Millimeter-wave propagation through a terrestrial atmosphere

At millimeter-wave frequencies, the terrestrial atmosphere is absorptive, dispersive, and inhomogeneous. Because it is inhomogeneous, rays are bent by refraction, and because it is dispersive, the amount of bending depends on the frequency. Thus the path length between two terminals depends on frequency, which means that there is an additional frequency distortion to be accounted for. The author derives an `effective reactivity' to do such an accounting. He shows that the correction involved is rather small