An integrated electronic radio-frequency transceiver circuit, including: at least one terminal intended to receive a signal to be transmitted or to transmit a received signal; at least one planar antenna, with a settable resonance frequency; at least one bidirectional coupler having a primary line interposed between the terminal and the antenna and having the respective terminals of a secondary line providing data representative of the transmitted power and of the power reflected on the primary line side; at least one detector of the transmitted power and of the reflected power; and a circuit for selecting the resonance frequency of the antenna according to the ratio between the transmitted power and the reflected power.