ordinary skill in the art having the benefit of the instant disclosure. 
     Conventional antenna technologies have had some drawbacks with respect to effectively combining bandwidth and gain enhancements for dual-polarized antennas. On the other hand, various embodiments disclosed herein provide for an effective, low profile dual-polarized high gain and wideband complementary antenna utilizing a folded dipole and shorted patch antenna. In this regard, and now referring to  FIGS. 1 and 2 , block diagrams ( 100  and  200 ) of electric dipoles ( 110 ,  120 ,  130 ,  140 ) and magnetic dipoles ( 210 ,  220 ,  230 , and  240 ) of a dual-polarized antenna are illustrated, in accordance with various embodiments. As illustrated by  FIGS. 1 and 2 , ports  102  and  104  comprise two feeding sources—A 1  and B 1  for port  102 , and A 2  and B 2  for port  104 . Each feeding source is configured to generate one electric dipole—A 1  generating electric dipole  110  for port  102 , B 1  generating electric dipole  120  for port  102 , A 2  generating electric dipole  130  for port  104 , and B 2  generating electric dipole  140  for port  104 . Further, each feeding source is configured to generate one magnetic dipole—A 1  generating magnetic dipole  210  for port  102 , B 1  generating magnetic dipole  220  for port  102 , A 2  generating magnetic dipole  230  for port  104 , and B 2  generating magnetic dipole  240  for port  104 . 
     In an embodiment, the magnitudes of the two feeding sources are the same at each port, e.g., electric dipole  110 =electric dipole  120 ={right arrow over (J 1 )}, and magnetic dipole  210 =magnetic dipole  220 ={right arrow over (M 1 )} for port  102 ; electric dipole  130 =electric dipole  140 ={right arrow over (J 2 )}, and magnetic dipole  230 =magnetic dipole  240 ={right arrow over (M 2 )} for port  104 . In this regard, the dual-polarized antenna effectively generates two electric dipoles and two magnetic dipoles, with their electrical characteristic (2{right arrow over (J 1 )}+2{right arrow over (M 1 )}) and (2{right arrow over (J 2 )}+2{right arrow over (M 2 )}) being doubled—achieving around 3 dB gain higher than conventional magneto-electric dipole antennas. 
     Referring now to  FIG. 3 , a block diagram ( 300 ) of top views of a feeding mechanism for a first port ( 102 ) of a dual-polarized antenna and a second port ( 104 ) of the dual-polarized antenna are illustrated, in accordance with various embodiments. In this regard, the feeding mechanism, network, etc. (e.g., see  410  below) of port  102  comprises H-shaped ground plane  350  and pair of microstrip lines  310  and stub  320  with shorting pin  330  electrically connected to pair of L-shaped strips  340 . In an embodiment illustrated by  FIG. 4 , pair of microstrip lines  310 , stub  320 , and pair of L-shaped strips  340  can be printed, formed, etc. on a top layer of substrate  420 , and H-shaped ground plane  350  can be printed, formed, etc. on a bottom layer of substrate  420  to form feeding mechanism  410 . 
     The feeding mechanism, network, etc. (e.g., see  440  below) of port  104  comprises H-shaped ground plane  395  and pair of microstrip lines  360  and stub  370  with shorting pin  380  electrically connected to pair of L-shaped strips  390 . In an embodiment illustrated by  FIG. 4 , pair of microstrip lines  360 , stub  370 , and pair of L-shaped strips  390  can be printed, formed, etc. on a bottom layer of substrate  430 , and H-shaped ground plane  395  can be printed, formed, etc. on a top layer of substrate  430  to form feeding mechanism  440 . 
     Table I below defines geometrical parameters corresponding to the feeding mechanisms for the first and second ports ( 102  and  104 ) of the dual-polarized antenna, in which λ o  is the free-space wavelength of the center frequency of the antenna: 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE I 
               
               
                   
               
               
                 Parameters 
                 P w1   
                 P s1   
                 S w1   
                 S 1   
                 T x1   
                 T xs1   
                 L h1   
                 L 1   
                 L h2   
                 L 2   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Values 
                 62 
                 16 
                 5 
                 24.5 
                 37.5 
                 2.75 
                 10 
                 13.5 
                 10.4 
                 12.5 
               
               
                 (mm) 
                 0.661λ 0   
                 0.171λ 0   
                 0.053λ 0   
                 0.261λ 0   
                 0.4λ 0   
                 0.029λ 0   
                 0.107λ 0   
                 0.144λ 0   
                 0.111λ 0   
                 0.133λ 0   
               
               
                   
               
            
           
         
       
     
