Articoli di riviste: "ISM radio band"

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Wysocki, Tadeusz A., e Hans-Jurgen Zepernick. "Characterization of the indoor radio propagation channel at 2.4 GHz". Journal of Telecommunications and Information Technology, n. 3-4 (30 dicembre 2000): 84–90. http://dx.doi.org/10.26636/jtit.2000.3-4.23.

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The unlicensed industrial, scientific, and medical (ISM) band at 2.4 GHz has gained increased attention recently due to the high data rate communication systems developed to operate in this band. The paper presents measurement results of fading characteristics, multipath parameters and background interference for these frequencies. Some statistical analysis of the measured data is presented. The paper provides information that may be useful in design and deployment of communication systems operating in the 2.4 GHz ISM band, like those compliant with IEEE 802.11 standard and Bluetooth open wireless standard

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Guo, Y., e K. Feher. "Modem/radio IC architectures for ISM band wireless applications". IEEE Transactions on Consumer Electronics 39, n. 2 (maggio 1993): 100–106. http://dx.doi.org/10.1109/30.214814.

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Bello, N., e K. O. Ogbeide. "Designing a Real-time Swept Spectrum Analyser with USRP B210". Nigerian Journal of Environmental Sciences and Technology 5, n. 2 (ottobre 2021): 329–39. http://dx.doi.org/10.36263/nijest.2021.02.0275.

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Cognitive radio has received considerable amount of attention as a promising technique to provide dynamic spectrum allocation. Spectrum sensing is one of the basic functions in the cognitive radio and is crucial to all other functions. Software- defined radios (SDRs) are considered due to its very high flexibility and have become a common platform for CR implementation replacing expensive spectrum analysers. The most popular among various SDR platforms is the universal software-defined radio peripheral (USRP). This paper presents a real-time swept spectrum sensing solution based on USRP B210. It also presents a detailed explanation of the concept of energy detection and the methodology for wide-band sensing. Finally, the performance of the proposed sensing solution is analysed through FFT graphs and spectrogram plot taken for 8 hours. The results showed that the proposed sensing solution was capable of achieving high resolution in the frequency domain of the wide band measured which implies that wide bands with heterogenous signals like the ISM band can be accurately resolved and analysed.

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van den Eijnden, J., I. Heywood, R. Fender, S. Mohamed, G. R. Sivakoff, P. Saikia, T. D. Russell, S. Motta, J. C. A. Miller-Jones e P. A. Woudt. "MeerKAT discovery of radio emission from the Vela X-1 bow shock". Monthly Notices of the Royal Astronomical Society 510, n. 1 (24 novembre 2021): 515–30. http://dx.doi.org/10.1093/mnras/stab3395.

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ABSTRACT Vela X-1 is a runaway X-ray binary system hosting a massive donor star, whose strong stellar wind creates a bow shock as it interacts with the interstellar medium (ISM). This bow shock has previously been detected in H α and infrared, but, similar to all but one bow shock from a massive runaway star (BD+43o3654), has escaped detection in other wavebands. We report on the discovery of 1.3 GHz radio emission from the Vela X-1 bow shock with the MeerKAT telescope. The MeerKAT observations reveal how the radio emission closely traces the H α line emission, both in the bow shock and in the larger scale diffuse structures known from existing H α surveys. The Vela X-1 bow shock is the first stellar-wind-driven radio bow shock detected around an X-ray binary. In the absence of a radio spectral index measurement, we explore other avenues to constrain the radio emission mechanism. We find that thermal/free–free emission can account for the radio and H α properties, for a combination of electron temperature and density consistent with earlier estimates of ISM density and the shock enhancement. In this explanation, the presence of a local ISM overdensity is essential for the detection of radio emission. Alternatively, we consider a non-thermal/synchrotron scenario, evaluating the magnetic field and broad-band spectrum of the shock. However, we find that exceptionally high fractions (≳ 13 per cent) of the kinetic wind power would need to be injected into the relativistic electron population to explain the radio emission. Assuming lower fractions implies a hybrid scenario, dominated by free–free radio emission. Finally, we speculate about the detectability of radio bow shocks and whether it requires exceptional ISM or stellar wind properties.

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Morabito, Leah K., J. B. R. Oonk, Francisco Salgado, M. Carmen Toribio, Xander Tielens e Huub Röttgering. "Discovery of Carbon Radio Recombination Lines in M82". Proceedings of the International Astronomical Union 10, S309 (luglio 2014): 141–44. http://dx.doi.org/10.1017/s174392131400948x.

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AbstractCold, diffuse HI clouds are a key component of the interstellar medium (ISM), and play an important role in the evolution of galaxies. Carbon radio recombination lines (CRRLs) trace this ISM stage, and with the enormous sensitivity of LOFAR we have already begun to map and constrain the physical properties of this gas in our own Galaxy. Using LOFAR's low band antenna, we have observed M 82 and present the first ever extragalactic detection of CRRLs. We stack 22 lines to find a 8.5-sigma detection. The line peak to continuum ratio is ∼0.003, with a FWHM of 31 km s−1. The CRRL feature is consistent with an origin in the cold, neutral medium in the direction of the nucleus of M 82.

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Rammala, Isabella, Aris Karastergiou e Griffin Foster. "Broadband observations of pulsar profiles and frequency dependent DMs". Proceedings of the International Astronomical Union 13, S337 (settembre 2017): 400–401. http://dx.doi.org/10.1017/s1743921317010353.

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AbstractThe aim of our project is to search for ways to best extract information on pulsar profiles and the interstellar medium (ISM), using the wide frequency bands that are typical of radio telescopes today. Pulsar profiles typically show a strong dependence on frequency. This depends both on the intrinsic radio emission mechanism, and the interaction of the radio waves with the ISM that lies between the pulsars and our detectors on Earth, due mostly to the effects of dispersion and scattering. In this work, we make use of radio pulsar beam models from the existing literature, to generate simulated pulse profiles, observed across various bands (centre frequencies and bandwidths), for each beam model. For all the chosen geometric parameters of the pulsar beam, observed in any frequency band, the simulated profiles manifest a relative shift in phase in their observed components, as a result of the intrinsic profile evolution. This relative shift in phase could be interpreted as an additional component to the ISM induced dispersion measure (DM). This additional DM component due to profile evolution is frequency dependent. We discuss the systematics introduced to pulsar data due to this effect.

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Pan, Yong, Zi Ye Hou, Jiang Xiong e Kai Hua Liu. "Research on the System of Radio Frequency Identification and Localization Works in Microwave". Applied Mechanics and Materials 441 (dicembre 2013): 993–96. http://dx.doi.org/10.4028/www.scientific.net/amm.441.993.

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Radio frequency identification and localization is a key technology in the Internet of Things. This paper reports an ARM Cortex-M3 processor based hand-held radio frequency identification and localization terminal and a 8051 processor based active radio frequency tags. The terminal and the tags utilize STM32F103VET6 and the low power consumption STC12LE4052AD as their master controller, respectively. Both of them use Nordic nRF24L01 as their radio frequency identification module. The system works in 2.4GHz ISM microwave band and can read, write and locate radio frequency tags within 20m indoors. The actual measurement of active radio frequency tags shows that this terminal is highly stable and comparable in 2.4GHz microwave frequency radio identification and localization.

