The advantages offered by microwave and millimeter waves have attracted immense interest from academia and the communications industry. The main characteristics of both waves include short wavelength (hence small components), large bandwidth, and frequency re-use. An electromagnetic wave of these bands propagating through a region containing raindrops suffers two attenuating effects: one is absorbed through which part of its energy is absorbed by the raindrops and transformed into heat; and the other is scattering where part of the energy is scattered in all directions. In this book, rain characteristics are presented in relation to radio and satellite links. The book reviewed rain rate integration time, rain rate and its drop size distribution models. In addition, the book explained in details proposed conversion methods, and suggested rain rate and raindrop size distribution models for South Africa. The results resented in this book may be of great interest to communication system designers and radio planning engineers.