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Готові списки джерел за темами / Q multibande

Добірка наукової літератури з теми "Q multibande"

Автор: Grafiati

Опубліковано: 8 червня 2022

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Статті в журналах
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Тези доповідей конференцій

Статті в журналах з теми "Q multibande":

1

Cismasu, Marius, and Mats Gustafsson. "Multiband Antenna ${Q}$ Optimization Using Stored Energy Expressions." IEEE Antennas and Wireless Propagation Letters 13 (2014): 646–49. http://dx.doi.org/10.1109/lawp.2014.2313656.

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2

Journal, Baghdad Science. "design of multiband reflectors adapting the concept of stack." Baghdad Science Journal 2, no. 2 (June 5, 2005): 253–59. http://dx.doi.org/10.21123/bsj.2.2.253-259.

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Designed Mirrors double and triple package adoption concept heap where they were changing the thickness of the layers within periodic basis of the pile and different ratios (p: q) in addition to change the refractive index of materials within periodic basis and its impact on sites Dhour tops high reflectivity study included spectral region visible and infrared, depending on NdharahFeatured matrix adjusted fall of light close to the vertical arrangement multilayer dielectric materials and thin films homogeneous and uniform

3

Zhou, Jin, Zhengqi Liu, Xiaoshan Liu, Pingping Pan, Xuefeng Zhan, and Zhongmin Liu. "Silicon-Au nanowire resonators for high-Q multiband near-infrared wave absorption." Nanotechnology 31, no. 37 (June 30, 2020): 375201. http://dx.doi.org/10.1088/1361-6528/ab98be.

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4

Marttila, Jaakko, Markus Allén та Mikko Valkama. "Quadrature ΣΔ Modulators for Cognitive Radio—I/Q Imbalance Analysis and Complex Multiband Principle". Circuits, Systems, and Signal Processing 30, № 4 (4 травня 2011): 775–97. http://dx.doi.org/10.1007/s00034-011-9302-0.

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5

Albarracin-Vargas, Fernando, Felix Vega, Chaouki Kasmi, David Martinez, and Lars Ole Fichte. "Enhanced integrated multiband HPM radiator, combining a hyperband source with a high-Q frequency selective surface." Comptes Rendus. Physique 22, S1 (May 6, 2021): 1–10. http://dx.doi.org/10.5802/crphys.63.

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6

Xiong, Zhonggang, Liping Shang, Hu Deng, Liang Xiong, Linyu Chen, Jin Guo, and Guilin Li. "High-Sensitivity Multiband Detection Based on the Local Enhancement Effect of an Electric Field at Terahertz Frequency." Journal of Sensors 2022 (April 25, 2022): 1–13. http://dx.doi.org/10.1155/2022/1533866.

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The terahertz detection sensitivity interaction with other substances has received extensive attention and remains challenging due to the loss of terahertz waves. Herein, a terahertz, multiband sensor with high sensitivity based on the local enhancement effect of an electric field at terahertz frequency is proposed. The designed terahertz sensor is based on a common metamaterial sandwich absorber of electromagnetic energy that only employs an asymmetric metallic strip, which produces three resonance peaks with an absorption coefficient of greater than 95% in the 0.2-1.5 THz range and a maximum Q -factor of 46 at 1.397. Based on the principle of impedance matching, the high absorption of electromagnetic wave energy is reasonably analyzed. Furthermore, the influence of the top metal structure on the absorptivity and resonance frequency is analyzed by simulation optimization, and the optimum structural parameters are obtained. In addition, the influence of the refractive index (RI) change of the sample and dielectric layer on the resonance characteristics of the sensor is analyzed. When the thickness of the surface sample of the terahertz sensor metamaterial-based absorber is changed so that the RI changes in 1-2, the RI sensitivity increases up to 208 GHz/RIU, which can be used as an RI sensor. Furthermore, the influence of the sensor sensitivity and reflection coefficient on the thickness parameters of the sample covered by the sensor surface is analyzed, and the optimal sample thickness is 6 μm. The influence of the incident angle of the THz wave on the detection performance in the TM polarization mode is analyzed, and it is determined that the change in the incident angle in the range of 0-40 degrees has minimal influence on the resonance peak and absorption rate of multiband detection. Therefore, we suggest that our proposed sensor has considerable potential in biomedicine and trace detection applications.

