As wireless infrastructure expands toward dense Internet of Things (IoT) and Cyber-Physical Systems (CPS), there is increasing demand for wireless sensing nodes capable of long-range communication, localization, and sensing while operating with limited power. Millimeter-wave (mmWave) technologies provide large bandwidth supporting high data rates and improved sensing performance; however, maintaining reliable operation over long distances remains challenging for compact, low-power devices. Conventional low-frequency Radio-Frequency Identification (RFID) systems cannot simultaneously provide long-range operation, high data throughput, and compact size. While mmWave backscatter platforms offer higher bandwidth and sensing capabilities, maintaining reliable operation from small devices across orientations remains difficult. Many existing solutions rely on bulky dielectric lenses, large phased arrays, or active transmitters, increasing complexity, cost, and power consumption. As a result, compact antenna and lens architectures are needed for reliable long-range operation while preserving ultra-low-power operation. This dissertation addresses these challenges through the development of broadbeam ultra-low-power mmWave identification (mmID) platforms enabling long-range detection, localization, communication, and energy harvesting. The proposed systems investigate antenna and lens architectures, including dielectric lens-enabled mmID platforms, harmonic backscatter systems, reconfigurable metasurface lenses, planar metalens-based devices, and scalable mmWave energy harvesting modules. These architectures improve signal visibility, maintain wide coverage, and enable sensing and communication while preserving compact size. Experimental prototypes were developed and characterized to validate the proposed systems, demonstrating ultra-long-range mmWave detection, wide angular coverage, multi-gigabit backscatter communication, and scalable mmWave energy harvesting, establishing practical design approaches for ultra-low-power mmWave sensing and communication platforms for next-generation IoT infrastructure and wireless sensing networks.