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Grass, Eckhard, Klaus Tittelbach-Helmrich, Chang-Soon Choi, Frank Winkler, Thilo Ohlemüller e Rolf Kraemer. "Communication systems operating in the 60 GHz ISM band: Overview". International Journal of Microwave and Wireless Technologies 3, n. 2 (25 marzo 2011): 89–97. http://dx.doi.org/10.1017/s1759078711000249.

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This paper gives an overview of frequency regulation, standardization, and applications of 60 GHz communication systems. Based on forecasted developments of mobile IP traffic, the motivation for investigating circuits, and systems for the 60 GHz band is underlined. Some physical properties of 60 GHz radio waves are outlined and implications on potential applications are sketched. The current international and European frequency regulation aspects are presented. The main parameters of three different international standards are summarized and compared with each other. Details of channel spacing and channel bonding are given. Based on the investigation of different applications, the main system requirements are derived. Finally, some information on protocol issues and system integration aspects are given.

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Pan, Yong, Kai Hua Liu, Yi Gao e Rui Zhao. "A Study on the System of Radio Frequency Identification and Localization Works in UHF". Advanced Materials Research 588-589 (novembre 2012): 932–35. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.932.

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This paper designs a hand-held radio frequency identification and localization terminal based on ARM Cortex-M3 processor and active radio frequency tags based on 8051 processor. This terminal uses STM32F103VET6 as its master controller, these tags use STC12C2052AD as their master controller. They all use Nordic nRF905 as their radio frequency identification module. The system works in 433M/868M/915MHz ISM UHF band and can read, write and locate radio frequency tags within 50m indoors. The actual measurement of active radio frequency tags shows that this terminal is highly stable and comparable in 433M/868M/915M ultra-high frequency radio identification and localization. The test results of this system are also analyzed and presented.

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Das, Deepa, e Susmita Das. "A novel approach for cognitive radio application in 2.4-GHz ISM band". International Journal of Electronics 104, n. 5 (21 ottobre 2016): 792–804. http://dx.doi.org/10.1080/00207217.2016.1244865.

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Ribadeneira-Ramírez, Jefferson, Jorge Santamaria, Patricio Romero e Mario Alejandro Paguay. "Radio Frequency Energy Harvesting Device at ISM Band for Low Power IoT". Progress In Electromagnetics Research M 122 (2023): 11–20. http://dx.doi.org/10.2528/pierm23091504.

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Jeong, Won Ho, Hong-Rak Choi e Kyung-Seok Kim. "Empirical Path-Loss Modeling and a RF Detection Scheme for Various Drones". Wireless Communications and Mobile Computing 2018 (6 dicembre 2018): 1–17. http://dx.doi.org/10.1155/2018/6795931.

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This paper presents a path-loss model based on a radio-frequency (RF) detection scheme for various drones using 5G aerial communication over an industrial, scientific, and medical radio band (ISM band) network. We considered three communication modes of the ISM band for the channel characteristics analysis: the DJI Enhanced Spread Spectrum Technology (DESST) protocol, Wi-Fi, and Bluetooth. The drone signal detection scheme extracts the drone signal from the environment mixed with the general signal. The drone DESST signal is identified through cross-correlation of the received signal. The Wi-Fi and Bluetooth signals are identified with the singular-value decomposition (SVD) algorithm by using the hopping characteristics. General and drone Wi-Fi signals are separated by in-phase/quadrature (I/Q) phase analysis over the measurement time. The windowed received signal strength indicator (RSSI) moving detection (WRMD) analysis identifies the drone Bluetooth signal according to the movement of the drone. The detected drone signal is channel modeled by the horizontal distance d according to the altitude θ. Finally, they verify their model by a ray-tracing simulation similar to the real environment. The model provides a simple and accurate prediction for designing future aerial communications systems according to changes in drone movement.

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Ruf, K., E. Fürst, K. Grypstra, J. Neidhöfer e M. Schumacher. "Response of the Effelsberg 100m radio telescope to signals in the near-field at 24 GHz". Advances in Radio Science 1 (5 maggio 2003): 329–33. http://dx.doi.org/10.5194/ars-1-329-2003.

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Abstract. Short range radar (SRR) for cars has been proposed to operate over 5 GHz of bandwidth at the 24 GHz ISM band. To estimate the level of interference from these devices on radio telescopes, the near-field antenna pattern has to be known. We report on new measurements with the Effelsberg 100 m radio telescope. These measurements were performed with a transmitter set up at a distance of 1.7 km from the telescope. The strength of the signal picked up by the telescope sidelobes shows that the proposed SRR would interfere with sensitive radio astronomical observations.

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Mathialagan, Srimathi. "Design of CPW-fed tapered MIMO antenna for ISM band applications". International Journal of Microwave and Wireless Technologies 9, n. 1 (29 luglio 2015): 227–30. http://dx.doi.org/10.1017/s175907871500121x.

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In this paper, an implantable coplanar waveguide-fed tapered monopole antenna for industrial scientific and medical band (2.4–2.48 GHz) applications is proposed. This proposed design has an overall dimension of 44 × 44 × 0.5 mm3. The designed antenna is made compatible for implantation on human tissues such as skin, fat, or muscles by embedding it on the RT Duroid substrate and the 10 dB return loss bandwidth is 6.12% ranging from 2.35 to 2.5 GHz. This proposed antenna can be significantly used in implantable medical devices and radio frequency (RF), because of its merits such as conformability, flexibility in design and shape, biocompatibility, patient safety, miniaturization, power consumption, etc.

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Jin, Zi Long, Beom Seok Kim, Dong Hai Guan e Jin Sung Cho. "A Probabilistic Routing Protocol Based on Priori Information for Cognitive Radio Sensor Networks". Applied Mechanics and Materials 303-306 (febbraio 2013): 210–14. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.210.

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The cognitive radio technology has been adopted as a promised solution to deal with overcrowded problem in ISM band. In wireless sensor networks, the cognitive radio technology enables sensor nodes to occupy licensed band in opportunistic manner and introduces advantages of improving spectrum utilization and increasing system throughput. By considering the opportunistic spectrum access nature, in this paper, we aim to provide a stable path selection scheme for cognitive radio sensor networks. The proposed routing protocol utilizes priori delivery information and derives a novel routing metric for the optimal path selection. The routing metric is derived from naïve Bayes inference and used to indicate the path stability by means of delivery probability. We show through extensive simulations that the proposed routing protocol is efficient to find the most probable delivery path and increase the system throughput.

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Kozłowski, Sebastian, e Krzysztof Kurek. "Channel Occupancy Measurements in 868 MHz ISM Band in Residential Areas". Sensors 21, n. 23 (24 novembre 2021): 7805. http://dx.doi.org/10.3390/s21237805.

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The rapid development of Internet of Things (IoT) has led to more and more devices using ISM frequency bands. Because they are not time synchronized, medium access collisions are unavoidable. The probability of such a collision is usually reasonably low; however, it increases with the number of transmitters competing for the same frequency channel. For this reason, ISM bands’ occupancy is regularly monitored by researchers. This paper presents the results of the measurement campaign during which a selected part of the 868 MHz ISM frequency band was monitored for the presence of transmissions in six locations in various residential areas in Warsaw, Poland. For the purpose of the campaign, a dedicated measurement set-up comprising a software-defined radio (SDR) module was assembled. The measurements results showed that the channel occupancy is in most cases lower than 1% with a maximum observed value of 2%. The paper presents selected characteristics of the detected signals. Additionally, distribution over time of the detected signals was used together with the Monte Carlo simulations to analyze how long idle time blocks are available for new transmitters that could be deployed in the band under testing.

