Patent Publication Number: US-11024946-B2

Title: Antenna device and wireless communication device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of International Application PCT/JP2018/012696 filed on Mar. 28, 2018 and designated the U.S., the entire contents of which are incorporated herein by reference. The International Application PCT/JP2018/012696 is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-118088, filed on Jun. 15, 2017, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The embodiments discussed herein are related to antenna devices and wireless communication devices. 
     BACKGROUND 
     Conventionally, an antenna device is provided. 
     Related art is disclosed in Japanese Laid-open Patent Publication No. 2010-028521. 
     SUMMARY 
     According to one aspect of the embodiments, an antenna device includes: a ground plane which has an edge side; a metal member arranged along the edge side of the ground plane; a first connection line which couples the metal member and the ground plane; a second connection line which couples the metal member and the ground plane; and a power feeding element which has a power feeding point, extends along the metal member from the power feeding point between the first connection line and the second connection line, and is electromagnetic-field-coupled to the metal member. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram depicting a wireless communication device  200  including an antenna device  100  of an embodiment. 
         FIG. 2  is a diagram depicting the wireless communication device  200  including the antenna device  100  of the embodiment. 
         FIG. 3  is a diagram depicting the antenna device  100 . 
         FIG. 4  is a plan view of the antenna device  100  in an enlarged manner. 
         FIG. 5  is a perspective view of the antenna device  100  in an enlarged manner. 
         FIG. 6  is a diagram depicting dimensions of each unit of the wireless communication device  200  including the antenna device  100  of the embodiment. 
         FIG. 7  is a diagram depicting dimensions of each unit of the antenna device  100  of the embodiment. 
         FIG. 8  is a diagram depicting a frequency characteristic of an S 11  parameter of the antenna device  100 . 
         FIG. 9  is a diagram depicting a frequency characteristic of total efficiency of the antenna device  100 . 
         FIG. 10  is a diagram depicting a current distribution of the antenna device  100 . 
         FIG. 11  is a diagram depicting a current distribution of the antenna device  100 . 
         FIG. 12  is a diagram depicting a current distribution of the antenna device  100 . 
         FIG. 13  is a diagram depicting a current distribution of the antenna device  100 . 
         FIG. 14  is a diagram depicting dependency of frequency characteristics of the S 11  parameter with respect to the length of a power feeding element  110 . 
         FIG. 15  is a diagram depicting differences in frequency characteristic of the S 11  parameter depending on the presence or absence of a housing  210 . 
         FIG. 16  is a diagram depicting frequency characteristics of the S 11  parameter when the position of a connection line  132  is changed. 
         FIG. 17  is a diagram depicting frequency characteristics of the S 11  parameter when the position of a connection line  133  is changed. 
         FIG. 18  is a diagram depicting frequency characteristics of the S 11  parameter when the position of a connection line  131  is changed. 
         FIG. 19  is a diagram depicting an antenna device  100 A of a modification example of the embodiment. 
         FIG. 20  is a diagram depicting an antenna device  100 B of a modification example of the embodiment. 
         FIG. 21  is a diagram depicting frequency characteristics of the S 11  parameter of the antenna devices  100 ,  100 A, and  100 B. 
         FIG. 22  is a diagram depicting an antenna device  100 C of a modification example of the embodiment. 
         FIG. 23  is a diagram depicting frequency characteristics of the S 11  parameter of the antenna device  100 C when the impedance of an adjustment circuit  152  is changed. 
         FIG. 24  is a diagram depicting frequency characteristics of the S 11  parameter of the antenna device  100 C when the impedance of an adjustment circuit  153  is changed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     For example, an antenna device includes a power feeding element, a parasitic element capable of being coupled to the power feeding element in a high frequency manner, a substrate for generating electric images of the power feeding element and the parasitic element, and switching means which switches, for each of a plurality of switching locations defined in advance of the parasitic element, between a short-circuited state in which the switching location and the substrate are short-circuited and an open state in which the switching location is opened. 
     Meanwhile, the antenna device achieves a plurality of resonance frequencies by switching the switching means (switch), and the structure may not be simple. 
     An antenna device with a simple structure and a wireless communication device may be provided. 
     In the following, an embodiment to which the antenna device and the wireless communication device of the present invention are applied is described. 
     Embodiment 
       FIG. 1  and  FIG. 2  are diagrams depicting a wireless communication device  200  including an antenna device  100  of an embodiment.  FIG. 3  is a diagram depicting the antenna device  100 .  FIG. 4  and  FIG. 5  are a plan view and a perspective view of the antenna device  100  in an enlarged manner. In the following, description is made by defining an XYZ coordinate system. Also, a planar view refers to an XY planar view. 
     The wireless communication device  200  includes a wiring substrate  10 , the antenna device  100 , a housing  210 , a duplexer (DUP)  310 , a low noise amplifier (LNA)/power amplifier (PA)  320 , a modulator/demodulator  330 , and a central processing unit (CPU) chip  340 . The wireless communication device  200  is included in an electronic device such as, for example, a smartphone terminal or a tablet computer. 
     The antenna device  100  includes a ground plane  50 , a contact spring  101 , a power feeding element  110 , a metal plate  120 , and connection lines  131 ,  132 ,  133 ,  134 A,  134 B,  134 C,  134 D,  135 A,  135 B,  135 C, and  135 D. 
     The housing  210  depicted in  FIG. 1  has a rectangular annular shape in a planar view, and is arranged so as to surround the outer periphery of the wiring substrate  10 . In  FIG. 1 , the housing  210  is depicted in gray. The housing  210  is made of resin, and a positive direction side (right side) of the X axis and a negative direction side (left side) of the X axis are fixed in a state of being interposed by the ground plane  50  and the metal plate  120 . In  FIG. 1 , although depiction is omitted, in a state in which an electronic device including the wireless communication device  200  is assembled, a cover is provided on a positive direction side of the Z axis of the ground plane  50 , and is fixed to the housing  210 . Also, when the electronic device including the wireless communication device  200  includes a display panel and/or touch panel, by way of example, the display panel and/or touch panel is arranged on a negative direction side of the Z axis of the wiring substrate  10 . 
