IMPEDANCE MATCHING METHOD FOR A MULTI-BAND ANTENNA, AND TRANSMISSION OR RECEPTION CHANNEL HAVING AUTOMATIC MATCHING

摘要

The invention relates to an automatic impedance matching method for an antenna for a radiofrequency transmission circuit. An impedance matching network (MN) is inserted between the amplifier (PA) and the antenna (ANT). The output current i and voltage V of the amplifier and the phase-shifting thereof are measured by variable measurement impedance (Ca), and the complex impedance of the amplifier load is deduced therefrom. The impedance of the antenna is calculated on the basis of said complex impedance and on the basis of the current known values of the impedances of the matching network. New values for the matching network are calculated from the found value of the impedance of the antenna, making it possible to match the load to the nominal impedance of the amplifier. The measurement impedance has a value that is controllable by the calculation processor in accordance with the use, and in particular in accordance with the working frequency and with the nominal impedance of the amplifier. The invention can be used in miniature antennas for telephony or in medical telemetry.