Software-Controlled Polarization for Longer-Range RFID Reading and Localization

The majority of existing RFID readers rely on circu-larly polarized or switched polarization antennas for powering and communicating with tags. In this paper, we argue that a new form of software-controlled polarization brings important benefits to the tasks of powering, communicating with, and localizing RFID tags. Using only two linearly polarized antennas, we demonstrate how one could generate an arbitrarily linear po-larization in the same plane relying entirely on software control. We incorporate this approach into a protocol that automatically discovers RFID orientations in the environment and show how this approach increases the range (or alternatively reduces the transmit power) of RFID readers. We also demonstrate this approach in an end-to-end RFID localization application.