Ionosphere

Electrical engineering

Physics

Channel (broadcasting)

Aerospace engineering

Radio channel

High frequency

Wireless

Transponder (aeronautics)

Astronomy

Engineering

Radio-frequency identification

Antenna (radio)

Electronic engineering

Computer science

Backscatter (email)

Computer security

Radio frequency

Telecommunications

Link budget

Ultra high frequency

IEEE Antennas and Propagation Magazine

Backscatter radio - wireless communication by modulating signals scattered from a transponder (RF tag) - is fundamentally different from conventional radio because it involves two distinct links: the power-up link for powering passive RF tags, and the backscatter link for describing backscatter communication. Because of severe power constraints on the RF tag, a thorough knowledge of the backscatter channel is necessary to maximize backscatter-radio and radio-frequency identification (RFID) system performance. This article presents four link budgets that account for the major propagation mechanisms of the backscatter channel, along with a detailed discussion of each. Use of the link budgets is demonstrated by a practical UHF RFID portal example. The benefits of future 5.8 GHz multi-antenna backscatter-radio systems are shown. An intuitive analogy for understanding the antenna polarization of RF tag systems is presented.

Complete Link Budgets for Backscatter-Radio and RFID Systems