Patent Publication Number: US-2013237162-A1

Title: Mobile communication device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2012-0023485, filed on Mar. 7, 2012, which is incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     1. Field 
     The following description relates to a mobile communication device, and more particularly, to a mobile communication device including a frequency-tunable antenna to selectively shift a resonance frequency in a multi-band or single-band antenna module. 
     2. Discussion of the Background 
     As various kinds of mobile communication services have been commercialized for mobile communication devices, the number of resonance frequency bands supported by a single terminal is gradually increasing. In addition, in order to support global roaming without being limited to a specific communication service provider, mobile communication devices having an antenna capable of realizing multi-band and ultra wideband with a small size or volume are being studied to reduce the size and/or volume of the antenna and pursue slim products and enhanced designs. 
     Particularly, in a case of a terminal supporting Long Term Evolution (LTE), various tunable antennas or switching antennas are being studied to overcome the difficulty of realizing a wide band of an antenna. 
     However, tunable antennas are expensive, and may experience deteriorated emission efficiency in frequency bands other than the switching band. In other words, after switching between a high frequency band and a low frequency band, the frequency matching characteristic of the antenna may deteriorate in some frequency bands. 
       FIG. 1  is a schematic view illustrating a general antenna according to the related art.  FIG. 1  is a circuitry diagram illustrating a general multi-band antenna. A wave traveling toward an antenna and a wave reflected from the antenna may be detected by a power detector  15 , and a value of a digital-analog converter  12  may be digitally adjusted to maintain an amount of reflection from the antenna below a reference value so that an inductance value and a capacitance value in a tunable antenna module  11  may be controlled, thereby adjusting a matching value of the antenna in real time. 
     In the case of  FIG. 1 , an algorithm for performance optimization may be complicated, and a unit price of the general multi-band antenna may increase because an expensive tunable antenna module is applied. In addition, a complicated control circuit  13  is needed to control the complicated tunable antenna, and accordingly a board-mounting region for other components may fall short of what is needed. Moreover, since the capacitance value C and inductance value L to enlarge a frequency receiving bandwidth are great, a loss in board-mounting region increases due to the use of a concentrating element. Accordingly, a noise problem may occur in the antenna due to the application of an external DC power. 
       FIG. 2  is a schematic view illustrating a general antenna according to the related art.  FIG. 2  is a circuitry diagram showing a configuration to switch to a selected frequency by controlling an antenna ground supply location. Various matching circuits may be implemented by using a first switch  22  and a second switch  23 . 
     Referring to  FIG. 2 , by adjusting resonance length L 1  and resonance length L 2  of the antenna if the first switch  22  is connected and if the second switch  23  is connected, the resonance frequency may be shifted. 
     In the case of  FIG. 2 , the degree of frequency shifting varies according to a separation distance D between the two switches, which are the ground source. If the distance from a signal supply pin increases over a reference level, an antenna matching characteristic of a specific frequency band may deteriorate. Therefore, if great frequency shifting is required, frequency bands not selected by the ON/OFF operation of the switch may have deteriorated characteristics. In addition, since the antenna pattern may be electrically connected to the DC power of the switch, noise may be generated by the power, which may cause deterioration in the sensitivity of the antenna. 
       FIG. 3A  and  FIG. 3B  are graphs illustrating matching characteristics of antennas according to the related art.  FIG. 3A  illustrates a frequency matching characteristics before frequency shifting.  FIG. 3B  illustrates a frequency matching characteristic after frequency shifting. 
     Referring to  FIG. 3A , before frequency shifting, the standing wave ratio may be close to 1 in both a high frequency band and a low frequency band, and thus it may be considered that excellent matching characteristics are ensured. However, referring to  FIG. 3B , in a case where a frequency in a high frequency band shifts, it can be found that the shifted high frequency region has a standing wave ratio close to about 4. In other words, it may be seen that the noise increases when compared to the case before frequency shifting. Therefore, various attempts have been made to improve antenna emission efficiency, reduce noise, and improve matching characteristics. 
     SUMMARY 
     Exemplary embodiments of the present invention provide a mobile communication device including a frequency-tunable antenna to selectively shift a resonance frequency in a multi-band or single-band antenna module. 
     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
     An exemplary embodiment of the present invention discloses a mobile terminal including an antenna, including: a first antenna pattern line with a first length determined according to a first frequency to be received or transmitted by the first antenna pattern line; a first capacitor unit having a first electrode disposed on the first antenna pattern line and a second electrode disposed opposite the first electrode; and a first switch to selectively connect the second electrode to a ground to shift a resonant frequency of the first antenna pattern. 
     An exemplary embodiment of the present invention also discloses an antenna unit, including: an antenna pattern line; an electrode disposed opposite at least a portion of the antenna pattern line; a switch to selectively connect the electrode to a ground to shift a resonant frequency of the antenna pattern. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention 
         FIG. 1  is a schematic view illustrating a general antenna according to the related art. 
         FIG. 2  is a schematic view illustrating a general antenna according to the related art. 
         FIG. 3A  and  FIG. 3B  are graphs illustrating matching characteristics of antennas according to the related art. 
         FIG. 4  is a circuitry diagram illustrating an antenna unit according to an exemplary embodiment of the present disclosure. 
         FIG. 5A  and  FIG. 5B  are graphs illustrating a voltage distribution of an antenna according to an exemplary embodiment of the present disclosure. 
         FIG. 6  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure. 
         FIG. 7  is a circuitry diagram illustrating the antenna unit and the capacitor unit of  FIG. 6 . 
         FIGS. 8A ,  8 B, and  8 C are graphs illustrating standing wave ratios according to an exemplary embodiment of the present disclosure. 
         FIG. 9  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure. 
         FIG. 10  is a circuitry diagram illustrating an antenna unit and a capacitor unit of  FIG. 9 . 
