Статті в журналах: "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

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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.

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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.

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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.

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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.

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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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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 er= 4.4, thickness h=0.8 mm, and tan d= 0.026. The proposed QB-LNA was designed and analyzed by Advanced Design System (ADS).The simulation has shown that QB-LNA achieves gain (S21) 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 (S11) 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.

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11

Vallis, Geoffrey K., Greg Colyer, Ruth Geen, Edwin Gerber, Martin Jucker, Penelope Maher, Alexander Paterson, Marianne Pietschnig, James Penn, and Stephen I. Thomson. "Isca, v1.0: a framework for the global modelling of the atmospheres of Earth and other planets at varying levels of complexity." Geoscientific Model Development 11, no. 3 (March 6, 2018): 843–59. http://dx.doi.org/10.5194/gmd-11-843-2018.

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Abstract. Isca is a framework for the idealized modelling of the global circulation of planetary atmospheres at varying levels of complexity and realism. The framework is an outgrowth of models from the Geophysical Fluid Dynamics Laboratory in Princeton, USA, designed for Earth's atmosphere, but it may readily be extended into other planetary regimes. Various forcing and radiation options are available, from dry, time invariant, Newtonian thermal relaxation to moist dynamics with radiative transfer. Options are available in the dry thermal relaxation scheme to account for the effects of obliquity and eccentricity (and so seasonality), different atmospheric optical depths and a surface mixed layer. An idealized grey radiation scheme, a two-band scheme, and a multiband scheme are also available, all with simple moist effects and astronomically based solar forcing. At the complex end of the spectrum the framework provides a direct connection to comprehensive atmospheric general circulation models. For Earth modelling, options include an aquaplanet and configurable continental outlines and topography. Continents may be defined by changing albedo, heat capacity, and evaporative parameters and/or by using a simple bucket hydrology model. Oceanic Q fluxes may be added to reproduce specified sea surface temperatures, with arbitrary continental distributions. Planetary atmospheres may be configured by changing planetary size and mass, solar forcing, atmospheric mass, radiation, and other parameters. Examples are given of various Earth configurations as well as a giant planet simulation, a slowly rotating terrestrial planet simulation, and tidally locked and other orbitally resonant exoplanet simulations. The underlying model is written in Fortran and may largely be configured with Python scripts. Python scripts are also used to run the model on different architectures, to archive the output, and for diagnostics, graphics, and post-processing. All of these features are publicly available in a Git-based repository.

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12

"Design, Simulation and Fabrication of Multiband Antenna using HFSS." International Journal of Recent Technology and Engineering 8, no. 2 (July 30, 2019): 5851–59. http://dx.doi.org/10.35940/ijrte.b3775.078219.

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Microstrip antennas are popular because of their low profile, light weight and low cost but narrow bandwidth and gain are the main disadvantages of this antenna. In this paper Multiband Octagonal Patch Antenna has been designed by ring slot technique for working in nine different frequencies presented in multi band C-band, X-band, Ku-band, K-band, Ka-band, Q-band and U-bands. Main applications of these bands are used in terrestrial microwave communications. In this research work, the performance of octagonal patch antenna operating at 7 different bands is analyzed. The Design methodology of the proposed research carried in 2 major modules. 1. Design of Single Octagonal Ring Slot antenna, 2. Design of Double Octagonal Ring Slot antenna. In the first design a single octagonal ring slot microstrip patch antenna is developed which resonates at six frequencies of five different frequency bands of C-band, Ku-band, K-band, Q-band and U-bands. In the second design a double octagonal ring slot microstrip patch antenna is developed which resonates at nine frequencies of six different frequency bands of X-band, Ku-band, K-band, Ka-band, Q-band and U-bands. The proposed antenna has been simulated by HFSS and measured by combinational analyzer.

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13

"Design of Concentric Circular Antenna for Multiband applications." International Journal of Recent Technology and Engineering 8, no. 2 (July 30, 2019): 4060–64. http://dx.doi.org/10.35940/ijrte.b3469.078219.

