Method for generating microwave or rf electromagnetic wave beams with non zero orbital angular momentum and with intensity distribution concentrated in a limited angular region

Method for generating a microwave or RF electromagnetic wave beam with non-zero Orbital Angular Momentum propagating along a propagation direction (z) and with intensity distribution mainly concentrated in a single limited main lobe, the intersection of which with a plane (γ), located at a great distance from the beam source and perpendicular to said propagation direction (z), is contained in a circle segment having its vertex on the axis of propagation (z) and an angular aperture θ 2 paraxial and coherent wave beams, said N beams being substantially coaxial and having : -) the same wavelength λκ=λ for each K=1,2,..,N; -) values of the Orbital Angular Momentum OAM lk, of said N beams (i.e. K=1,2,..N), which are non-zero, integer, consecutive and of the same sign: b) coherent superposition of said N selected wave beams.