Abstract
This paper describes the characteristics of a physical road-vehicle link in the 1 - 10 GHz frequency range. Existing systems which use this technology include automatic toll systems and road guidance systems. We emphasize some intrinsic features as the attenuation in air or due to a conducting layer on the windscreen near the transmitting antenna. Then the multipath and masking effects are studied. The range being an important parameter, the applications are classified in two categories : short range and medium range link. These two kinds of link are successively analyzed, both in ideal condition (no vehicle in the vicinity of the receiving car) and in normal traffic conditions. (A)