Abstract: The deep integration of active and passive radar, which combines the high-precision measurement capability of active radar with the strong concealment and survivability advantages of passive radar, is regarded as a crucial direction in the evolution of modern radar technology. A focused study is conducted on the Deployable Multi-band Active/Passive Radar (DMPAR) project led by the NATO Science and Technology Organization. The developmental trajectory of this technology is summarized, and the entire process, from its initial conceptualization and theoretical simulation to multinational collaborative validation and productization, is described in detail. Key technologies, including multi-source information fusion, multi-band collaborative architecture design, advanced signal processing, collaborative mission planning and resource management, as well as experimental verification and performance evaluation, are discussed. Finally, the future development trends of this technology, such as deep full-link integration, intelligentization, distributed networked coordination, and miniaturization with low cost and high mobility, are explored.