7

Xiong, Zhonggang, Liping Shang, Hu Deng, Liang Xiong, Linyu Chen, Jin Guo, and Guilin Li. "High-Sensitivity Multiband Detection Based on the Local Enhancement Effect of an Electric Field at Terahertz Frequency." Journal of Sensors 2022 (April 25, 2022): 1–13. http://dx.doi.org/10.1155/2022/1533866.

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The terahertz detection sensitivity interaction with other substances has received extensive attention and remains challenging due to the loss of terahertz waves. Herein, a terahertz, multiband sensor with high sensitivity based on the local enhancement effect of an electric field at terahertz frequency is proposed. The designed terahertz sensor is based on a common metamaterial sandwich absorber of electromagnetic energy that only employs an asymmetric metallic strip, which produces three resonance peaks with an absorption coefficient of greater than 95% in the 0.2-1.5 THz range and a maximum Q -factor of 46 at 1.397. Based on the principle of impedance matching, the high absorption of electromagnetic wave energy is reasonably analyzed. Furthermore, the influence of the top metal structure on the absorptivity and resonance frequency is analyzed by simulation optimization, and the optimum structural parameters are obtained. In addition, the influence of the refractive index (RI) change of the sample and dielectric layer on the resonance characteristics of the sensor is analyzed. When the thickness of the surface sample of the terahertz sensor metamaterial-based absorber is changed so that the RI changes in 1-2, the RI sensitivity increases up to 208 GHz/RIU, which can be used as an RI sensor. Furthermore, the influence of the sensor sensitivity and reflection coefficient on the thickness parameters of the sample covered by the sensor surface is analyzed, and the optimal sample thickness is 6 μm. The influence of the incident angle of the THz wave on the detection performance in the TM polarization mode is analyzed, and it is determined that the change in the incident angle in the range of 0-40 degrees has minimal influence on the resonance peak and absorption rate of multiband detection. Therefore, we suggest that our proposed sensor has considerable potential in biomedicine and trace detection applications.

8

AEPPLI, G. "MAGNETIC FLUCTUATIONS IN METALLIC AND SUPERCONDUCTING La2−xSrxCuO4." International Journal of Modern Physics B 06, no. 05n06 (March 1992): 451–52. http://dx.doi.org/10.1142/s0217979292000244.

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The full momentum and energy dependent magnetic susceptibility χ(Q, ω) is a fundamental quantity which determines many readily measured properties, such as bulk susceptibilities and nuclear magnetic relaxation rates. Because there is still no agreement on the origin of the many anomalous properties of the high-Tc compounds, we have used inelastic neutron scattering to establish χ(Q, ω) in insulating metallic and superconducting samples of La 2−x Sr x CuO 4, arguably the simplest of the layered cuprous oxides. For the (x=0) insulator χ(Q, ω) has been determined throughout the Brioullin zone. At ω/ T >1, it is dominated by spin waves with a zone edge energy of 0.312±0.005 eV. (1,2) As x is increased and the metallic phase approached, the long wavelength anitiferromagnetic fluctuations become more rapid in a manner consistent with the marginal Fermi liquid Ansatz.(3) Finally, for the most metallic samples, the peak in the magnetic response found in the insulator at (π,π) (the antiferromagnetic ordering vector of pure La 2 CuO 4) splits into four maxima.(4) The correlation length at (π,π)±(π,0)δ and (π,π)±(0,π)δ does not depend strongly on x, and for x=0.14, is considerably longer than the spacing between holes in the CuO2 planes. However, ξ is strongly temperature-dependent, in contrast to what occurs for more insulating (lower x) crystals. Taken together, the results can be taken as evidence for the emergence of a Fermi surface, with the incommensurabilities corresponding to nesting vectors, and ξ corresponding to a mean free path for the carriers. In other words, the neutron scattering measurement is giving information of a type ordinarily yielded by de Haas van Alphen data. While the relatively large values for δ are inconsistent with single-band models for the CuO 2 planes, P. Littlewood and collaborators(5) have shown that Fermi surface nesting in a multiband model with reasonable hopping parameters can account for the observations at low temperatures.

