A culmination of Ashok Agrawal's 35 years of experience working on active phased array antenna systems this comprehensive guide covers design and development of an active phased array antenna system involving inputs from multiple disciplines such as aperture design, T/R module design, hybrid lab, beam steering control, mechanical engineering, and manufacturing. With key topics covered such as radar system-level advantages of active phased arrays over passive phased arrays such as Increased sensitivity, Improved Target Detection in Clutter, Improved Waveform and Pattern Flexibility, Improved Wideband Operation, Increased reliability, Reduced Cost, broadband frequency operation, lower noise temperature/figure, and reduction in prime power. This book will be beneficial to new engineers as well as experienced engineers working on active phased array antenna systems.