Figure 5

(a) Imperfectly arranged UCA_(1×16), where Δθ is the azimuthal deviation and \(\Delta \theta =\frac{2\pi }{160}\); (b) phase pattern of the IOAM mode l =−4 under transmission distance z = 20λ; (c) phase pattern of the IOAM mode l = −4 under transmission distance z = 2 × 10³λ.