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Van den Eijnden, J., P. Saikia e S. Mohamed. "Radio detections of IR-selected runaway stellar bow shocks". Monthly Notices of the Royal Astronomical Society 512, n. 4 (24 marzo 2022): 5374–89. http://dx.doi.org/10.1093/mnras/stac823.

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ABSTRACT Massive stars moving at supersonic peculiar velocities through the interstellar medium (ISM) can create bow shocks, arc-like structures at the interface between the stellar wind and the ISM. Many such bow shocks have been detected and catalogued at IR wavelengths, but detections in other wavebands remain rare. Strikingly, while electrons are expected to be accelerated in the bow shock and their non-thermal emission may include synchrotron emission at low frequencies, only two massive runaway stellar bow shocks have to date been detected in the radio band. Here, we examine a sample of fifty IR-detected bow shocks from the E-BOSS catalogues in recently released radio images from the Rapid ASKAP Continuum Survey. We identify three confident and three likely counterparts, as well as three inconclusive candidates requiring confirmation via follow-up observations. These detections significantly increase the number of known radio massive stellar bow shocks and highlight the advantage of dedicated searches with current and next-generation radio telescopes. We investigate the underlying radio emission mechanism for these radio sources, finding a mix of free–free-dominated and synchrotron-dominated systems. We also discuss the non-detected targets by putting constraints on their emission properties and investigating their detectability with future observations. Finally, we propose several future avenues of research to advance the study and understanding of bow shocks at radio frequencies.

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Sandoval, Ruben M., Antonio-Javier Garcia-Sanchez, Jose-Maria Molina-Garcia-Pardo, Felipe Garcia-Sanchez e Joan Garcia-Haro. "Radio-Channel Characterization of Smart Grid Substations in the 2.4-GHz ISM Band". IEEE Transactions on Wireless Communications 16, n. 2 (febbraio 2017): 1294–307. http://dx.doi.org/10.1109/twc.2016.2644610.

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Ahmed, Arslan, Ghulam Hussain e Ali Raza. "Ultra-Wide Band Horseshoe Antenna for Cognitive Radio Applications". Journal of Applied Engineering & Technology (JAET) 5, n. 1 (30 giugno 2021): 9–18. http://dx.doi.org/10.55447/jaet.05.01.34.

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In this paper, an Ultra-wide band (UWB) micro-strip antenna design is proposed to be suitable for Cognitive radio applications. The geometry of proposed antenna is composed of two semi-circles with their interior modified to achieve higher impedance bandwidth. The semi-etched ground enhances bandwidth to achieve higher data rate. The proposed antenna is fabricated on an inexpensive dielectric substrate FR-4 with relative permittivity of 4.4 and thickness of 1.6mm. The overall dimension of UWB antenna is 60x60x1.6mm and have a bandwidth of 5.7 GHz. The designed antenna covers the most commonly used wireless communication bands such as DCS-1800, ISM bands, GPS, Wi-MAX, WLAN, 3-G, 4-G, etc. The design process and the variations in antenna’s performance is due to different parameters such as structure, thickness and material. The design and simulation of the antenna are carried out in the Ansys simulation software on Desktop HFSS 17. The measured results are in good agreement with simulated results and exhibits better performance than the existing designed antennas.

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Vasylkivskyi, Y., O. Konovalenko e S. Stepkin. "Observations of decameter carbon radio recombination lines in several galactic directions. Part 1. Experimental study". RADIO PHYSICS AND RADIO ASTRONOMY 28, n. 3 (2023): 201–11. http://dx.doi.org/10.15407/rpra28.03.201.

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Subject and Purpose. Since decameter carbon radio recombination lines (RRLs) were detected for the first time more than forty years ago, they have significantly extended our knowledge of the physics, kinematics and chemistry of the cold rarefied interstellar medium (ISM). A large number of these lines have been observed towards various Galactic radio sources. The present paper describes our studies of decameter carbon RRLs in such Galactic directions as the sight-lines to the S140 emission nebula and to the large volume of cold neutral hydrogen known as the GSH 139-03-69 super shell. Methods and Methodology. Observations within a 1-MHz frequency band centered at 26 MHz were performed using the UTR-2 radio telescope and a multi-channel digital correlator. The UTR-2 is still the world largest and the most sensitive low-frequency radio telescope. Results.We report the detection of decameter carbon RRL series C627α – C637α from the medium lying towards the S140 nebula. The extents of RRL forming regions have been estimated. It is suggested that RRLs in the S140 direction are formed in the local ISM lying along the line of sight. The RRL-forming region is probably associated with omnipresent diffuse neutral HI gas in the Galactic plane rather than with S140 nebula itself. Toward the GSH 139-03-69 super shell, decameter RRLs have been detected as well. Likewise, they apparently originate from the local medium lying along the sight-line. Yet, the spectrum contains a RRL component corresponding to the absorption of the cold gas of the GSH 139-03-69 itself in the ISM. Conclusions. The obtained results indicate great possibilities of decameter carbon RRLs not only for cold ISM probing but also for making a good auxiliary tool for studying large complexes of extremely cold hydrogen HI in the Galaxy.

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Dangkham, Piyapong, Sitthichai Dentri, Chuwong Phongcharoenpanich e Prayoot Akkaraekthalin. "Circularly Polarized Omnidirectional Antenna with Dipole Core and Diagonally Adjoined Parasitic Braces for ISM Band Applications". International Journal of Antennas and Propagation 2019 (21 agosto 2019): 1–11. http://dx.doi.org/10.1155/2019/2463871.

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This research proposes a circularly polarized (CP) single-fed omnidirectional dipole antenna operable in 2.45 GHz frequency for the industrial, scientific, and medical (ISM) radio band applications. The proposed antenna consisted of bisectional dipole core, a pair of quarter-wave baluns, and four diagonally adjoined parasitic braces. The bisectional dipole core was utilized to improve the antenna gain and realize omnidirectional radiation pattern, and the quarter-wave baluns were to symmetrize the current on the bisectional core. The four parasitic braces collectively generated circular polarization. In the study, simulations were conducted using CST Microwave Studio and a prototype antenna fabricated. To validate, experiments were carried out, and simulation and experimental results compared. The finding revealed good agreement between the simulation and experimental results. Essentially, in addition to achieving an antenna gain of 2.07 dBic, the proposed CP single-fed omnidirectional antenna is suited to ISM frequency band applications.

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Jin, Jie, Xianming Wu e Zhijun Li. "Ultra low power mixer with out-of-band RF energy harvesting for wireless sensor networks applications". Engineering review 40, n. 1 (27 gennaio 2020): 1–6. http://dx.doi.org/10.30765/er.40.1.01.

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An ultra low power mixer with out-of-band radio frequency (RF) energy harvesting suitable for the wireless sensors network (WSN) application is proposed in this paper. The presented mixer is able to harvest the out-of-band RF energy and keep it working in ultra low power condition and extend the battery life of the WSN. The mixer is designed and simulated with Global Foundries ’ 0.18 μ m CMOS RF process, and it operates at 2.4GHz industrial, scientific, and medical (ISM) band. The Cadence IC Design Tools post-layout simulation results demonstrate that the proposed mixer consumes 248 μ W from a 1V supply voltage. Furthermore, the power consumption can be reduced to 120.8 μ W by the out-of-band RF energy harvesting rectifier.

