Radio-Frequency Identification Zones in Open Environments

In this article, we consider the problem of determining the backscattered signal reading zone of a high-speed tag in an open environment as a function of system geometry and radiation features. A two-dimensional (2-D) parametric model using the Friis equation in a two-ray approximation is obtained. The model is applied to the problem of optimizing the reading time of the moving tag as a function of all system parameters. In particular, we consider the reading zone optimization as a function of all of a structure's position angles and relative distances. We find optimal positioning angles and apply a statistical model for predicting the reading failure probability as a function of electromagnetic parameters in addition to speed and reading rates. Measurements taken in an open environment over paved ground confirm the model predictions. © 1990-2011 IEEE.