Figure 6
Normalized spiral spectrum of IOAM modes under transmission distance, (a) z = 20λ; (b) z = 2 × 102λ; (c) z = 2 × 103λ; (d) z = 2 × 104λ respectively; (e) spiral spectrum of IOAM mode l = −4 under the transmission distance z = 20λ, z = 2 × 102λ, z = 2 × 103λ and z = 2 × 104λ. The radius of UCA(1×16) is r = 2λ and the radius of receiver aperture is rd = 2λ and \(\Delta \theta =\frac{\pi }{80}\).
