Impact of Sharp Corner Geometries in Tunnels on the Performance of Wireless Digital Links: a Study Using a Scaled-Down Model

This study investigates the impact of tunnel structure and its geometry on radio wave propagation in multipath environments, revealing critical influences on digital communication performance. In elongated, narrow tunnels, links can be sustained over tens of meters; however, introduction of corners along the tunnel leads to significant performance degradation, with increased interference as a result of specific polarization and higher symbol rate transmission. Notably, in tall and narrow tunnels, vertical polarization enhances performance. It is shown that a truncated corner demonstrates up to three times better error vector magnitude (EVM) performance compared to a right-angled corner. These findings underscore the importance of considering tunnel geometry in the design and optimization of robust indoor communication systems.