Epoch-making progresses in meteorology and the atmospheric science were always quickened by the development of advanced observational technologies, in particular, the radar technology. It depends upon the comprehensive sciences, which widely involve different disciplines from electrical engineering and electronics to computer sciences and atmospheric physics, although there are many fields common among the different radars. However, each type of radar has its own history, and independently developed. The respective radar activities have been conducted within the respective narrow community. Up to now, this typical interdisciplinary research field had not been discussed in one book consistently, which contains fundamental theories, observational methods and results. This book is written by two authors who have long been in academism and industry, respectively, and are supposed to be the best partner for writing on the comprehensive sciences and technologies.