         FIGS. 11A ,  11 B, and  11 C are graphs illustrating standing wave ratios according to an exemplary embodiment of the present disclosure. 
         FIG. 12  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure. 
         FIG. 13  is a circuitry diagram illustrating the antenna unit and the capacitor unit of  FIG. 12 . 
         FIG. 14A ,  FIG. 14B , and  FIG. 14C  are graphs illustrating standing wave ratios according to an exemplary embodiment of the present disclosure. 
         FIG. 15  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure. 
         FIG. 16  is a circuitry diagram illustrating the antenna unit and the capacitor unit of  FIG. 15 . 
         FIG. 17  is a graph illustrating a standing wave according to an exemplary embodiment of the present disclosure. 
         FIG. 18  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure. 
         FIG. 19A  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure. 
         FIG. 19B  is a rear view illustrating the antenna unit and the capacitor unit of  FIG. 19A . 
         FIG. 20A  and  FIG. 20B  are graphs illustrating matching characteristics of an antenna unit according to an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Exemplary embodiments are described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity Like reference numerals in the drawings denote like elements. Although features may be shown as separate, such features may be implemented together or individually. Further, although features may be illustrated in association with an exemplary embodiment, features for one or more exemplary embodiments may be combinable with features from one or more other exemplary embodiments. 
     It will be understood that when an element or layer is referred to as being “on” or “connected to” another element or layer, it can be directly on or directly connected to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on” or “directly connected to” another element or layer, there are no intervening elements or layers present. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). 
     Hereinafter, a mobile communication device including an antenna module according to exemplary embodiments of the present disclosure will be described in detail with reference the drawings. 
     An antenna module of a mobile communication device includes an antenna unit and a capacitor unit. 
       FIG. 4  is a circuitry diagram illustrating an antenna unit according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG. 4 , an antenna unit  100  includes at least one antenna line with a reference length according to a wavelength of a frequency to be received, which has a first antenna pattern line  110  and a second antenna pattern line  120 . The second antenna line  120  may be longer than the first antenna pattern line  110 . The antenna unit may include a first region S 1 , a second region S 2  and a third region S 3  and will be described below with reference to  FIG. 5A  and  FIG. 5B . 
     The antenna unit  100  may be connected to a power supply V. The first antenna pattern line  110  and the second antenna pattern line  120  may include open point O 1 , open point O 2 , ground point P 1 , and ground point P 2 . Ground point P 1  and P 2  may be connected to a ground terminal. The antenna unit  100  may include a coupling ground line  130  electrically insulated and grounded from the first antenna pattern line  110  and second antenna pattern line  120 . The coupling ground line  130  may be used to generate multi-resonance in a high frequency band. 
     The length of the first antenna pattern line  110  and the second antenna pattern line  120  may refer to a length along the first antenna pattern line  110  and the second antenna pattern line  120  from the open point O 1  and the open point O 2 , respectively, to the ground point P 1  and the ground point P 2 . 
       FIG. 5A  and  FIG. 5B  are graphs illustrating voltage distribution of an antenna unit according to an exemplary embodiment of the present disclosure. Although  FIG. 5A  and  FIG. 5B  will described with reference to  FIG. 4 , aspects of the exemplary embodiments are not limited thereto. 
     Herein, a wavelength having a frequency of 2 GHz is used to represent a wavelength of a high frequency band, and a wavelength having a frequency of 700 MHz is used to represent a wavelength of a low frequency band; however, the exemplary embodiments are not limited thereto, and various wavelengths may be used in various high frequency bands and various low frequency bands. 
       FIG. 5A  may be a graph illustrating voltage distribution based on the ground point P 1  and the ground point P 2 , and  FIG. 5B  may be a graph illustrating voltage distribution based on the open point O 1  and the open point O 2 . 
     Referring to  FIG. 5A  and  FIG. 5B , in the case of the ground point P 1  and ground point P 2 , the voltage may be 0 V due to grounding, and the open point O 1  and the open point O 2  may have a maximum potential due to the power supply V. The voltage distribution may be determined according to the frequency of a power supplied to the antenna unit  100 . A line “a” represents voltage distribution if a frequency of a low frequency band is supplied and a line “b” represents voltage distribution if a frequency of a high frequency band is supplied. 
     Referring to  FIG. 4 ,  FIG. 5A  and  FIG. 5B , the first region S 1 , the second region S 2  and the third region S 3  are regions of the antenna unit  100 . 
     The first region S 1  is a region adjacent to the ground point P 1  of the first antenna pattern line  110 , and the second region S 2  is a region between the open point O 2  and the ground point P 2  of the second antenna pattern line  120 . Third region S 3  represents a region adjacent to the open point O 2  of the second antenna pattern line  120 . 
     Referring to  FIG. 5A , in the first region S 1 , the voltage may be relatively high with respect to the frequency of a high frequency band, but the voltage may be relatively low in case of the frequency of a low frequency band. If the wavelength of a high frequency band received by the antenna unit is λ 1  and a wavelength of a low frequency band is λ 2 , the first region S 1  may be a region from the ground point P 1  on the first antenna pattern line  110  to a ¼ point (λ 1 /4) of the wavelength λ 1  of the high frequency band to be received. 
     Referring to  FIG. 5A  and  FIG. 5B , in the second region S 2 , the voltage may be close to 0 V in the frequency of the high frequency band, but the voltage may be relatively high in the low frequency band. The second region S 2  may be a region from the open point O 2  on the second antenna pattern line  120  between a ⅛ point (λ 1 /8) and ⅜ point ( 3 λ 1 /8) of the wavelength λ 1  of the high frequency band to be received. However, the second region S 2  is not limited thereto, and the second region S 2  may also be a region adjacent to a ⅛ point (λ 2 /8) based on the wavelength λ 2  of the low frequency band. 
     The third region S 3  may be a region adjacent to the open point O 2 , the voltage may be high in the high frequency band and the low frequency band. The third region S 3  may be a region from the open point O 2  on the second antenna pattern line  120  to a ⅛ point (λ 1 /8) of the wavelength λ 1  of the high frequency band to be received. 
     A coupling capacitance C may be expressed by the following equation. 
     
