1,720,982 research outputs found
A Simple Nondestructive Radio Frequency Measurement Technique for the Analysis of Liquids
No full textAbstract—Dielectric resonators (DRs) are widely used in microwave and millimeter-wave applications, including antennas and bandpass filters. In this study, we exploit the properties of these resonators in a different way, demonstrating how a common container filled with liquid can be assimilated to a DR. The typical properties of DRs are used to investigate the physical and chemical properties of the content and their evolution, providing a contactless, noninvasive, and nondestructive evaluation (NDE)
of its characteristics. The level of the liquid, its conductivity, and dielectric constant can be easily determined in real time, and used as parameters for in-line monitoring, quality control, and chemical composition assessment. Results are reported using a common wine bottle as a container, but are very easily transferable to other types of liquid containers, including plastic
bottles or larger containers
Integration of Modulated Scattering Technique (MST) tags with IoT devices
No full textInternet of things (IoT) has transformed numerous fields while providing better connectivity. In such scenario, the integration of various IoT devices have to be satisfied. The downside of commuting between cross platform IoT devices are difficult to achieve, because low power high range communication front end is mandatory. This paper proposes to utilize the Modulated Scattering Technique (MST) to integrate with IoT devices and to achieve the radio frequency communication capabilities. An MST system works similarly to an RFID, is highly miniaturized and exhibits good performances at microwave frequency bands without the necessity of radio frequency front-end. MST communication systems provide an high operative range with respect to standard RFID systems, and a very low consumption with respect to standard wireless radio frequency front ends, such as WiFi modules. This work proposes the integration of MST communication paradigms with an IoT system, in particular a prototype of air quality IoT sensor is presented and assessed
Ultra-Wideband Antenna Array based on Orbital Angular Momentum
No full textIn this work, an antenna array able to generate orbital angular momentum (OAM) electromagnetic waves with ultra-wideband (UWB) characteristics is proposed. In particular the proposed array antenna is based on cavity back UWB antennas. In particular each array element is backed with a surface impedance waveguide SIW to improve the performances and reduce the single element dimensions. The array elements are a circularly arranged and the correct phase shift, mandatory to obtain a suitable OAM wave, have been obtained with reconfigurable reflection type phase shifters based on two quadrature hybrids and commercial pin diodes. The phase shifters are driven by mean of a suitable micro-controller. A proof of concept prototype has been designed fabricated and experimentally assessed. The obtained results were quite promising
Optimizing the number of printed layers in a PET inkjet-printed chipless RFID sensor
No full textThis paper presents a preliminary optimization study of the performance of conductive resonators inkjet-printed on polyethylene terephthalate (PET) with an increasing number of printed layers in a range 1-20 layers. Samples were tested and the amplitude of the frequency response was demonstrated to follow a power function with the increasing number of layers. Results indicate that with only 2 printed layers the signal intensity approaches 70% of the maximum intensity obtained with the highest number of layers (20), and that with 5 printed layers the signal reaches 83%. This demonstrates that only few deposited layers can be considered a good compromise for the production of Radio-Frequency IDentification (RFID) resonators by inkjet-printing on PET. Finally, the selected sample was tested as a chipless humidity sensor in a configuration with a 150μm-thick Nafion 117 sensitive material
A COMPACT ULTRA-WIDE BAND PRINTED LOG-PERIODIC ANTENNA USING A BOW-TIE STRUCTURE
Full text linkIn this letter, an ultra-wideband compact printed log periodic dipole (LPD) array antenna is designed to operate between 500MHz and 6 GHz frequencies. The proposed LPD antenna structure consists of one bow-tie dipole and 15 regular dipole elements. The bow-tie element is introduced to improve the antenna's performance at the lowest frequencies below 1 GHz and at the same time to reduce the antenna size maintaining a good performance. An experimental antenna prototype has been designed, optimized, fabricated, numerically and experimentally assessed. The obtained results are very promising, and they demonstrated that the presented antenna prototype is able to operate in the range between 500MHz and 6 GHz with an average gain of 6 dBi and a very compact size
A Simple Frequency Domain-Based Chipless Radio Frequency Identifier (RFID) System
No full textThis paper proposes a chip-less RFID tag based on microstrip resonators that works in the microwave frequency bands. The chip-less tag proposed is low-cost, easy to fabricate, and can be read wirelessly at long distances. Two tag prototypes, one with a single and the other with multiple resonators, have been designed, fabricated, and experimentally assessed. In particular, microstrip square resonators slotted in the center and loaded with capacitive structures have been considered. Moreover, to improve the sensibility and the operative range and to avoid alignment problems, the tags have been mounted on the focus of a linear 2D parabolic mirror. The obtained results are quite satisfactory in terms of operative range, sensibility, and accuracy. The preliminary experimental assessment shows that the proposed chip-less configuration can be easily adapted to different application scenarios to improve the passive signal and wireless reading capability
A Preliminary Microwave Frequency Characterization of a Nafion-Based Chipless Sensor for Humidity Monitoring
No full textA low-profile humidity sensor based on a frequency-domain chipless sensing technology is proposed in this study. The chipless microwave sensor is composed by a microstrip resonator gap-coupled with a 50Ω microstrip transmission line and loaded with a Nafion 117 sensitive material layer. The response of the sensor at fixed temperature (25°C) and for a relative humidity (RH) variation in the range 0% - 90% has been simulated and tested in experimental conditions. The preliminary results are promising and pave the way for a future in-depth characterization of the sensor and an analysis of the performance under real-world conditions
Nafion-Based Chipless RFID Humidity Sensor for Smart Tag Applications
No full textA humidity sensor based on frequency-domain microwave chipless technology is studied and experimentally characterized in this paper.
The chipless microwave sensor is composed of a microwave resonator coupled with a 50 Ohm microstrip transmission line, covered with a 180 μm-thick Nafion layer, which acts as sensitive material. The response of the sensor at 25 °C and for a relative humidity (RH) variation in the range of 0–40% has been experimentally assessed. The sensor shows good sensitivity both in terms of frequency and intensity variations and good linearity. The sensor follows the RH variations in a fully reversible way and the response time is estimated in a few seconds
Multiparameter chipless RFID sensor tag for humidity and NO2 determination
No full textThis paper reports a chipless RFID sensor tag to be used for the simultaneous determination of both humidity and NO2 concentration in the environment. The tag is based on the use of functionalized ELC resonators with two different sensitive materials. The detection strategy allows for a wireless determination of both environmental parameters because the resonators work at different frequencies and react differently to the selected environmental parameters
Tailoring the Performance of a Nafion 117 Humidity Chipless RFID Sensor: The Choice of the Substrate
No full textChipless radio-frequency identification (RFID) sensors are not yet widespread in practical applications because of their limited sensitivity and selectivity when compared to more mature sensing technologies. The search for a suitable material to perform the sensing function has often been focused on the most common materials used in electrochemical sensing approaches, but little work has been done to directly relate the performances of chipless or microwave sensors to the characteristics of the materials used to fabricate them. In this work we are simulating the impact of the substrate material on the performances of a chipless RFID sensor for humidity detection. The dielectric parameters of the substrate material turn out to be very important to maximize the sensor performances, in relation to the operative range of the sensor (based on the desired application) and to the effective dielectric properties of the sensitive material used, we verify the simulated results with measurements of real chipless humidity cells with Nafion 117 sensitive material. We show which types of substrate are preferable for low-humidity detection and which substrates’ features are instead fundamental to operate in a wider humidity range
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