An ultrasound system for an ultrasound therapy (ablation or hyperthermia) of a region of interest comprising: a patch comprising a two-dimensional array of ultrasonic transducers (preferably CMUTs ) arranged on a support, wherein a plurality of the transducers is adapted to operate in a variable frequency range a transducer controller means adopted to activate at least two groups of the plurality of the transducers in the array for a transmission of the ultrasound signals, wherein each of the at least two groups: is arranged in a pattern and operates at a frequency different from other groups frequency.
