Patent Publication Number: US-8525749-B2

Title: Ground structure of antenna of mobile terminal

Description:
PRIORITY 
     This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed on Aug. 28, 2009 in the Korean Intellectual Property Office and assigned Serial No. 10-2009-0080754, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention: 
     The present invention relates to a mobile terminal. More particularly, the present invention relates to a ground structure of an antenna of a mobile terminal having an optimized arrangement in a restricted space of the mobile terminal. 
     2. Description of the Related Art: 
     Mobile terminals provide various user functions such as a mobile communication function, a game function, a scheduling function, and other functions while maintaining mobility and are widely used by a great number of users. 
     However, the mobile terminal should be small in order to support mobility and must bear various designs for the satisfaction of user&#39;s various demands. Since recent mobile terminals should provide various functions, a great number of parts are arranged in the mobile terminal. Thus, the mobile terminal must be designed to maximize a restricted space therein. 
     More particularly, since an antenna should guarantee proper mobile communication performance, there is a limit of the degree to which the antenna may be reduced in size and still retain a proper ground structure. However, a mobile terminal of the related art does not make good use of space and has a limited degree to which communication performance can be guaranteed by increasing transmission power to satisfy a Specific Absorption Rate (SAR) that is set by an international standard. In the mobile terminal of the related art, in order to conform to SAR and to guarantee performance, antenna patterns are arranged far from the human body. However, it is difficult to design a relatively large antenna pattern within the restricted space of the mobile terminal of the related art. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a ground structure of an antenna enabling communication performance of a mobile terminal. 
     In accordance with an aspect of the present invention, an antenna ground apparatus of a mobile terminal is provided. The apparatus includes an antenna, a printed circuit board disposed adjacent to the antenna, and a ground pattern formed on the printed circuit board and electrically connected to a ground unit of the antenna. 
     In accordance with another aspect of the present invention, a mobile terminal is provided. The terminal includes an antenna, a printed circuit board disposed adjacent to the antenna, a ground pattern formed on the printed circuit board and electrically connected to a ground unit of the antenna, and a case for encasing the antenna and the printed circuit board. 
     According to the ground structure of an antenna of a mobile terminal, an area of ground of the antenna is maximized within a restricted space of the mobile terminal so that communication performance may be improved and performance of the antenna may be optimized. 
     Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic view illustrating an exterior of a mobile terminal according to an exemplary embodiment of the present invention; 
         FIG. 2  is an exploded perspective view illustrating a keypad Printed Circuit Board (PCB) and other elements arranged near an antenna according to an exemplary embodiment of the present invention; 
         FIG. 3  is an exploded perspective view illustrating a keypad PCB of an antenna according to an exemplary embodiment of the present invention; 
         FIG. 4  is an exploded perspective view illustrating an interior of a mobile terminal according to an exemplary embodiment of the present invention; 
         FIG. 5  is a perspective view illustrating a front side of a sub-PCB to which an antenna is attached according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a perspective view illustrating a rear side of a sub-PCB on which a ground pattern is formed according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     The terms or words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
       FIG. 1  is a schematic view illustrating an exterior of a mobile terminal according to an exemplary embodiment of the present invention.  FIG. 2  is an exploded perspective view illustrating a keypad Printed Circuit Board (PCB) and other elements arranged near an antenna according to an exemplary embodiment of the present invention.  FIG. 3  is an exploded perspective view illustrating a keypad PCB of an antenna according to an exemplary embodiment of the present invention. A mobile terminal  100 , which is illustrated in  FIGS. 1 to 3 , includes a main PCB directly connected to an antenna. While a bar type mobile terminal may be illustrated in  FIGS. 1-3  and described herein, the present invention is not limited to any particular type of mobile terminal. 
     Referring to  FIGS. 1 to 3 , the mobile terminal  100  may include an antenna  230  for transmission and reception of signals that are used for communication, a main PCB  210  for processing signals to be transmitted and received through the antenna  230 , a display unit  140  for displaying a screen supporting a communication procedure and a user to use the mobile terminal, a keypad  110  for inputting a key actuation, a keypad PCB  120  positioned under the keypad  110  and having at least one of a first ground pattern GNDP 1  and a second ground pattern GNDP 2 , and a case  170  for supporting the display unit  140  and the keypad  110  and for encasing the antenna  230 , the main PCB  210 , and the keypad PCB  120 . 
