Abstract:
The invention relates to a tunable antenna installed inside a mobile communication terminal to process multiple bands according to selection of reception frequency of a signal, and a control unit therefor. The tunable antenna includes an antenna for processing at least two different RF signals and an RF processor for receiving the RF signal from the antenna through a data signal line to convert the signal to a baseband signal. The tunable antenna further includes an antenna controller for providing a direct-current control signal for converting a band processed by the antenna through the data signal line, and an antenna tuner for receiving the direct-current control signal to convert the band processed by the antenna.

Description:
CLAIM OF PRIORITY  
       [0001]     This application claims the benefit of Korean Patent Application No. 2005-56158 filed on Jun. 28, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an antenna of a mobile communication terminal, and more particularly, to a tunable antenna unit installed in a mobile communication terminal to process multiple bands according to selection of a frequency of a reception signal, and a control unit therefor.  
         [0004]     2. Description of the Related Art  
         [0005]     Recently, advancement in mobile technologies for a mobile communication terminal has led to diversity in frequency bands used by the antenna of the mobile communication terminal.  
         [0006]     Specifically, the frequency bands used by the mobile communication terminal include 800 MHz-2 GHz (mobile phone), 2.4 GHz, 5 GHz (wireless LAN), 113.56 MHz (non-contact RFID), 2.4 GHz (Bluetooth), 1.575 GHz (GPS), 76-90 MHz (FM radio), 470-770 MHz (Television broadcasting), UWB, Zigbee and Digital Multimedia Broadcasting (DMB) and Digital Video Broadcasting (DVB-H). The DMB is divided into a satellite DMB using ultra high frequency (UHF) (2535-2655 MHz) and a terrestrial DMB using very high frequency (VHF) (174-216 MHz).  
         [0007]     Also, the DVB-H is categorized into an UHF DVB-H using UHF and a satellite DVB-H using L-Band frequencies.  
         [0008]     The mobile communication terminal needs to be miniaturized and light-weighted while at the same time, capable of providing various services.  
         [0009]     In order to meet such needs, the antenna and other components adopted in the mobile communication terminal are becoming more multi-functional and miniaturized. These days, the antenna for the mobile telecommunication terminal is installed inside the terminal. Thus, the antenna for the mobile communication terminal is required to occupy little space inside the terminal while performing with satisfactory capabilities.  
         [0010]     As discussed above, various types of tunable antennas are used for receiving different bands of communication or broadcast signals through the mobile communication terminal. And by supplying a particular control signal to such a tunable antenna, the reception frequency band can be converted to allow the mobile communication terminal to provide various services.  
         [0011]      FIG. 1  is a block diagram illustrating a control unit for converting a band of a conventional antenna.  
         [0012]     Referring to  FIG. 1 , the conventional tunable antenna control unit includes a tunable antenna unit  10  for receiving different bands of RF signals and a receiver  13  for recovering the RF signal received through the tunable antenna unit  10 .  
         [0013]     The tunable antenna unit  10  includes an antenna  11  and an antenna tuning circuit  12 . The antenna  11  is capable of adjusting impedance to receive different bands of signals. The antenna tuning circuit  12  provides an antenna control signal for selecting a frequency band processed by the antenna  11 .  
         [0014]     The receiver  13  includes an RF processor  14  and an antenna controller  15 . The RF processor  14  receives an RF data signal from the antenna  11  through a data signal line  16 , and converts the RF signal into a baseband signal. The antenna controller  15  provides a control signal for selecting the band processed by the antenna  11  to the antenna tuning circuit  12  through a control signal line  17 . Thereby, the band of the signal processed by the antenna  11  can be converted in order for the mobile communication to provide various communication services.  
         [0015]     As described above, the conventional tunable antenna control unit is provided with the data signal line  16  for receiving a data signal as well as the control signal line  17  for supplying a control signal for converting the frequency band at which the antenna  11  receives a signal, connecting between the tunable antenna unit  10  including the antenna  11  and the receiver  13 . However, separate configuration of the data signal line  16  and the control signal line  17  complicates the circuit, and as the control signal line  17  occupies a separate area inside the terminal, miniaturization of the mobile communication terminal is difficult. Furthermore, since the control signal line  17  is separately formed adjacent to the antenna  11 , the control signal transmitted through the control signal line  17  may affect the capabilities of the antenna  11 , distorting the reception signal.  
       SUMMARY OF THE INVENTION  
       [0016]     The present invention has been made to solve the foregoing problems of the prior art and therefore an object of certain embodiments of the present invention is to provide a tunable antenna unit installed in a small size inside a mobile communication terminal to receive and process various frequency bands of signals.  