       FIG. 5  illustrates a block diagram ( 500 ) of a top view of combined feeding mechanisms for a dual-polarized antenna, in accordance with various embodiments. As illustrated by  FIG. 5 , a dual-polarized combined feeding mechanism can be formed by orthogonally crossing feeding mechanism  410  and feeding mechanism  440 —securing, as illustrated by  FIG. 6 , H-shaped ground plane  350  to H-shaped ground plane  395 . In this regard, the coordinates of feeding mechanism  410  and  440  have been rotated at φ=−45° and 45°, respectively, for viewing the dual polarized antenna structure more easily. 
     Feeding points  510  can be located at the middle of respective pairs of microstrip lines (e.g.,  310 ,  360 ). In an embodiment, short-circuited stubs (e.g.,  320 ,  370 ) can be used for performing fine tuning and/or impedance matching for the dual-polarized antenna. In another embodiment, each L-shaped strip (e.g.,  340 ,  390 ) can have a portion overlapping with open slot(s) of the H-shaped ground planes (e.g.,  350 ,  395 ). Further, each feeding mechanism (e.g.,  410 ,  440 ) can form a Marchand balun source that can provide a precise 180° phase difference across an open slot on a ground plane at A −   1  and A +   1 , B −   1  and B +   1 , A −   2  and A +   2 , or B −   2  and B +   2 , with minimum transmission loss and equal balanced impedances. 
     In embodiment(s) illustrated by  FIG. 7 , gap  710  can be included between the H-shaped ground planes (e.g.,  350 ,  395 ). In other embodiment(s), (see e.g.  FIG. 6 ), no gap exists between the H-shaped ground planes. 
     Now referring to  FIGS. 8-10 , a perspective of a dual-polarized antenna, a top view of the dual-polarized antenna, and a side view of the dual-polarized antenna are illustrated, in accordance with various embodiments. As illustrated by  FIGS. 8 and 9 , an H-shaped ground plane (e.g.,  350 ,  395 ) of the dual-polarized combined feeding mechanism (see  FIG. 5 ) can be connected to four folded dipoles ( 810 ). In this regard, folded dipoles (e.g.,  2   a  and  2   b ) can be connected to an open end of a vertically-oriented shorted patch antenna (e.g., formed by  2   c ,  2   d  and  2   e ), with a metal plate  820  located below such feeding mechanism for back radiation reduction. 
     In one or more embodiments, the length of a folded dipole ( 810 ), D 1 , and height of shorted patch antenna (see  2   c ,  2   d , and  2   e ), h D , are 0.245λ o  and 0.115λ o , respectively. In other embodiment(s), the separation of the two vertical metal plates ( 2   c  and  2   e ), P s1 , of the shorted patch antenna is 0.171λ. In yet other embodiment(s), the size of the metal plate ( 820 ), L R , can be optimized to obtain a back radiation of less than −20 dBi. 
     As illustrated by  FIG. 10 , support pillars  1010  can comprise an insulator or a conductor and can separate feeding mechanisms ( 410  and  440 ) from metal plate  820 , which can act as a reflector of electromagnetic waves for the dual-polarized antenna, e.g., when support pillars  1010  comprise an insulator. In another embodiment, when support pillars comprise a conductor,  350  and  395  can be electrically connected to metal plate  820 , e.g., which becomes a ground plane. Connectors  1020  can be electronically coupled, connected, shorted, etc. to feeding points  510  (see above). Further, Table II below defines geometrical parameters corresponding to the dual-polarized antenna illustrated by  FIGS. 8-10 , in which λ o  is the free-space wavelength of the center frequency of the dual-polarized antenna: 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE II 
               
               
                   
               
               
                 Parameters 
                 L R   
                 D 1   
                 h t   
                 h D   
                 h DF   
                 h sub   
                 h sp   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Values 
                 150 
                 23 
                 18 
                 10.8 
                 6 
                 1 
                 6.2 
               
               
                 (mm) 
                 1.6λ 0   
                 0.245λ 0   
                 0.192λ 0   
                 0.115λ 0   
                 0.064λ 0   
                 0.011λ 0   
                 0.066λ 0   
               
               
                   
               
            
           
         
       
     
