RF Systems Design for Simultaneous Wireless Information and Power Transfer (SWIPT) in Automation and Transportation

This work presents some recent solutions that exploit the wireless power transfer (WPT) technology for energizing moving vehicles and machinery tools. Such technology is currently experiencing unprecedented interests in non-traditional RF/microwave sectors fields, such the industrial automation and the railway transportation safety. Near-field electromagnetic coupling solutions are presented showing that, in order to obtain efficient performances for broad ranges of operating conditions, the nonlinear electromagnetic co-design of the entire WPT system, from the energy source to the receiver load, needs to be carried out. This technology can be combined with wireless data transfer, thus realizing integrated systems able to simultaneously control the energy transfer and the transmission of data. The adopted operating frequencies are in the MHz range, which is only recently considered for this kind of applications. In particular this work focuses on three different systems: the first one demonstrates the constant powering of “on the move” industrial charts at 6.78 MHz, regardless of the relative position of the transmitter and the receiver sub-systems; the second one presents a novel design of a balise transportation system adopting a high efficiency GaN-based transmitter designed to keep its performance over a wide range of loading conditions; the last one consists of the simultaneous wireless power and data transfer, to a rotating machinery tool, automatically controlled by the powering system based on the coexistence of frequency-diverse inductive and capacitive couplings

THz rectennas and their design rules

The increasing demand for more efficient energy harvesting solutions has urged research for better harvesting solutions than the presently-available ones. While p-n junction solar cells have become commercially widespread, they are expensive and suffer from poor efficiency figures hardly reaching 20%. Other radiation-electricity converters such as rectennas have a theoretical limit in excess of 80%. However, no efficient rectenna solution for the terahertz frequency band has been commercialized or presented in the academic literature. In fact, there are many obstructions to an efficient solution. The aim of this paper is to address the key points towards an efficient and commercially-available solution by briefly reviewing the relevant literature and so identifying five factors that should be addressed in order to reach an efficient solution

TIME-BASED ARRAYS FOR PRECISE TAGS LOCALIZATION

The paper describes a time-modulated compact antenna array suitable for future 5G IoT applications. Each antenna is selectively activated in order to localize tagged objects, randomly distributed in harsh electromagnetic environments, in almost real-time. The system positively exploits a well-known property of the time-modulation technique: the simultaneous radiation at both the carrier frequency and the sideband harmonics created by the superposition of the nonlinear switches driving (or modulation) frequency. Despite their architectural simplicity, these arrays are potential candidate for modern wireless applications because of their ease of reconfiguration. This paper shows some results of a two-element array for localization purposes

Wireless Power Transfer Using Smart Antenna Techniques

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Optimization of a 27 MHz Wireless Power Transmitter for Unknown Receiver

This work describes the design of a WPT transmitter connected to a planar coil, designed by EM simulation, for the near-field wireless power transfer (WPT) of 25 W at 27 MHz to an almost unknown receiving section. A class-E inverter in GaN technology has been adopted to achieve constant current condition and high performance for its load-independent operation. A careful control of the overall efficiency of the WPT systems is provided during the different steps of the optimization process. The manuscript highlights the importance of the realistic description of both the amplifier and the loop for the sake of the project reliability

Efficient Simulation Method for Wireless Power Transfer

With the development of the internet of things, it becomes necessary to wirelessly power distributed sensors. However, it is not straightforward to accurately estimate the available wireless power at certain points in a specific propagation scenario using traditional methods. This is due to the compro- mised accuracy for large problems and the long time required to run their simulation. In this paper, we present a novel model to accurately calculate the received power by distributed RF sensors using the wave integral equation solver and a developed calculation method using reciprocity theorem. The model is tested in a prototype to simulate a propagation scenario in harsh electromagnetic environments with a reverberation-like behaviour. The propagation scenario consists of a transmitter placed ahead of the prototype aperture and a receiver is moved inside the prototype and the obtained results are compared from both simulation and measurement to rigorously investigate their accuracy and model performance. Based on comparison with measurements and benchmarking with the time domain results, the proposed model is superior for both time and accuracy as it is 20 times faster and gives closer results to measurements than its time domain counterpart

Millimeter Wave Agile Transmitter for IoT Operations

Wireless Power Transfer (WPT) technology has been gathering a large interest in the last decade due to its increasing efficiency. Starting from low-frequency systems via magnetic coupling, the trend has been evolving toward high- frequency solutions, with a particular attention to the emerging 5G wireless communication equipment for the internet of things (IoT). In this respect, WPT has to face new challenges to become competitive at frequencies that will be of utmost importance in the near future, like the 28 GHz band. In this paper, we offer a rigorous combined electromagnetic/nonlinear circuit approach to evaluate the performance of a novel WPT system combining state-of-the-art time-modulated array (TMA) technology and high-performance metal-insulator-metal (MIM) diodes with fast switching time. Merging the advantages of TMAs with MIMs gives rise to a new family of low-power WPT devices, able to efficiently supply energy to the electronics used in IoT networks

RF-powered low-energy sensor nodes for predictive maintenance in electromagnetically harsh industrial environments

This work describes the design, implementation, and validation of a wireless sensor network for predictive maintenance and remote monitoring in metal-rich, electromagnetically harsh environments. Energy is provided wirelessly at 2.45 GHz employing a system of three co-located active antennas designed with a conformal shape such that it can power, on-demand, sensor nodes located in non-line-of-sight (NLOS) and difficult-to-reach positions. This allows for eliminating the periodic battery replacement of the customized sensor nodes, which are designed to be compact, low-power, and robust. A measurement campaign has been conducted in a real scenario, i.e., the engine compartment of a car, assuming the exploitation of the system in the automotive field. Our work demonstrates that a one radio-frequency (RF) source (illuminator) with a maximum effective isotropic radiated power (EIRP) of 27 dBm is capable of transferring the energy of 4.8 mJ required to fully charge the sensor node in less than 170 s, in the worst case of 112-cm distance between illuminator and node (NLOS). We also show how, in the worst case, the transferred power allows the node to operate every 60 s, where operation includes sampling accelerometer data for 1 s, extracting statistical information, transmitting a 20-byte payload, and receiving a 3-byte acknowledgment using the extremely robust Long Range (LoRa) communication technology. The energy requirement for an active cycle is between 1.45 and 1.65 mJ, while sleep mode current consumption is less than 150 nA, allowing for achieving the targeted battery-free operation with duty cycles as high as 1.7%.ISSN:1424-822