Uso di fasci vorticosi nelle comunicazioni radio.

It is well known that light beams can carry orbital angular momentum (OAM) in addition to spin, assuming a peculiar helical structure in their wavefronts. This thesis considers the possibility of exploiting the orbital angular momentum of light in radio communications, starting from the public experiment 'Onde sulle Onde' performed in Venice by Fabrizio Tamburini et al. Despite the originality of the idea, it is important to discover if the use of twisted beams in a radio communication context will really introduce something new with respect to preexisting technologies, like MIMO techniques. After an overview of the general behaviour of beams carrying OAM, this dissertation outlines how in the near-field region the Venice experiment can be considered as a specific type of MIMO system and how the interferometric receiving apparatus used by Tamburini fails in the far-field zone. Finally, for further information, the existence of nondiffracting vortex wave modes, the possibility of creating beams carrying fractional orbital angular momentum (FOAM) and the several methods employed in the production of all these kinds of beams are briefly illustrated.