     In the mobile terminal  100 , the ground structure of the antenna  230  may be expanded when the antenna  230  is connected to at least one of the first ground pattern GNDP 1  and the second ground pattern GNDP 2  that are provided on the keypad PCB  120 . The area of the ground of the antenna  230  may be increased by at least one of the first ground pattern GNDP 1  and the second ground pattern GNDP 2  so that performance and a Specific Absorption Rate (SAR) of the antenna  230  may be improved. Hereinafter, elements of the mobile terminal  100  will be described below in more detail. 
     The antenna  230  radiates a signal to be transmitted in the air and receives signals radiated in the air when the communication function is activated. The antenna  230  may be provided in the case  170 . The antenna  230  may have a preset pattern so as to be disposed in the case  170 . A least one of a length and a volume of the antenna  230  may vary according to the communication protocol supported by the mobile terminal  100 . The antenna  230  may have at least one of a length and a volume supporting respective communication protocols when the mobile terminal  100  supports several communication protocols. For example, when the mobile terminal  100  supports one of Global System for Mobile communication (GSM) and Wideband Code Division Multiple Access (WCDMA), the antenna  230  has at least one of a length and a volume for supporting the respective one of GSM and WCDMA. The antenna  230  may be disposed at a lower side of the case  170  and may encase the edges of the display unit  140 . In this case, the antenna  230  may be coupled with various locking steps or protrusions that are formed in the case  170  in order to prevent the antenna  230  from moving after the antenna  230  is disposed in the case  170 . For example, when the antenna  230  has patterns, the antenna  230  may have holes formed in the respective patterns such that the respective patterns are coupled with protrusions provided in the case  170 . A ground unit GND of the antenna  230  contacts at least one of the first ground pattern GNDP 1  and the second ground pattern GNDP 2  of the keypad PCB  120 . The antenna  230  may further include a ground line to contact at least one of the first and second ground patterns GNDP 1  and GNDP 2  of the keypad PCB  120 . For example, when the antenna  230  is spaced apart from the keypad PCB  120  by a distance, the antenna  230  may be positioned to face at least one of the first and second ground patterns GNDP 1  and GNDP 2  of the keypad PCB  120 . In this case, the mobile terminal  100  may have a protrusion  121  serving as the ground line electrically connecting at least one of the first and second ground patterns GNDP 1  and GNDP 2  to the antenna  230 . Referring to  FIG. 3 , the protrusion  121  may be formed in the second ground pattern GNDP 2  or at a side of the antenna  230 . 
     The main PCB  210  controls overall user functions provided by the mobile terminal  100 . The main PCB  210  may control electric power fed from a power supply to respective units of the mobile terminal  100  to boot the mobile terminal  100 . The main PCB  210  controls power to be fed to a communication module and signal transmission and reception to be performed through the antenna  230  when a user function, for example, a mobile communication function, is requested. Moreover, the main PCB  210  may control various modules such as a broadcasting receiver module, a Global Positioning System (GPS) module, and an MP3 or MP4 module and may control the various modules to be activated in response to a request for a specific function transmitted from the keypad  110 . The main PCB  210  may store various routines for supporting and controlling the respective functions of the mobile terminal  100  and may load the routines to prepare activation of the loaded functions during the booting. The main PCB  210  may store various information generated when the user function is performed in a storage unit according to a user command. Moreover, the main PCB  210  may be electrically connected to the antenna  230 , transmit signals for the mobile communication to the antenna  230 , and process signals received by the antenna  230 . 
     The display unit  140  outputs images during the activation of the various functions of the mobile terminal  100 . For example, the display unit  140  may display an image between respective booting procedures during the booting of the mobile terminal  100  and may output an image related to activation of a specific user function according to a user command. That is, the display unit  140  may display various menus of the mobile terminal  100 , information input by a user, information provided to the user, and may provide various screens such as a standby screen, a menu screen, a message writing screen, a dialing screen, etc. The display unit  140  may be a flat display such as a Liquid Crystal Display (LCD), an Organic Light Emitting Diode (OLED), and the like. When the flat display is a touch screen, the display unit  140  may be included in an input device. When the display unit  140  is realized by a touch screen, the display unit  140  may include a display panel and a touch sensor arranged on the display panel. The mobile terminal may provide various menu screens performed by the touch screen, that is, the display unit  140 . Since edges of the display unit  140  are supported by the case  170 , the display unit  140  may be prevented from moving and may prevent light leakage, which is light emitted from a backlight through sides of the display unit. 
