volume desaccordable antenna for imaging apparatus by nuclear magnetic resonance

The present invention relates to a radio frequency antenna (100) having a plurality of longitudinal conductors (2) and a detuning circuit to change the resonant frequency of the eigenmode of said antenna (100), said antenna (100) being characterized in that said detuning circuit is a circuit adapted to tune said antenna (100) without contact with said longitudinal conductors (2), said detuning circuitry being arranged to resonate: a first resonance frequency near the mode resonant frequency characteristic of said antenna so as to induce inductive reactance effect on each longitudinal conductor (2) and to modify the resonant frequency of the eigenmode of said antenna (100); at a second resonant frequency higher or lower than the resonant frequency of the eigenmode of said antenna so as to minimize the coupling with the longitudinal conductors (2).