Making a Low-Cost Software-Defined UHF RFID Reader

In this article, we discuss how one can make, with modern and low-cost tools, a software-defined ultra high-frequency (UHF) RF identification (RFID) reader. Since we have chosen to leave the discussion of the top-level reader implementation until the very end, an introductory outline is warranted to help guide our audience. We first provide the uninitiated with some background context by answering four questions: What is UHF RFID? How does it work? What happened with UHF RFID? And, finally, what's next? That is, how do we envision the technology evolving in the future with the support of a broad community? Second, we describe the fundamental metrics and performance budgeting of RFID readers. Following this, we provide an overview on how to design, make, and automatically tune two critical components of UHF RFID readers: the antenna and transmit leakage canceller. Third, we delve even further into details of the transmit leakage canceller. Finally, we describe the complete high-level architecture of a proposed low-cost reader.