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Design of Concentric Circular Antenna for Multiband Applications should be presented in this paper. In this paper the concentric circular antenna has been designed and propound and then operates at S, C, X, Ku, K, Ka and Q bands. In order to improve the radiation characteristics the concentric slots are introduced. The designed antenna operated at a frequency from 1 to 40 GHZ for return loss -10dB. The designed antenna substrate length (L1) and width (W1) are 34 mm x 36 mm and it coated with FR4 epoxy material. The line capacitance and inductance of circular patch are increased by use of concentric circular slots. The concentric circular antenna is studied and simulated to operate at seven different frequencies at 3.43GHZ, 7.63GHZ, 10.51GHZ, 15.98GHZ, 24.58GHZ, 30.28GHZ and 35.67GHZ. The concentric circular antenna uses HFSS v.13.0 (High Frequency Structure simulator) for design and simulation purposes.

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14

Bhattacharya, Angana, Rakesh Sarkar, Naval K. Sharma, Bhairov K. Bhowmik, Amir Ahmad, and Gagan Kumar. "Multiband transparency effect induced by toroidal excitation in a strongly coupled planar terahertz metamaterial." Scientific Reports 11, no. 1 (September 28, 2021). http://dx.doi.org/10.1038/s41598-021-98498-4.

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AbstractThe multiband transparency effect in terahertz (THz) domain has intrigued the scientific community due to its significance in developing THz multiband devices. In this article, we have proposed a planar metamaterial geometry comprised of a toroidal split ring resonator (TSRR) flanked by two asymmetric C resonators. The proposed geometry results in multi-band transparency windows in the THz region via strong near field coupling of the toroidal excitation with the dipolar C-resonators of the meta molecule. The geometry displays dominant toroidal excitation as demonstrated by a multipolar analysis of scattered radiation. High Q factor resonances of the metamaterial configuration is reported which can find significance in sensing applications. We report the frequency modulation of transparency windows by changing the separation between TSRR and the C resonators. The numerically simulated findings have been interpreted and validated using an equivalent theoretical model based upon three coupled oscillators system. Such modeling of toroidal resonances may be utilized in future studies on toroidal excitation based EIT responses in metamaterials. Our study has the potential to impact the development of terahertz photonic components useful in building next generation devices.

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15

Moniruzzaman, Md, Mohammad Tariqul Islam, Norbahiah Misran, Md Samsuzzaman, Touhidul Alam, and Muhammad E. H. Chowdhury. "Inductively tuned modified split ring resonator based quad band epsilon negative (ENG) with near zero index (NZI) metamaterial for multiband antenna performance enhancement." Scientific Reports 11, no. 1 (June 7, 2021). http://dx.doi.org/10.1038/s41598-021-91432-8.

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AbstractAn inductively tuned modified split-ring resonator-based metamaterial (MTM) is presented in this article that provides multiple resonances covering S, C, X, and Ku-bands. The MTM is designed on an FR-4 substrate with a thickness of 1.5 mm and an electrical dimension of 0.063λ × 0.063λ where wavelength, λ is calculated at 2.38 GHz. The resonator part is a combination of three squared copper rings and one circular ring in which all the square rings are modified shaped, and the inner two rings are interconnected. The resonance frequency is tuned by adding inductive metal strips in parallel two vertical splits of the outer ring that causes a significant shift of resonances towards the lower frequencies and a highly effective medium ratio (EMR) of 15.75. Numerical simulation software CST microwave studio is used for the simulation and performance analysis of the proposed unit cell. The MTM unit cell exhibits six resonances of transmission coefficient (S21) at 2.38, 4.24, 5.98, 9.55, 12.1, and 14.34 GHz covering S, C, X, and Ku-bands with epsilon negative (ENG), near-zero permeability, and near-zero refractive index (NZI). The simulated result is validated by experiment with good agreement between them. The performance of the array of the unit cells is also investigated in both simulation and measurement. The equivalent circuit modeling has been accomplished using Advanced Design Software (ADS) that shows a similar S21 response compared to CST simulation. Noteworthy to mention that with the copper backplane, the same unit cell provides multiband absorption properties with four major absorption peaks of 99.6%, 95.7%, 99.9%, 92.7% with quality factors(Q-factor) of 28.4, 34.4, 23, and 32 at 3.98, 5.5, 11.73 and 13.47 GHz, respectively which can be applied for sensing and detecting purposes. The application of an array of the unit cells is investigated using it as a superstrate of an antenna that provides a 73% (average) increase of antenna gain. Due to its simple design, compact dimension with high EMR, ENG property with near-zero permeability, this multiband NZI metamaterial can be used for microwave applications, especially for multiband antenna gain enhancement.

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Статті в журналах з теми "Q multibande"

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