     The case  170  encases the edges of the display unit  140  and the edges of the keypad  110  and includes a first case and a second case interposing the patterns of the antenna  230  and the keypad PCB  120 . The case  170  may substantially encase the structures of the mobile terminal  100 , have various structures preventing the respective structure from moving, and be designed in various architectural shapes for durability and/or aesthetics. 
     The keypad  110  is disposed in a region adjacent to the display unit  140  such that the edges of the keypad  110  are supported by the case  170 . The keypad  110  may have various shapes, for example, a protrusion protruding upwardly from a plane parallel to the case  170  by a distance, or may contact a preset contact point provided in the keypad PCB  120  using a pressure generated by a user&#39;s touch. Then, the keypad PCB  120  may generate an input signal allocated to a corresponding contact point and transmit the generated signal to the main PCB  210 . The keypad  110  may be made of silicon, metal alloys, etc. When the keypad  110  is made of a metal alloy, the keypad  110  may not protrude toward the case  170 . In the mobile terminal  100  according to the exemplary embodiment of the present invention, the keypad  110  may be independent from the display unit  140  and the mobile terminal  100  may further include a keypad PCB  120  to convert a pressure generated from the keypad  110  into an electrical signal. The number and types of keys provided in the keypad  110  may vary according to a designer&#39;s intent. That is, the keypad  110  may be a numeric keypad, an alphabetic keypad, an arrow keypad, a hotkey keypad, etc. 
     The keypad PCB  120  may be disposed under the keypad  110  and have various contact points to contact a pressed portion when a specific point of the keypad  110  is pressed. The keypad PCB  120  may generate an electrical signal corresponding to the contact generated at the contact point and may transmit the generated electrical signal to the main PCB  210 . The contact points and shape of the keypad PCB  120  may be modified according to the shape of the keypad  110 . More particularly, the keypad PCB  120  has at least one of the first and second ground patterns GNDP 1  and GNDP 2  formed on a side thereof. The first and second ground patterns GNDP 1  and GNDP 2  contact the ground unit GND of the antenna  230  to expand the area of the ground of the antenna  230 . To this end, the first and second ground patterns GNDP 1  and GNDP 2  may be made by coating a conductive material in a preset shape. The keypad PCB  120  may be made of a copper plate with a coated side. The first and second ground patterns GNDP 1  and GNDP 2  are formed on the coated portion of the copper plate such that generation and transmission of the electrical signal of the keypad PCB are not impaired. The keypad PCB  120  may further include a ground line electrically connected to at least one of the first and second ground patterns GNDP 1  and GNDP 2  for contact with the ground unit GND of the antenna  230 . The ground line may be provided at a side of the keypad PCB  120  or at a side of the case  170 . The ground line may be formed as a tape that connects at least one of the first and second ground patterns GNDP 1  and GNDP 2  to the ground unit GND. The first and second ground patterns GNDP 1  and GNDP 2  may be made by various processes of forming patterns on the keypad PCB  120 . For example, the patterns on the keypad PCB  120  may be deposited by a surface mounting technology. 
     The second ground pattern GNDP 2 , as illustrated in  FIG. 3 , may be deposited on a separated ground pattern structure  123  such as a dummy PCB. The upper side on which the ground pattern structure  123  is placed may be coated with non-conductive material to prevent an electrical signal from being transmitted and the second ground pattern GNDP 2  may be deposited on the ground pattern structure  123 . The ground pattern structure  123  may further include a ground line to electrically connect the second ground pattern GNDP 2  to the ground unit GND of the antenna  230  and/or the first ground pattern GNDP 1 . The ground line may be made in the form of a protrusion  121 . The ground pattern structure  123  may be partially cut off in order to provide a high ground function to a restricted area. Adhesive may be coated between the ground pattern structure  123  and the keypad PCB  120  to prevent the ground pattern structure  123 , which is disposed on the keypad PCB  120 , from moving. Alternatively, the ground pattern structure  123  may be mounted on the keypad PCB  120  using the surface mounting technology and may be prevented from moving after disposition. 
     All of the first and second ground patterns GNDP 1  and GNDP 2  may be formed on the keypad PCB  120 . In other words, when the first ground pattern GNDP 1  is formed on the keypad PCB  120 , the ground pattern structure  123  may be disposed on the first ground pattern GNDP 1  and the second ground pattern GNDP 2  may be formed on the ground pattern structure  123 . In this case, the ground pattern structure  123  may further include a ground line to electrically connect the first ground pattern GNDP 1  to the second ground pattern GNDP 2 . 
     As described above, in the mobile terminal  100  according to an exemplary embodiment of the present invention, the first ground pattern GNDP 1  may be provided on the keypad PCB  120  or the second ground pattern GNDP 2  may be provided on the ground pattern structure  123  so as to contact the ground unit GND of the antenna  230  so that the area of the ground unit GND of the antenna  230  may be expanded. 
