Search results for "Ultra high frequency"
showing 10 items of 19 documents
Measurements on partial discharge in on‐site operating power transformer: a case study
2018
This study presents the case study of a substation in-service power transformer referred to the on-site partial discharge (PD) detection and evaluation methods. An original methodology for simultaneous application of three methods is proposed: electrical, acoustic and ultra-high frequency. Transformer is powered by the power grid and no external generator is required according to the proposed methodology. Furthermore, several possibilities of applying these concurrent measurements and benefits of such solution in terms of result interpretation, interference resistance and on-site measurement applicability are indicated. The proposed methodology allows for a fast, accurate and secure PD diag…
Passive RFID Strain-Sensor Based on Meander-Line Antennas
2011
The processing of backscattered signals coming from RFID tags is potentially useful to detect the physical state of the tagged object. It is here shown how to design a completely passive UHF RFID sensor for strain monitoring starting from a flexible meander-line dipole whose shape factor and feed section are engineered to achieve the desired sensing resolution and dynamic range. This class of devices is low-cost, promises sub-millimeter resolution and may found interesting applications in the Structural Health Monitoring of damaged structures and vehicles as well as during extreme and adverse events.
Humidity Sensing by Polymer-Loaded UHF RFID Antennas
2012
Passive ultra high-frequency radio frequency identification tags, besides item labeling, are also able to exploit capability to sense the physical state of the tagged object as well as of the surrounding environment. Here, a new family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT:PSS is used to load a shaped slot, carved into a folded-like patch tag. The communication and sensing capabilities of the resulting radio-sensor are investigated by means of simulation and measurements that show how to control and balance above opposite requirements by a proper deposition of the sensitive material. The …
Sub-Millimeter Displacement Sensing by Passive UHF RFID Antennas
2014
A slotted patch is transformed into a wireless passive UHF-RFID sensor of uni-dimensional displacements by introducing a mechanic-electromagnetic modulation capable to convert sub-millimeter deformations into changes of the antenna's response, remotely detectable. A design methodology allows to obtain the desired sensitivity and dynamic range in a fully controllable way. The sensor and the methodology are discussed through the help of preliminary laboratory experimentations on a concrete brick, showing the possibility to achieve resolutions better than 0.1 mm with low cost readers.
Experimental characterization of bodycentric passive RFID systems
2011
Recent progresses in the design of wearable RFID tag antennas stimulate the idea of passive bodycentric systems wherein the required power to drive the wearable tags is directly scavenged from the interrogation signal emitted by the reader unit. While active bodycentric links have been extensively investigated, the feasibility of passive systems is still questionable due to the poor sensitivity of the tags and to the modest read distances. This paper describes an articulated measurement campaign with textile wearable low-profile tags in the UHF RFID band. It is demonstrated that both on-body and off-body links are feasible with a power budget fully compliant with the available technology. T…
Feasibility of Body-centric Systems by Using passive textile RFID tags
2012
Recent progresses in the design of wearable RFID-tag antennas stimulate the idea of passive body-centric systems, wherein the required power to drive the wearable tags is directly scavenged from the interrogation signal emitted by the reader unit. While active body-centric links have been extensively investigated, the feasibility of passive systems is still questionable, due to the poor sensitivity of the tags and due to the modest reading distances. This paper describes a systematic measurement campaign involving low-profile wearable textile tags in the UHF RFID band. It was demonstrated that both on-body and off-body links are affordable, with a power budget fully compliant with the avail…
Feasibility, limitations and potentiality of UHF-RFID passive implants
2012
Implanted RFID may play an important role in the personal Healthcare of next future. Antenna embedded into prosthesis or into other implanted medical devices could permit to monitor physiological and pathological processes, providing a natural interconnection to remote services. The big technical challenge is to establish a stable RFID link with the interior of the human body in spite of the high electromagnetic losses of the tissues. By using parametric electromagnetic models and some early result, it is here investigated the potentiality and limitation of the UHF implants with special attention to the body district, the overall mass, and the size of the antennas.
Sensor-Oriented Passive RFID
2010
This chapter addresses the design of new UHF tag antennas for sensing applications able to host detectors and additional electronics but also to act as passive sensor itself for some modification of the target. Starting from the consideration that the tag is both a digital and an analog device, sensing data may be achieved without using microcontrollers by a simple signal processing of the tag response and of the turn-on power. The chapter is particularly focused on the monitoring of human body features even if the proposed ideas and devices, here demonstrated by simulations and experimentation, may also be applied in a variety of scenarios.
Multipactor Analysis in Coaxial Waveguides for Satellite Applications using Frequency-Domain Methods
2006
This work presents the analysis, manufacturing and testing of a coaxial sample in order to investigate the multipactor effect in this kind of waveguide structures. Several in-home and commercial software have been used to design a quarter-wave transformer coaxial circuit centered at 1.35 GHz. The multipactor analysis of this device has been carried out allowing the prediction of the RF breakdown multipactor threshold. Moreover, the multipactor onset of such a prototype has been measured showing a very good agreement with our simulations. In addition to this, comparison has been also done with results from the technical literature fully validating the new algorithm developed.
Dielectric characterization of biocompatible hydrogels for application to Epidermal RFID devices
2015
Functionalized skin-like membranes are currently under investigation for the design of a new class of Epidermal Electronics devices for sensing and healing applications. The dynamic response of epidermal antennas in presence of absorption and release of fluids is a key-point to design RFID radio-sensors and actuators. This paper addresses the characterization of the dielectric property of PVA-based biocompatible hydrogel membranes in the UHF RFID band by means of a modified ring resonator. Samples having different compositions are measured in the dry state as well as when exposed to a progressive release of body fluids emulating perspirations or wound exudates. It was found that the permitt…