Evaluating Vegetation Attenuation Characteristics at the 300-GHz Band

Abstract

This study examines the seasonal variation in vegetation loss and the effects of moving foliage on signal propagation at the 300 GHz band. The variation in vegetation loss across seasons aligns well with the ITU-R model when parameters are adjusted for the month exhibiting maximum vegetation loss. During leafless seasons, slow fading is characterized by a frequency component below 0.2 Hz and occurs predominantly due to branch vibrations caused by wind. In environments where foliage consistently obstructs the line of sight between transmitter and receiver (quasi-line-of-sight, QLOS), rapid fading occurs due to foliage movement, with frequency components reaching up to 20 Hz. Both slow and rapid fading patterns in vegetation loss approximate the Nakagami distribution. Conversely, when foliage is sparse and wind causes intermittent shifts between line-of-sight and QLOS conditions, neither the Rician nor Nakagami models adequately represent the experimental data. This discrepancy is primarily due to significant variations in median vegetation loss values depending on whether the propagation path is obstructed by foliage. This study provides new insights into the dynamics of vegetation-induced signal fading at the 300 GHz band and demonstrates that seasonal variations significantly influence propagation characteristics.