9

Ueda, Takahiro, Akimasa Kataoka, and Takashi Tsukagoshi. "Massive Compact Dust Disk with a Gap around CW Tau Revealed by ALMA Multiband Observations." Astrophysical Journal 930, no. 1 (May 1, 2022): 56. http://dx.doi.org/10.3847/1538-4357/ac634d.

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Abstract Compact protoplanetary disks with a radius of ≲50 au are common around young low-mass stars. We report high-resolution ALMA dust continuum observations toward a compact disk around CW Tau at Bands 4 (λ = 2.2 mm), 6 (1.3 mm), 7 (0.89 mm), and 8 (0.75 mm). The spectral energy distribution shows the spectral slope of 2.0 ± 0.24 between 0.75 and 1.3 mm, while it is 3.7 ± 0.29 between 2.17 and 3.56 mm. The steep slope between 2.17 and 3.56 mm is consistent with that of optically thin emission from small grains (≲350 μm). We perform parametric fitting of the ALMA data to characterize the dust disk. Interestingly, if the dust-to-gas mass ratio is 0.01, the Toomre Q parameter reaches ∼1–3, suggesting that the CW Tau disk might be marginally gravitationally unstable. The total dust mass is estimated as ∼250 M ⊕ for the maximum dust size of 140 μm that is inferred from the previous Band 7 polarimetric observation and at least 80 M ⊕ even for larger grain sizes. This result shows that the CW Tau disk is quite massive in spite of its smallness. Furthermore, we clearly identify a gap structure located at ∼20 au, which might be induced by a giant planet. In spite of these interesting characteristics, the CW Tau disk has normal disk luminosity, size, and spectral index at ALMA Band 6, which could be a clue to the mass budget problem in Class II disks.

10

Firmansyah, Teguh, Anggoro Suryo Pramudyo, Siswo Wardoyo, Romi Wiryadinata, and Alimuddin Alimuddin. "Concurrent Quad-band Low Noise Amplifier (QB-LNA) using Multisection Impedance Transformer." International Journal of Electrical and Computer Engineering (IJECE) 7, no. 4 (August 1, 2017): 2061. http://dx.doi.org/10.11591/ijece.v7i4.pp2061-2070.

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<span>A quad-band low noise amplifier (QB-LNA) based on multisection impedance transformer designed and evaluated in this research. As a novelty, a multisection impedance transformer was used to produce QB-LNA. A multisection impedance transformer is used as input and output impedance matching because it has higher stability, large Q factor, and low noise than lumpedcomponent.The QB-LNA was designed on FR4 microstrip substrate with </span><span>e</span><span>r= 4.4, thickness h=0.8 mm, and tan </span><span>d</span><span>= 0.026. The proposed QB-LNA was designed and analyzed by Advanced Design System (ADS).The simulation has shown that QB-LNA achieves gain (S<sub>21</sub>) of 22.91 dB, 16.5 dB, 11.18 dB, and 7.25 dB at 0.92 GHz, 1.84 GHz, 2.61 GHz, and 3.54 GHz, respectively.The QB-LNA obtainreturn loss (S<sub>11</sub>) of -21.28 dB, -31.87 dB, -28.08 dB, and -30.85 dB at 0.92 GHz, 1.84 GHz, 2.61 GHz, and 3.54 GHz, respectively. It also achieves a noise figure (nf) of 2.35 dB, 2.13 dB, 2.56 dB, and 3.55 dB at 0.92 GHz, 1.84 GHz, 2.61 GHz, and 3.54 GHz, respectively. This research also has shown that the figure of merit (FoM) of the proposed QB-LNA is higher than that of another multiband LNA.</span>

Більше джерел

Дисертації з теми "Q multibande":

1

Abdi, Abyaneh Mohammad. "Génération des signaux agrégés en fréquences dans le contexte de LTE-A." Thesis, Paris, ENST, 2016. https://pastel.archives-ouvertes.fr/tel-03689710.

