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- 2018
- GaN HEMTs
- Power amplifier
- Broadband power amplifier
- SC band
- Power combining
- concentrated capacitive load
- distribution of the complex current at the antenna
- broadband antenna
- standing wave voltage factor
- antenna gain factor
- Electronic Science and Technology
- Oles Honchar Dnipro National University
- University of Tehran
- Gdansk University of Technology
- V. N. Karazin Kharkiv National University
- Reykjavik University
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74.38 Tb/s Transmission Over 6300 km Single Mode Fibre Enabled by C+L Amplification and Geometrically Shaped PDM-64QAM
摘要： Ultrawide-bandwidth optical amplification over almost 90 nm, covering the C+L bands, is described. Complemented by system-tailored geometrical constellation shaping and nonlinearity compensation, it enabled a record capacity transmission of 74.38 Tb/s over 6,300 km of G.654 single-mode fibre. The hybrid scheme, combining backward Raman pre-amplification with EDFA, significantly improves the average effective noise figure across the entire bandwidth, allowing the use of span lengths of 70 km. The system-tailored GS-64QAM constellation was optimised to both linear link impairments and transceiver nonlinearities, improving the gap to the AWGN channel capacity relative to square 64QAM from 0.6 bit/symbol to 0.35 bit/symbol. We experimentally evaluated the system performance using the bit-wise achievable information rate (AIR) and signal-to-noise ratio (SNR) at the end of transmission, as well as post SD-FEC BER.
关键词： geometric constellation shaping,nonlinear compensation,Erbium-doped fibre amplifier,Raman amplification,Broadband C+L band transoceanic transmission
更新于2025-09-11 14:15:04
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Continuously Tunable Acoustic Metasurface for Transmitted Wavefront Modulation
摘要： Previously reported acoustic metasurfaces consisting of fixed channels are untunable to meet broadband requirements and alterable functionalities. To overcome this limitation, we propose a screw-and-nut mechanism of tunability and design a type of continuously tunable acoustic metasurface with unit components of helical cylinders which are screwed into a plate. The spiral channel length can be tuned continuously by the screwed depth, and thus a metasurface with a continuously tunable acoustic phase of independent pixels is attained. Different distributions of the unit components can form an arbitrary metasurface profile. We also develop an approximate equivalent medium model to predict the tunability of the unit component. As an example, we present the design details of a circular tunable metasurface for three-dimensional (3D) adjustable broadband acoustic focusing of different airborne sound sources in a wide frequency range. A sample of the metasurface is manufactured by polylactic acid plastic with 3D-printed helical cylinders. Experiments of the adjustable acoustic focusing are performed to validate the equivalent medium model and the finite element simulation. It is shown that the results of the equivalent medium model, the finite element simulation, and the experiments are in good agreement.
关键词： 3D printing,acoustic metasurface,acoustic focusing,broadband,tunable
更新于2025-09-11 14:15:04
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Signal-to-Noise Ratio of True-Time Delay Beamformers Based on Microwave Photonic Links Using an Incoherent Broadband Optical Source
摘要： The signal-to-noise ratio (SNR) of true-time delay beamformers based on microwave photonic links using an incoherent broadband optical source (IBOS) is investigated. A comprehensive theory considering the bias angle of the Mach-Zehnder modulator employed in the microwave photonic link is presented to analyze the SNR. When the RF signal at the fundamental frequency is fed by the beamformer, the SNR is a function of the bias angle, the frequency of the applied RF signal, the modulation index, the system dispersion and the shape of the IBOS. We ?nd that by biasing the MZM near the minimum transmission point, the SNR at the fundamental frequency is maximized. On the other hand, by exactly biasing the MZM at the minimum transmission point, the RF signal at the double frequency can be fed by the beamformer with maximum power. The maximum SNR at the double frequency is a function of the frequency of the applied RF signal, the system dispersion and the shape of the IBOS while its dependence on the modulation index is eliminated. In both cases, the relationship between the SNR and the frequency of the RF signal, the system dispersion and the shape of the IBOS is also investigated. An experiment is carried out to verify the theoretical analysis, and the experiment results agree well with the calculation.
关键词： modulation,dispersion,true-time delay,incoherent broadband optical source,signal-to-noise ratio,Microwave photonics,phased array antennas
更新于2025-09-11 14:15:04
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Polarization-Insensisitve Broadband Multi-layered Absorber Using Screen Printed Patterns of Resistive Ink
摘要： Design and implementation of a broadband polarization-insensitive multi-layered microwave absorber using resistive ink has been presented here. The proposed absorber is constructed using layers of resistive surface where each layer consists of periodic arrangement of resistive patterns printed on a low cost FR4 sheet using resistive ink. Due to the multilayered nature, the proposed absorber shows broadband absorption having simulated reflection co-efficient less than -10dB in the frequency range from 2.00 GHz to 18.50 GHz under normal incidence which covers the entire S, C, X and Ku bands with the smallest thickness of 0.082λL (at lowest operating frequency of the absorption band) as compared to the state-of the-art absorbers. In order to validate the proposed absorber, the equivalent circuit model has also been presented. The equivalent circuit model shows good match with the proposed absorber. The proposed absorber is experimentally verified and the experimental results shows good agreement with the simulated results.
