WP 3M addresses radiowave propagation over point-to-point terrestrial paths and Earth-space paths, both for wanted and unwanted signals. For terrestrial paths, prediction methods are developed for both line-of sight and over-the-horizon links, taking into account the possible mechanisms that can give rise to fading and distortion of the wanted signal. Similarly, propagation impairments on slant paths from satellites are treated by a series prediction procedures which seek to quantify and assess the overall propagation loss, fading behavior and signal depolarization.