The main purpose of this article is to enhance the systematicness, comprehensiveness, and profundity of the counter-unmanned aerial system (C-UAS) theoretical system, laying a theoretical foundation for the development of C-UAS technologies and weapons, thereby further improving the ability to deal with air threats such as unmanned aerial vehicles in the future. In the discussion process, it mines information, reveals inherent laws, and thereby puts forward the concept of "active defense technology" in the C-UAS mission. Simultaneously, it carries out a comprehensive summary and systematic classification of various technologies. Then, it analyzes every technology from its main characteristics, theoretical breakthroughs, practical applications in detail and in-depth, and comprehensively compares their respective advantages and limitations. Meanwhile, it focuses on the analysis of directed energy countermeasures. Horizontally, it makes an almost complete summary of the current high-energy laser weapon on a global scale; longitudinally, it cards the actual combat cases of directed energy weapons in C-UAS missions with time as a clue. Furthermore, to better integrate with reality, it conducts an extensive market survey of 581 C-UAS systems from 282 manufacturers in 39 countries around the world based on literature and practice, making them a statistical analysis from four aspects. On this basis, it classifies and summarizes the most advanced weapon systems according to different technologies. Finally, it put forward several prominent and bottleneck problems faced in the current research from three aspects of confrontation, maturity, and law. Correspondingly, it prospects several future development directions and proposes several constructive suggestions from technology and tactic.