       
         
           
             C 
             = 
             
               
                 S 
                 × 
                 V 
               
               d 
             
           
         
       
     
     The coupling capacitance C may be determined according to an opposite area S of two opposite electrodes that overlap with each other, a voltage V and a distance d between the opposite electrodes. 
     A capacitor unit may be included to form a coupling capacitance at the antenna unit  100 . 
     The capacitor unit may include a first electrode disposed on the antenna unit, a second electrode electrically insulated from the first electrode and disposed to have a first opposite area which overlaps with the first electrode, and a switch to selectively connect the second electrode to a ground terminal. An opposite area may refer to the area of the second electrode which is disposed opposing the area of the first electrode and may correspond to the opposite area S. 
     The capacitor unit may include a partial region of the antenna unit, i.e., a partial region on the antenna pattern line, as the first electrode, and the second electrode to have a first opposite area disposed to be opposing to the first electrode such that the first electrode and the to second electrode may form a coupling capacitance. 
     The second electrode may be disposed to be selectively connected to a ground electrode such that a voltage difference is formed between the second electrode and the first electrode. The second electrode may be selectively connected to an active position if the second electrode is connected to the ground terminal to form a coupling capacitance and to an inactive position if the second electrode and the ground terminal are opened using the switch. 
     If the coupling capacitance is formed in the antenna unit  100 , a resonance frequency may shift. An amount of frequency shifting may be adjusted according to the magnitude of the coupling capacitance. The coupling capacitance may be controlled by adjusting a potential difference V between the first electrode and the second electrode, an opposite area of the first electrode and the second electrode, or a distance d between the first electrode and the second electrode. 
     The capacitance of the capacitor unit may be determined according to the potential difference between the first electrode and the second electrode. Referring to  FIG. 5A  and  FIG. 5B , because the voltage distribution on the antenna pattern line varies according to a location on the antenna pattern line, the magnitude of the coupling capacitance may be adjusted according to a location of the second electrode on the antenna line pattern. 
     If the capacitor units are formed in each of the first region S 1 , the second region S 2  and the third region S 3 , the coupling capacitance may be expressed as shown in Table 1 below according to the voltage distribution of the antenna pattern line, as described above. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 Coupling 
                 Resonance 
               
