Distribution of electric field strength around and under a rough surface street is analyzed by measurements and FVTD simulations. This study has been conducted to investigate effects of roughness of streets on electromagnetic waves propagating an underground cavity. For this aim the results obtained by using the following three different conditions have been examined: (1) a surface of street is flat and rough, (2) there is a cavity or no cavity underground, and (3) there is a connection hole or no hole between an aboveground and an underground cavity. These comparisons give the results that roughness of the street surface makes more reflection to the upper part of the street, electromagnetic waves transmit inside an underground cavity easily regardless of whether being flat or rough, and the electric field strength around the points being far from the source point are little changed due to existence of a connection hole.
