Rayleigh distance

Rayleigh distance

[′rā·lē ‚dis·təns]
(physics)
For electromagnetic, acoustic, or elastic waves emitted from a uniformly excited planar array transmitting a sinusoidal signal, the distance from the array at which there is a transition from a near-field region, in which the radiated energy is confined to a cylindrical region, to a far-field region, in which the wave field exhibits spherical spreading and the field amplitude varies inversely with range.
References in periodicals archive ?
Based on that, Huawei proposes the 5G microwave MIMO solution which can improve the microwave spectrum efficiency by 100% to double the capacity, shorten the installation distance (Rayleigh distance) by 67%, and reduce the requirement of MIMO deployment of tower space.
Following equations show the pressure in the near (x [less than or equal to] [R.sub.0]) and far (x [greater than or equal to] [R.sub.0]) fields where [R.sub.0] is the Rayleigh distance and is defined as a/[lambda] where [lambda] is the acoustic wavelength:
where [w.sub.0] is the waist radius at the propagation distance of Z = 0 m, w(z) is the beam waist radius at the propagation distance of Z > 0 m, [z.sub.R] = [pi][w.sub.0.sup.2]/[lambda] is Rayleigh distance, and k = 2[pi]/[lambda] is wave vector.