Rigorous Investigation of Interactions between Passive RFID Tags by Means of Nonlinear/Electromagnetic Co-simulation

Abstract

The paper proposes a rigorous approach to the prediction of electromagnetic interaction between tags of an RFID system powered by the incident field radiated by the reader.The design of a 2.45 GHz band passive transponder and its integrated antenna is first developed making use of a numerical optimization based on EM analysis coupled with the harmonic-balance technique. A couple of tags, located at varying mutual positions, is then analysed under digitally modulated RF drive. The results show a significant modification of the electrical and radiation performance of each tag and suggest the need for a multi-tag design procedure to account for these coupling effects.

RFID Grids: Part I—Electromagnetic Theory

“…By applying (1) for both reader and grids' ports and after simple mathematical manipulations the collected signal is conveniently written as (14) The backscattering modulation imposes that the microchip impedance at the th port is switched between two states: and and hence the corresponding received signals will be and . The grid impedance matrix will be accordingly modulated as (15) where is an all-zeroes matrix except for the element:…”

“…Back in the 1970s, it was already shown [12] that the electromagnetic coupling between antennas in transmitting and receiving modes are different and that such a coupling may be mitigated by a proper non-linear loading at the antennas' port. More recently, the coupling mechanism involving non-linear loads has been theoretically addressed in [6] for general purpose applications, while [14] has put into evidence, by means of a combined antenna/non-linear model, the need for a multi-tag design procedure to balance the coupling effects. Rich experimentations have been presented in [15], [16] concerning stacked planes of RFID tag antennas [17].…”

Consolidating the Electromagnetic Education of Graduate Students Through an Integrated Course

“…In microwave circuit design, the nonlinear/electromagnetic co-design approach [17] of both radiating and nonradiating circuits can be useful in a plethora of engineering solutions beyond just telecommunications purposes; these might include energy-aware systems design (radio frequency energy harvesting [18], passive RFID tags [19]) or smart environment management [20].…”

Integration of numerical and field-theoretical techniques in the design of single- and multi-band rectennas for micro-power generation

“…This may be accomplished by extracting the required power from many sources that are present in the environment, such as propagating radio waves, sunlight or vibrations. Devices powered by radio waves have been widely used in passive radio identification (RFID) [1]. In this case, battery-free transceivers (tags) extract the power needed to turn on the active devices from the field radiated by a reader of known position.…”