     Since the DUP  310 , the LNA/PA  320 , the modulator/demodulator  330 , and the CPU chip  340  depicted in  FIG. 2  are provided on a surface opposite to a surface where the antenna device  100  of the wiring substrate  10  is implemented, the position of the antenna device  100  is indicated by broken lines in  FIG. 2 . 
     Here, the DUP  310 , the LNA/PA  320 , the modulator/demodulator  330 , and the CPU chip  340  are described first. The DUP  310 , the LNA/PA  320 , the modulator/demodulator  330 , and the CPU chip  340  are connected via a wiring  360 . 
     The DUP  310  is connected to the antenna device  100  via a wiring  350  and a via not depicted to perform switching between transmission and reception. Since the DUP  310  has a function as a filter, when the antenna device  100  receives signals of a plurality of frequencies, the signals of the respective frequencies may be separated inside. 
     The LNA/PA  320  amplifies power of transmission waves and reception waves. The modulator/demodulator  330  performs modulation of transmission waves and demodulation of reception waves. The CPU chip  340  has a function as a communication-purpose processor which performs communication process of the electronic device including the wireless communication device  200  and a function as an application processor which executes an application program. Note that the CPU chip  340  has an internal memory which stores data to be transmitted or data to be received and so forth. 
     Note that the wirings  350  and  360  are formed by, for example, patterning a copper foil on the surface of the wiring substrate  10 . Also, although omitted in  FIG. 2 , a matching circuit for adjusting an impedance characteristic is provided between the antenna device  100  and the DUP  310 . 
     Next, the antenna device  100  is described. 
     The wiring substrate  10  is, for example, a wiring substrate under flame retardant type 4 (FR-4) standards, and has an insulating layer  10 A and the ground plane  50 . The insulating layer  10 A is, for example, a prepreg layer. The wiring substrate  10  may be configured to have a plurality of insulating layers  10 A. On the outer periphery of the wiring substrate  10 , the housing  210  and the metal plate  120  are provided. 
     The ground plane  50  is a metal layer arranged on a surface or inner layer of the wiring substrate  10 . Here, by way of example, the ground plane  50  is provided on the back surface of the wiring substrate  10 . The wiring substrate  10  has a rectangular shape in a planar view, and has vertexes  11 ,  12 ,  13 , and  14 . The ground plane  50  is not provided to an end on the Y axis positive direction side and an end on the Y axis negative direction side of the front surface of the wiring substrate  10  on the Z axis positive direction side, and the insulating layer  10 A of the wiring substrate  10  is exposed. 
     The ground plane  50  is a metal layer retained at a ground potential, and is a rectangular metal layer having vertexes  51 ,  52 ,  53 , and  54 . The vertexes  51 ,  52 ,  53 , and  54  are respectively positioned near the vertexes  11 ,  12 ,  13 , and  14  of the wiring substrate  10 . The ground plane  50  may be handled as a ground layer, a grounding plate, or a bottom board. 
     The ground plane  50  has edge sides  50 A,  50 B,  50 C, and  50 D. The edge side  50 A is a side connecting the vertexes  51  and  52 , the edge side  50 B is a side connecting the vertexes  51  and  54 , the edge side  50 C is a side connecting the vertexes  52  and  53 , and the edge side  50 D is a side connecting the vertexes  53  and  54 . The edge sides  50 A and  50 D are positioned to be offset from an edge side of the wiring substrate  10  on the Y axis positive direction side (edge side between the vertexes  11  and  12 ) and an edge side thereof on the Y axis negative direction side (edge side between the vertexes  13  and  14 ). Thus, the insulating layer  10 A of the wiring substrate  10  is exposed on the Y axis positive direction side and the Y axis negative direction side of the edge sides  50 A and  50 D. Also, the edge sides  50 B and  50 C are at the substantially same positions as those of an edge side of the wiring substrate  10  on the X axis positive direction side (edge side between the vertexes  12  and  13 ) and an edge side thereof on the X axis negative direction side (edge side between the vertexes  11  and  14 ). 
     Also, on the edge side  50 A of the ground plane  50 , a point corresponding to a power feeding point  111  of the power feeding element  110  in the X axis direction (hereinafter referred to as a ground point  55 ) is a point to which a shield line of a coaxial cable is connected when a core wire of the coaxial cable is connected to the power feeding point of the power feeding element  110 , for example. 
     Note that while the ground plane  50  with the edge sides  50 A,  50 B,  50 C, and  50 D each being linear is depicted herein, any edge side may not be linear, for example, with asperities provided so as to match the internal shape of the housing of the electronic device including the antenna device  100 , or the like. 
     The contact spring  101  is arranged on the front surface of the insulating layer  10 A to connect the power feeding point  111  of the power feeding element  110  and the via penetrating through the insulating layer  10 A. The via penetrating through the insulating layer  10 A is connected to the wiring  350 . The spring of the contact spring  101  itself is surrounded by the resin-made housing, and is not viewable from outside. 
     The power feeding element  110  has the power feeding point  111  and an open end  112 . The power feeding element  110  is a linear power feeding element extending along the line  121  of the metal plate  120  from the power feeding point  111  along the open end  112 . The power feeding element  110  extends to the X axis direction in parallel with the line  121 , and is electromagnetic-field-coupled to the line  121 . The power feeding element  110  is provided to feed power to the metal plate  120 . Note that the power feeding element  110  may be handled as an antenna element. 
     The metal plate  120  is a metal member in a rectangular annular shape in a planar view having lines  121 ,  122 ,  123 , and  124 . Each of the lines  121 ,  122 ,  123 , and  124  is a thin-plate-shaped, narrowly-elongated metal member, with a longitudinal direction being in a direction in which a side surface is viewable in a planar view (X axis direction or Y axis direction). 
     The lines  121 ,  122 ,  123 , and  124  are respectively arranged so as to be opposed to the edge side between the vertexes  11  and  12 , the edge side between vertexes  11  and  14 , the edge side between the vertexes  12  and  13 , and the edge side between the vertexes  13  and  14  of the wiring substrate  10 . The lines  121 ,  122 ,  123 , and  124  are connected in a rectangular annular shape in a clockwise direction in the order of the lines  121 ,  123 ,  124 , and  122  in a planar view. 