               
                 Position 
                 Band 
                 Voltage 
                 capacitance 
                 frequency 
               
               
                   
               
             
            
               
                 first region S 1   
                 high frequency 
                 V 1   
                 C1 
                 f h -α 
               
               
                   
                 low frequency 
                 →0 
                 →0 
                 f L   
               
               
                 second region S 2   
                 high frequency 
                  0 
                  0 
                 f h   
               
               
                   
                 low frequency 
                 V 2   
                 C2 
                 f L -β 
               
               
                 third region S 3   
                 high frequency 
                 V 31   
                 C31 
                 f h -α 
               
               
                   
                 low frequency 
                 V 32   
                 C32 
                 f L -β 
               
               
                   
               
            
           
         
       
     
     V 1  may represent a voltage according to a high frequency band in the first region S 1 , V 2  may represent a voltage according to a low frequency band in the second region S 2 , and V 31  and V 32 , respectively, may represent voltages according to a high frequency band and a low frequency band in the third region S 3 . 
     C 1  may represent a coupling capacitance from the capacitor unit formed in the first region S 1 , C 2  may represent a coupling capacitance from the capacitor unit formed in the second region S 2 , and C 31  and C 32 , respectively, may represent coupling capacitances of a component which influences the high frequency band and the low frequency band formed in the third region S 3 . 
     If a capacitance is formed in the antenna unit  100 , the resonance frequency of the antenna unit  100  may shift. Therefore, if frequency shifting is selected in the antenna unit  100 , the capacitor unit may be formed in at least one of the first region S 1 , the second region S 2 , and the third region S 3 . 
     If a capacitor unit is formed in each region, particularly in the first region S 1 , the frequency of the high frequency band may shift from f h  as much as α, but the frequency f L  of the low frequency band may be maintained. In the second region S 2 , the frequency of the high frequency band may be maintained at f h , but the frequency f L  of the low frequency band may shift as much as β. In the third region S 3 , the frequency of the high frequency band may shift from f h  as much as α, and the frequency of the low frequency band may shift from f L  as much as β. 
     If the first capacitor unit is disposed in the first region such that the second electrode has an overlapping area, the frequency of the high frequency band may be selectively shifted. If the second capacitor unit is disposed in the second region S 2  such that the second electrode has an overlapping area, the frequency of the low frequency band may be selectively shifted. If the third capacitor unit is disposed in the third region such that the second electrode has an opposite area, the frequency may be shifted in both the high frequency band and the low frequency band. 
       FIG. 6  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure.  FIG. 7  is a circuitry diagram illustrating the antenna unit and the capacitor unit in  FIG. 6 . 
     Referring to  FIG. 6  and  FIG. 7 , an antenna unit  100  includes a first antenna pattern line  110  and a second antenna pattern line  120 . A first region S 1  may be formed on the first pattern line  110 . The first region S 1  may include first electrode  115  and second electrode  171 . The second electrode  171  may be connected to connection member  191  and a switch  181  and the first electrode  115  may be connected to a power supply V. The first electrode  115  and second electrode  171  may be separated by a distance d 1 . A second region S 2  may be formed on the second antenna pattern  120 . The second region S 2  may include a first electrode  125  and a second electrode  172 . The second electrode  172  may be connected to a connection unit  192  and a second switch  182  and the first electrode  125  may be connected to power supply V. The first electrode  125  and the second electrode  172  may be separated by a distance d 2 . 
     Referring to  FIG. 6 , the antenna unit  100  includes a main antenna. The main antenna may include a first antenna pattern line  110  and a second antenna pattern line  120 . The main antenna may include the signal supply line  111  connected to a signal line, and a ground line  112  connected to a ground. 
     With respect to a wavelength λ 1  of the high frequency band and a wavelength λ 2  of the low frequency band, the resonance frequency of the high frequency band may be expressed as f h1 , and the resonance frequency of the low frequency band may be expressed as f L . 
     The coupling ground line  130  to be used for multi resonance in the high frequency band may be included in the antenna unit  100 . The resonance frequency of the high frequency band generated by the coupling ground line  130  may be represented by f h2 . 
     Referring to  FIG. 6  and  FIG. 7 , a first capacitor unit C 1  and a second capacitor unit C 2  formed in the first region S 1  are included. 
     The first capacitor unit C 1  may include a second electrode  171  adjacent to a space from the ground point P 1  of the first antenna pattern line  110  which is the first region S 1  to a λ 1 /4 point, and a first switch  181  for selectively connecting the second electrode  171  to a ground terminal. The second electrode  171  and the first switch  181  may be connected by a connection unit  191 . 
     A through hole H 1  may be formed in the first region S 1  of the first antenna pattern line  110 , and the first electrode  115  may be formed on the first antenna pattern line  110  by the electrical charge of the second electrode  171 . The electrical charge of the second electrode  171  may influence the first antenna pattern line  110  via the through hole H 1 . 
     The second electrode  171  may be formed in or substantially surrounded by the through hole H 1 , and the first electrode  115  and the second electrode  171  may be disposed in the same plane. 
     Referring to  FIG. 7 , a first coupling capacitance C 1  may be formed at the first capacitor unit C 1 . The first capacitor unit C 1  may be formed of four sub-capacitors formed between a first electrode  115   a  and a second electrode  171   a , a first electrode  115   b  and a second electrode  171   b , a first electrode  115   c  and a second electrode  115   c , a first electrode  115   d  and a second electrode  171   d . Each electrode of each sub-capacitor may have an opposite area. The combined area of each electrode in the sub-capacitor may be referred to as an opposite area of a first electrode and a second electrode. The four sub-capacitors may be disposed on four sides surrounding the hole H 1 . The four sub-capacitors may be connected in parallel and the first coupling capacitance C 1  may be proportional to the sum of four sub-capacitance areas. Although illustrated and described as being four, aspects need not be limited thereto such that the first capacitor unit C 1  may include more or fewer sub-capacitors, i.e., the hole H 1  of  110  and the  171  may have other shapes, for example, the H 1  and the  171  may be triangular, pentagonal, hexagonal, etc. 
     The first coupling capacitance C 1  formed between the first electrode  115  and the second electrode  171  may be determined according to a voltage of the first region S 1  of the first electrode  115 , a distance d 1  between the first electrode  115  and the second electrode  171 , and a first opposite area between the first electrode  115  and the second electrode  171 . 
     According to the voltage distribution of the first region S 1 , the resonance frequency f h1  may shift to resonance frequency f h1 ′ in a high frequency band by the antenna unit  100 , but the resonance frequency f L  of the low frequency band may be maintained. The first capacitor unit C 1  does not influence the coupling ground line  130 , and thus resonance frequency f h2  may not shift even though the resonance frequency f h1  of the high frequency band may shift to resonance frequency f h1 ′. 
     The first coupling capacitance C 1  may decrease as the distance d 1  between the first electrode  115  and the second electrode  171  increases, and the first coupling capacitance C 1  of the first capacitor unit C 1  may be adjusted by adjusting the distance d 1 . 
     The first opposite area of the first electrode  115  and the second electrode  171  may be determined by determining the area of the four sides of the second electrode  171  disposed towards the through hole H 1  and an area of a surface of the first electrode  115  opposite to the area of the four sides of the second electrode  171 . Since the first coupling capacitance C 1  increases as the first opposite area increases, the first coupling capacitance C 1  may be controlled by adjusting the area of the four sides of the second electrode  171  and an area of the surface of the first electrode  115  opposite to the second electrode  171 . 
     Referring to  FIG. 6  and  FIG. 7 , the coupling ground line  130  may be disposed adjacent to the first region S 1 . The second electrode  171 , the antenna pattern line  110  of the first region S 1 , and the coupling ground line  130  may be disposed in this order, but are not limited thereto. 
     The antenna pattern line  110  may be disposed between the second electrode  171  and the coupling ground line  130 . The second electrode  171  may not influence the coupling ground line  130 , and a coupling capacitance may not be formed at the coupling ground line  130  although the second electrode  171  is activated. 
     The second capacitor unit C 2  may include the second electrode  172  disposed adjacent to the second region S 2 , and a second switch  182  to selectively connect the second electrode  172  to a ground terminal. The second electrode  172  and the second switch  182  may be connected to a connection unit  192 . 
     A through hole H 2  may be formed in the second region S 2  of the second antenna pattern line  120 , and a first electrode  125  may be formed on the second antenna pattern line  120  by the electrical charge of the second electrode  172 . The electrical charge of the second electrode  172  may influence the second antenna pattern line  120  via the through hole H 2 . 
     The second electrode  172  may be formed in or substantially surrounded by the through hole H 2 , and the first electrode  125  and the second electrode  172  may be disposed in the same plane. 
     Referring to  FIG. 7 , the second coupling capacitance C 2  may be formed by the second capacitor unit C 2 . The second capacitor unit C 2  may be formed of four sub-capacitors formed between a first electrode  125   a  and a second electrode  172   a , a first electrode  125   b  and a second electrode  172   b , a first electrode  125   c  and a second electrode  172   c , a first electrode  125   d  and a second electrode  172   d . Each sub-capacitor may have an opposite area formed by the opposite areas of the four sub-capacitors. The four sub-capacitors may be connected in parallel, and the sum of the capacitances of the four sub-capacitors may be the second coupling capacitance C 2  formed by the second capacitor unit C 2 . 
     As described above with reference to the first capacitor unit C 1 , the second coupling capacitance C 2  of the second capacitor unit C 2  may be determined according to a voltage of the second region S 2  of the first electrode  125 , the distance d 2  between the first electrode  125  and the second electrode  172 , and a first opposite area of the first electrode  125  and the second electrode  172 . 
     According to the voltage distribution of the second region S 2 , the resonance frequency may shift from resonance frequency f L  to resonance frequency f L ′ in the low frequency band, but the resonance frequency f h1  and the resonance frequency f h2  of the high frequency band may be maintained. 
     The coupling capacitance C 2  may decrease as the distance d 2  between the first electrode  125  and the second electrode  172  increases, and the second coupling capacitance C 2  of the second capacitor unit C 2  may be controlled by adjusting the distance d 2 . 
     The first opposite area of the first electrode  125  and the second electrode  172  may be determined by determining the area of the four sides of the second electrode  172  disposed toward the through hole H 2  and an area or a surface of the first electrode  125  opposite to the area of the four sides of the second electrode  172 . Since the second coupling capacitance C 2  increases as the first opposite area increases, the second coupling capacitance C 2  may be controlled by adjusting the area of the four sides of the second electrode  172  and an area of the surface of the first electrode  125  opposite to the second electrode  172 . 
       FIG. 8A ,  FIG. 8B  and  FIG. 8C  are graphs illustrating standing wave ratios according to an exemplary embodiment of the present disclosure.  FIG. 8A ,  FIG. 8B , and  FIG. 8C  illustrate standing waves according to an ON/OFF state of the first switch  181  and the second switch  182  of  FIG. 6  and  FIG. 7 . Although described with reference to  FIG. 6  and  FIG. 7 , the graphs of  FIG. 8A ,  FIG. 8B , and  FIG. 8C  are not limited thereto. 
     Referring to  FIGS. 6 and 7 , if the first capacitor unit C 1  and the second capacitor unit C 2  are formed in the antenna unit  100 , the frequency of the antenna unit  100  may shift as shown in Table 2 below according to whether the first capacitor unit C 1  and the second capacitor unit C 2  are activated. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Coupling 
                 Resonance 
               
