Radar Cross-Section Analysis of Backscattering RFID Tags

Improving Backscatter Radio Tag Efficiency

“…Denote complex that corresponds to load and RCS with and the unknown . (reactive load) with m [10]. The result of the above calculation provides an exact value of .…”

“…This work studies what is needed to be maximized (or minimized) for efficient tag-to-reader communication, employing detection theory and no Thevenin modeling (and thus, applies to any tag antenna, including minimum scattering antennas as a special case); is a valid representation of the backscattered power from tag to reader, only for minimum scattering antennas and not for the general tag antenna case: from Thevenin-produced equations (6) and (7), it can be seen that for open circuit load , the backscattered power from the tag is zero (9) justifying the characterization minimum scattering antenna. On the contrary, from (3), which applies to the general tag antenna case, it can be seen that RCS (and consecutively backscattered power from the tag to the reader) for the open circuit load is not zero (10) The latter produces a zero power backscattered signal only for . The antenna structural mode need not be unity, as shown in [10], where semipassive tags were studied, while was estimated using graphical methods.…”

“…On the contrary, from (3), which applies to the general tag antenna case, it can be seen that RCS (and consecutively backscattered power from the tag to the reader) for the open circuit load is not zero (10) The latter produces a zero power backscattered signal only for . The antenna structural mode need not be unity, as shown in [10], where semipassive tags were studied, while was estimated using graphical methods. In this study, we provide closed-form calculation, while we study both passive, as well as semipassive, tags within more generalized context; our approach provides tag load selection constraints and rules without restricting discussion to specific tag/reader circuitry or minimum scattering antennas [11].…”

Design of Space-Filling Antennas for Passive UHF RFID Tags

“…Because of the growing use of RFID systems, many different areas of research have also been developed to improve the performance of such systems. A few of these areas of research include novel antenna designs (Rao et at., 2005;Calabrese & Marrocco, 2008;Amin et al 2009), analysis on the backscatter properties of RFID tags (Yen et al, 2007;Feng et al, 2006), mutual coupling between RFID tags (Li et al, 2008;Owen et al, 2009) and the deployment of RFID systems to complex and extreme environments (Qing & Chen, 2007;Sanford, 2008). There are many aspects to each area of research in RFID.…”

Backscatter Communication for Wireless-Powered Communication Networks

“…where   represents a complex-valued term related to the antenna structural mode [8], [9], frequency and random initial phase are   and   ∈ for bits ∈ [7]. Thus,    represents the fundamental frequency component of a 50% duty cycle waveform of amplitude 1.…”