     The metal plate  120  is arranged so as to surround the outer periphery of the wiring substrate  10 , and has a role in reinforcing the housing  210  and a role in functioning as a radiation element in cooperation with the power feeding element  110 . The metal plate  120  is one example of a metal member. 
     The line  121  extends to the X axis direction on the Y axis positive direction side of the wiring substrate  10 , and is connected to the edge side  50 A of the ground plane  50  by the connection line  131 . Also, the lines  122  and  123  are connected to both ends of the line  121 . 
     A location where the connection line  131  is connected to the line  121  is a side near an end of the line  121  on the X axis positive direction side (a point of connection with the line  123 ). Also, on a side near an end on the X axis negative direction side (a point of connection with the line  122 ), the line  121  is arranged in parallel with the power feeding element  110 . 
     A space in the Y axis direction between the line  121  and the power feeding element  110  is a space to the extent that electromagnetic field coupling occurs between the power feeding element  110  and the line  121  when power is fed to the power feeding element  110 . The line  121  is fed with power by the power feeding element  110 . Note that feeding the line  121  with power by the power feeding element  110  is synonymous with feeding at least part of the metal plate  120  with power by the power feeding element  110 . 
     The line  122  extends to the Y axis direction on the X axis negative direction side of the wiring substrate  10 , and is connected to the edge side  50 B of the ground plane  50  by the connection lines  132 ,  135 A,  135 B,  135 C, and  135 D. Also, the lines  121  and  124  are connected to both ends of the line  122 . 
     The positions of the connection lines  132 ,  135 A,  135 B,  135 C, and  135 D are defined based on a relation between the line  121  and the connection line  131  and a relation between the line  123  and the connection line  133 . Details about the positions of the connection lines  132 ,  135 A,  135 B,  135 C, and  135 D will be described further below. 
     The line  123  extends to the Y axis direction on the X axis positive direction side of the wiring substrate  10 , and is connected to the edge side  50 C of the ground plane  50  by the connection lines  133 ,  134 A,  134 B,  134 C, and  134 D. Also, the lines  121  and  124  are connected to both ends of the line  123 . 
     The positions of the connection lines  133 ,  134 A,  134 B,  134 C, and  134 D are defined based on a relation between the line  121  and the connection line  131  and a relation between the line  122  and the connection line  132 . Details about the positions of the connection lines  133 ,  134 A,  134 B,  134 C, and  134 D will be described further below. 
     The line  124  extends to the X axis direction on the Y axis negative direction side of the wiring substrate  10 , and has the wirings  122  and  123  connected to both ends. The line  124  is retained by the lines  122  and  123 , and has not connected thereto connection lines such as the connection lines  131 ,  132 , and  133 . 
     The connection line  131  extends from the edge side  50 A to the Y axis positive direction on a side near the vertex  52  (X axis positive direction side) rather than the vertex  51  of the ground plane  50 , and is connected to the line  121 . The connection line  131  is one example of a first connection line. 
     When power is fed to the power feeding element  110 , a loop current flows through the connection line  131 , the line  121 , the power feeding element  110 , and the edge side  50 A (a portion between the ground point  55  and a connection point between the ground plane  50  and the connection line  131 ). This is because the power feeding element  110  and mainly the lines  121  and  122  of the metal plate  120  are electromagnetic-field-coupled, the power feeding point  111  is connected to the core wire of the coaxial cable, and the ground point  55  is connected to the shield line of the coaxial cable, thereby causing a loop to occur in an alternating manner. 
     Thus, the distance between the ground point  55  and the connection point between the ground plane  50  and the connection line  131  is set at a distance represented by a length of ½ of the electrical length of the wavelength at a frequency f 4 . Here, as described above, the edge side  50 A of the ground plane  50  may not be linear. Also in this case, it is only required that the distance between the ground point  55  and the connection point between the ground plane  50  and the connection line  131  is set at a distance represented by a length (4/2), which is ½ of the electrical length of a wavelength  4  at the frequency f 4 . Note that the frequency f 4  is, by way of example, 2.4 GHz, and is a frequency higher than frequencies f 1 , f 2 , and f 3 , which will be described further below. 
     The length (4/2), which is ½ of the electrical length of the wavelength  4  at the frequency f 4 , is one example of a length corresponding to a length of ½ of the wavelength  4  at the frequency f 4 . 
     The connection line  132  constructs a loop antenna in cooperation with the connection line  131 , the lines  121  and  122  of the metal plate  120 , the edge side  50 A, and the edge side  50 B. The connection line  132  is one example of a second connection line. 
     Here, the length of the loop constructed of the connection lines  131  and  132 , the lines  121  and  122  of the metal plate  120 , the edge side  50 A, and the edge side  50 B is an electrical length (1) of a wavelength at the frequency f 1 , and is also a length which is a double of the electrical length (2) of a wavelength at the frequency f 2  which is double of the frequency f 1 . This loop is one example of a first loop. 
     To construct a loop antenna which resonates at the frequency f 1 , the length of the metal plate  120  between the connection line  131  and the connection line  132  is set at a length (½), which is ½ of the electrical length of the wavelength  1  at the frequency f 1 . The frequency f 1  is, by way of example, 0.85 GHz, which is a frequency lower than the frequencies f 2 , f 3 , and f 4 . 
     The length (½), which is ½ of the electrical length (1) of the wavelength at the frequency f 1 , is one example of a length corresponding to ½ of a first wavelength at the frequency f 1 . 
     Note that the length of the metal plate  120  between the connection line  131  and the connection line  132  is a length between a connection point where the metal plate  120  (line  121 ) is connected to the connection line  131  and a connection point where the metal plate  120  (line  122 ) is connected to the connection line  132 , but may include at least part of the length of the connection line  131  and/or the connection line  132 . 
     To construct a loop antenna which resonates at the frequency f 2 , the length of the metal plate  120  between the connection line  131  and the connection line  132  is set at an electrical length (2) of the wavelength  2  at a frequency f 2 . The frequency f 2  is, by way of example, 1.65 GHz, which is a frequency lower than the frequencies f 3  and f 4 . 
