In this paper, we describe an equivalent circuit approach to analyze one of the most common UHF RFID tag antennas, a T-matched dipole. We derive analytically closed-form expressions for all three tag resonant frequencies (two for tag sensitivity and one for backscatter). We show using a practical tag example, a 70 mm x 14 mm antenna designed for various items, how an equivalent circuit model can be extracted and effectively used for understanding tag behavior and optimizing its performance. We also present experimental data that demonstrates good agreement with the model.

In this paper, we analyze UHF (RAIN) RFID tags with open dipole antennas using an equivalent circuit approach. We derive original closed form expressions for tag threshold sensitivity and backscatter resonances and mathematically analyze those. We also present a practical 42 mm x 16 mm RFID tag example, including modeling, simulations, equivalent circuit extraction and analysis, and measurements on dielectrics that represent practical use scenarios in real tagging applications.

In this paper, we show how wideband measurement of threshold sensitivity and backscatter curves from generic T-matched RAIN (passive UHF) RFID tags can be used for determining magnetic properties of the tagged items. The method is based on measuring all three tag resonances (two for sensitivity and one for backscatter), calculating from those the natural resonant frequency of the tag antenna loop portion and its frequency shift relative to free space, and then extracting effective magnetic permeability. The method is robust to the presence of non-magnetic materials. Possible applications include item sortation for reuse/recycling and smart package inspection.

In this paper, we discuss UHF (RAIN) RFID tags with open-ended slot type antennas. We show that such tags can be analyzed using the same equivalent circuit that represents T-matched dipole tags. We explore the correspondence between slot type tag antenna geometry and its equivalent circuit parameters. We also present a practical $80\ \text{mm}\times 25\ \text{mm}$ RFID tag example with good agreement between model and measurements.

In this paper, we show how measurement of backscattered signal from commercial off-the-shelf RAIN (passive UHF) RFID tags attached to dielectric materials can be used for reliable measurement of dielectric properties of those materials. The method is robust, in that the tags can be generic and do not need to be specially designed or calibrated. The directly measured quantity is the frequency of backscatter (POTR) peak resonance, from which effective dielectric permittivity can be extracted. We show that it is almost independent of tag type used for measurement. Our approach can differentiate between at least four different types of dielectrics that we used in testing. One possible application of this sensing technique is identification for sorting items in recycling and sustainability use cases, such as plastics.

In this paper, we analyze a reversed T-matching used in UHF RFID tag antennas. We investigate similarities and differences between T-match and reversed T-match using EM simulations and an equivalent circuit approach applied to a generic 70 x 14 mm RFID tag antenna for M700 IC.

In this paper, we analyze one of the most common UHF RFID tag antenna structures, a T-matched dipole. We for the first time derive the closed-form solutions for the resonant frequencies of tag sensitivity and backscatter responses as functions of tag equivalent circuit parameters. We apply our general analysis to a 70 mm x 14 mm T-matched RFID tag with Monza R6 and show a good agreement between the model, the measurements, and the derived formulas.

In this paper, we explain how to design a UHF RFID tag antenna for ARC requirements, which are industry tag certification specifications. We focus on a 50 mm×30 mm tag design that passes specs A through I. We explain how to model tag performance on complicated items that are part of ARC specs (such as jeans), and present modeling and simulation results which are in good agreement with measured data.

This work presents an experimental implementation of a passive Gen2 RFID system operating in 2.4 GHz band. The system re-uses existing off-the shelf RFID hardware: Impinj Speedway reader and Monza R6 IC. We analyze system performance and discuss various aspects of operating passive RFID in 2.4 GHz band.