               
                   
                 Band 
                 capacitance 
                 frequency 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 first switch OFF 
                 high frequency band 
                 — 
                 f h1   
               
               
                 second switch OFF 
                   
                 — 
                 f h2   
               
               
                   
                 low frequency band 
                 — 
                 f L   
               
               
                 first switch ON 
                 high frequency band 
                 C1 
                 f h1  → f h1 ′ 
               
               
                 second switch OFF 
                   
                 — 
                 f h2   
               
               
                 (see FIG. 8A) 
                 low frequency band 
                 →0 
                 f L   
               
               
                 first switch OFF 
                 high frequency band 
                 — 
                 f h1   
               
               
                 second switch ON 
                   
                 — 
                 f h2   
               
               
                 (see FIG. 8B) 
                 low frequency band 
                 C2 
                 f L  → f L ′ 
               
               
                 first switch ON 
                 high frequency band 
                 C1 
                 f h1  → f h1 ′ 
               
               
                 second switch ON 
                   
                 — 
                 f h2   
               
               
                 (see FIG. 8C) 
                 low frequency band 
                 C2 
                 f L  → f L ′ 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 8A ,  FIG. 8B ,  FIG. 8C , and Table 2, if the first capacitor unit C 1  is activated or in an ON state, the resonance frequency f h1  of the high frequency band of the antenna unit  100  may shift to the resonance frequency f h1 ′, and the remaining resonance frequencies, i.e., a resonance frequency f h2  and the resonance frequency f L , may not shift. If the second capacitor unit C 2  is activated or in an ON state, a resonance frequency f L  of the low frequency band may shift to the resonance frequency f L ′, and remaining frequencies, i.e., the resonance frequency f h1  and the resonance frequency f h2 , may not shift. If the first capacitor unit C 1  and second capacitor unit C 2  are activated, the resonance frequency f h1  of the high frequency band may shift to the resonance frequency f h1 ′, and the resonance frequency f L  of the low frequency band may shift to the resonance frequency f L ′. 
     According to exemplary embodiments, a selected resonance frequency may shift without changing the length of the first antenna pattern line  110  and second antenna pattern line  120  of the antenna unit  100 . Therefore, a mobile communication device including the antenna unit  100  may have an improved matching characteristic or an improved standing characteristic may be provided by the antenna unit  100 . 
       FIG. 9  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure.  FIG. 10  is a circuitry diagram illustrating an antenna unit and a capacitor unit of  FIG. 9 . 
     Referring to  FIG. 9  and  FIG. 10 , an antenna unit  100  includes a first antenna pattern line  110  and a second antenna pattern line  120 . A first region S 1  may be partially formed on the first pattern line  110 . The first region S 1  may include first electrode  116  and second electrode  171 ′. The second electrode  171 ′ may be connected to connection member  191  and a switch  181 ′ and the first electrode  116  may be connected to a power supply V. The first electrode  116  and second electrode  171 ′ may be separated by a distance d 1 ′. A fourth capacitor unit C 4  may be formed on a coupling ground line  130  adjacent to the first region S 1 . A second region S 2  may be formed on the second antenna pattern  120 . The second region S 2  may include a first electrode and a second electrode  172 . The second region S 2  may be similar to the second region S 2  of  FIG. 6  and  FIG. 7 , and therefore descriptions thereof may be omitted for brevity. 
     The first capacitor unit C 1 ′ may include the second electrode  171 ′ disposed in the first region S 1 , and a first switch  181 ′ disposed adjacent to the first region S 1  to selectively connect the second electrode  171 ′ to a ground terminal. The second electrode  171 ′ and the first switch  181 ′ may be connected to a connection unit  191 . 
     The second electrode  171 ′ may be disposed adjacent to the first antenna pattern line  110 . Accordingly, a portion of the first antenna pattern line  110  adjacent to and opposite to the second electrode  171 ′ may become the first electrode  116 . 
     Referring to  FIG. 10 , the coupling capacitance C 1 ′ may be formed by the first capacitor unit C 1 ′ including the first electrode  116  and the second electrode  171 ′, the coupling capacitance C 1 ′ may be determined by a voltage of the first region S 1  of the first electrode  116 , the distance d 1 ′ between the first electrode  116  and the second electrode  171 ′, and a first opposite area of the first electrode  116  and the second electrode  171 ′. 
     In the voltage distribution of the first region S 1 , the resonance frequency f h1  shifts to the resonance frequency f h1 ′ in a high frequency band of the antenna unit  100 , and the resonance frequency f L  of the low frequency band is maintained. 
     Referring to  FIG. 9 , the coupling ground line  130  may be disposed adjacent to the first region S 1 . The first electrode  116  may be disposed directly adjacent to the second electrode  171 ′ and the second electrode  171 ′ may be disposed directly adjacent to the coupling ground line  130 , but are not limited thereto. 
     If the second electrode  171 ′ is charged, because the charge on the second electrode  171 ′ influences the first electrode  116  and the coupling ground line  130 , a first coupling capacitance C 1 ′ may be formed between the first electrode  116  and the second electrode  171 ′, and a fourth coupling capacitance C 4  may be formed between the coupling ground line  130  and the second electrode  171 ′, separated by distance d 4 . 
     The frequency emitted from the coupling ground line  130  may correspond to a wavelength of a high frequency band, similar to the resonance frequency f h1 , and a resonance frequency f h2  in the high frequency band may shift to a resonance frequency f h2 ′ because of the formation of the fourth coupling capacitance C 4  on the coupling ground line  130 . 
     The first coupling capacitance C 1 ′ may decrease as the distance d 1 ′ between the first electrode  116  and the second electrode  171 ′ increases, and the first coupling capacitance C 1 ′ formed by the first capacitor unit C 1 ′ may be controlled by adjusting the distance d 1 ′. 
     The fourth coupling capacitance C 4  may be controlled by adjusting the distance d 4 ′ between the second electrode  171 ′ and the coupling ground line  130 . 
     The first coupling capacitance C 1 ′ may increase as a first opposite area of the first electrode  116  and the second electrode  171 ′ increases. The first coupling capacitance C 1 ′ may be controlled by adjusting the first opposite area of the second electrode  171 ′ and the first electrode  116 . The fourth coupling capacitance C 4  may be controlled by adjusting a fourth opposite area of the second electrode  171 ′ and the coupling ground line  130 . 
     The second capacitor unit C 2  may be similar to the second capacitor unit C 2  of  FIG. 6  and  FIG. 7 , and the second capacitor unit C 2  may allow a resonance frequency in a low frequency band to shift from resonance frequency f L  to resonance frequency f L ′, while allowing the resonance frequency f h1  and the resonance frequency f h2  of a high frequency band to be maintained. 
       FIG. 11A ,  FIG. 11B  and  FIG. 11C  are graphs illustrating standing wave ratios according to an exemplary embodiment of the present disclosure.  FIG. 11A ,  FIG. 11B  and  FIG. 11C  illustrate standing waves according to an ON/OFF state of the first switch  181 ′ and the second switch  182  of  FIG. 9  and  FIG. 10 . Although described with reference to  FIG. 9  and  FIG. 10 , the graphs of  FIG. 11A ,  FIG. 11B , and  FIG. 11C  are not limited thereto. 
     Referring to  FIG. 9  and  FIG. 10 , if the first capacitor unit C 1 ′ and the second capacitor unit C 2  are formed in the antenna unit  100 , the frequency of the antenna unit  100  may shift as shown in Table 3 below according to whether the first capacitor unit C 1 ′ and the second capacitor unit C 2  are activated. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                   
                 Resonance 
               
               
                   
                 Band 
                 Coupling capacitance 
                 frequency 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 first switch OFF 
                 high frequency 
                 — 
                 f h1   
               
               
                 second switch OFF 
                 band 
                 — 
                 f h2   
               
               
                   
                 low frequency 
                 — 
                 f L   
               
               
                   
                 band 
               
               
                 first switch ON 
                 high frequency 
                 C1′ 
                 f h1  → f h1 ′ 
               
               
                 second switch OFF 
                 band 
                 C4 
                 f h2  → f h2 ′ 
               
               
                 (see FIG. 11A) 
                 low frequency 
                 →0 
                 f L   
               
               
                   
                 band 
               
               
                 first switch OFF 
                 high frequency 
                 — 
                 f h1   
               
               
                 second switch ON 
                 band 
                 — 
                 f h2   
               
               
                 (see FIG. 11B) 
                 low frequency 
                 C2 
                 f L  → f L ′ 
               
               
                   
                 band 
               
               
                 first switch ON 
                 high frequency 
                 C1′ 
                 f h1  → f h1 ′ 
               
               
                 second switch ON 
                 band 
                 C4 
                 f h2  → f h2 ′ 
               
               
                 (see FIG. 11C) 
                 low frequency 
                 C2 
                 f L  → f L ′ 
               