     The electrical length (2) of the wavelength at the frequency f 2  is one example of a length corresponding to a second wavelength at a second frequency. 
     The connection line  133  constructs a loop antenna in cooperation with the connection line  131 , the lines  121  and  123  of the metal plate  120 , the edge side  50 A, and the edge side  50 C. The connection line  133  is one example of a third connection line. 
     This is because when power is fed to the power feeding element  110 , a current flows through the line  121  of the metal plate  120  and the connection line  131 , and thus flows also through the loop including the connection lines  131  and  133 . This loop is one example of a second loop. 
     Here, the length of the loop constructed of the connection lines  131  and  133 , the lines  121  and  123  of the metal plate  120 , the edge side  50 A, and the edge side  50 C is an electrical length (3) of a wavelength at the frequency f 3 . 
     To construct a loop antenna which resonates at the frequency f 3 , the length of the metal plate  120  between the connection line  131  and the connection line  133  is set at a length (3/2), which is ½ of the electrical length of the wavelength  3  at the frequency f 3 . The frequency f 3  is, by way of example, 2.0 GHz. 
     Also, the length (3/2), which is ½ of the electrical length of the wavelength  3  at the frequency f 3 , is one example of a length corresponding to ½ of a third wavelength at a third frequency. 
     Note that the length of the metal plate  120  between the connection line  131  and the connection line  133  is a length between a connection point where the metal plate  120  (line  121 ) is connected to the connection line  131  and a connection point where the metal plate  120  (line  123 ) is connected to the connection line  133 , but may be thought to include at least part of the length of the connection line  131  and/or the connection line  133 . 
     The connection lines  134 A,  134 B,  134 C, and  134 D are provided on the Y axis negative direction side of the connection line  133  in this order so as to connect between the edge side  50 C of the ground plane  50  and the line  123  of the metal plate  120 . 
     The position of the connection line  134 A is set so that the length of a loop constructed of the connection line  133 , the connection line  134 A, the line  123  of the metal plate  120 , and the edge side  50 C is shorter than the electrical length (3) of the wavelength  4  at the highest frequency f 4  among the frequencies f 1 , f 2 , f 3 , and f 4 . 
     In other words, the length between the connection line  134 A and the connection line  133  of the metal plate  120  is set so as to be shorter than the length (4/2), which is ½ of the electrical length of the wavelength  4  at the frequency f 4 . 
     This is to restrain resonance adjacent to the frequencies f 1 , f 2 , f 3 , and f 4  from occurring in the loop constructed of the connection line  133 , the connection line  134 A, the line  123  of the metal plate  120 , and the edge side  50 C. For example, when resonance adjacent to a band at the frequency f 4  occurs, the characteristic at the frequency f 4  itself may be degraded. The same goes for the frequencies f 1 , f 2 , and f 3 . 
     Note that it is only required that the positions of the connection lines  134 B,  134 C, and  134 D are set so that the length of the metal plate  120  between each of these connection lines  134 B,  134 C, and  134 D and its relevant one of the connection lines  134 A,  134 B, and  134 C adjacent on the Y axis positive direction side is shorter than the length (4/2), which is ½ of the electrical length of the wavelength  4  at the frequency f 4 . However, as compared with the connection line  134 A, the connection lines  134 B,  134 C, and  134 D are positioned further away from the connection line  133 . Therefore, the positional constraint as described above may not be provided if there is no possibility of occurrence of characteristic degradation due to occurrence of resonance. 
     The connection lines  135 A,  135 B,  135 C, and  135 D are provided on the Y axis negative direction side of the connection line  132  in this order so as to connect between the edge side  50 B of the ground plane  50  and the line  122  of the metal plate  120 . 
     The position of the connection line  135 A is set so that the length of a loop constructed of the connection line  132 , the connection line  135 A, the line  122  of the metal plate  120 , and the edge side  50 B is shorter than the electrical length (3) of the wavelength  4  at the highest frequency f 4  among the frequencies f 1 , f 2 , f 3 , and f 4 . 
     In other words, the length between the connection line  135 A and the connection line  132  of the metal plate  120  is set so as to be shorter than the length (4/2), which is ½ of the electrical length of the wavelength  4  at the frequency f 4 . The reason for this is similar to the reason for setting the position of the connection line  134 A with respect to the connection line  133 . The positions of the connection lines  135 B,  135 C, and  135 D is also set in a similar manner as for the positions of the connection lines  134 B,  134 C, and  134 D. 
       FIG. 6  and  FIG. 7  are diagrams depicting dimensions of each unit of the wireless communication device  200  including the antenna device  100  of the embodiment. 
     As depicted in  FIG. 6 , the length of the metal plate  120  in the X axis direction (the length of each of the lines  121  and  124 ) is 74 mm. The length of the metal plate  120  in the Y axis direction (the length of each of the lines  122  and  123 ) is 156 mm. Also, the width of the metal plate  120  in the Z axis direction is 4.5 mm. 
     As depicted in  FIG. 7 , the length of the power feeding element  110  in the X axis direction is 20 mm. The length of the connection line  131  in the Y axis direction is 9 mm. The length of the line  121  on the X axis positive direction side of the connection line  131  is 7 mm. 
     The length of the metal plate  120  between a joint part between the lines  121  and  123  and the connection line  133  is 46 mm. The length of the metal plate  120  between the connection lines  133  and  134 A is 24 mm. The length of the metal plate  120  between the connection lines  134 A and  134 B, the length thereof between the connection lines  134 B and  134 C, and the length thereof between the connection lines  134 C and  134 D are 24 mm each. 
     The length of the metal plate  120  between a joint part between the lines  121  and  122  and the connection line  132  is 65 mm. The length of the metal plate  120  between the connection lines  132  and  135 A, the length thereof between the connection lines  135 A and  135 B, the length thereof between the connection lines  135 B and  135 C, and the length thereof between the connection lines  135 C and  135 D are 20 mm each. Also, the width of the ground plane  50  in the X axis direction is 68 mm. 