       FIG. 11  illustrates a block diagram ( 1100 ) of a dual-polarized antenna array, in accordance with various embodiments. Dual-polarized antenna elements ( 1110 ,  1120 ,  1130 ,  1140 ) can include dual-polarized antennas described above (see also  FIGS. 5-10 ). In this regard, as illustrated by  FIG. 11 , dual-polarized antenna array includes four dual-polarized antennas separated by element spacing, L es , which have been placed over metal plate  1105 . In order to obtain a specific gain or half power beamwidth for some wireless communication systems, an M×N antenna array can be constructed. 
       FIGS. 12-13  illustrate measured and simulated standing wave ratio (SWR) against frequency for a first port ( 102 ) and a second port ( 104 ), respectively, of a dual-polarized antenna, in accordance with various embodiments. In this regard, the dual-polarized antenna has wide measured impedance bandwidths of 55.9% (with SWR≦2 from 2.36 GHz to 4.19 GHz) at port  102  and 51.7% (with SWR≦2 from 2.44 GHz to 4.14 GHz) at port  104 , respectively. 
       FIG. 14  illustrates measured and simulated isolation between two ports (e.g.,  102  and  104 ) of a dual-polarized antenna, in accordance with various embodiments. In this regard, measured isolation is more than 35 dB across the entire operating bandwidth of the dual-polarized antenna. 
       FIGS. 15-16  illustrate measured and simulated gain against frequency for a first port ( 102 ) and a second port ( 104 ) of a dual-polarized antenna, in accordance with various embodiments. In this regard, the dual-polarized antenna has stable gain and an average measured gain of 10.5 dBi at each port, varying from 9.28 dBi to 10.78 dBi at port  102  and from 9.54 dBi to 10.52 dBi at port  104 . 
       FIGS. 17-21  illustrate measured and simulated radiation patterns for a first port ( 102 ) of a dual-polarized antenna, in accordance with various embodiments. In this regard, measured and simulated radiation patterns for the dual-polarized antenna are illustrated at frequencies of 2.6, 2.9, 3.2, 3.5, and 3.8 GHz. 
     For the half power beamwidth at port  102 , described in Table III below, the measured beamwidths are also 57.4° at 2.6 GHz at both planes. When the operating frequency increases from 2.6 GHz to 3.8 GHz, the beamwidths decrease monotonically from 57.4° to 40°. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE III 
               
             
            
               
                   
                   
               
               
                   
                 Half power beamwidth 
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Measured 
                   
                 Simulated 
                   
               
            
           
           
               
               
               
               
               
            
               
                 Plane 
                 0° 
                 90° 
                 0° 
                 90° 
               
               
                   
               
               
                 2.6 GHz 
                 57.4° 
                 57.4° 
                 55.5° 
                 55.4° 
               
               
                 2.9 GHz 
                 53.5° 
                 53.9° 
                     54° 
                 53.5° 
               
               
                 3.2 GHz 
                 46.1° 
                 47.8° 
                 48.5° 
                 48.3° 
               
               
                 3.5 GHz 
                 41.7° 
                 43.3° 
                 43.5° 
                 43.5° 
               
               
                 3.8 GHz 
                 39.9° 
                     40° 
                     40° 
                 40.5° 
               
               
                   
               
            
           
         
       
     
       FIGS. 22-26  illustrate measured and simulated radiation patterns for a second port ( 104 ) of a dual-polarized antenna, in accordance with various embodiments. In this regard, measured and simulated radiation patterns for the dual-polarized antenna are illustrated at frequencies of 2.6, 2.9, 3.2, 3.5, and 3.8 GHz. 
     As described in Table IV below, the variation of the half power beamwidth at port  104  is same as port  102 , and the beamwidths also decrease from 52° to 39° with increasing the operating frequency. In an embodiment, the height of the feeding points ( 510 ) of the feeding mechanisms can cause high cross polarization at both ports at high operating frequency. In this regard, the high cross polarization can be reduced by reducing the height of feeding points  510 , while the overall height of the dual-polarized antenna is kept the same, e.g., at the expense of an increase in gain variations. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE IV 
               
             
            
               
                   
                   
               
               
                   
                 Half power beamwidth 
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Measured 
                   
                 Simulated 
                   
               
            
           
           
               
               
               
               
               
            
               
                 Plane 
                 0° 
                 90° 
                 0° 
                 90° 
               
               
                   
               
               
                 2.6 GHz 
                 52.9° 
                 51.5° 
                     55° 
                     55° 
               
               
                 2.9 GHz 
                 50.5° 
                 51.3° 
                 50.5° 
                     53° 
               
               
                 3.2 GHz 
                 46.6° 
                 46.9° 
                     47° 
                 47.5° 
               
               
                 3.5 GHz 
                 40.9° 
                 41.8° 
                 42.6° 
                 42.8° 
               
               
                 3.8 GHz 
                 39.2° 
                     39° 
                 40.4° 
                 40.3° 
               
               
                   
               
            
           
         
       
     
     The above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize. 
     In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding Figures, where applicable, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed in breadth and scope in accordance with the appended claims below.