Device for matching frequency of antenna automatically in wireless terminal

An apparatus for automatically matching antenna frequencies in a portable terminal is provided to prevent the impedance matching of an antenna frequency from being distorted in an open held mode and to prevent the performance of a portable terminal from being deteriorated due to a change in the VSWR(Voltage Standing Wave Ratio) of the antenna and the mismatching of the antenna. An apparatus for automatically matching antenna frequencies in a portable terminal comprises a duplexer(110), an automatic matching part(180), and a control part(160). The duplexer(110), classifying the frequencies transmitted/received through the antenna of the portable terminal, transmits an Rx frequency, received from the antenna, to the automatic matching part(180) and a Tx frequency, received from the automatic matching part(180), to the antenna. The automatic matching part(180) automatically matches impedance for the Rx frequency, received from the duplexer(110), and transmits it to an amplification part. Also the automatic matching part(180) automatically matches impedance for the Tx frequency, received from the amplification part, and transmits it to the duplexer(110). The control part(160) controls the automatic matching part(180) so as to automatically match impedance for the Tx/Rx frequencies.