       FIG. 8  is a diagram depicting a frequency characteristic of an S 11  parameter of the antenna device  100 .  FIG. 9  is a diagram depicting a frequency characteristic of total efficiency of the antenna device  100 .  FIG. 8  and  FIG. 9  depict results acquired from electromagnetic field simulations. 
     As depicted in  FIG. 8 , in the frequency characteristic of the S 11  parameter, it was found that the S 11  parameter is equal to or lower than −6 dB at frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz), allowing a favorable radiation characteristic with less radiation to be acquired. 
     Also as depicted in  FIG. 9 , in the frequency characteristic of total efficiency, it was found that total efficiency is equal to or higher than −3 dB at the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz), allowing a favorable radiation characteristic to be acquired. 
       FIG. 10  to  FIG. 13  are diagrams each depicting a current distribution of the antenna device  100 . The current distributions of  FIG. 10  to  FIG. 13  have been acquired from electromagnetic field simulations, and each depict a current distribution at the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz). Note that each current distribution represents that the current density is higher as the current distribution is blacker (thicker) and the current density is lower as the current distribution is whiter (thinner). 
     At the frequency f 1  (0.85 GHz) depicted in  FIG. 10 , it is found that a current flows through the power feeding element  110  and flows through a loop constructed of the connection line  131 , the line  121 , the line  122 , the connection line  132 , the edge side  50 B, and the edge side  50 A. In particular, since current density of the connection lines  131  and  132  is high, it is found that antinodes of resonance current occur at two locations, that is, the connection lines  131  and  132 . Also, since current density of a connection part between the lines  121  and  122  and the vertex  51  is low, it is found that nodes of resonance current occur at two locations, that is, the connection part between the lines  121  and  122  and the vertex  51 . 
     That is, from the current distribution depicted in  FIG. 10 , it is found that resonance for one wavelength occurs in the loop constructed of the connection line  131 , the line  121 , the line  122 , the connection line  132 , the edge side  50 B, and the edge side  50 A. In other words, it is found that a portion having the length (½), which is ½ of the electrical length of the wavelength  1  at the frequency f 1 , extends between the connection line  131  and the connection line  132  of the metal plate  120 . 
     At the frequency f 2  (1.65 GHz) depicted in  FIG. 11 , it is found that a current flows through the power feeding element  110  and flows through the loop constructed of the connection line  131 , the line  121 , the line  122 , the connection line  132 , the edge side  50 B, and the edge side  50 A. In particular, since current density of the connection lines  131  and  132 , the connection part between the lines  121  and  122 , and the vertex  51  is high, it is found that antinodes of resonance current occur at four locations, that is, the connection lines  131  and  132 , the connection part between the lines  121  and  122 , and the vertex  51 , and also current density is low and nodes of resonance current occur at four locations between these. 
     That is, from the current distribution depicted in  FIG. 11 , it is found that resonance for two wavelengths occurs in the loop constructed of the connection line  131 , the line  121 , the line  122 , the connection line  132 , the edge side  50 B, and the edge side  50 A. In other words, it is found that a portion having the electrical length (2) of the wavelength  2  at the frequency f 2  extends between the connection line  131  and the connection line  132  of the metal plate  120 . 
     From  FIG. 10  and  FIG. 11 , it was confirmed that resonance for one wavelength and resonance for two wavelengths occur in the loop constructed of the connection line  131 , the line  121 , the line  122 , the connection line  132 , the edge side  50 B, and the edge side  50 A and resonance at the frequency f 1  (0.85 GHz) and the frequency f 2  (1.65 GHz), which is approximately double the frequency f 1 , occurs. 
     At the frequency f 3  (2.0 GHz) depicted in  FIG. 12 , it is found that a current flows through the power feeding element  110  and flows through a loop constructed of the connection line  131 , the line  121 , the line  123 , the connection line  133 , the edge side  50 C, and the edge side  50 A. In particular, since current density of the connection lines  131  and  133  is high, it is found that antinodes of resonance current occur at two locations, that is, the connection lines  131  and  133 . Also, since current density of a portion between the antinodes at the two locations is low, it is found that two antinodes and two nodes of resonance current occur. 
     That is, from the current distribution depicted in  FIG. 12 , it is found that resonance for one wavelength occurs in the loop constructed of the connection line  131 , the line  121 , the line  123 , the connection line  133 , the edge side  50 C, and the edge side  50 A. In other words, it is found that a portion having the length (3/2), which is ½ of the electrical length of the wavelength  3  at the frequency f 3 , extends between the connection line  131  and the connection line  132  of the metal plate  120 . 
     At the frequency f 4  (2.4 GHz) depicted in  FIG. 13 , it is found that a current flows through the power feeding element  110  and a loop current flows through the line  121 , the connection line  131 , the edge side  50 A, and the power feeding element  110 . In particular, since current density of the power feeding element  110  and the connection line  131  is high, it is found that antinodes of resonance current occur at two locations, that is, the power feeding element  110  and the connection line  131 . Also, since current density of a portion between the antinodes at the two locations is low, it is found that two antinodes and two nodes of resonance current occur. 
     That is, from the current distribution depicted in  FIG. 13 , it is found that resonance for one wavelength occurs in the loop-shaped portion constructed of the line  121 , the connection line  131 , the edge side  50 A, and the power feeding element  110 . In other words, it is found that a portion having the length (4/2), which is ½ of the electrical length of the wavelength  4  at the frequency f 4 , extends in a portion of the edge side  50 A between the power feeding element  110  and the connection line  131 . 
       FIG. 14  is a diagram depicting dependency of frequency characteristics of the S 11  parameter with respect to the length of the power feeding element  110 . Here, in a simulation, frequency characteristics of the S 11  parameter are described when the length of the power feeding element  110  is set at 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm by changing the position of the power feeding point  111 , with the position of the open end  112  of the power feeding element  110  being fixed. 
     When the length of the power feeding element  110  is 15 mm, 20 mm, and 25 mm, substantially favorable values were acquired at the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz). However, when the length of the power feeding element  110  is 10 mm and 30 mm, a tendency of reflection to increase was observed. 