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Leslie, S. K., M. T. Sargent, E. Schinnerer, B. Groves, A. van der Wel, G. Zamorani, Y. Fudamoto, P. Lang e V. Smolčić. "Probing star formation and ISM properties using galaxy disk inclination". Astronomy & Astrophysics 615 (luglio 2018): A7. http://dx.doi.org/10.1051/0004-6361/201732255.

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Disk galaxies at intermediate redshift (z ~ 0.7) have been found in previous work to display more optically thick behaviour than their local counterparts in the rest-frame B-band surface brightness, suggesting an evolution in dust properties over the past ~6 Gyr. We compare the measured luminosities of face-on and edge-on star-forming galaxies at different wavelengths (Ultraviolet (UV), mid-infrared (MIR), far-infrared (FIR), and radio) for two well-matched samples of disk-dominated galaxies: a local Sloan Digital Sky Survey (SDSS)-selected sample at z ~ 0.07 and a sample of disks at z ~ 0.7 drawn from Cosmic Evolution Survey (COSMOS). We have derived correction factors to account for the inclination dependence of the parameters used for sample selection. We find that typical galaxies are transparent at MIR wavelengths at both redshifts, and that the FIR and radio emission is also transparent as expected. However, reduced sensitivity at these wavelengths limits our analysis; we cannot rule out opacity in the FIR or radio. Ultra-violet attenuation has increased between z ~ 0 and z ~ 0.7, with the z ~ 0.7 sample being a factor of ~3.4 more attenuated. The larger UV attenuation at z ~ 0.7 can be explained by more clumpy dust around nascent star-forming regions. There is good agreement between the fitted evolution of the normalisation of the SFRUV versus 1 − cos(i) trend (interpreted as the clumpiness fraction) and the molecular gas fraction/dust fraction evolution of galaxies found out to z < 1.

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Krishnakumar, M. A., P. K. Manoharan, B. C. Joshi, R. Girgaonkar, S. Desai, M. Bagchi, K. Nobleson et al. "High precision measurements of interstellar dispersion measure with the upgraded GMRT". Astronomy & Astrophysics 651 (luglio 2021): A5. http://dx.doi.org/10.1051/0004-6361/202140340.

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Context. Pulsar radio emission undergoes dispersion due to the presence of free electrons in the interstellar medium (ISM). The dispersive delay in the arrival time of the pulsar signal changes over time due to the varying ISM electron column density along the line of sight. Accurately correcting for this delay is crucial for the detection of nanohertz gravitational waves using pulsar timing arrays. Aims. We aim to demonstrate the precision in the measurement of the dispersion delay achieved by combining 400−500 MHz (BAND3) wide-band data with those at 1360−1460 MHz (BAND5) observed using the upgraded GMRT, employing two different template alignment methods. Methods. To estimate the high precision dispersion measure (DM), we measure high precision times-of-arrival (ToAs) of pulses using carefully generated templates and the currently available pulsar timing techniques. We use two different methods for aligning the templates across frequency to obtain ToAs over multiple sub-bands and therefrom measure the DMs. We study the effects of these two different methods on the measured DM values in detail. Results. We present in-band and inter-band DM estimates of four pulsars over the timescale of a year using two different template alignment methods. The DMs obtained using both these methods show only subtle differences for PSRs J1713+0747 and J1909−3744. A considerable offset is seen in the DM of PSRs J1939+2134 and J2145−0750 between the two methods. This could be due to the presence of scattering in the former and profile evolution in the latter. We find that both methods are useful but could have a systematic offset between the DMs obtained. Irrespective of the template alignment methods followed, the precision on the DMs obtained is about 10−3 pc cm−3 using only BAND3 and 10−4 pc cm−3 after combining data from BAND3 and BAND5 of the uGMRT. In a particular result, we detected a DM excess of about 5 × 10−3 pc cm−3 on 24 February 2019 for PSR J2145−0750. This excess appears to be due to the interaction region created by fast solar wind from a coronal hole and a coronal mass ejection observed from the Sun on that epoch. A detailed analysis of this interesting event is presented.

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Brzycki, Bryan, Andrew P. V. Siemion, Imke de Pater, Carmen Choza, Steve Croft, Vishal Gajjar, Jamie Drew, Brian C. Lacki, Danny C. Price e Sofia Z. Sheikh. "The Breakthrough Listen Search for Intelligent Life: Galactic Center Search for Scintillated Technosignatures". Astronomical Journal 168, n. 6 (22 novembre 2024): 284. http://dx.doi.org/10.3847/1538-3881/ad7e18.

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Abstract The search for extraterrestrial intelligence at radio frequencies has focused on spatial filtering as a primary discriminant from terrestrial interference. Individual search campaigns further choose targets or frequencies based on criteria that theoretically maximize the likelihood of detection, serving as high-level filters for interesting targets. Most filters for technosignatures do not rely on intrinsic signal properties, as the radio-frequency interference (RFI) environment is difficult to characterize. In B. Brzycki et al. (2023), we proposed that the effects of interstellar medium (ISM) scintillation on narrowband technosignatures may be detectable under certain conditions. In this work, we perform a dedicated survey for scintillated technosignatures toward the Galactic center and Galactic plane at the C band (3.95–8.0 GHz) using the Robert C. Byrd Green Bank Telescope (GBT) as part of the Breakthrough Listen program. We conduct a Doppler drift search and directional filter to identify potential candidates and analyze results for evidence of scintillation. We characterize the C-band RFI environment at the GBT across multiple observing sessions spread over months and detect RFI signals with confounding scintillation-like intensity modulation. We do not find evidence of putative narrowband transmitters with drift rates between ±10 Hz s−1 toward the Galactic center, ISM-scintillated or otherwise, above an equivalent isotropic radiated power of 1.9 × 1017 W up to 8.5 kpc.

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Gemignani, Matteo, e Salvo Marcuccio. "Dynamic Characterization of a High-Altitude Balloon during a Flight Campaign for the Detection of ISM Radio Background in the Stratosphere". Aerospace 8, n. 1 (17 gennaio 2021): 21. http://dx.doi.org/10.3390/aerospace8010021.

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Sounding balloons, available at very low cost from commercial vendors and operable with minimal training, have an excellent potential as testing platforms in the near-space environment. The work reported here was motivated by the need to perform an experimental assessment of the radio frequency (RF) background present in the ISM (Industrial, Scientific and Medical) bands, namely 868 MHz (Ultra High Frequency—UHF) and 2.4 GHz (S-Band), simulating the operational environment of a Low Earth Orbit (LEO) constellation forInternet of Things (IoT) telecommunications. To this end, five balloons were flown with a dedicated RF payload. Along with the radio measurements, the flights provided a convenient opportunity to collect data on the dynamic behavior of the payload gondola. We report on the system design and the operational phase of the mission, and discuss the data collected throughout the successful flight campaign. As a result, a preliminary understanding of the gondola dynamics has been gained, including both linear accelerations and attitude oscillations. It is also concluded that the two ISM bands considered are actually suitable for IoT ground-to-LEO links.

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Sandeep Duvvada, Ram, Prabakaran Narayanaswamy, Madhav Phani e Narayana Lakshmi. "Circularly Polarized Jute Textile Antenna for Wi-MAX, WLAN and ISM Band Sensing Applications". Applied Computational Electromagnetics Society 35, n. 12 (15 febbraio 2021): 1493–99. http://dx.doi.org/10.47037/2020.aces.j.351206.

