Simple Molecular Absorption Loss Model for 200—450 Gigahertz Frequency Band

This paper derives a simplified polynomial molecular absorption loss model for 200—450 GHz band. This band has a high potential for near future short range, high data rate applications due to large spectral resources and reasonable path loss. The frequencies around 300 GHz are among the first ones where the molecular absorption loss becomes a significant factor. This loss increases exponentially with the distance and is not a major issue at short distances (few meters), but entirely blocks signals over large distances. Modeling of the molecular absorption loss is relatively straightforward, but requires large numbers of parameters from spectroscopic databases. This paper derives a simplified polynomial absorption loss model for the major absorption lines. This extends and gives more accurate absorption loss values in comparison to the existing ITU-R absorption loss models. The simplified polynomial expressions by ITU-R are mostly limited to about 350 GHz frequency, although being rather accurate up to about 400 GHz. This paper gives a simpler and more accurate absorption loss model to those bands. A part of the considered band, 275—450 GHz band, is subject to World Radiocommunication Conference 2019 (WRC-19) for allocation and operational characterization for the future communication applications.