     In particular, when comparisons at the frequency f 2  (1.65 GHz) are made among the cases when the length of the power feeding element  110  is 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm, fluctuations of the S 11  parameter were significant. When the length of the power feeding element  110  is 10 mm and 30 mm, the S 11  parameter significantly exceeded −6 dB, and a favorable radiation characteristic was not acquired. From this, it was found that the length of the power feeding element  110  is preferably set within a range longer than 10 mm and shorter than 30 mm. 
     Here, since the metal plate  120  is positioned near the housing  210 , a wavelength shortening effect occurs. When a wavelength shortening ratio is set at 0.7 to find a wavelength (electrical length 2) at 1.65 GHz,  2  is approximately 131 mm. A range longer than 10 mm and shorter than 30 mm may be represented as 0.07 2&lt;the length of the power feeding element  110 &lt;0.2 2 when normalized by the wavelength at 1.65 GHz. 
       FIG. 15  is a diagram depicting differences in frequency characteristic of the S 11  parameter depending on the presence or absence of the housing  210 . A characteristic with the housing  210  is indicated by a solid line, and a characteristic without the housing  210  is indicated by a broken line. Here, as compared with the case without the housing  210 , it was confirmed that the S 11  parameter in the case with the housing  210  is shifted to a low frequency side as a whole. From this, it was confirmed that a wavelength shortening effect occurs in the case with the housing  210 . 
     The frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz) in the case with the housing  210  are lower by approximately 30%, as compared with the four frequencies (approximately 1.2 GHz, approximately 2.2 GHz, approximately 2.7 GHz, and approximately 3.0 GHz) in the case without the housing  210 . This represents that the wavelength shortening effect is approximately 30%, which is the result substantially consistent with the wavelength shortening ratio (0.7) described by using  FIG. 14 . 
       FIG. 16  is a diagram depicting frequency characteristics of the S 11  parameter when the position of the connection line  132  is changed. Changing the position of the connection line  132  refers to changing the distance from an end of the line  122  in the Y axis positive direction (a connection part between the lines  121  and  122 ) to the connection line  132 . While a mode of 65 mm is depicted in  FIG. 7 , frequency characteristics of the S 11  parameter in the case of 60 mm and 55 mm in addition to 65 mm were found herein. Note that the characteristic in the case of 65 mm is indicated by a solid line, the characteristic in the case of 60 mm is indicated by a broken line, and the characteristic in the case of 55 mm is indicated by a one-dot-chain line. 
     Since the connection line  132  is related to the frequencies f 1  (0.85 GHz) and f 2  (1.65 GHz), the frequencies f 1  (0.85 GHz) and f 2  (1.65 GHz) fluctuated as depicted in  FIG. 16 . Specifically, when the position of the connection line  132  was made closer to the end of the line  122  in the Y axis positive direction as 65 mm, 60 mm, and 55 mm, the frequencies f 1  (0.85 GHz) and f 2  (1.65 GHz) were shifted to a high frequency side. 
     The reason for this occurrence is thought as follows. When the position of the connection line  132  is made closer to the end of the line  122  in the Y axis positive direction, the length of a loop constructed of the connection lines  131  and  132 , the lines  121  and  122  of the metal plate  120 , the edge side  50 A, and the edge side  50 B is shortened and the resonance frequency of the loop antenna is shifted to the high frequency side. 
       FIG. 17  is a diagram depicting frequency characteristics of the S 11  parameter when the position of the connection line  133  is changed. Changing the position of the connection line  133  refers to changing the distance from an end of the line  123  in the Y axis positive direction (a connection part between the lines  121  and  123 ) to the connection line  133 . While a mode of 46 mm is depicted in  FIG. 7 , frequency characteristics of the S 11  parameter in the case of 44 mm and 42 mm in addition to 46 mm were found herein. Note that the characteristic in the case of 46 mm is indicated by a solid line, the characteristic in the case of 44 mm is indicated by a broken line, and the characteristic in the case of 42 mm is indicated by a one-dot-chain line. 
     Since the connection line  133  is related to the frequency f 3  (2.0 GHz), the frequency f 3  (2.0 GHz) fluctuated as depicted in  FIG. 17 . Specifically, when the position of the connection line  133  was made closer to the end of the line  123  in the Y axis positive direction as 46 mm, 44 mm, and 42 mm, the frequency f 3  (2.0 GHz) was shifted to a high frequency side. 
     The reason for this occurrence is thought as follows. When the position of the connection line  133  is made closer to the end of the line  123  in the Y axis positive direction, the length of the loop constructed of the connection lines  131  and  133 , the lines  121  and  123  of the metal plate  120 , the edge side  50 A, and the edge side  50 C is shortened and the resonance frequency of the loop antenna is shifted to the high frequency side. 
       FIG. 18  is a diagram depicting frequency characteristics of the S 11  parameter when the position of the connection line  131  is changed. Changing the position of the connection line  131  refers to changing the distance from an end of the line  121  in the X axis positive direction (a connection part between the lines  121  and  123 ) to the connection line  131 . While a mode of 7 mm is depicted in  FIG. 7 , frequency characteristics of the S 11  parameter in the case of 10 mm and 13 mm in addition to 7 mm are depicted herein. Note that the characteristic in the case of 7 mm is indicated by a solid line, the characteristic in the case of 10 mm is indicated by a broken line, and the characteristic in the case of 13 mm is indicated by a one-dot-chain line. 
     Since the connection line  131  is related to all of the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz), the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz) fluctuated as depicted in  FIG. 18 . Specifically, when the position of the connection line  131  was made closer to the end of the line  121  in the X axis positive direction as 13 mm, 10 mm, and 7 mm, the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), and f 4  (2.4 GHz) were shifted to a low frequency side, and the frequency f 3  (2.0 GHz) was shifted to a high frequency side. 
     The reason for this is thought as follows. When the position of the connection line  131  is made closer to the end of the line  121  in the X axis positive direction, the loop resonating at the frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), and f 4  (2.4 GHz) becomes long and the resonance frequency is thus shifted to the low frequency side and the loop resonating at the frequency f 3  (2.0 GHz) becomes short and the resonance frequency is thus shifted to the high frequency side. 
     These results are consistent with the fact that a loop current is acquired at the above-described four frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz). 
