RFID on the road—some considerations about passive tag antennas

This paper presents an investigation of tag antenna performance in the scenario of a passive RFID tag placed on an asphalt road and inquired by readers in vehicles. Three types of antennas were chosen and their properties were studied for various dielectric properties of the asphalt paving. Water on the pavement (e.g. due to rainfall) was also taken into account, with various layer thicknesses. Based on the results of numerical experiments performed using the finite-difference time-domain (FDTD) method we demonstrate how the communication range between the tag and a reader varies depending on the materials surrounding the tag and wave polarization.