This paper presents a radio frequency identification (RFID) augmented module for smart environmental sensing (RAMSES), which is a fully passive device with sensing and computation capabilities conceived to explore novel and unconventional RFID applications. RAMSES implements an RF energy-harvesting circuit enhanced by a dc-dc voltage booster in silicon-on-insulator technology, an ultralow-power microcontroller, temperature, light, and acceleration sensors, and a new-generation I²C-RFID chip to wirelessly deliver sensor data to standard RFID EPCglobal Class-1 Generation-2 readers. A preliminary RAMSES prototype, fabricated on a printed circuit board using low-cost off-the-shelf discrete components, has been extensively tested through experiments conducted both in lab and real-world application scenarios. The achieved results have demonstrated the ability of RAMSES to harvest the RF energy emitted by an interrogator placed up to 10 m of distance and autonomously perform sensing, computation, and data communication. To our knowledge, this is the longest range ever reported for fully passive RFID sensors. Furthermore, for applications requiring larger operating distances, RAMSES provides also a battery-assisted passive mode yielding up to 22-m communication range.

This paper presents the design, realization, and experimental validation of a battery-assisted radio frequency identification (RFID) tag with sensing and computing capabilities conceived to explore heterogeneous RFID-based sensor network applications. The tag (hereafter called mote) features an ultra-low-power ferroelectric random-access-memory microcontroller, a LED, temperature and light sensors, three-axis accelerometer, non-volatile storage, and a new-generation I²C-RFID chip for communication with standard UHF EPCglobal Class-1 Generation-2 readers. A preliminary RFID mote prototype, fabricated on a printed circuit board using low-cost discrete components and equipped with a small 225-mAh coin battery, provides an estimated lifetime of 3 years when sensing and computing tasks are performed every 30 s. In addition, the reliable RFID communication range up to 22 m achieved in an indoor scenario represents, to the best of our knowledge, the longest distance ever reported for similar sensor-enhanced RFID tags.

The recent advent of general-purpose graphics-processing units (GPGPUs) as inexpensive arithmetic-processing units brings a relevant amount of computing power to modern desktop PCs. This thus providing an interesting pathway to the acceleration of several numerical electromagnetic methods. In this paper, we explain how to exploit GPGPU features by examining how the computational time of the Finite-Difference Time-Domain Method can be reduced. The attainable efficiency is demonstrated by providing numerical results achieved on a two-dimensional study of a human-antenna interaction problem.

An RF-DC converter enhanced by a DC-DC voltage booster in silicon-on-insulator technology for UHF radio frequency identification (RFID) energy harvesting is presented in this letter. When the received RF power level is -14 dBm or higher, the system, fabricated on an FR4 substrate using off-the-shelf low-cost discrete components and connected to a flexible dipole antenna, is able to produce 2.4 V DC voltage to power general-purpose electronic devices. As a simple proof of concept, a device comprising microcontroller, temperature sensor, and EEPROM is considered in this work. The experimental results demonstrate the capability of the system to autonomously perform temperature data logging up to a distance of 5 m from a conventional UHF RFID reader used as an RF energy source.

The rigorous characterization of ultrahigh-frequency passive radio-frequency identification (RFID) tags is a challenging but mandatory task. Indeed, tags are the most critical devices in RFID systems: their performance should be adequately good, although stringent requirements in terms of compactness, used materials, and costs must be satisfied. Factors such as the goodness of the conjugate impedance matching between the chip and the antenna, the chip sensitivity, and the quality of the backscattered signal affect tag performance. Tag sensitivity and differential radar cross section (RCS) are the most significant metrics for tag characterization: they define the forward (from the reader to the tag) and the backward (from the tag to the reader) link reliability, respectively. Nevertheless, measurement of such metrics cannot be approached with conventional methods based on vector network analyzers or conventional RFID readers. Vice versa, commercially available instrumentation and solutions are very expensive and not totally flexible. In this paper, a novel approach for performance characterization of RFID tags is explored. To this end, we developed a very cheap (below $1000) and flexible tool based on software-defined radio, which enables measurement of tag sensitivity and differential RCS. An exhaustive experimental campaign has been carried out on ten commercial and four built-in laboratory RFID tags. Achieved results demonstrate the flexibility, accuracy, and appropriateness of the proposed approach.