     As described above, according to the embodiment, the antenna device  100  is acquired, the antenna device  100  being capable of communication at the four frequencies f 1  (0.85 GHz), f 2  (1.65 GHz), f 3  (2.0 GHz), and f 4  (2.4 GHz) with a simple structure using the ground plane  50 , the power feeding element  110 , the metal plate  120 , and the connection lines  131 ,  132 , and  133 . 
     The antenna device  100  is capable of communication at the four bands with a fixed, simple structure including the power feeding element  110 , the metal plate  120 , and the connection lines  131 ,  132 , and  133 , without switching connection by a switch or the like. That is, the antenna device  100  rendered multiband with a simple structure may be provided. 
     Also, since communication at the four bands is not achieved by switching by a switch or the like but is available at any time, it is possible to easily support carrier aggregation. 
     Also, the metal plate  120  is present on an exterior surface of the wireless communication device  200  including the antenna device  100  and the electronic device, and has a role in reinforcing the housing  210 . This means that the reinforcing member (metal plate  120 ) is used as an antenna element. That is, with a simple structure using the reinforcing member as an antenna element, the multiband antenna device  100  capable of supporting carrier aggregation may be provided. 
     Also, the length of the metal plate  120  between the connection line  134 A and the connection line  133  is set to be shorter than the length (4/2), which is ½ of the electrical length of the wavelength  4  at the frequency f 4 , thereby keeping communication characteristics at the frequencies f 1 , f 2 , f 3 , and f 4  from degradation. The same goes for the position of the connection line  135 A. Since the connection lines  134 A and  135 A are metal members supporting the metal plate  120 , the antenna device  100  rendered multiband with a simple structure is achieved by optimizing the position of the metal members supporting the metal plate  120 . 
     Note that the mode has been described above in which the four corners (joint parts of the lines  121  to  124 ) of the metal plate  120  are each bent at the right angle, but a shape with rounded four corners may be adopted. 
     Also, a structure may be adopted in which a fifth communication band may be provided by loading a branch element to the power feeding element  110 .  FIG. 19  is a diagram depicting an antenna device  100 A of a modification example of the embodiment.  FIG. 20  is a diagram depicting an antenna device  100 B of a modification example of the embodiment. 
     The antenna device  100 A depicted in  FIG. 19  has a structure with the power feeding element  110  of the antenna device  100  depicted in  FIG. 1  to  FIG. 5  additionally provided with a branch element  140 A. The branch element  140 A is a linear antenna element having a connection end  141 A and an open end  142 A. 
     The branch element  140 A has the connection end  141 A connected to the power feeding point  111 , and extends to the open end  142 A to the X axis direction. The length of the branch element  140 A from the connection end  141 A to the open end  142 A is set at a length (5/4), which is ¼ of the electrical length of a wavelength  5  at a frequency f 5 . 
     The frequency f 5  is, by way of example, 3.5 GHz, which is a frequency higher than the frequencies f 1 , f 2 , f 3 , and f 4 . The branch element  140 A functions as a monopole antenna in cooperation with the ground plane  50 , allowing communication at the frequency f 5 . Note that the length of the branch element  140 A is, by way of example, 8.5 mm. 
     Also, the antenna device  100 B depicted in  FIG. 20  has a structure in which a branch element  140 B is added to the power feeding element  110  of the antenna device  100  depicted in  FIG. 1  to  FIG. 5 . The branch element  140 B is an L-shaped antenna element having a connection end  141 B, an open end  142 B, and a bent part  143 B. 
     The branch element  140 B has the connection end  141 B connected to the power feeding point  111 , extends from the connection end  141 B to the bent part  143 B to a Y axis negative direction side, is bent at the bent part  143 B at the right angle to the X axis positive direction, and extends to the open end  142 B to the X axis direction. 
     The length of the branch element  140 B from the connection end  141 B via the bent part  143 B to the open end  142 B is set at a length (5/4), which is ¼ of the electrical length of the wavelength  5  at the frequency f 5 . The frequency f 5  is, by way of example, 3.5 GHz. The branch element  140 B functions as a monopole antenna in cooperation with the ground plane  50 , allowing communication at the frequency f 5 . Note that the length of the branch element  140 B is, by way of example, 4 mm between the connection end  141 B and the bent part  143 B and 10 mm between the bent part  143 B and the open end  142 B. 
       FIG. 21  is a diagram depicting frequency characteristics of the S 11  parameter of the antenna devices  100 ,  100 A, and  100 B. The characteristic of the antenna device  100  is indicated by a solid line, the characteristic of the antenna device  100 A is indicated by a broken line, and the characteristic of the antenna device  100 B is indicated by a one-dot-chain line. The characteristic of the antenna device  100  is identical to the characteristic depicted in  FIG. 8 . 
     As compared with the antenna device  100 , in the antenna devices  100 A and  1006 , resonance at frequencies higher than the frequency f 4  was acquired. Resonance occurred at approximately 4 GHz in the antenna device  100 A, and resonance occurred at 3.5 GHz (f 5 ) in the antenna device  1006 . While the resonance frequency of the antenna device  100 A is higher than f 5 , it is thought that this is adjustable to 3.5 GHz (f 5 ) by using a matching circuit. 
     As depicted in  FIG. 19  to  FIG. 21 , the antenna device  100 A including the branch element  140 A and the antenna device  100 B including the branch element  140 B are capable of communication at the five bands with a fixed, simple structure. That is, the antenna devices  100 A and  100 B each rendered multiband with a simple structure may be provided. 
       FIG. 22  is a diagram depicting an antenna device  100 C of a modification example of the embodiment. The antenna device  100 C has a structure in which the branch element  140 B (refer to  FIG. 20 ) is added to the antenna device  100  depicted in  FIG. 4  and adjustment circuits  152  and  153  are inserted between the connection lines  132  and  133  and the ground plane  50 . Note that the length between the connection line  132  and an end of the line  122  on the Y axis positive direction side is 65 mm, and the length between the connection line  133  and an end of the line  123  on the Y axis positive direction side is 41 mm. 