         [0017]     Another object of certain embodiments of the invention is to provide a tunable antenna control unit capable of controlling the tunable antenna unit through a data signal line without using a separate control signal line, thereby preventing the effects of an outside circuit or current that may distort a data signal.  
         [0018]     According to an aspect of the invention for realizing the object, there is provided a tunable antenna control unit including: an antenna for processing at least two different radio frequency (RF) signals; an RF processor for receiving each of the RF signals from the antenna through a data signal line to convert the RF signal to a baseband signal; an antenna controller for providing a direct-current control signal through the data signal line to convert a band processed by the antenna; and an antenna tuner for receiving the direct-current control signal to convert the band processed by the antenna.  
         [0019]     According to another aspect of the invention for realizing the object, there is provided a tunable antenna unit including: an antenna having a plurality of radiators for processing at least two different RF signals and providing RF signals received from the plurality of radiators through a data signal line to an RF processor; and an antenna tuner for receiving a direct current control signal to convert a band processed by the antenna through the data signal line, thereby converting the band processed by the antenna. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0021]      FIG. 1  is a block diagram illustrating a conventional tunable antenna control unit;  
         [0022]      FIG. 2  is a block diagram illustrating a tunable antenna control unit according to a certain embodiment of the present invention;  
         [0023]      FIG. 3  is a block diagram illustrating a tunable antenna unit according to a certain embodiment of the present invention: and  
         [0024]      FIG. 4  is a block diagram illustrating a tunable antenna unit according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]     Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
         [0026]     The same reference numerals are used throughout to designate the same or similar components. In the following description, well-known functions and constructions are not described in detail since they would obscure the intention in unnecessary detail.  
         [0027]      FIG. 2  is a block diagram illustrating a tunable antenna control unit according to a certain embodiment of the present invention.  
         [0028]     Referring to  FIG. 2 , the tunable antenna control unit according to a certain embodiment of the invention includes a tunable antenna unit  20  mounted in a mobile communication terminal, capable of receiving a plurality of bands of signals, and a receiver  23  for recovering a signal received at the tunable antenna unit  20 .  
         [0029]     The tunable antenna unit  20  includes an antenna  21  and an antenna tuner  22 . The antenna  21  is capable of adjusting impedance to receive multiple bands of signals. The antenna tuner  22  provides an antenna control signal for selecting a frequency band processed by the antenna  21 .  
         [0030]     The receiver  23  includes an RF processor  24 , an antenna controller  25 , a Low Pass Filter (LPF)  27  and a High Pass Filter (HPF)  28 .  
         [0031]     The RF processor  24  is connected to the antenna  21  through a data signal line  26 , and receives an RF data signal through the data signal line  26  from the antenna  21 . The RF signal received by the RF processor  24  is converted to a baseband signal which is provided to a baseband processor (not shown) where the data is interpreted.  
         [0032]     The antenna controller  25  provides a direct-current control signal for converting a band processed by the antenna  21  through the data signal line  26 .  
         [0033]     The LPF  27  has an end connected to the data signal line  26  and the other end connected to the antenna controller  25 . The LPF  27  passes the direct-current control signal provided by the antenna controller  25  while blocking the RF signal running on the data signal line  26  from entering the antenna controller  25 .  
         [0034]     The HPF  28  connects between the antenna  21  and the RF processor  24  and functions to block the direct-current control signal provided by the antenna controller  25  from entering the RF processor  24 . A capacitor can be adopted for the HPF  28  to prevent the direct-current control signal from entering the RF processor  24 , as shown in  FIG. 2 .  
         [0035]      FIG. 3  is a configuration view illustrating a tunable antenna unit according to a certain embodiment of the present invention.  
         [0036]     Referring to  FIG. 3 , the tunable antenna unit according to a certain embodiment of the invention includes an antenna  21  having a plurality of radiators L 1  and L 2  ( 31  and  32 ) and an antenna tuner  22  for converting a band processed by the antenna  21 .  
         [0037]     The antenna  21  includes a first radiator L 1  for processing an RF signal of a first band, and a second radiator L 2  for processing an RF signal of a second band together with the first radiator L 1 . The antenna  21  provides the RF signal received through the first and second radiators L 1  and L 2  to an RF processor  24  of a receiver  23  through a data signal line  26 .  
         [0038]     The first radiator L 1 , if used singly, can be formed in an electric resonance length for transmitting and receiving, for example, high frequency band of 750 MHz among the ultra high frequency (UHF) band (470 to 7500 MHz). The second radiator L 2 , if used in connection with the first radiator L 1 , the sum length of the first radiator L 1  and the second radiator L 2  can equal an electric resonance length for transmitting and receiving, for example, a low frequency band of 470 MHz among the ultra high frequency (UHF) band (470 to 7500 MHz). The first and second radiators L 1  and L 2  can be formed in various types such as a helical type, meander type, plate type and strip line.  
