Search results for "ANTENNA"
showing 10 items of 250 documents
Impact of Spreading Factor Imperfect Orthogonality in LoRa Communications
2017
In this paper we study the impact of imperfect-orthogonality in LoRa spreading factors (SFs) in simulation and real-world experiments. First, we analyze LoRa modulation numerically and show that collisions between packets of different SFs can indeed cause packet loss if the interference power received is strong enough. Second, we validate such findings using commercial devices, confirming our numerical results. Third, we modified and extended LoRaSim, an open-source LoRa simulator, to measure the impact of inter-SF collisions and fading (which was not taken into account previously in the simulator). Our results show that non-orthogonality of the SFs can deteriorate significantly the perform…
Positioning Accuracy Comparison of GNSS Receivers Used for Mapping and Guidance of Agricultural Machines
2020
Global Navigation Satellite Systems (GNSS) allow the determination of the 3D position of a point on the Earth&rsquo
The RFID technology for neurosciences: feasibility of limbs' monitoring in sleep diseases.
2009
This contribution investigates the feasibility of the passive UHF RF identification technology for the wireless monitoring of human body movements in some common sleep disorders by means of passive tags equipped with inertial switches. Electromagnetic and mechanical models as well as preliminary experimentations are introduced to analyze all the significant issues concerning the required power, the tag antenna design, the read distance, and the expected biosignals collected by the interrogation device.
Multi-beam capabilities for high precision astrometry at low frequencies using VLBI
2011
We are carrying out a simulation study to characterise the advantages of VLBI with multiple beams, which will be a feature of the next generation of instruments. We will focus on VLBI astrometric measurements at lower frequencies (1.4 GHz and below). For our simulations, we have selected a network consisting of ASKAP, the Australian SKA precursor, plus existing Australian antennas from the LBA (Long Baseline Array) and the new antenna in New Zealand (figure 1a). We have used different models to represent the ionospheric turbulences and frequencies. The preliminary results show an improvement of an order of magnitude in the astrometric precision achieved using multiple calibrators with angul…
A contention-based multiple access protocol in cooperative wireless networks
2010
Cooperative communication has emerged as a promising technique to enhance system performance in wireless networks. This paper proposes a contention-based cooperative multiple medium access control protocol by means of multiple retransmissions of the same packet from different relay nodes. The proposed scheme exploits cooperative communication capability not only from time diversity derived from multiple temporal transmissions but also spatial diversity derived from distributed multiple relays. A Markov chain is introduced to analyze the throughput performance of the proposed cooperative scheme. The performance evaluation of the protocol is validated and compared with non-cooperative ARQ pro…
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 …
How Do We Know If There’s a Message?
2010
As we have seen, radio waves can be excellent candidates for interplanetary communication, due to the fact that our galaxy is transparent to them. The problem lies in properly identifying the origin – artificial or natural – of an arriving signal. When we tune a radio receiver and we turn the antenna toward the cosmos, we gather hundreds of different signals. Even some of the natural signals are quite suggestive, and one can be tempted to consider them emissions from other civilizations.
Evaluation of an Optical Energy Harvester for SHM Application
2019
Abstract In this paper a preliminary study on an array configuration of rectified optical nanoantennas for energy harvesting application is proposed. Currently, the major impediments for the use of the rectified optical nanoantenna known as rectenna are the relatively low conversion efficiency and low power transfer to the load, both of them caused mainly by the mismatch between the impedance of the rectifier (several kilo ohms) and that of the antenna (hundreds of ohm). For this reason, the design of the array represents a crucial point to obtain the maximum energy transfer from the rectenna to the load, represented as a typical DC/DC boost power converter, and modeled by an equivalent inp…
A Novel Angle Estimation for mmWave FMCW Radars Using Machine Learning
2021
In this article, we present a novel machine learning based angle estimation and field of view (FoV) enhancement techniques for mmWave FMCW radars operating in the frequency range of 77 - 81 GHz. Field of view is enhanced in both azimuth and elevation. The Elevation FoV enhancement is achieved by keeping the orientation of antenna elements in elevation. In this orientation, radar focuses the beam in vertical direction there by enhancing the elevation FoV. An Azimuth FoV enhancement is achieved by mechanically rotating the radar horizontally, which has antenna elements in the elevation. With the proposed angle estimation technique for such rotating radars, root mean square error (RMSE) of 2.5…
Editorial Article for Open Journal of Antennas and Propagation
2013
Antennas help communicate the World. Antennas make possible that millions of people can watch the Champions League. Antennas allow the positioning of billions of vehicles around our planet. And they also allow handling vehicles through our neighbor planets. By propagating waves through antennas you can send huge amounts of data in milliseconds. Besides, you can also tell somebody that you love him or her. Antennas have allowed communicate the people in these places where cables cannot. But antennas are not only used for communication. Antennas can be used for heating food, for detecting people, for guiding vessels, for founding treasures, for monitoring breath, for harvesting energy and so …