Radar cross-section analysis for passive RFID systems

The authors analyse radar cross-section (RCS) for operational optimisation of radio frequency identification (RFID) systems. The research work is based on both theoretical analysis and scattering pattern measurements over tag antennas with four different loads. Furthermore, the influence of the tags´ antenna ground plane size to their performance is analysed. Theoretically, short circuited tags scatter all the incoming field to their environment, while a perfectly matched antenna does not scatter at all. Furthermore, the antenna shape has a significant role in the total scattered RCS, while antenna mode RCS is under 1 m² for both measured antennas. In addition, as the dimension of the antenna´s ground plane is increased, the maximum identification range with reliable identification is not increased; instead, only the maximum achievable identification range increases. The results presented are useful when optimising tag performance, and further identification range.