       FIG. 4  is an exploded perspective view illustrating an interior of a mobile terminal according to an exemplary embodiment of the present invention. The mobile terminal  100  may be a full screen mobile terminal without a separated keypad and may have a structure in which the main PCB  210  is spaced apart from the antenna  230  by a distance. Since the mobile terminal described below has similar elements as those of the mobile terminal described above, the same reference numerals are assigned to the same or similar elements. 
     Referring to  FIG. 4 , the case  170  of the mobile terminal  100  may have a first case  170 A and a second case  170 B. Various structures supporting the functions of the mobile terminal  100  may be arranged in the case  170 . By doing so, the rims of the first and second cases  170 A and  170 B are coupled with each other to encase the various structures and to prevent the structures from moving. 
     The first case  170 A, as illustrated, may include an opening  141  through which the display unit  140  is exposed and a first sub-PCB seat  145 , on which a sub-PCB  220  to which patterns of the antenna  230  are attached, is seated. The first case  170 A may support the opening  141  and may include sidewalls  143  covering edges of the display unit when the display unit is disposed inside the opening  141 . The first case  170 A may include a first screen coupling structure  147  formed in a region adjacent to the first sub-PCB seat  145  fastened to the second case  170 B with a screw. A part of the first sub-PCB seat  145  facing the opening  141  may serve as one of the sidewalls  143  to cover the edge of the display unit. Each of the sidewalls  143  has an L-shaped section and structures of the sidewalls  143  facing the opening  141  contact the edges of the display unit. The sidewalls  143  may have auxiliary structures formed at a preset interval to support the sidewalls securely. 
     The first sub-PCB seat  145  is a structure on which the sub-PCB  220 , to which the patterns of the antenna  230  are attached, is seated and may be formed to correspond to the shape of the sub-PCB  220 . The first sub-PCB seat  145  may be formed similar to the outer appearance of the sub-PCB  220  to prevent the sub-PCB  220  from moving after the sub-PCB  220  is seated or such that the sub-PCB  220  is press-fitted into the first sub-PCB seat  145 . Alternatively, the first sub-PCB seat  145  may have a locking structure, such as a step or protrusion, to lock the sub-PCB  220  at a specific position in order to prevent the sub-PCB  220  from moving or being separated after the sub-PCB  220  is seated. The locking structure is coupled with a corresponding structure, such as a protrusion or a hole, formed in the sub-PCB  220  to prevent the sub-PCB  220  from moving. 
     The second case  170 B may have an opening (not shown) in which a battery is seated and L-shaped sidewalls in which various structures are seated. Various structures may be seated in the second case  170 B, for example, the main PCB  210  may be seated in an upper portion thereof and the sub-PCB  220  may be seated in the lower portion thereof. A space defined by the main PCB  210  and the sub-PCB  220  may serve as a battery seat  181  on which the battery is seated. Although not illustrated, other structures such as a camera module, a broadcasting receiver module, an MP3 or MP4 module, etc. may be seated on the lower end of the main PCB  210 . The second case  170 B may further include a second sub-PCB seat  178  formed in the lower end of the second case  170 B on which the sub-PCB  220  is seated. Thus, a PCB surface of the sub-PCB  220 , to which the antenna  230  is attached, is seated on the first sub-PCB seat  145  and the opposite surface to which the antenna  230  is not attached, that is, the surface in which the ground pattern GNDP is formed is seated on the second sub-PCB seat  178 . The second sub-PCB seat  178  formed in the lower end of the second case  170 B, in order to fix the sub-PCB  220 , may include various structures such as a protrusion  171  coupled with the hole formed in the sub-PCB  220  and a locking step  173  fixing a side of the sub-PCB  220 . In addition, the second sub-PCB seat  178  may further include sidewalls covering and guiding the sides of the sub-PCB  220  in the coupling of the sub-PCB  220 . The second case  170 B may have a second screw coupling structure  187  formed in a side of the second case  170 B, corresponding to the first screw coupling structure  147  formed in the first case  170 A. A cable  240  connecting a signaling unit SIG of the antenna  230  that is attached to a side of the sub-PCB  220  to the contact point formed in a side of the main PCB  210  may be disposed along one of the sidewalls of the second case  170 B. 
     The sub-PCB  220 , on which the ground pattern GNDP is disposed, will be described in further detail below with reference to  FIGS. 5 and 6 . 
       FIG. 5  is a perspective view illustrating a front side of a sub-PCB to which an antenna is attached according to an exemplary embodiment of the present invention.  FIG. 6  is a perspective view illustrating a back side of a sub-PCB on which a ground pattern is formed according to an exemplary embodiment of the present invention. 
