The electronic toll collection (ETC) and the dedicated short range communication (DSRC) in intelligent transport systems (ITS) are realized. To improve electromagnetic environment of ITS beacon antenna, a wave absorbing pavement material consists of a carbon fiber has been developed. However, the oblique incidence characteristic of the pavement material that has been developed for the ETC is not enough to use for ETC and DSRC. Therefore, this research group is developing the wave absorbing pavement that mixed with DSM (Daido Special Recycling Process for Dust and Slag Melting) slag into asphalt. On the other hand, there was a base concrete layer under two asphalt layers. To design the wave absorbing pavement, we calculated with consideration of the impedance of the base concrete layer. In this paper, the relative complex permeability and permittivity of the pavement material were measured by the free space methods and the waveguide method. And the impedance of the base concrete layer was measured by the free space method. Then, the wave absorbing pavement of the oblique incidence characteristic was designed using the obtained material constants.
