The present invention refers to a reconfigurable antenna structure. The antenna structure comprises a radiating structure comprising one or more first radiating elements and a secondary radiating structure, operationally associated with said primary radiating structure. Said secondary radiating structure comprises a plurality of second radiating elements that can be selectively electrically connected/disconnected to each other to vary the configuration of said secondary radiating structure, so as to vary the radiating properties of the antenna structure. The antenna structure also comprises first reactive loads, electrically connected between said primary and secondary radiating structures, and second reactive loads, electrically connected to said secondary radiating structure. Said first reactive loads, said second reactive loads and said second radiating elements forming one or more circuitry structures that are electrically resonant in the operating frequency band of said antenna structure and that are electrically connected/disconnected to each other in a selective manner in accordance to the configuration selected for said second radiating structure, thereby maintaining constantly equal to zero the overall reactive load that is electrically connected to said primary radiating structure.