       FIG. 23  is a diagram depicting frequency characteristics of the S 11  parameter of the antenna device  100 C when the impedance of the adjustment circuit  152  is changed. S 11  parameters were found in the cases in which the adjustment circuit  152  was short-circuited (solid line), an inductor of 2 nH was inserted in series to the connection line  132  (broken line), and a capacitor of 10 pF was inserted in series to the connection line  132  (one-dot-chain line). Note that the case in which the adjustment circuit  152  was short-circuited is the case in which the ground plane  50  and the metal plate  120  were connected by the connection line  132  as depicted in  FIG. 4  without insertion of the adjustment circuit  152 . 
     As compared with the case in which the adjustment circuit  152  was short-circuited, the 800 MHz band and the 1.5 GHz band were shifted to a low frequency side when the inductor was inserted, and the 800 MHz band and the 1.5 GHz band were shifted to a high frequency side when the capacitor was inserted. From this, it was confirmed that the resonance frequency is adjustable by inserting the adjustment circuit  152  as an inductor or capacitor into the connection line  132 . 
       FIG. 24  is a diagram depicting frequency characteristics of the S 11  parameter of the antenna device  100 C when the impedance of the adjustment circuit  153  is changed. S 11  parameters were found in the cases in which the adjustment circuit  153  was short-circuited (solid line), an inductor of 2 nH was inserted in series to the connection line  133  (broken line), and a capacitor of 10 pF was inserted in series to the connection line  133  (one-dot-chain line). Note that the case in which the adjustment circuit  153  was short-circuited is the case in which the ground plane  50  and the metal plate  120  were connected by the connection line  133  as depicted in  FIG. 4  without insertion of the adjustment circuit  153 . 
     As compared with the case in which the adjustment circuit  153  was short-circuited, the 1.9 GHz band was shifted to a low frequency side when the inductor was inserted, and the 1.9 GHz band was shifted to a high frequency side when the capacitor was inserted. From this, it was confirmed that the resonance frequency is adjustable by inserting the adjustment circuit  153  as an inductor or capacitor into the connection line  133 . 
     Also, it was confirmed from this that the resonance frequency is adjustable by inserting the adjustment circuit  153  without changing the position of the connection line  133  to the Y axis direction. For example, when the position of the connection line  133  is limited due to the positional relation with a circuit component included in the electronic device or the like, the use of the adjustment circuit  153  allows impedance matching at a desired resonance frequency. 
     Also, while the above description has been made by using the wavelengths  1 ,  2 ,  3 ,  4 , and  5  of basic waves of the frequencies f 1 , f 2 , f 3 , f 4 , and f 5 , communications at the frequencies f 1 , f 2 , f 3 , f 4 , and f 5  may be made possible by setting so that the wavelengths of harmonics of orders equal to or higher than the second order at the frequencies f 1 , f 2 , f 3 , f 4 , and f 5  satisfy the above-described conditions. 
     While the antenna device and the wireless communication device of the exemplary embodiment of the present invention has been described above, the present invention is not limited to the specifically disclosed embodiment and may be variously modified or changed without deviating from the scope of the claims. 
     The following appendices are further disclosed regarding the above-described embodiment. 
     (Appendix 1) 
     An antenna device including: 
     a ground plane which has an edge side; 
     a metal member arranged along the edge side of the ground plane; 
     a first connection line which connects the metal member and the ground plane; 
     a second connection line which connects the metal member and the ground plane; and 
     a power feeding element which has a power feeding point, extends along the metal member from the power feeding point between the first connection line and the second connection line, and is electromagnetic-field-coupled to the metal member. 
     (Appendix 2) 
     The antenna device according to appendix 1, in which 
     a length of the metal member between the first connection line and the second connection line is a length corresponding to ½ of a first wavelength at a first frequency and is a length corresponding to a second wavelength at a second frequency which is a double of the first frequency. 
     (Appendix 3) 
     The antenna device according to appendix 2, in which 
     a first loop constructed of the metal member, the first connection line, the second connection line, and the ground plane constructs a loop antenna which resonates at the first frequency and the second frequency. 
     (Appendix 4) 
     The antenna device according to appendix 2 or 3, in which 
     a length of the power feeding element is longer than 0.07 times of a length of a wavelength at the second frequency and shorter than 0.2 times of the length of the wavelength at the second frequency. 
     (Appendix 5) 
     The antenna device according to any one of appendices 1 to 4, further including: 
     an inductor or capacitor loaded on the second connection line. 
     (Appendix 6) 
     The antenna device according to any one of appendices 1 to 5, further including: 
     a third connection line which connects the metal member and the ground plane oppositely to the second connection line with respect to the first connection line. 
     (Appendix 7) 
     The antenna device according to appendix 6, further including: 
     an inductor or capacitor loaded on the third connection line. 
     (Appendix 8) 
     The antenna device according to appendix 6 or 7, in which 
     a length of the metal member between the first connection line and the third connection line is a length corresponding to ½ of a third wavelength at a third frequency. 
     (Appendix 9) 
     The antenna device according to appendix 8, in which 
     a second loop constructed of the metal member, the first connection line, the third connection line, and the ground plane constructs a loop antenna which resonates at the third frequency. 
     (Appendix 10) 
     The antenna device according to any one of appendices 1 to 9, in which 
     a distance between a position corresponding to the power feeding point on the edge side of the ground plane and a position where the first connection line is connected to the ground plane is set at a distance represented by a length corresponding to ½ of a fourth wavelength in a fourth frequency. 
     (Appendix 11) 
     The antenna device according to any one of appendices 1 to 10, further including: 
     a branch element which is connected to the power feeding element at the power feeding point, extends from the power feeding point to a direction opposite to the power feeding element along the metal member, and has a length corresponding to ¼ of a wavelength at a fifth frequency. 
     (Appendix 12) 
     A wireless communication device including: 
     a substrate; and 
     an antenna device disposed on the substrate, in which 
     the antenna device includes 
     a ground plane which has an edge side, 
     a metal member arranged along the edge side of the ground plane, 
     a first connection line which connects the metal member and the ground plane, 
     a second connection line which connects the metal member and the ground plane, and 
     a power feeding element which has a power feeding point, extends along the metal member from the power feeding point between the first connection line and the second connection line, and is electromagnetic-field-coupled to the metal member. 
     All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.