     Referring to  FIGS. 5 and 6 , the pattern of the antenna  230  is attached to the entire front side of the sub-PCB  220 . The sub-PCB  220  may be made of a plastic injection molding and may have a shape corresponding to a pre-designed pattern of the antenna  230 . For example, when the pattern of the antenna  230  is stepped to form the preset pattern, the sub-PCB  220  may have a step corresponding to the stepped pattern of the antenna  230 . In order to prevent the pattern of the antenna  230  from moving after the pattern is attached to the sub-PCB  220 , various structures may be provided or adhesive may be coated between the pattern of the antenna  230  and the sub-PCB  220 . For example, the sub-PCB  220  may have a plurality of protrusions and locking steps formed in a side of the sub-PCB  220  and the pattern of the antenna  230  may have through-holes coupled with the protrusions of the sub-PCB  220 . 
     The antenna  230 , as described above, may be modified in size, shape, area, and volume according to the communication protocol supported by the mobile terminal  100 . The antenna  230  includes a signaling unit SIG, a ground unit GND, and a body BODY provided between the signaling unit SIG and the ground unit GND for the transmission of the signal transmitted from the main PCB  210  in the air and reception of signals transmitted in the air. The signaling unit SIG is a region contacting the signal line of the main PCB  210 , for example, the cable  240 . When the mobile terminal  100  supports a dual communication mode and the antenna  230  is designed to support the dual communication mode, the antenna  230  may have at least two signaling units SIG. The ground unit GND is a region providing a ground function of the antenna  230  and may be electrically connected to the ground pattern GNDP formed on the rear side of the sub-PCB  220 . The ground pattern GNDP may be provided on the rear side of the sub-PCB  220  and may be electrically connected to the ground unit GND formed on the front side thereof. When the front side of the sub-PCB  220  has a step, the rear side thereof may have a recess corresponding to the step. That is, when a part of the front side of the sub-PCB  220  protrudes by a preset height, the rear side of the sub-PCB  220  may be depressed to correspond to the protrusion. The protrusion and the depression may be modified by a designer of the sub-PCB  220 . Meanwhile, the ground pattern GNDP may be formed in a preset region of the rear side of the sub-PCB  220  in a preset shape. In this case, the ground pattern GNDP may be designed to be proportional to the volume of the antenna  230  and may be patterned to provide an optimal ground function within a part of the entire area of the sub-PCB  220 . The ground pattern GNDP may be made by mounting a material to provide the ground function such as metal on the rear side of the sub-PCB  220  in the surface mounting technology or by bonding a preset pattern to the rear side with adhesive. The ground pattern GNDP may have a signal pad PAD formed on a side of the ground pattern GNDP and be electrically connected to the ground unit GND on the front side of the sub-PCB  220 . The signal pad PAD electrically connects the ground pattern GNDP to the ground unit GND of the antenna  230  and to this end may be formed when the sub-PCB  220  is constructed or may be formed of a metal tape. 
     As described above, in the ground structure of an antenna of the mobile terminal according to an exemplary embodiment of the present invention, the ground pattern GNDP is provided on a side of the sub-PCB  220  on which the antenna  230  is disposed and the ground pattern GNDP is connected to the ground unit GND of the antenna  230  so that the area of the ground may be expanded by as much as the area of the ground pattern GNDP. Thus, the mobile terminal of an exemplary embodiment of the present invention may provide a stable ground function by expanding the ground area so that SAR and the communication performance may be improved. 
     At least one of the approach of providing the first ground pattern GNDP 1  on the keypad PCB  120  according to the exemplary embodiment of the present invention, the approach of providing the ground pattern structure  123  on the keypad PCB  120  corresponding to the dummy PCB and of providing the second ground pattern GNDP 2  on the ground pattern structure  123 , and the approach of providing the ground pattern GNDP on the sub-PCB  220  according to another exemplary embodiment of the present invention, may be applied to the mobile terminal  100 . That is, in the mobile terminal  100 , the first ground pattern GNDP 1  may be provided on the keypad PCB  120  and the ground pattern structure  123  on which the second ground pattern GNDP 2  is mounted on the dummy PCB may be electrically connected to the first ground pattern GNDP 1  of the keypad PCB  120 . Otherwise, the keypad PCB  120  on which the first ground pattern GNDP 1 , the ground pattern structure  123 , and the second ground pattern GNDP 2  are formed and the ground pattern GNDP formed on the sub-PCB  220  may be applied to the mobile terminal  100  when the mobile terminal  100  is manufactured. The first and second ground patterns GNDP 1  and GNDP 2  and the ground pattern GNDP may have various shapes and the shapes may be modified according to the shape of a PCB disposed adjacent to the region in which the antenna is disposed and which may be changed according to the communication protocol or a model of the mobile terminal. In the following tables, results of performance tests are shown. The term “TIS” denotes Total Isotropic Sensitivity. The term “TRP” denotes Total Radiated Power. 
     Table 1 shows results of a performance test carried out when the ground pattern is not applied to a specific model of a mobile terminal. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 WCDMA band (CH) 
                 TIS 
                 TRP 
                 SAR 
               