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Abstract (sommario):

This study exhibits a circularly polarized (CP) conformal antenna actualized by using a jute textile as a substrate. Its sensing 3.5, 4.9, and 5.8 GHz in the Wi-MAX, WLAN, and ISM radio bands. The topology of the proposed antenna has relied on a curvature structure as the prime radiating element, and ground structure whirled in contradictive arrangement to the patch. Conductivity was materialized by applying copper paint through the traditional painting approach, i.e., brush painting. This fabrication method allows attaining the conformability with minimized size, lightweight, and low sensitivity to the environment without weakening the radiating performance. These attributes allowed the jute textile antenna appropriately for the incorporation in wearable devices for body-driven applications. The electromagnetic properties of the projected jute textile antenna accomplished in simulations were confirmed through the measurement of the antenna in an anechoic chamber. The CP jute textile antenna shows a peak gain of 4.93, 8.86, and 10.07dBi at 3.5, 4.9, and 5.8 GHz (WiMAX, WLAN, and ISM).

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28

Najumunnisa, Md, Ambadapudi Srinivasa Chandrasekhara Sastry, Boddapati Taraka Phani Madhav, Sudipta Das, Niamat Hussain, Syed Samser Ali e Muhammad Aslam. "A Metamaterial Inspired AMC Backed Dual Band Antenna for ISM and RFID Applications". Sensors 22, n. 20 (21 ottobre 2022): 8065. http://dx.doi.org/10.3390/s22208065.

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Abstract (sommario):

This work presents the design and fabrication of a metamaterial-based stimulated dual band antenna on FR4 material (dielectric constant 4.3) to operate in Industrial, Scientific and Medical (ISM) and Radio-frequency Identification (RFID) applications. The antenna model had an overall dimension of 70 × 31 × 1.6 mm3 with etched T-slots and L-slots for dual band resonance. The main objective of this work was to enhance the gain performance characteristic at the selected dual band frequencies of 0.915 GHz and 2.45 GHz. Initially, it achieved a narrow bandwidth of 0.018 GHz with a gain of 1.53 dBi at a lower frequency, and 0.13 GHz of bandwidth featuring 4.49 dBi of gain at a higher frequency. The antenna provided an impedance bandwidth of 2% (0.905–0.923 GHz) and 5% (2.382–2.516 GHz) at two resonating frequencies. The antenna was integrated with a designed novel AMC structure to enhance the gain in CST Microwave Studio software with the finite integration method. The characteristic features of the AMC unit cell were observed at 0.915 GHz and 2.45 GHz frequencies and after antenna integration, the final prototype achieved a gain of 2.87 dBi at 0.915 GHz and 6.8 dBi at 2.45 GHz frequencies.

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29

Kim, Yung-Ser, e Seung-Hwan Park. "Study on Radio Interference Generation of Medical Telemetry Instruments with ISM Band in Hospital Environment". Journal of Korean Institute of Information Technology 14, n. 12 (31 dicembre 2016): 117. http://dx.doi.org/10.14801/jkiit.2016.14.12.117.

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30

Vivekanand, Chettiyar Vani, T. M. Inbamalar, Kannan Pauliah Nadar, V. Kannagi e P. Arthi Devarani. "Energy-Efficient Compressed Sensing in Cognitive Radio Network for Telemedicine Services". Wireless Communications and Mobile Computing 2023 (17 giugno 2023): 1–12. http://dx.doi.org/10.1155/2023/5415616.

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Abstract (sommario):

Wireless body area networks (WBAN) are becoming a promising solution for health care applications. WBAN allows monitoring of patients continuously in their own comfort zone. These devices use the industrial, scientific, and medical band (ISM) for communication. This band is overcrowded due to the increasing number of wireless medical devices and other wireless devices occupying this band. This causes interference, which can be damaging and could result in a change in received power. However, WBAN also needs minimum and reliable energy communication for a longer lifetime and improved quality of service. This work addresses both problems and proposes solutions for the same. A cognitive radio controller is employed as a centralized controller with dynamic spectrum allocation properties to mitigate the interference. The sensing of the spectrum is based on compressed sensing with a nonreconstruction model to save energy. To quantify interference measurement, the interference mitigation factor is introduced. Further, to increase energy efficiency, the K-means algorithm is used to cluster WBANs. However, critical emergency data and normal data are categorized as priority data and normal data, respectively, by the proposed priority scheduling algorithm. The performance of this cognitive radio-based system for telemedicine applications is analyzed through simulations. The simulations are performed using MATLAB 2019.

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31

Bianchi, Simone, Matteo Murgia, Andrea Melis, Viviana Casasola, Maud Galametz, Frédéric Galliano, Federica Govoni et al. "The mm-to-cm SED of spiral galaxies". EPJ Web of Conferences 257 (2022): 00005. http://dx.doi.org/10.1051/epjconf/202225700005.

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Abstract (sommario):

The mm-to-cm range of the Spectral Energy Distribution of spiral galaxies remains largely unexplored. Its coverage is required to disentangle the contribution of dust emission, free-free and synchrotron radiation and can provide constraints on dust models, star-formation rates and ISM properties. We present the case for a synergy between NIKA2 observations of nearby spirals and those from planned and current instrumentation at the Sardinia Radio Telescope, and report on a pilot K-band program to search for Anomalous Microwave Emission, an elusive emission component which is presumably related to dust.

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32

Moutoulas, Evangelos, Muhammad Hamidullah e Themis Prodromakis. "Surface Acoustic Wave Resonators for Wireless Sensor Network Applications in the 433.92 MHz ISM Band". Sensors 20, n. 15 (31 luglio 2020): 4294. http://dx.doi.org/10.3390/s20154294.

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Abstract (sommario):

Surface acoustic wave (SAW) resonators are low cost devices that can operate wirelessly on a received radio frequency (RF) signal with no requirement for an additional power source. Multiple SAW resonators operating as transponders that form a wireless sensor network (WSN), often need to operate at tightly spaced, different frequencies inside the industrial, scientific and medical (ISM) bands. This requires nanometer precision in the design and fabrication processes. Here, we present results demonstrating a reliable and repeatable fabrication process that yields at least four arrays on a single 4-inch wafer. Each array consists of four single-port resonators with center frequencies allocated inside four different sub-bands that have less than 50 kHz bandwidth and quality factors exceeding 8000. We see promise of standard, low-cost photolithography techniques being used to fabricate multiple SAW resonators with different center resonances all inside the 433.05 MHz–434.79 MHz ISM band and a mere 100 kHz spacing. We achieved that by leveraging the intrinsic process variation of photolithography and the impact of the metallization ratio and metal thickness in rendering distinct resonant frequencies.

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33

Streifinger, M., T. Müller, J. F. Luy e E. M. Biebl. "A software-radio front-end for microwave applications". Advances in Radio Science 1 (5 maggio 2003): 201–5. http://dx.doi.org/10.5194/ars-1-201-2003.

