The present invention relates to a multiband planar antenna consisting of at least one resonator formed of an element having a closed shape made on a substrate and dimensioned so as to operate in its fundamental mode at the resonant frequency of the lowest band. The resonator is fed by a feed line in such a way as to operate in all the higher modes. The resonator comprises means for modifying the resonant frequencies of the various modes in such a way as to cover the bands concerned.