Agilent Measurement Journal - Issue 4 - 2008 - (Page 14)

Principle of operation for RFID tags Reader with transmitting antenna Passive or active RFID tag on object to identify Absorbed energy to reader R↔T reflected energy with “data found” info R↔T with data and power for tag Switch Transmission to ground RC circuit to ground Short Figure 1. Diagram of RFID operation Examining the challenges of RFID testing The three main elements of an RFID system are an antenna, a transponder (the tag) and a transceiver (the reader). When a passive transponder receives an RF read signal, a small portion of that signal activates the tag. The tag then reacts according to the absorption parameters of its design, reﬂecting its data to the reader through backscattering (Figure 1). These systems use simple modulation and coding/decoding algorithms that are often spectrally inefﬁcient. As a result, any given transmission rate needs a wide enough RF bandwidth to allow the transmitted data to be delivered within a serial information stream. This further complicates the coding and decoding processes. Tag design affects the efﬁciency of the data transfer. This is due mainly to low-precision timing sources onboard the tag. Another factor is the need for transmit power strong enough to activate the tag under anticollision protocols and allow reading of all tags within range of the reader. This combination of factors presents many measurement challenges, particularly in the analysis of transient signals, bandwidth-inefﬁcient modulation schemes and backscattered data. The backscattered data, for example, is usually at the same frequency as the absorbed energy from the reader but its amplitude is much smaller and therefore difﬁcult to measure accurately. Performance considerations include tag-reading speed, a tag’s ability to operate in a dense reader environment, and the distance between tag and reader. To meet these needs, a variety of instruments are needed to address these challenges, especially in R&D and manufacturing environments for the reader: oscilloscopes, logic analyzers, power meters and advanced spectrum or signal analyzers. 14 Agilent Measurement Journal

Table of Contents Feed for the Digital Edition of Agilent Measurement Journal - Issue 4 - 2008

Agilent Measurement Journal - Issue 4 - 2008 Delivering Confidence through Compliance with Standards Contents Emerging Innovations Trying Early Device Implementations at the IEEE 1588 PlugFest Achieving Greater Confidence in Measurement Accuracy through Consistency in Calibration Services Overcoming the Challenges of RFID Component Testing 3GPP LTE: Introducing Single- Carrier FDMA Ensuring Reliable Operation and Performance in Converged IP Networks Testing Storage Area Networks and Devices at 8.5-Gb/s Fibre Channel Rates Choosing an Appropriate Calibration Method for Vector Network Analysis Making Traceable EVM Measurements with Digital Oscilloscopes Exploring Terahertz Measurement, Imaging and Spectroscopy: The Electromagnetic Spectrum’s Final Frontier Interpreting Quoted Specifications when Selecting Digitizers

Agilent Measurement Journal - Issue 4 - 2008

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