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Abstract (sommario):

Abstract. In modern communication, sensor and signal processing systems digitisation methods are gaining importance. They allow for building software configurable systems and provide better stability and reproducibility. Moreover digital front-ends cover a wider range of applications and have better performance compared with analog ones. The quest for new architectures in radio frequency front-ends is a clear consequence of the ever increasing number of different standards and the resulting task to provide a platform which covers as many standards as possible. At microwave frequencies, in particular at frequencies beyond 10 GHz, no direct sampling receivers are available yet. A look at the roadmap of the development of commercial analog-to-digital-converters (ADC) shows clearly, that they can neither be expected in near future. We present a novel architecture, which is capable of direct sampling of band-limited signals at frequencies beyond 10 GHz by means of an over-sampling technique. The wellknown Nyquist criterion states that wide-band digitisation of an RF-signal with a maximum frequency ƒ requires a minimum sampling rate of 2 · ƒ . But for a band-limited signal of bandwidth B the demands for the minimum sampling rate of the ADC relax to the value 2 · B. Employing a noise-forming sigma-delta ADC architecture even with a 1-bit-ADC a signal-to-noise ratio sufficient for many applications can be achieved. The key component of this architecture is the sample-and-hold switch. The required bandwidth of this switch must be well above 2 · ƒ . We designed, fabricated and characterized a preliminary demonstrator for the ISM-band at 2.4 GHz employing silicon Schottky diodes as a switch and SiGe-based MMICs as impedance transformers and comparators. Simulated and measured results will be presented.

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34

Ullah, Md, Mohammad Islam, Touhidul Alam e Farhad Ashraf. "Paper-Based Flexible Antenna for Wearable Telemedicine Applications at 2.4 GHz ISM Band". Sensors 18, n. 12 (1 dicembre 2018): 4214. http://dx.doi.org/10.3390/s18124214.

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Abstract (sommario):

This paper demonstrates the performance of a potential design of a paper substrate-based flexible antenna for intrabody telemedicine systems in the 2.4 GHz industrial, scientific, and medical radio (ISM) bands. The antenna was fabricated using 0.54 mm thick flexible photo paper and 0.03 mm copper strips as radiating elements. Design and performance analyses of the antenna were performed using Computer Simulation Technology (CST) Microwave Studio software. The antenna performances were investigated based on the reflection coefficient in normal and bent conditions. The total dimensions of the proposed antenna are 40 × 35 × 0.6 mm3. The antenna operates at 2.33–2.53 GHz in the normal condition. More than an 8% fractional bandwidth is expressed by the antenna. Computational analysis was performed at different flexible curvatures by bending the antenna. The minimum fractional bandwidth deviation is 5.04% and the maximum is 24.97%. Moreover, it was mounted on a homogeneous phantom muscle and a four-layer human tissue phantom. Up to a 70% radiation efficiency with a 2 dB gain was achieved by the antenna. Finally, the performance of the antenna with a homogeneous phantom muscle was measured and found reliable for wearable telemedicine applications.

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35

Abdulhamid, Mohanad, e James Karugu. "On the design of class-J microwave power amplifier". International Review of Applied Sciences and Engineering 10, n. 3 (dicembre 2019): 225–32. http://dx.doi.org/10.1556/1848.2019.0026.

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Abstract (sommario):

Due to the ISM band being unlicensed for communication applications, a lot of applications have been developed in this band and a good example is WiFi IEEE 802.11a, b, g, n of Bluetooth. This numeracy of applications motivated this paper. The paper is concerned with the design of a low distortion 20 dBm 2.4 GHz class-J power amplifier (PA) since PAs are indispensable in radio communications. The design is based on the AVAGO ATF-52189 transistor with a transition frequency of 6 GHz. The design is done as a hybrid circuit network realized using microstrip elements and surface mount device (SMD) capacitors. The schematic design and simulation are carried out using Keysight's Advanced Design System version 2016.01. The simulated PA exhibited a drain efficiency of 69% and a power output of 21 dBm.

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36

Abdulhamid, Mohanad, Karugu James e Muaayed Farhan. "On the Design of Class-J Microwave Power Amplifier". Scientific Bulletin of Electrical Engineering Faculty 19, n. 1 (1 aprile 2019): 6–12. http://dx.doi.org/10.1515/sbeef-2019-0002.

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Abstract (sommario):

AbstractDue to the ISM band being unlicensed for communication applications, a lot of applications have been developed in this band and a good example is WiFi IEEE802.11a, b, g, n of Bluetooth. This numeracy of applications motivated this paper. The paper is concerned with the design of a low distortion 20dBm 2.4GHz class-J power amplifier (PA) since PAs are indispensable in radio communications. The design is based on the AVAGO ATF-52189 transistor with a transition frequency of 6GHz. The design is done as a hybrid circuit network realized using microstrip elements and surface mount device (SMD) capacitors. The schematic design, and simulation are carried out using Keysight’s Advanced Design System version 2016.01. The simulated PA exhibited a drain efficiency of 69% and a power output of21dBm.

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37

Wilkinson, T. A., I. R. Johnson e S. K. Barton. "Performance of direct sequence spread spectrum ISM band radio LANs in a multipath time dispersive channel". Electronics Letters 29, n. 24 (1993): 2084. http://dx.doi.org/10.1049/el:19931392.

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38

Su. Suganthi, Dr, S. Aishwarya, S. Keerthana e B. R. Sandhya. "Raspberry PI based advanced communication for disaster management". International Journal of Engineering & Technology 7, n. 2.31 (29 maggio 2018): 74. http://dx.doi.org/10.14419/ijet.v7i2.31.13400.

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Abstract (sommario):

When a natural disaster occurs one of the major crisis is communication. This is mainly because when a calamity occurs all the cellular networks, towers and other contemporary means of network goes down making it impossible to communicate with others. Thus in this paper we propose an alternative solution for communication during disaster which can be achieved using a Long range radio transceiver module, which can operate without the help of any towers or base stations. The proposed transceiver model is a standalone device which can transmit and receive voice signals which operates on ISM band of frequency range 902 to 928 MHz, providing a hinderance free good communication, and as an additional feature is made to receive FM station signals using FM radio module, to keep us updated with the news, rescue and relief activities.

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39

Elhamraoui, Ahmed, El Hassan Abdelmounim, Jamal Zbitou, Ahmed Errkik, Hamid Bennis e Mohamed Latrach. "A new compact CPW-Fed dual-band monopole antenna for RFID applications". Indonesian Journal of Electrical Engineering and Computer Science 8, n. 1 (1 ottobre 2017): 69. http://dx.doi.org/10.11591/ijeecs.v8.i1.pp69-76.

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Abstract (sommario):

This paper presents a study of a new dual-band monopole antenna fed by a Coplanar Waveguide (CPW) line suitable for Radio Frequency Identification (RFID) applications especially designed for RFID readers and covering free ISM bands of 2.45GHz and 5.8GHz. The proposed antenna benefits from the advantages of the CPW line to simplify the structure of the antenna into a single metallic level, by consequent making it easier for integration with microwave integrated circuits. The simulation of the antenna was carried out using ADS from Agilent technologies and CST Microwave Studio electromagnetic solvers. A good impedance bandwidth of 500MHz is achieved in measurement (from 2.1GHz to 2.6GHz for the lower band), while the upper band covers 800MHz (from 5.2GHz to 6GHz). Details of the proposed antenna design and both simulated and experimental results are described and discussed.

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40

Zebiri, Sayad, Elfergani, Iqbal, Mshwat, Kosha, Rodriguez e Abd-Alhameed. "A Compact Semi-Circular and Arc-Shaped Slot Antenna for Heterogeneous RF Front-Ends". Electronics 8, n. 10 (6 ottobre 2019): 1123. http://dx.doi.org/10.3390/electronics8101123.

