What characterizes libration fading of an EME signal?

Earth-Moon-Earth (EME) or 'moonbounce' communications involve reflecting radio signals off the surface of the Moon. Because the Moon's surface is rocky, heavily cratered, and physically irregular, it does not act like a smooth mirror for radio waves. As the Moon orbits the Earth, it exhibits a slight wobbling motion known as libration. Because of this wobble and the uneven lunar surface, returning radio waves bounce off different parts of the Moon and arrive back at Earth at slightly different times and phases. When these scattered, multipath signals recombine at your receiving antenna, they interfere with one another. This constant shifting of phase and amplitude produces the fluttery, irregular fading characteristic of libration fading.