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Dans ce travail de thèse, on a proposé une structure de génération des signaux multi-porteuse afin de créer plusieurs oscillateurs locaux (OL ) tout en utilisant qu’un modulateur I/Q. Ces signaux peuvent être utilisés dans les récepteurs de LTE-A pour la transposition des signaux agrégé en fréquence vers la bande de base. On développe la structure afin de l’utiliser en émetteur répondant aux normes du standard LTE-A. La nouvelle structure nous permet de générer n signaux agrégés en fréquences, de manière simultanée, par une seule chaîne de transmission (c.a.d un modulateur I/Q, un OL). En utilisant cette structure on réduit le nombre de circuits utilisés, en comparaison du cas où n signaux agrégés en fréquences sont générés par n émetteurs. La fréquence d’échantillonnage est réduite dans notre cas par rapport au cas où les signaux sont générés directement de la bande de base à la bande RF avec des convertisseurs analogiques numériques adéquats. Dans la troisième partie, on se concentre sur les imperfections et les non linéarités du modulateur I/Q dans le cadre de notre structure multibande. On modélise le fonctionnement du modulateur multi-bande en utilisant les échantillons en entrée et en sortie. Notre modèle est dérivé de la série de Volterra qui prends en compte les effets non linéaires et les effets mémoires ainsi que les imperfections du modulateur I/Q. Puis, on obtient la fonction "inverse" du modèle et on l’applique à l’entrée du modulateur afin de corriger et linéariser la sortie du modulateur I/Q. La fonction "inverse" est appelée DPD (en anglais : Digital Pre-Distortion). Enfin, on a évalué le modèle et la DPD en simulations et en mesures
In this dissertation, a signal generation structure is proposed using which a multitone Local Oscillator (LO) signal is created by a single I/Q modulator. These LOs can be used in the CA receivers to down-convert the transmitted component carriers simultaneously. The multi-tone LO signal structure is further developed to be used at the transmitter as a CA generation solution. Using the proposed structure n-component carriers can be generated in parallel. This structures requires lower sampling rates with respect to the case where RF signals are synthesized directly by digital-to- analog converters. Moreover, less circuitry is required, because one single I/Q modulator is used to generate n component carriers, instead of n I/Q modulators. This work follows on investigating the origin of impairments and mild nonlinearities in our I/Q modulator. To overcome these problems, we focus on the functionality of the overall system rather than each component of the I/Q modulator. This method is called behavioral modeling. Once the nonlinear model is obtained, if its inverse function is applied to the input, a linearized output is expected. The generation of the inverse function is called Digital Pre-Distortion (DPD). We propose a tri-band behavioral model for nonlinearities and impairments in tri-band CA using our I/Q modulator. Furthermore, the DPD of the model is evaluated in simulations and experiments

2

Maxwell, Michael. "Multiband observations of recurrent novae." Thesis, University of Central Lancashire, 2014. http://clok.uclan.ac.uk/10719/.

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Recurrent novae are binary systems which undergo outbursts due to a thermonuclear runaway on a timescale of decades. Two systems, U Scorpii and RS Ophiuchi, are the main focus of this thesis having gone into outburst in 2010 and 2006 respectively. Optical and near-IR spectroscopy of U Sco obtained with facilities including the Liverpool Telescope, the Very Large Telescope, and the Southern African Large Telescope, as well as ultra-violet and optical spectroscopy of RS Oph obtained with the Ultra-Violet and Optical Telescope, are presented here. Observations of U Sco obtained in outburst are used to determine the helium abundance of the ejecta, with observations in quiescence used to constrain the nature of the companion star and the accretion disc. Observations of RS Oph are used to produce lightcurves of the decline from maximum to the post-outburst minimum. Analysis of optical and near-IR spectra following the 2010 outburst of U Sco leads to the determination of the reddening and the helium abundance. The reddening is found to be E(B-V) = 0.17 ± 0.14, consistent with previous estimates. The helium abundance, N(He)/N(H), is determined to be 0.122 ± 0.018, lower than previous estimates and suggesting that the companion is not helium rich. The fitting of model stellar atmospheres to observations of U Sco in quiescence, obtained ∼18-30 months after the 2010 outburst, constrains the effective temperature of the companion and indicates that it is a cool F or hot G star. The accretion disc is found to be still in a state of development until at least ∼18 months after outburst, contrary to previous studies. The strength of the Heii 4686 ̊A line in quiescence is found to be consistent with a high mass white dwarf accreting solar-abundance material at a high rate. The He line strengths do not require an overabundance of helium, as has been previously suggested, consistent with the solar abundance of helium found in the ejecta of the 2010 outburst. UVOT observations of RS Oph following the 2006 outburst are used to produce B and u′ lightcurves of the decline to minimum. These lightcurves are used in con- junction with published V and B lightcurves to show the change in the colour of the system throughout the outburst. Spectra of RS Oph show the spectroscopic evolution during the initial decline, plateau, final decline, and post-outburst minimum phases. SALT spectra obtained during the late decline phase of the 2011 outburst of a third recurrent nova, T Pyxidis, are used to derive a helium abundance of N(He)/N(H)= 0.161 ± 0.013, approximately twice the solar value. Very strong [O iii] lines are also detected.