               
                   
                 band 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 11A ,  FIG. 11B ,  FIG. 11C , and Table 3, if the first capacitor unit C 1 ′ is activated, the resonance frequency f h1  and the resonance frequency f h2  of the high frequency band of the antenna unit shifts to the resonance frequency f h1 ′ and the resonance frequency f h2 ′, respectively, and the resonance frequency f L  of the low frequency band does not shift. If the second capacitor unit C 2  is activated, the resonance frequency f L  of the low frequency band shifts to the resonance frequency f L ′, and the remaining resonance frequencies, i.e., the resonance frequency f h1  and the resonance frequency f h2  do not shift. If the first capacitor unit C 1 ′ and second capacitor unit C 2  are activated, the resonance frequency f h1  and the resonance frequency f h2  of the high frequency band shift to the resonance frequency f h1 ′ and the to resonance frequency f h2 ′, respectively, and the resonance frequency f L  of the low frequency band shifts to the resonance frequency f L ′. 
       FIG. 12  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure.  FIG. 13  is a circuitry diagram illustrating the antenna unit and the capacitor unit of  FIG. 12 . 
     Referring to  FIG. 12  and  FIG. 13 , an antenna unit  100  includes a first antenna pattern line  110  and a second antenna pattern line  120 . A coupling ground line  130  may be disposed adjacent to the first antenna pattern line  110 . A second electrode  171 ″ may be disposed adjacent to the coupling ground line  130  and may be connected to a switch  181 ″. The second electrode  171 ″ may be separated by a distance d 4 ′ from a coupling ground line  130 . A fourth capacitor unit C 4  may be formed between the coupling ground line  130  and the second electrode  171 ″. A second region S 2  may be formed on the second antenna pattern  120 . The second region S 2  may include a first electrode and a second electrode  172  and may be similar to the second region of  FIG. 6  and  FIG. 7 , and therefore descriptions thereof may be omitted for brevity. 
     A fourth capacitor unit may include the second electrode  171 ″ disposed adjacent to the first region S 1 , and the first switch  181 ″ to selectively connect the second electrode  171 ″ to a ground terminal. 
     Referring to  FIG. 12 , the coupling ground line  130  may be disposed adjacent to the first region S 1 . The first antenna pattern line  110  may be disposed directly adjacent to the coupling ground line  130 , and the coupling ground line  130  may be disposed directly adjacent to the second electrode  171 ″, but are not limited thereto. 
     The coupling ground line  130  may be disposed between the first antenna pattern line  110  and the second electrode  171 ″. The charge on the second electrode  171 ″ may not influence the first antenna pattern line  110 . Therefore, a first coupling capacitance similar to the first coupling capacitance C 1  and the first coupling capacitance C 1 ′ of  FIG. 7  and  FIG. 10 , respectively, is not formed in the antenna unit  100  of  FIG. 12  and  FIG. 13 . In the antenna device of  FIG. 12  and  FIG. 13 , the fourth coupling capacitance C 4 ′ is formed at the coupling ground line  130 . 
     The fourth coupling capacitance C 4 ′ may vary according to the voltage distribution in the first region S 1 , the distance between the second electrode  171 ″ and the coupling ground line  130  and the opposite area of the second electrode  171 ″ and the coupling ground line  130 . 
     The resonance frequency of the coupling ground line  130  may correspond to a wavelength of a high frequency band. The coupling ground line  130  may be disposed adjacent to the first region, and the resonance frequency f h2  of the coupling ground line  130  may shift to the resonance frequency f h2 ′ according to the fourth coupling capacitance C 4 ′. 
     The fourth coupling capacitance C 4 ′ may be adjusted by adjusting the distance d 4 ′ between the second electrode  171 ″ and the coupling ground line  130 . The fourth coupling capacitance C 4 ′ may be adjusted by adjusting the opposite area of the second electrode  171 ″ and the coupling ground line  130 . 
     The second capacitor unit C 2  may be disposed in the second region S 2 , and may be substantially similar to the second capacitor unit C 2  of  FIG. 6  and  FIG. 7 . The second capacitor unit C 2  may allow the resonance frequency of the low frequency band to shift from a resonance frequency f L  to a resonance frequency f L ′ and allow the resonance frequency f h1  and the resonance frequency f h2  of the high frequency band to be maintained. 
       FIG. 14A ,  FIG. 14B , and  FIG. 14C  are graphs illustrating standing wave ratios according to an exemplary embodiment of the present disclosure.  FIG. 14A ,  FIG. 14B , and  FIG. 14C  illustrate standing waves according to an ON/OFF state of a first switch  181 ″ and a second switch  182  of  FIG. 12  and  FIG. 13 . Although described with reference to  FIG. 12  and  FIG. 13 , the graphs of  FIG. 14A ,  FIG. 14B , and  FIG. 14C  are not limited thereto. 
     If, the fourth capacitor unit and the second capacitor unit C 2  are formed, the frequency of the antenna unit  100  may shift as shown in Table 4 below according to whether the fourth capacitor unit and the second capacitor unit C 2  are activated. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                 Coupling 
                 Resonance 
               
               
                   
                 Band 
                 capacitance 
                 frequency 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 first switch OFF 
                 high frequency band 
                 — 
                 f h1   
               
               
                 second switch OFF 
                   
                 — 
                 f h2   
               
               
                   
                 low frequency band 
                 — 
                 f L   
               
               
                 first switch ON 
                 high frequency band 
                 — 
                 f h1   
               
               
                 second switch OFF 
                   
                 C4′ 
                 f h2  → f h2 ′ 
               
               
                 (see FIG. 14A) 
                 low frequency band 
                 →0 
                 f L   
               
               
                 first switch OFF 
                 high frequency band 
                 — 
                 f h1   
               
               
                 second switch ON 
                   
                 — 
                 f h2   
               
               
                 (see FIG., 14B) 
                 low frequency band 
                 C2 
                 f L  → f L ′ 
               
               
                 first switch ON 
                 high frequency band 
                 — 
                 f h1   
               
