This book provides an introduction to the principles of phased array antenna design. It is a set of 12 lecture notes that originally accompanied a series of intensive short courses presented in the mid-70s. With an explicitly tutorial approach, this book offers a concise, introductory-level survey of the fundamentals without dwelling on extensive mathematical derivations or abstruse theory. Its presentation focuses on step-by-step design procedures and provides practical results using extensive curves, tables and illustrative examples.