The SWR operation unit may include: a reflection coefficient calculation part calculating a reflection coefficient by using the forward power detected by the forward power detection unit and the reflected power detected by the reflected power detection unit and an SWR calculation part calculating an SWR from the reflection coefficient calculated by the reflection coefficient calculation part. In one embodiment, an apparatus for matching impedance using Standing Wave Ratio (SWR) information, includes: a directional coupler extracting forward power of a transmission signal traveling to be transmitted through an antenna, and reflected power of the transmission signal reflected from the antenna an impedance matching unit matching impedance of the antenna by varying impedance according to a control signal a forward power detection unit detecting the forward power from an output signal of the directional coupler a reflected power detection unit detecting the reflected power from the output signal of the directional coupler an SWR operation unit calculating an SWR by using the forward power detected by the forward power detection unit and the reflected power detected by the reflected power detection unit and an impedance control unit controlling impedance of the impedance matching unit while determining a region of a smith chart in which initial total impedance of the impedance matching unit and the antenna is located, by using the SWR calculated by the SWR operation unit, the impedance control unit controlling the impedance of the impedance matching unit according to the determined region to thus control impedance of the antenna to be matched. ![]() However, the above impedance matching of the antenna is associated with finding the point where the SWR is at the minimum level within a local area, rather than finding the point within the entire area where the impedance of the antenna can be varied.Īlso, there are instances where it is impossible to control the SWR to be equal to or lower than a predetermined value.Įmbodiments provide apparatuses and methods for matching impedance using standing wave ratio (SWR) information, capable of correctly matching the impedance of an antenna by finding a region of a Smith chart in which the impedance of an impedance matching circuit is located by using SWR information calculated from forward power and reflected power, and varying the impedance according to the found region of the Smith chart. To this end, the communication devices include a directional coupler, and detect reflected power and forward power output from the directional coupler.Īlso, the impedance of the antenna is matched by changing the impedance of the impedance matching unit according to the magnitude of the detected reflected power and forward power to become a standing wave ratio (SWR). To allow an antenna to maintain its optimum transmission and reception radiation performance, impedance changes of the antenna need to be detected. Therefore, communication devices automatically control antenna impedance when the impedance matching conditions of antennas are changed, such that the antennas achieve optimum transmission and reception radiation performance. Particularly, to use a mobile communication terminal, a user holds a terminal body in his hand and brings a speaker close to a speaker, or uses an earphone while placing the mobile communication terminal in a pocket, a bag or the like.Īs a user uses a mobile communication terminal by holding the terminal body in his hand and bringing it close to the ear, or uses it with the body placed in a packet, a bag or the like, the impedance matching conditions of the antenna are varied, thus impairing the transmission and reception radiation performance of the antenna, the impedance of which has matched in a free space. The impedance matching of the antenna is made in the state where the antenna is located in a free space, and the impedance matching conditions of the antenna are varied according to changes in surroundings. The antenna impedance matching is made to an optimum level by controlling the impedance of the impedance matching unit. ![]() Therefore, a related art communication device includes an impedance matching unit using a capacitor, an inductor and the like. In general, various communication devices, such as mobile communication terminals, have antennas through which signals of a predetermined frequency are received and transmitted.Īs for the antennas, the impedance thereof needs to be correctly made so as to achieve optimum transmission and reception radiation performance. The present disclosure relates to an apparatus and method for matching impedance using Standing Wave Ratio (SWR) information.
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