3

Reja, Md Mahbub. "Design of Active CMOS Multiband Ultra-Wideband Receiver Front-End." Phd thesis, 2011. http://hdl.handle.net/10048/1922.

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Inductors are extensively used in the design of radio-frequency circuits. In the last decade, the integration of passive components, especially inductors on silicon chips, has led to the widespread development and implementation of Radio Frequency Integrated Circuits (RFICs) in CMOS technologies. However, on-chip passive inductors occupy a large silicon chip area and hardly scale down with technology scaling. Therefore, on-chip passive inductors become formidable obstacles to the realization of highly dense RFICs to be integrated with other highly dense digital circuits on a single chip using a common fabrication process. In recent years, researchers have focused on replacing passive inductors with transistor-only active circuits, namely active inductors. Active inductors can be realized with only a few transistors, which scale down with technology scaling. Therefore, they occupy a fraction of the chip area of their passive counterparts, and can be implemented densely in CMOS processes. Unlike passive inductors, bias dependent operations of active inductors allow for the tuning of their inductance and quality factor Q, and in turn, tuning the performance parameters of RFICs. This thesis focuses on the design and development of passive inductorless CMOS RFICs for ultra-wideband (UWB) receiver front-ends using active inductors. A new Q-enhanced and a new bandwidth-extended tunable active inductors are designed. Using the Q-enhanced active inductor, two tunable UWB low-noise amplifiers (LNAs) (two-stage and three-stage UWB LNAs), a UWB mixer and a wideband local-oscillator (LO) driver are designed. Active inductors are utilized to develop a novel wideband active shunt-peaking technique that decreases high-frequency losses to yield a flat gain over a wide bandwidth. A tunable multiband-UWB front-end integrating a two-stage UWB LNA, and a pair of UWB mixers driven by a pair of wideband LO drivers, is fabricated in a 90nm digital CMOS process. The passive inductorless two-stage UWB LNA, three-stage UWB LNA and UWB front-end occupy chip areas of only 0.0114mm2, 0.0227mm2, and 0.1485mm2, respectively. The active CMOS UWB front-end exhibits a measured flat gain of 22.5dB over 2.5-8.8 GHz bandwidth, and its tunability allows for varying the gain and bandwidth.
Integrated Circuits and Systems

Тези доповідей конференцій з теми "Q multibande":

1

Nguyen, Ha Q., Binh T. Nguyen, Trung Q. Dong, Dat T. Ngo, and Tuan A. Nguyen. "Deep Q-Learning with Multiband Sensing for Dynamic Spectrum Access." In 2018 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN). IEEE, 2018. http://dx.doi.org/10.1109/dyspan.2018.8610402.

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2

Shoufeng Lu, Ximin Liu, and Shiqiang Dai. "Adaptive and coordinated traffic signal control based on Q-learning and Multiband model." In 2008 IEEE Conference on Cybernetics and Intelligent Systems (CIS). IEEE, 2008. http://dx.doi.org/10.1109/iccis.2008.4670819.

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3

Gamlath, Chris, Eyad Arabi, Kevin A. Morris, and Mark Beach. "A design technique for concurrent multiband tunable loads from 0.4–6GHz with independent Q tuning." In 2017 IEEE Asia Pacific Microwave Conference (APMC). IEEE, 2017. http://dx.doi.org/10.1109/apmc.2017.8251615.

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4

Rosa, Gabriele Di, Robert Emmerich, Matheus Sena, Johannes K. Fischer, Colja Schubert, and Andre Richter. "Impact of Wavelength-Dependent I/Q Imbalances of Standard C-Band Transceivers in Rate-Adaptive Multiband Systems." In 2021 European Conference on Optical Communication (ECOC). IEEE, 2021. http://dx.doi.org/10.1109/ecoc52684.2021.9606117.

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