关键词： Frequency selective surface,resistive ink,multi-layered absorber,Broadband absorber
更新于2025-09-11 14:15:04
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A Novel Approach for Computation of High-Order Axial Modes in a Gyrotron Resonator
摘要： This paper presents a novel approach for computation of high-order axial modes (HOAMs) in a conventional and uptapered gyrotron resonator. A code has been developed which computes the eigenfrequency, Q-factor and axial ?eld pro?le of HOAMs in the absence of electron beam in the resonator. Cyclic coordinate search method has been used for the optimization of complex eigenfrequencies, which obviates the computation of gradients of radiation boundary conditions and, hence, reduces computational complexity. HOAMs have been computed for resonators operating at 10, 132, 203, and 424 GHz, and the results obtained have been found to be in good quantitative agreement with the experimental and numerical data available in the published literature. Broadband continuous frequency tuning bandwidth found for subterahertz resonators also agrees well with the published results. HOAMs computed for 1-THz gyrotron resonator designed at CSIR-CEERI have also been presented.
关键词： Broadband continuous frequency tuning (CFT),subterahertz,optimization,open resonator,terahertz,high-order axial modes (HOAMs),gyrotron
更新于2025-09-11 14:15:04
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Review of Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBBCEAS) for Gas Sensing
摘要： Incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) is of importance for gas detection in environmental monitoring. This review summarizes the unique properties, development and recent progress of the IBBCEAS technique. Principle of IBBCEAS for gas sensing is described, and the development of IBBCEAS from the perspective of system structure is elaborated, including light source, cavity and detection scheme. Performances of the reported IBBCEAS sensor system in laboratory and field measurements are reported. Potential applications of this technique are discussed.
关键词： supercontinuum light source,incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS),gas sensing,broadband light source,molecular spectroscopy
更新于2025-09-10 09:29:36
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[IEEE 2017 IEEE HISTory of ELectrotechnolgy CONference (HISTELCON) - Kobe, Japan (2017.8.7-2017.8.8)] 2017 IEEE HISTory of ELectrotechnolgy CONference (HISTELCON) - Principle of Self-Complementarity and Application to Broadband Antennas
摘要： Theory of self-complementarity which was derived through an investigation of the input impedance of slot antennas with arbitrary shape is described. Examples of self-complementary antennas, modified self-complementary antennas, and their application are presented. It is pointed out that the self-complementarity is very important to obtain the wide frequency band.
关键词： broadband antenna,self-complementary antenna,constant impedance antenna,wireless broadband
更新于2025-09-10 09:29:36
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[IEEE 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Xuzhou, China (2018.7.21-2018.7.24)] 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Capacitive Probe Fed Broadband Circularly Polarized Omnidirectional Antenna
摘要： A (CP) omnidirectional antenna fed by a capacitive probe is presented in this paper. To attain wideband vertical polarization, a circular monopole patch connecting to the ground by a set of shorting pins is applied. Two groups of curved branches are introduced to create wideband horizontal polarization. The CP radiation can be generated with a proper phase difference between the vertical polarization and the horizontal polarization. The antenna is fabricated and measured. It exhibits an impedance bandwidth (VSWR≤2) of 34.6% (ranges from 4.50 to 6.38 GHz) and an axial ratio bandwidth (AR≤3dB) of 33.5% (ranges from 4.60 to 6.45 GHz). The profile of the antenna is merely 0.06λL (λL is the wavelength corresponding to the lowest operating frequency).
关键词： low profile,circularly polarized,coupling feed structure,omnidirectional antenna,broadband
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - A Single Layer Broadband Reflectarray for Dual Polarizing Beam Splitting
摘要： A single layer broadband reflectarray is proposed, which is capable of generating independent reflect beams according to the polarization. The reflectarray element is composed of two sets of paralleled dipoles overlapping orthogonally on the surface of the substrate, and each set of the dipoles provide phase compensation for the certain polarization. Independent phase distributions can be achieved respectively on the same surface to perform separate beams with an included angle of 30 degrees between TE and TM polarizations. Operating as a polarizing reflect-beam splitter, a broadband performance (11.3-13.1 GHz) is acquired in simulation and the measurement result is exhibited.
关键词： parallel dipole,broadband,orthogonal polarization,single layer reflectarray,beam splitter
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Broadband Full Polarimetric Scatterometry for Monitoring Soil Moisture and Vegetation Properties Over a Tibetan Meadow
摘要： A scatterometer is installed on a meadow over the Tibetan Plateau in August 2017 to measure the full polarimetric backscattering coefficient ??0 over a wide frequency range (1 - 10 GHz) year-round. In this paper we describe the setup of scatterometer as well as the activities undertaken to test the reliability of the system. The measured radar cross section of a dihedral reflector matches the theoretical model for 3 – 10 GHz after the calibration. The temperature-induced systematic error in the radar return will be accounted for by using the antenna cross coupling as a reference. For the retrieval of ?0 the frequency-dependent antenna radiation pattern and the site geometry are accounted for. Fading will be dealt with by using frequency agility techniques.
关键词： Radar cross section calibration,Time-domain gating,Tibetan Plateau,Broadband,Scatterometer
更新于2025-09-10 09:29:36