Patent Publication Number: US-7587228-B2

Title: Antenna device for portable terminal

Description:
PRIORITY 
     This application claims priority to an application entitled “ANTENNA DEVICE FOR PORTABLE TERMINAL” filed in the Korean Industrial Property Office on Sep. 8, 2005 and assigned Serial No. 2005-83568, the contents of which are incorporated by herein reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an antenna device for a portable terminal. Particularly, the present invention relates to an antenna device for a portable terminal, which includes an antenna module disposed in an antenna jack of a terminal capable of TV service where the antenna module receives broadcasting signals depending on mounting/demounting of an external antenna. 
     2. Description of the Related Art 
     Recently, portable terminals have become multi-functional and downsized due to demands of consumers. Particularly, such multi-functional terminals provide voice communication service, radio service, and MP3 music download service via Internet. Additionally, it is possible to obtain digital information about various data and images with ease from portable terminals, Personal Digital Assistants (PDAs), computers and notebook computers. 
     Portable terminals generally include a Liquid Crystal Display (LCD) as data output device. Conventionally, a keypad including a plurality of keys is used for input of data. 
     In addition to the above, a portable terminal has an antenna device, located at a position with adequate space in its main body, for receiving signals transmitted from a counterpart terminal. 
     In some cases, a so-called fading phenomenon occurs in portable terminals during a transmission/reception process with a base station. The fading phenomenon is caused when the same signal is received through at least two different paths at different times, such that the received signals are distorted. In order to prevent the above-mentioned problem, a terminal is provided with a diversity antenna device, in addition to a standard antenna device, so that signals received from each antenna are combined to extract optimized signals and to ensure communication quality. 
     Additionally, it is possible to improve data communication speed of a terminal by using a diversity antenna device. 
     In one embodiment of a portable terminal, the above-mentioned diversity antenna device is disposed on the exterior of a terminal in the form of a set of a whip antenna and a helical antenna. The external antenna device is mounted with an internal antenna device. 
     Portable terminals with the above-described structure have spread quickly to consumers and are used widely. Also, there is a tendency to develop multi-functional portable terminals having various functions for satisfying the diverse needs of consumers, in addition to simple communication service. For example, besides voice communication, additional services for users include Video-On-Demand (VOD) service, image communication service, digital camera functions, Internet service, TV service, etc. 
     A portable terminal capable of TV service among the above additional services is referred to as a digital multimedia-broadcasting (DMB) terminal, which allows a user to watch TV programs through a display device, while also performing a mobile telecommunication function. 
     The portable terminal capable of TV service includes at least two Radio Frequency (RF) modules, because a frequency band necessary for transception of voices and data is different from a frequency band for broadcasting. Accordingly, the portable terminal capable of TV service is operated in a phone mode, waiting mode, and a broadcasting service mode, which is an image reception mode combined with a waiting mode. 
     As shown in  FIGS. 1-3 , the terminal has a diversity antenna device  3  including a broadcasting signal receiving module (not shown). An antenna jack  1   a  is disposed on a printed circuit board  4  embedded in the terminal  1  for interconnecting an external antenna  2  for exclusive use in broadcasting service with the broadcasting signal receiving module. The antenna jack  1   a  and connection jack  2   a  of the external antenna  2  for exclusive use in broadcasting service are joined with each other to receive TV broadcasting signals. Such received signals are applied to a broadcasting signal input module  5  disposed in the terminal. 
     As described above, signals received from the external antenna for exclusive use in the broadcasting service and from the diversity antenna device are combined to extract optimized signals, thereby preventing the so-called fading phenomenon and improving communication quality. As a result of the distance between the diversity antenna device and the external antenna (for exclusive use in the broadcasting service) increases, it is possible to obtain increasingly improved effects. 
     However, when a user watches TV using a conventional DMB terminal, it is necessary to use both the external antenna for exclusive use in the broadcasting service and the diversity antenna device. Therefore, it is necessary to provide a separate space in the terminal for mounting the diversity antenna, because a separate diversity antenna is mounted additionally to the terminal after connecting the antenna jack of the terminal with the external antenna for exclusive use of broadcasting service. As a result, it is inevitable that additional terminal space is required, thereby adversely affecting the ability to downsize of the terminal. 
     Additionally, because it is necessary to mount a separate diversity antenna to the terminal, the cost of antenna production increases and the time needed for assembly of the terminal increases due to the increased number of component elements. 
     Further, it is necessary for users to carry a conventional antenna for exclusive use of broadcasting service in their hands at all times in order to use it on demand. Therefore, there is a possibility of the loss of the antenna, resulting in degradation of its portability. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art. An object of the present invention is to provide an antenna device for a portable terminal, which includes an antenna module for receiving broadcasting signals mounted on the outer surface of an antenna jack housing of a terminal capable of TV service, so that a space needed for mounting an antenna device for exclusive use of broadcasting service can be reduced and thus the terminal can be downsized. 
     Another object of the present invention is to provide an antenna device for a portable terminal, which is provided with an antenna module including meander lines on the antenna jack housing of a terminal capable of TV service so that the number of components forming the antenna can be reduced and thus manufacturing costs can be saved. 
     Still another object of the present invention is to provide an antenna device for a portable terminal, which includes an antenna module disposed in an antenna jack of a terminal capable of TV service, wherein the antenna module receives broadcasting signals depending on mounting/demounting of an external antenna for exclusive use in the broadcasting service, so that users can watch TV with no need of a separate portable external antenna for exclusive use of broadcasting service. 
     In order to accomplish the above objects, there is provided a portable terminal having an antenna jack connected electrically with an external antenna, the antenna device including an antenna module disposed along the outer circumference of the antenna jack, which receives broadcasting signals depending on mounting/demounting of the external antenna; an insulator module disposed at the bottom of the antenna jack; and an antenna switch module disposed in the antenna jack, which makes an electric contact point with a jack ground point disposed inside the antenna jack, so as to be connected electrically with a contact point of a signal input module disposed in the terminal when the external antenna is joined with the antenna jack, and which causes the electric contact point to be separated from the jack ground point while making another electric contact point with an antenna ground point of the antenna module, so as to be connected electrically with the contact point of the signal input module when the external antenna is separated from the antenna jack. 
    
