1,721,064 research outputs found
On the possibility of sensing an early stage fire in moving vehicles by microwave radiometry
No full textThis paper deals with passive remote sensing of fire spots in moving vehicles by a ground-based microwave radiometer mounted near a rail or a road. Images have been simulated at 30 GHz, identifying also dielectric properties of the vehicle wall able to guarantee a penetration of the microwave radiation. The 30-GHz operative frequency can be considered a trade-off between the antenna system dimensions and the penetration capability of microwave radiation through a dielectric wall. It has been seen that the radiation associated to the fire spot emerges distinctly through a dielectric wall in several cases, depending also on fire dimensions, loss tangent values of the wall, and its thickness. This study confirms that the detection of an early stage fire through a dielectric wall by microwave radiometry is promising, taking into account that the use of infrared sensor systems mainly depends on emissivity knowledge of the vehicle surface and on the heating of the monitored external wal
Theory of Zero-Power RFID Sensors Based on Harmonic Generation and Orthogonally Polarized Antennas
No full textIn this paper a novel approach is proposed to solve the issue of the absolute accuracy required by the most of passive chip-less RFID sensors. To this purpose the sensor information is encoded as the phase difference between two signals, one of the two acting as the reference signal for the other one. First the tag receives a carrier at frequency f0, then two equal signals at frequency 2 f0 are generated by means of a diode-based frequency doubler and a power divider. At this point one of the two signals is phase-shifted using a passive sensing element. Finally the 2 f0 signals are re-irradiated by exploiting two orthogonally polarized antennas. With this approach the sensor information can be extracted by a suitable reader equipped with two complex (I/Q) receivers. The idea will be first developed from a theoretical basis and then verified with several particular cases. The novel tag concept is compatible with paper substrate and ink-jet printing technology since antennas diodes and passive sensing elements, i.e. all the main tag components, are going to be developed on paper materials
Sistema di codifica, decodifica e ricetrasmissione senza fili di dati sensoriali
No full textLa presente invenzione si riferisce a un sistema di ricetrasmissione dati senza fili il cui compito è quello di trasmettere dati a breve distanza
Automatic Design and 3D Electromagnetic Simulation of Sub-nH Spiral Inductors
No full textThe design of modern radiofrequency integrated circuits on silicon operating at millimeter-waves typically requires the integration of several spiral inductors. At such high frequencies, a typical design requires inductors with sub-nH values, which are traditionally not available in the design-kits of the technology processes. In this work, we present a tool based on VbScripts that automatically executes three-dimensional layout editing and electromagnetic simulating commands. In detail, it draws the inductor masks for the specific microelectronic process, including vias and underpasses, in less than one minute, and then performs the electromagnetic simulations. The outputs are the exportable DRC-errors free layout (GDS-II format) and the 2π-model parameters to be included in the schematic editor. This tool allows significant design automation compatible with traditional commercial CAD tools
A Novel Sample-and-Hold-Based Time-to-Digital Converter Architecture
No full textIn this paper, the design of a Time-to-Digital Converter (TDC) for measuring the Time of Flight (ToF) of a radio pulse is described. The novel idea is based on the adoption of a charge-pump time-to-voltage transducer followed by a Sample-and-Hold amplifier (SHA) and by a second-order discrete-time incremental delta-sigma converter to perform a single-shot conversion. The TDC architecture is capable of achieving a range of 220 ns, a time resolution of about 200 ps (with a 10-bit incremental delta-sigma converter) and robustness with respect to temperature variations. The design has been successfully verified through simulations both at system and transistor levels using a 0.25um complimentary metal-oxide-semiconductor (CMOS) technology with a -2.5 to +4V power supply
CubeSats for Future Science and Internet of Space: Challenges and Opportunities
No full texthis paper proposes, a review of the main challenges involved by the CubeSat revolution. These concern, mainly, electronic systems and circuits because extreme miniaturization, low-cost and space-grade reliability are posing new problems. In particular the focus will be on the high-frequency hardware that is used to perform science, remote sensing, telemetry and telecommunications. Equipped with these miniaturized, RF/microwave apparatuses CubeSats will perform unprecedented scientific missions opening the way to novel applications such as the high resolution imaging of the Earth and the Internet of Space (IoS)
Design of an UHF RFID antenna on flexible substrate magnetically coupled to the tag
No full textUHF RFID antennas that are magnetically coupled to the tag by using a transformer are designed and fabricated on flexible materials. The primary and secondary windings of the transformer are implemented on the antenna substrate and in the chip, respectively. In this way, galvanic contacts between the antenna and the tag are not required and the tag can be assembled on the antenna substrate by means of a mere placing and gluing process: the wire-bonding and the soldering processes are avoided reducing the production costs. Another important feature is the use of a flexible substrate. These features make this antenna attractive to the market of RFID and other applications, where the flexibility and the placing tolerances are mandatory. The design process of a bow-tie antenna with transformer, based on flexible substrate and operating in the UHF frequency band, is described step by step and validated by means of accurate full-wave simulations
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