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Abstract (sommario):

In this paper, a new miniaturized compact dual-band microstrip slot antenna is presented. To achieve the dual-band characteristics, two adjunct partial arc-shaped small slots are joined to two main circular slots embedded in the ground of the antenna structure. With a reduced size of 30 × 28.5 × 0.8 mm3, the proposed antenna presents a dual-band characteristic. The design is optimized using a High Frequency Structure Simulator (HFSS) followed by experimental verifications. An impedance bandwidth, for S11≤10 dB, that covers the 1.8 GHz and 2.4 GHz bands is accomplished, which makes the proposed antenna basically suitable for hand-held devices and medical applications. More applications such as digital communication system (DCS) 1.71–1.88 GHz, personal communication services (PCS) 1.85–1.99 GHz, Universal and mobile telecommunications system UMTS 1.92–2.17 GHz, Bluetooth 2.4–2.5 GHz, and Wi-Fi 2.4–2.454 GHz, Industrial Scientific and Medical radio frequency (RF) band ISM-2.4 GHz, Wireless Local Area Network (WLAN-2.4)are possible by simply changing one of the geometrical antenna dimensions. The antenna is characterized by stable radiation patterns as well.

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41

Bhuiyan, Mohammad Arif Sobhan, Md Torikul Islam Badal, Mamun Bin Ibne Reaz, Maria Liz Crespo e Andres Cicuttin. "Design Architectures of the CMOS Power Amplifier for 2.4 GHz ISM Band Applications: An Overview". Electronics 8, n. 5 (29 aprile 2019): 477. http://dx.doi.org/10.3390/electronics8050477.

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Abstract (sommario):

Power amplifiers (PAs) are among the most crucial functional blocks in the radio frequency (RF) frontend for reliable wireless communication. PAs amplify and boost the input signal to the required output power. The signal is amplified to make it sufficiently high for the transmitter to propagate the required distance to the receiver. Attempted advancements of PA have focused on attaining high-performance RF signals for transmitters. Such PAs are expected to require low power consumption while producing a relatively high output power with a high efficiency. However, current PA designs in nanometer and micrometer complementary metal–oxide semiconductor (CMOS) technology present inevitable drawbacks, such as oxide breakdown and hot electron effect. A well-defined architecture, including a linear and simple functional block synthesis, is critical in designing CMOS PA for various applications. This article describes the different state-of-the art design architectures of CMOS PA, including their circuit operations, and analyzes the performance of PAs for 2.4 GHz ISM (industrial, scientific, and medical) band applications.

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42

Sharma, Deepti, Rakesh N. Tiwari, Sachin Kumar, Satyendra Sharma e Ladislau Matekovits. "A Compact Wearable Textile Antenna for NB-IoT and ISM Band Patient Tracking Applications". Sensors 24, n. 15 (5 agosto 2024): 5077. http://dx.doi.org/10.3390/s24155077.

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Abstract (sommario):

This paper proposes a novel multi-band textile monopole antenna for patient tracking applications. The designed antenna has compact footprints (0.13λ02) and works in the narrow band-internet of things (NB-IoT) 1.8 GHz, radio frequency identification (RFID), and industrial, scientific, and medical (ISM) 2.45 GHz and 5.8 GHz bands. The impedance bandwidths and gain of the antenna at 1.8 GHz, 2.45 GHz, and 5.8 GHz are 310 MHz, 960 MHz, and 1140 MHz; 3.7 dBi, 5.3 dBi, and 9.6 dBi, respectively. Also, the antenna’s behavior is checked on different body parts of the human body in various bending scenarios. As per the evaluated link budget, the designed antenna can easily communicate up to 100 m of distance. The specific absorption rate values of the designed antenna are also within acceptable limits as per the (FCC/ICNIRP) standards at the reported frequency bands. Unlike traditional rigid antennas, the proposed textile antenna is non-intrusive, enhancing user safety and comfort. The denim material makes it comfortable for extended wear, reducing the risk of skin irritation. It can also withstand regular wear and tear, including stretching and bending. The presented denim-based antenna can be seamlessly integrated into clothing and accessories, making it less obtrusive and more aesthetically pleasing.

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43

Du, Qing Zhi, Yi Peng, Qiu Ping Yang e Xiu Mei Yang. "A Novel Cognitive Frequency Hopping Mechanism for Bluetooth Network". Applied Mechanics and Materials 303-306 (febbraio 2013): 2002–6. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.2002.

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Abstract (sommario):

Bluetooth is a short-range wireless technology that operates in the 2.4GHz unlicensed ISM band, so it will inevitably encounter the interference from other wireless systems and other Bluetooth piconets. Because of the flexible, efficient and reliable spectrum access by adapting the radio’s operating characteristics to the real-time conditions of the environment, cognitive radio technology is apply in Bluetooth network. In this paper, a novel cognitive frequency hopping (CFH) scheme based on channel quality detection is proposed. The coexistence mechanism of Bluetooth network and link quality detection method is described and discussed. Simulation results shown the performance of the proposed CFH system is improved.

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44

Muhendra, Rifki. "Jaringan Sensor Nirkabel: Studi dan Evaluasi Kinerja LoRa Transmitter dan Long Range Radio Frekuensi (RF) Pada Luar Ruang". Jurnal Jaring SainTek 3, n. 1 (28 aprile 2021): 6–12. http://dx.doi.org/10.31599/jaring-saintek.v3i1.347.

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Abstract (sommario):

Transmitter merupakan tulang punggung komunikasi pada Jaringan Sensor Nirkabel. Sebagian besar transmitter menggunakan frekuensi ism band sehingga jangkauan komunikasinya terbatas sejauh 100 m. Beberapa jenis transmitter yang memiliki kemampuan komunikasi jarak jauh adalah nRF24 1 km dan LoRa. Paper ini melaporkan studi komperasi antara nRF24 1 km dan LoRa dalam komunikasi data, konsumsi daya dan ketahanan terhadap halangan. Hasil studi menunjukkan bahwa LoRa memiliki kemampuan jangkauan 1,6 km dan nRF24 memiliki kemampuan pengiriman sejauh 1 km. NRF24 1 km lebih cocok digunakan untuk komunikasi jarak jauh yang membutuhkan kecepatan yang tinggi dan juga tahan terhadap halangan non- line of sight.

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Gutiérrez-Gómez, Amado, Víctor Rangel, Robert M. Edwards, John G. Davis, Raúl Aquino, Jesús López-De la Cruz, Oliver Mendoza-Cano, Miguel Lopez-Guerrero e Yu Geng. "A Propagation Study of LoRa P2P Links for IoT Applications: The Case of Near-Surface Measurements over Semitropical Rivers". Sensors 21, n. 20 (16 ottobre 2021): 6872. http://dx.doi.org/10.3390/s21206872.