    
     
       BRIEF DESCRIPTION OF. THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a portable terminal having an external antenna for exclusive use in a broadcasting service connected thereto according to the prior art; 
         FIG. 2  is a side view showing an antenna jack disposed in a portable terminal according to the prior art; 
         FIG. 3  is a perspective view showing an antenna jack, mounted to a printed circuit board embedded in a portable terminal, according to the prior art; 
         FIG. 4  is a perspective view showing an antenna device for a portable terminal according to a preferred embodiment of the present invention; 
         FIG. 5  is a side view showing the arrangement of the antenna device for a portable terminal according to a preferred embodiment of the present invention; 
         FIG. 6  is a schematic view showing how to electrically connect an external antenna, for exclusive use in a broadcasting service, with an antenna jack in the antenna device for a portable terminal according to a preferred embodiment of the present invention; 
         FIG. 7  is a schematic view showing how to electrically connect an antenna module with an antenna jack in the antenna device for a portable terminal according to a preferred embodiment of the present invention; and 
         FIG. 8  is a graph showing antenna gain and efficiency as a function of frequency in the antenna device for a portable terminal according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. 
     As shown in  FIG. 4 , an antenna device for a portable terminal includes an antenna module  10 , an insulator module  20  and an antenna switch module  30  (not shown), wherein the antenna module  10  is disposed along the outer circumference of an antenna jack  1   a , so as to receive broadcasting signals depending on mounting/demounting of an external antenna  2  for exclusive use in the broadcasting service. The insulator module  20  is disposed at the bottom of the antenna jack  1   a , so as to insulate the antenna module  10 . 
     As shown in  FIGS. 6 and 7 , the antenna switch module  30  is disposed in the antenna jack  1   a . On one hand (see  FIG. 6 ), when the external antenna  2  is joined with the antenna jack  1   a , the antenna switch module  30  makes an electric contact point with a jack ground point  31  disposed inside the antenna jack  1   a , so as to be connected electrically with a contact point  33  of a signal input module disposed in the terminal  1 . Thus the signals received by the external antenna  2  are applied to the terminal  1 . On the other hand (see  FIG. 7 ), when the external antenna  2  is separated from the antenna jack  1   a , the antenna switch module  30  causes the electric contact point with the jack ground point to be separated from the jack ground point  31  while making another electric contact point with an antenna ground point  32  of the antenna module  10 , so as to be connected electrically with the contact point  33  of the signal input module  5 . Thus the signals received by the antenna module  10  are applied to the terminal  1  through the signal input module  5 . 
     Additionally, as shown in  FIG. 5 , the antenna module  10  includes a diversity antenna  34  and has at least one meander line  11 . Further as shown in  FIG. 5 , the meander lines  11  have a constant thickness and are spaced apart from each other at a constant interval. More particularly, the meander lines have a thickness T 1  of 0.6 mm and are spaced apart from each other at an interval L 1  of 1.2 mm. 
     As shown in  FIGS. 6 and 7 , the antenna switch module  30  includes a jack ground point  31  and an antenna ground point  32 . The jack ground point  31  is disposed in the antenna jack  1   a  in such a manner that it can make electric contact with a connection jack  2   a  of the external antenna for exclusive use in a broadcasting service, when the connection jack  2   a  is joined with the antenna jack  1   a . Additionally, the antenna ground point  32  is disposed in the antenna jack  1   a  in such a manner that it can be separated from the jack ground point  31  while another electric contact point with the antenna module  10  is made, when the antenna jack  1   a  is separated from the connection jack  2   a.    
     Hereinafter, operation of the above-described antenna device for a portable terminal according to a preferred embodiment of the present invention will be explained in more detail with reference to  FIGS. 4-8 . 
     As shown in  FIG. 4 , the antenna device  10  for a portable terminal  1  includes the antenna jack  1   a  connected electrically with the external antenna for exclusive use in a broadcasting service, the antenna module  10 , insulator module  20 , and the antenna switch module  30 . The antenna module  10  is disposed along the outer circumference of the antenna jack  1   a  and the insulator module  20  is disposed at the bottom of the antenna module  10 . 