               
                 second switch ON 
                   
                 C4 
                 f h2  → f h2 ′ 
               
               
                 (see FIG. 14C) 
                 low frequency band 
                 C2 
                 f L  → f L ′ 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 14A ,  FIG. 14B ,  FIG. 14C , and Table 4, if the fourth capacitor unit is activated, the resonance frequency f h2  of the high frequency band of the antenna unit may shift to the resonance frequency f h2 ′, and the resonance frequency f h1  of the high frequency band of the antenna unit and the resonance frequency f L  of the low frequency band may not shift. If the second capacitor unit C 2  is activated, the resonance frequency f L  of the low frequency band may shift to the resonance frequency f L ′, and remaining frequencies, the resonance frequency f h1  and the resonance frequency f h2  may not shift. If the fourth capacitor unit and second capacitor unit C 2  are activated, the resonance frequency f h2  of the high frequency band may shift to the frequency f h2 ′ and the frequency f L  of the low frequency band may shift to the resonance frequency f L ′, but the resonance frequency f h1  of the high frequency band may not shift. 
       FIG. 15  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure.  FIG. 16  is a circuitry diagram illustrating the antenna unit and the capacitor unit of  FIG. 15 . Referring to  FIG. 15  and  FIG. 16 , an antenna unit  100  includes a first antenna pattern line  110 ′ and a second antenna pattern line  120 ′, and a first capacitor unit C 1 ″ disposed in a first region S 1  and a third capacitor unit C 3  disposed in a third region S 3 . 
     Referring to  FIG. 15  and  FIG. 16 , an antenna unit  100  includes a first antenna pattern line  110 ′ and a second antenna pattern line  120 ′. A first region S 1  may be formed on the first pattern line  110 ′. The first region S 1  may include first electrode  116  and second electrode  173 . The second electrode  173  may be connected to a connection member  193  and a switch  183  and the first electrode  116  may be connected to a power supply V. The first electrode  116  and second electrode  171  may be separated by a distance d 1 . A third region S 3  may be formed on the second antenna pattern  120 ′. The second region S 2  may include a first electrode  1265  and the second electrode  173 . The first electrode  126  may be connected to power supply V. The first electrode  126  and the second electrode  173  may be separated by a distance d 3 . 
     The second electrode  173  may be disposed adjacent to at least one of the first region S 1 , the second region S 2 , and the third region S 3  simultaneously. Referring to  FIG. 15  and  FIG. 16 , the second electrode  173  may be formed adjacent to the first region S 1  and the third region S 3  simultaneously. 
     The first capacitor unit C 1 ″ may include a second electrode  173  disposed adjacent to the first region S 1 , and a first switch  183  to selectively connect the second electrode  173  to a ground terminal. 
     The resonance frequency f h  of the high frequency band may be shifted by the first capacitor unit C 1 ″, and the resonance frequency f L  of the low frequency band may be maintained. 
     The first capacitance C 1 ″ formed by the first capacitor unit C 1 ″ may be adjusted according to the voltage distribution on the first electrode  116  of the first region S 1  disposed to be opposite to the second electrode  173 , the distance d 1 ″ between the first electrode  116  and the second electrode  173 , and the opposite area of the first electrode  116  and the second electrode  173 . 
     The third capacitor unit C 3  may be formed by inducing a coupling capacitance as the second electrode  173 . The second electrode  173  may be disposed to be opposite to the third region S 3  of the second antenna pattern line  120 ′ and may therefore induce a charge to build on the first electrode  126  and a capacitance to form between the first electrode  126  and the second electrode  173 . 
     The second electrode  173  may be activated in the first region S 1  and the third region S 3  if the first switch  183  is connected, thereby forming the first coupling capacitance C 1 ″ and the third coupling capacitance C 3 . 
     The third coupling capacitance C 3  may be determined according to the voltage distribution of a first electrode  126  of the third region S 3  opposite to the second electrode  173 , the distance d 3  between the first electrode  126  and the second electrode  173  and the opposite area of the first electrode  126  and the second electrode  173 . 
     The third capacitor unit C 3  may allow both a resonance frequency f h  of the high frequency band and a resonance frequency f L  of the low frequency band to shift, as described with reference to Table 1, because the third region S 3  is formed. 
     If the first switch  183  is connected, both the resonance frequency f h  and the resonance frequency f L  may shift by the first coupling capacitance C 1 ″ and the third coupling capacitance C 3 . 
       FIG. 17  is a graph illustrating a standing wave ratio according to an exemplary embodiment of the present disclosure.  FIG. 17  illustrates standing waves according to an ON/OFF state of the first switch  183  of  FIG. 15  and  FIG. 16 . Although described with reference to  FIG. 15  and  FIG. 16 , the graph of  FIG. 17  is not limited thereto. 
     Referring to  FIG. 17 , if the first capacitor unit C 1 ″ and the third capacitor unit C 3  are formed in the antenna unit  100 , the resonance frequency of the antenna unit  100  may shift as shown in Table 5 below according to whether the first capacitor unit C 1 ″ and the third capacitor unit C 3  are activated. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 5 
               
               
                   
                   
               
               
                   
                   
                   
                 Resonance 
               
               
                   
                 Band 
                 Coupling capacitance 
                 frequency 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 first switch 
                 high frequency 
                 — 
                 f h   
               
               
                 OFF 
                 band 
               
               
                   
                 low frequency 
                 — 
                 f L   
               
               
                   
                 band 
               
               
                 first switch 
                 high frequency 
                 C1, C31 
                 f h  → f h ″ 
               
               
                 ON 
                 band 
               
               
                 (see FIG. 17) 
                 low frequency 
                 C32 
                 f L  → f L ″ 
               
               
                   
