Signals and Telecommunication Journal Hsing-Cheng Liu 15 1 2025 https://doi.org/10.6025/stj/2026/15/1/15-28 https://www.dline.info/stj/fulltext/v15n1/stjv15n1_2.pdf This research document comprehensively examines terahertz (THz) communications leveraging orbital angular momentum (OAM) for next generation 6G wireless systems. It establishes that OAM provides an additional spatial multiplexing dimension, thereby enhancing spectral efficiency beyond conventional techniques. However, the analysis reveals fundamental physical constraints limiting practical deployment. Key findings demonstrate that THz propagation is governed by a dual loss mechanism: free space path loss and severe frequency selective molecular absorption particularly from water vapor resonances at 183, 325, and 380 GHz. These absorption peaks create distinct atmospheric transmission windows while rendering other bands unusable beyond short distances. Environmental factors critically impact performance: humidity variations introduce 6+ dB of path loss uncertainty at 500 m, and beam divergence combined with stringent alignment requirements further constrain reliability. The study presents a physics based simulation dataset comprising 270,000 samples across four deployment scenarios (laboratory, indoor, urban, and high mobility environments), characterized by 33 parameters spanning atmospheric conditions, channel physics, hardware impairments, and performance metrics. Results confirm THz OAM systems are inherently range limited (<100-500 m), environment sensitive, and require operation within specific atmospheric windows. Successful implementation demands adaptive strategies: dynamic frequency selection, high gain directional antennas ( 25 dBi), and AI-assisted beam steering. The technology is best suited for specialized short range applications indoor 6G networks, wireless backhaul, and device to device communications where environmental conditions can be controlled or dynamically adapted.