     As shown in  FIGS. 6 and 7 , when the external antenna  2 , which is used exclusively in the broadcasting service, is joined with the antenna jack  1   a , the jack ground point  31  disposed in the antenna switch module  30  makes electric contact point with the external antenna, and thus is connected electrically with the contact point  33  of the signal input module  5  disposed in the terminal  1 . On the other hand when the external antenna  2 , which is used exclusively for broadcasting service is separated from the antenna jack  1   a , the electric contact point is separated from the jack ground point  31 . Another electric contact point with the antenna ground point  32  of the antenna module  10  is made, so as to be connected electrically with the contact point  33  of the signal input module  5 . 
     Under the above conditions, the antenna module  10  is mounted to the printed circuit board  4  of the terminal  1 . 
     As shown in  FIG. 5 , the antenna module  10  includes a diversity antenna  34  and has at least one meander line  11 . More particularly, the meander lines  11  have a thickness T 1  of 0.6 mm and are spaced apart from each other at an interval L 1  of 1.2 mm. 
     Then (as shown in  FIG. 6 ) when the connection jack  2   a  of the external antenna  2 , which is used exclusively in the broadcasting service, is joined with the antenna jack  1   a , the connection jack  2   a  of the external antenna  2  makes an electric contact point with the jack ground point  31  of the antenna switch module  30 . At the same time, the jack ground point  31  makes an electric contact with the contact point  33  of the signal input module  5 . Accordingly, broadcasting signals received by the external antenna  2 , which is used exclusively in the broadcasting service, are applied to the terminal  1 , so that users can watch TV through the terminal  1 . 
     On the other hand, when the connection jack  2   a  of the external antenna  2 , is separated from the antenna jack  1   a , the electric contact point with the jack ground point is separated from the jack ground point  31  of the antenna switch module  30 . At the same time, another electric contact point with the antenna ground point  32  of the antenna module  10  is made, so as to be connected electrically with the contact point  33  of the signal input module  5 . Accordingly, broadcasting signals received by the antenna module  10  are applied to the terminal, so that users can watch TV through the terminal  1 . 
     As described above, the antenna module  10  then serves as an antenna for exclusive use of broadcasting service by making an electric contact with the contact point  33  of the signal input module, when the external antenna  2 , which is used exclusively for broadcasting service, is separated. 
       FIG. 8  and the following Table 1 show the results of antenna gain and efficiency depending on frequencies, when the antenna module  10  serves as an antenna for exclusive use in the broadcasting service. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 (expressed in dBi units) 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Frequency 
                 Peak 
                 Gain (Average) 
                 Efficiency (%) 
               
               
                   
                   
               
               
                   
                 2630 MHz 
                 1.8 
                 −3.1 
                 49% 
               
               
                   
                 2635 MHz 
                 1.8 
                 −3.0 
                 51% 
               
               
                   
                 2640 MHz 
                 2.1 
                 −2.9 
                 51% 
               
               
                   
                 2645 MHz 
                 1.9 
                 −2.9 
                 51% 
               
               
                   
                 2650 MHz 
                 1.9 
                 −3.0 
                 50% 
               
               
                   
                 2655 MHz 
                 2.3 
                 −2.5 
                 56% 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table 1 and  FIG. 8 , when the antenna module  10  is used as the antenna for exclusive use in the broadcasting service with variable frequencies, the average value of antenna gain is −2.9 dBi and antenna efficiency is 51%. 
     Therefore, the antenna module  10  shows stable antenna gain and efficiency when being used as antenna for exclusive use in the broadcasting service. 
     As described above, because the antenna device for a portable terminal according to the present invention includes an antenna module receiving broadcasting signals on the outer surface of an antenna jack housing of a terminal capable of TV service, it is possible to downsize the terminal by reducing the space needed for mounting an antenna device, which is used exclusively for broadcasting service. Additionally, because the antenna module includes meander lines, it is possible to reduce the number of components forming the antenna and thus to save manufacturing costs. 
     While the invention has been shown and described with reference to certain preferred 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 invention as defined by the appended claims.