         [0039]     The antenna tuner  22  includes a diode D ( 33 ) and a bias resistor R ( 34 ) and functions to electrically connect or disconnect between the first and second radiators L 1  and L 2 , thereby adjusting impedance of the antenna  20 , which allows the antenna  20  to use only the first radiator L 1  or both the first and second radiators L 1  and L 2  connected to each other.  
         [0040]     The diode D has an anode connected to an end of the first radiator L 1  and a cathode connected to an end of the second radiator L 2 . The diode D is electrically turned off if supplied with a direct-current control signal of, for example, less than 0.7 volts from the antenna controller  25 . At this time, the antenna  20  uses only the first radiator L 1 ,  31  to process an RF signal of a first band. On the other hand, the diode D,  33  is electrically turned on if supplied with a direct-current control signal of, for example, above 0.7 volts from the antenna controller  25 . At this time, the antenna  21  uses both the first and second radiators L 1  and L 2  connected to each other to process an RF signal of a second band.  
         [0041]     The bias resistor R has an end connected to a cathode path of the diode D and the other end grounded to provide bias to the diode D. Therefore, as shown in  FIG. 3 , the bias resistor R can have an end connected to the other end of the second radiator L 2  and the other end grounded. In addition, the bias resistor R needs to form a direct-current connection, and thus can have an end connected to a contact point of an end of the second radiator L 2  and a cathode of the diode D, and the other end grounded.  
         [0042]      FIG. 4  is a configuration view illustrating a tunable antenna unit according to another certain embodiment of the present invention.  
         [0043]     Referring to  FIG. 4 , the tunable antenna unit according to another embodiment of the invention includes an antenna  21  having a plurality of radiators L 1 , L 2 , . . . , LN ( 41 ,  42 , . . . ,  43 ) and an antenna tuner  22  for converting a band processed by the antenna  21 .  
         [0044]     As seen in comparison with the structure in  FIG. 3 , the antenna  21  has a plurality of radiators L 1 , L 2 , . . . , LN connected in cascade. The plurality of radiators L 1 , L 2 , . . . , LN are connected in series with one another to process different bands of signals in various combinations with one another, using the direct-current control signal received through the data signal line  26 , at a feeding terminal  40  formed at an end of the antenna  21 .  
         [0045]     The antenna tuner  22  includes a plurality of diodes D 1 , . . . , DN- 1  ( 44 , . . . ,  45 ) and a plurality of bias resistors R 1 , . . . , RN- 1  ( 46 , . . . ,  47 ). The plurality of diodes D 1 , . . . , DN- 1  are connected between the plurality of radiators L 1 , L 2 , . . . , LN. That is, the first diode D 1  has an anode connected to the first radiator L 1  and a cathode connected to a second radiator L 2 . The (N-1) th  diode DN- 1  has an anode connected to the (N-1) th  radiator LN- 1  (not shown) and a cathode connected to the N th  radiator LN. The plurality of diodes D 1 , . . . , DN- 1  are electrically turned on or off using the direct-current control signal provided through the data signal line  26 , thereby adjusting the electric resonance length of the antenna  21 . For example, when the first diode D 1  is turned off by the direct-current control signal, the antenna  20  uses only the first radiator L 1  to process an RF signal of a first band. On the other hand, when the plurality of diodes D 1 , . . . , DN- 1  are all electrically turned on by the direct-current control signal, the antenna  21  uses the plurality of radiators L 1 , L 2 , . . . , LN all connected to one another to process an RF signal of another N th  band. That is, the plurality of diodes D 1 , . . . , DN- 1  are selectively turned on or off by the direct-current control signal provided through the data signal line  26  to process various bands.  
         [0046]     Each of the plurality of bias resistors R 1 , . . . , RN- 1  has an end connected to a cathode path of a corresponding one of the plurality of diodes D 1 , . . . , DN- 1 , and the other end grounded to provide bias to the plurality of diodes D 1 , . . . , DN- 1 .  
         [0047]     According to certain embodiments of the present invention set forth above, a tunable antenna unit can be manufactured in a simple, small-sized structure, and can advantageously receive and process various bands of signals.  
         [0048]     In addition, a tunable antenna control unit can control the tunable antenna unit to convert a band processed by the tunable antenna unit using already established data signal line without forming an additional control signal line, thereby advantageously preventing distortion of a data signal by an outside circuit or current.  
         [0049]     While the present invention has been shown and described in connection with the preferred embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.