Effectiveness of electromagnetic wave absorbers to improve 5.8 GHz DSRC EM environment inside tunnel

Electromagnetic (EM) wave absorbers have been used to improve the EM environment of an electronic toll collection (ETC) system on an express highway or a wireless local area network (LAN) system in an indoor environment. In this paper, an efficient multi-ray propagation model, which uses a combination of image technique and grid approach to trace multiple signal rays from transmitter to receiver, is employed to analyze the EM environment of a dedicated short-range communication (DSRC) system inside tunnel. The validity of the model employed is discussed by the comparison with the results obtained by an experiment inside tunnel.