               
                   
                   
               
             
            
               
                   
                 9,714 
                 106.8 
                 19.91 
                 1.63 
               
               
                   
                 9,787 
                 106.3 
                 20.48 
                 2.32 
               
               
                   
                 9,886 
                 106.9 
                 19.90 
                 2.11 
               
               
                   
                   
               
            
           
         
       
     
     Table 2 shows results of a performance test carried out when the first ground pattern GNDP 1  is formed on the keypad PCB  120  in a specific model of a mobile terminal. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 WCDMA band (CH) 
                 TIS 
                 TRP 
                 SAR 
               
               
                   
                   
               
             
            
               
                   
                 9,714 
                 106.8 
                 20.01 
                 1.33 
               
               
                   
                 9,787 
                 106.7 
                 21.02 
                 1.82 
               
               
                   
                 9,886 
                 106.8 
                 20.70 
                 1.71 
               
               
                   
                   
               
            
           
         
       
     
     Table 3 shows results of a performance test carried out when the first ground pattern GNDP 1  formed on the keypad PCB  120  and the second ground pattern GNDP 2  formed on the ground pattern structure  123  are applied to a specific model of a mobile terminal. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 WCDMA band (CH) 
                 TIS 
                 TRP 
                 SAR 
               
               
                   
                   
               
             
            
               
                   
                 9,714 
                 107.3 
                 20.11 
                 1.23 
               
               
                   
                 9,787 
                 106.8 
                 21.08 
                 1.52 
               
               
                   
                 9,886 
                 107.1 
                 20.87 
                 1.43 
               
               
                   
                   
               
            
           
         
       
     
     Table 4 shows results of a performance test carried out when the first and second ground patterns GNDP 1  and GNDP 2  are formed on the keypad PCB  120  and when the ground pattern GNDP is formed on the sub-PCB  220  in a specific model of a mobile terminal. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 WCDMA band (CH) 
                 TIS 
                 TRP 
                 SAR 
               
               
                   
                   
               
             
            
               
                   
                 9,714 
                 107.1 
                 20.05 
                 1.13 
               
               
                   
                 9,787 
                 106.8 
                 21.28 
                 1.30 
               
               
                   
                 9,886 
                 107.1 
                 21.03 
                 1.23 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Tables 1 to 4, it is understood that satisfactory SAR and TIS/TRP are obtained as the ground pattern is increased. 
     As described above, the antenna ground structure of a mobile terminal according to an exemplary embodiment of the present invention is arranged to provide the ground pattern on a PCB adjacent to the antenna  230  and to connect the ground pattern to the ground unit GND of the antenna  230 , so that the ground area of the antenna  230  may be expanded to improve SAR and the communication performance. 
     While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents.