Contents 1. Introduction
Communications in tunnels are being underdevelopment in order to ensure a radio link between a mobile and a base station. Now more attentions have been paid on millimeter wave for its wide bandwidth. The paper mainly discusses the characteristics of millimeter wave propagation at a frequency of 38GHz, organized as follows. Section 2 describes the environment of measurement. In section 3, the approach of calculating electromagnetic field based on ray-tracing method is stated. Section 4 attempts to validate ray tracing modal by comparing simulated results with experimental data. Results for attenuation versus frequency both in straight and curved tunnels are presented, and the variation of path loss versus tunnels radius is also discussed. Finally, some conclusions are drawn in Section 5.