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Abstract (sommario):

Internet of Things (IoT) radio networks are becoming popular in several scenarios for short-range applications (e.g., wearables and home security) and medium-range applications (e.g., shipping container tracking and autonomous farming). They have also been proposed for water monitoring in flood warning systems. IoT communications may use long range (LoRa) radios working in the 915 MHz industrial, scientific and medical (ISM) band. In this research, we study the propagation characteristics of LoRa chirp radio signals close to and over water in a tropical meadow region. We use as a case study the Colima River in Mexico. We develop a novel point-to-point IoT measurement sounding system that does not require decoding of LoRa propriety bursts and provides accurate power versus distance profiles along the riparian zone of a steeply dropping mountain river. We used this system to obtain the measurements reported in this work, which are also analyzed and modeled. The results show that the LoRa signal propagation over water exhibits a log-normal distribution. As a result of the chirp signal processing, two new experimental path loss models are presented. The path loss results show a considerable degradation of the received signal power over water within vegetation and less signal degradation at antenna heights closer to the water surface.

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BharathiDevi, Boyapati, e Jayendra Kumar. "Small frequency range discrete bandwidth tunable multiband MIMO antenna for radio/LTE/ISM-2.4 GHz band applications". AEU - International Journal of Electronics and Communications 144 (febbraio 2022): 154060. http://dx.doi.org/10.1016/j.aeue.2021.154060.

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47

Shuriji, Mushreq Abdulhussain, e Raad Hamdan Thaher. "A reconfigurable switching diode loaded patch antenna for S, C, X, Ku, and K bands applications". Bulletin of Electrical Engineering and Informatics 13, n. 1 (1 febbraio 2024): 247–53. http://dx.doi.org/10.11591/eei.v13i1.5738.

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Abstract (sommario):

A reconfigurable patch loaded via a switching radio frequency (RF) diode has been designed, investigated, and fabricated. The fabricated microstrip is able to adjust among several frequencies. A spectrum analyzer is used to test and measure different modes of operations. The proposed antenna is offered a new solution of uncomplicated and incomplex design via eliminating the biasing circuit while maintaining the finest performance. Two fast-switching diodes have been inserted as a new electrical reconfiguration technique. Thus, the suggested antenna is skilled to function in different bands. An ultra-small size antenna of 31×21 mm2 has offered various operating frequencies such as S-band at 2.4 GHz, C-band at 4.97 GHz, 5.06 GHz, 5.18 GHz, 5.1 GHz, and 7.94 GHz, X-band at 10.73 GHz, 10.91 GHz, and 11.9 GHz, Ku-band at 13.52 GHz, 14.78 GHz, 14.97 GHz, 15.63 GHz, 16.4 GHz, 17.3 GHz, and 17.48 GHz, and K-band at 19 GHz. The manufactured reconfigurable patch antenna is proficient for several wireless technologies for instance industrial scientific medical band (ISM): Bluetooth, wireless-fidelity (Wi-Fi), ZigBee, internet of things (IoT), WiMAX, and smart power meters. Also, long term evolution (LTE), 5G applications, fixed wireless systems (FWS), and satellite communication applications.

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48

Van Brandt, Seppe, Robbe Van Thielen, Jo Verhaevert, Tanja Van Hecke e Hendrik Rogier. "Characterization of Path Loss and Large-Scale Fading for Rapid Intervention Team Communication in Underground Parking Garages". Sensors 19, n. 11 (28 maggio 2019): 2431. http://dx.doi.org/10.3390/s19112431.

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Abstract (sommario):

This paper reports the characterization of the 2.45-GHz-ISM-band radio wave propagation channel. Specifically, measurements were performed in an underground parking garage, with the aim of optimizing breadcrumb systems for a Rapid Intervention Team application. The effects of the high penetration loss and large reflections by the concrete reinforced building structure on the path loss and the large-scale fading were studied. Based on the analysis of the wireless channel, critical points for reliable communication between members of a Rapid Intervention Team were identified. In particular, attention was paid to dealing with large, spatially confined signal losses due to shadowing, the anticipation of corner losses and the ability of the system to operate on multiple floors.

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Li, Bing, Da Peng Li e Ji Ping Wang. "Fabrication and Evaluation of Electro-Textiles for Wearable Antenna Applications". Key Engineering Materials 671 (novembre 2015): 237–41. http://dx.doi.org/10.4028/www.scientific.net/kem.671.237.

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Abstract (sommario):

A compact wearable antenna fully made of textile-based materials for short range communication was designed and fabricated. A 3-axis automated dispensing robot coupled with a precision liquid dispenser was used to sequentially deliver copper sulfate (CuSO4) and sodium borohydride (NaBH4) on fabric surface to form conductive copper coatings. The copper coatings were characterized using scanning electron microscope (SEM) and X-Ray Diffraction (XRD). The performance of antennas assembled with such copper-coated conductive textiles was accessed by transmission line method for their S11parameter values. The results demonstrated that such electroconductive textile-based antennas may serve as a wearable device and operate in the license free 2.45 GHz industrial, scientific and medical (ISM) radio band.

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50

Cuzanauskas, Tomas, e Aurimas Anskaitis. "APPLYING GAME THEORY IN 802.11 WIRELESS NETWORKS / ŽAIDIMŲ TEORIJOS TAIKYMAS IEEE 802.11 TINKLUOSE". Mokslas – Lietuvos ateitis 7, n. 3 (13 luglio 2015): 345–49. http://dx.doi.org/10.3846/mla.2015.797.

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Abstract (sommario):

IEEE 802.11 is one of the most popular wireless technologies in recent days. Due to easiness of adaption and relatively low cost the demand for IEEE 802.11 devices is increasing exponentially. IEEE works in two bands 2.4 GHz and 5 GHz, these bands are known as ISM band. The unlicensed bands are managed by authority which set simple rules to follow when using unlicensed bands, the rules includes requirements as maximum power, out-of-band emissions control as well as interference mitigation. However these rules became outdated as IEEE 802.11 technology is emerging and evolving in hours the rules aren’t well suited for current capabilities of IEEE 802.11 devices. In this article we present game theory based algorithm for IEEE 802.11 wireless devices, we will show that by using game theory it’s possible to achieve better usage of unlicensed spectrum as well as partially decline CSMA/CA. Finally by using this approach we might relax the currently applied maximum power rules for ISM bands, which enable IEEE 802.11 to work on longer distance and have better propagation characteristics. Lengvai pritaikoma ir panaudojama įvairiuose sprendimuose IEEE 802.11 technologija tapo viena populiariausių bevielių technologijų. IEEE 802.11 įrenginiai veikia nelicencijuotais 5 GHz ir 2,4 GHz dažniais – pramonės, mokslo ir medicinos dažnių ruože (angl. Industrial, scientific and medical (ISM) radio bands). Šiam dažnių ruožui taikomos supaprastintos taisyklės, nurodančios, kad įrenginiai, veikiantys ISM dažniais, turi atitikti tik maksimalią signalo perdavimo galią ir interferencijos triukšmus bei neviršyti triukšmo normos už dažnių ruožo ribų. Tobulėjant IEEE 802.11 protokolo įrangai, šios taisyklės tapo nelanksčios ir neatitinka dabartinių įrenginių galimybių. Straipsnyje pristatomas naujas IEEE 802.11 įrenginių kanalo prieigos metodas, pagrįstas žaidimų teorija. Parodoma, kad taikant šį metodą galima pagerinti spektro panaudojimo efektyvumą bei kartu iš dalies atsisakyti dabar egzistuojančio CSMA/CA mechanizmo IEEE 802.11 įrenginiuose. Taikant efektyvesnį kanalo prieigos metodą atsiranda galimybė laikytis lankstesnių siųstuvo galių taisyklių ir taip padidinti skvarbą uždarose patalpose bei įrangos veikimo nuotolį.

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