                 band 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 17  and Table 5, if the first switch  183  is activated, both the resonance frequency f h  of the high frequency band and the resonance frequency f L  of the low frequency band shift to the resonance frequency f h ″ and the resonance frequency f L ″, respectively. 
     The resonance frequencies of the high frequency band and the low frequency band may shift by using a single switch. 
       FIG. 18  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure.  FIG. 18  may be similar to  FIG. 6 ,  FIG. 7 , and  FIG. 8  and descriptions of similar features will be omitted for brevity. 
     Referring to  FIG. 18 , in an antenna unit  100 , a first capacitor unit may be formed by a first electrode and a second electrode  240 . The first electrode of the first capacitor unit may be a portion of an antenna pattern line disposed opposite to the second electrode  240 . A second capacitor unit may be formed by a first electrode and a second electrode  260 . The first electrode of the second capacitor unit may be a portion of the antenna pattern line disposed opposite to the second electrode  260 . A switch  280  may be connected to the second electrode  240  and the second electrode  260 . 
     The first electrode and the second electrode  240  may be disposed on the same plane or parallel to each other. The second electrode  240  may have a ring shape or a plate shape, but is not limited thereto. The first electrode may be formed in the antenna pattern line  110 . The first electrode and the second electrode  260  may be disposed on the same plane or parallel to each other. The second electrode  260  may have a ring shape or a plate shape, but is not limited thereto. The first electrode may have any shape. 
     The second electrode  240  and the second electrode  260  may have a ring shape and may be disposed parallel to the antenna pattern line. 
     A first coupling capacitance of the first capacitor unit may be determined according to a voltage distribution of the first electrode disposed on the antenna pattern line parallel to and opposite to the second electrode  240 , the distance between the second electrode  240  and the antenna pattern line, and the opposite area of the second electrode  240  and the first electrode disposed on the antenna pattern opposite to the second electrode  240 . A second coupling capacitance of the second capacitor unit may be determined according to a voltage distribution of the first electrode disposed on the antenna pattern line parallel to and opposite to the second electrode  260 , the distance between the second electrode  260  and the antenna pattern line, and the opposite area of the second electrode  260  and the first electrode disposed on the antenna pattern opposite to the second electrode  260 . 
     The first capacitor unit and the second capacitor unit may be connected to the switch  280 . The resonance frequencies of the high frequency band and the low frequency band of the antenna unit of  FIG. 18  may shift by the operation of the switch  280 . 
       FIG. 19A  is a perspective view illustrating an antenna unit and a capacitor unit according to an exemplary embodiment of the present disclosure.  FIG. 19B  is a rear view illustrating the antenna unit and the capacitor unit of  FIG. 19A . 
     Referring to  FIG. 19A  and  FIG. 19B , in an antenna unit  100 , a first capacitor unit may be formed by a first electrode, a second electrode  240 , and a third electrode  250 . The first electrode of the first capacitor unit may be a portion of a second antenna pattern line  220  disposed opposite to the second electrode  240  and the third electrode  250 . A first switch  282  may be connected to the second electrode  240  and the third electrode  250 . A second capacitor unit may be formed by a first electrode, a second electrode  260 , and a third electrode  270 . The first electrode of the second capacitor unit may be a portion of a second antenna pattern line  220  disposed opposite to the second electrode  260  and the third electrode  270 . A second switch  281  may be connected to the second electrode  260  and the third electrode  270 . 
     Referring to  FIG. 19A  and  FIG. 19B , at least two opposite electrodes arranged in the same region and having an opposite area may be included in an antenna unit  100 . 
     The first capacitor unit may include at least two opposite electrodes. The first capacitor unit may include a second electrode and a third electrode. The opposite electrodes may be a ring shaped second electrode  240  and a flat plate shaped third electrode  250 . The ring shaped second electrode  240  and the flat plate shaped third electrode  250  may be disposed parallel to the first antenna pattern line  210  to be opposite to the same region of the first antenna pattern line  210 . The second electrode  240  and the third electrode  250  may be connected to a ground terminal by the first switch  282 . 
     Although the second electrode  240  may be a ring shaped second electrode and the third electrode  250  may be a flat plate shaped third electrode, the present disclosure is not limited thereto. For example, and the second electrode  240  may be flat plate shaped and the third electrode  250  may be ring shaped. Further, the ring shaped second electrode  240  may have a square ring, circular ring, elliptical ring, or other ring shape. 
     The first switch  282  may selectively connect the second electrode  240  and the third electrode  250 . The first switch  282  may connect both the second electrode  240  and the third electrode  250  to a ground terminal. The first switch  282  may be connected to the second electrode  240  and the third electrode  250  by a digital circuit. 
     The second electrode  240  and the third electrode  250  may be connected to the ground terminal to form a first coupling capacitance. The first coupling capacitance may be determined according to the voltage distribution of the first electrode, which may be a region of the second antenna pattern line  220  opposite to the second electrode  240  and the third electrode  250 , a distance d 5  between the first electrode disposed on the second antenna pattern line  220  and the second electrode  240  or a distance d 6  between the first electrode and the third electrode  250 , and a first opposite area and a second opposite area in which the ring shape second electrode  240  and the flat plate shape third electrode  250  are, respectively, opposite to the first electrode. 
     The first opposite area of the second electrode  240  and the first electrode and the second opposite area of the third electrode  250  and the first electrode may be disposed to be parallel to each other. The first opposite area of the second electrode  240  and the first electrode and the second opposite area of the third electrode  250  and the first electrode may be determined according to the areas of the second electrode  240  and the third electrode  260 , respectively, because the antenna pattern line has a relatively large size. 
     The second electrode  240  and the third electrode  250  may have different areas and may be spaced apart from the first electrode by distance d 5  and distance d 6 , respectively. The distance d 5  and d 6  may differ from each other. The second electrode  240  and the third electrode  250  may have different coupling capacitance values. 
     The first coupling capacitance may change in value depending on which opposite electrode between the second electrode  240  and the third electrode  240  is connected to a ground terminal. 
     The second capacitor unit may include a ring shaped second electrode  260  and a flat plate shaped third electrode  270 . The second electrode  260  and the third electrode  270  may be connected to a second switch  281 . Further, the ring shaped second electrode  260  may have a square ring, circular ring, elliptical ring, or other ring shape. Although the second electrode  260  may be ring shaped and the third electrode  270  may be flat plate shaped, the present disclosure is not limited thereto. For example, and the second electrode  260  may be flat plate shaped and the third electrode  270  may be ring shaped. 
     The second coupling capacitance may be determined according to the voltage distribution of the first electrode, which may be a region of the first antenna pattern line  210  opposite to the second electrode  260  and the third electrode  270 , the distance between the first electrode and the second electrode  260  or the distance between the first electrode and the third electrode  270 , and a first opposite area and a second opposite area in which the ring shape second electrode  260  and the flat plate shape third electrode  270  are, respectively, opposite to the first electrode. The second coupling capacitance may be determined based on whether the opposite electrode between the second electrode  260  and the third electrode  250  is connected. 
     According to the exemplary embodiments, the location and shape of the second electrode in an antenna unit may be controlled in various ways to adjust a coupling capacitance value, and the coupling capacitance value may be controlled to adjust the resonance frequency of the antenna unit. 
     According to the exemplary embodiment of the present disclosure, the second electrode may be made of materials with conductivity or high dielectric permittivity. A material with high dielectric permittivity may induce a greater coupling capacitance. 
       FIG. 20A  and  FIG. 20B  are graphs illustrating matching characteristics of an antenna unit according to an exemplary embodiment of the present disclosure. 
       FIG. 20A  is a graph illustrating a standing wave ratio if the first capacitor unit is in an activated state and in an inactivated state.  FIG. 20B  is a graph illustrating a standing wave ratio if the second capacitor unit is in an activated state and in an inactivated state. 
     Referring to  FIG. 20A  and  FIG. 20B , both the standing wave ratios before and after frequency shifting in the high frequency band and the low frequency band have a value close to 1. In other words, because the resonance frequency shifts by forming a coupling capacitance while maintaining the length of the antenna pattern line without guiding frequency shifting by extending the antenna pattern line, the antenna unit may have improved matching characteristic and improved emission efficiency may be obtained in both the first region and the second region. 
     According to the exemplary embodiment, a resonance frequency may shift selectively by utilizing a capacitor unit. Because the capacitor unit is not connected to the antenna pattern line, an antenna module may have improved matching characteristic and improved emission characteristics may be implemented. 
     Even though a frequency band other than the band selected by a switch may cause a change of an electric length of an antenna and may deteriorate the entire characteristics in the related art, the length of the antenna element of the present disclosure does not change since the selective coupling capacitor is not directly connected to the antenna. Therefore, it may be possible to reduce electric characteristics from deteriorating due to the length change of the antenna. 
     In addition, because the exemplary embodiments do not use a structure which uses parasitic resonance according to a change of a length of the antenna pattern, it is possible to reduce the emission efficiency from rapidly deteriorating at a resonance frequency of a main antenna due to the interference of the parasitic resonance frequency. 
     Moreover, because the power source of the switch is not electrically connected to the antenna, noise may not be generated even though a switch is added to the antenna unit. 
     Since the coupling capacitor of the exemplary embodiments may be applied adjacent to the antenna pattern, the coupling capacitor may be applied to various products in a simple way, and may be applicable not only to multi-band antennas but also to single-band antennas. 
     It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.