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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
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- Gdansk University of Technology
- V. N. Karazin Kharkiv National University
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[IEEE 2018 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT) - Melbourne, Australia (2018.8.15-2018.8.17)] 2018 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT) - A Fully-Integrated <tex>$S$</tex>-Band Differential LNA in <tex>$0.15-\mu \mathrm{m}$</tex> GaAs pHEMT for Radio Astronomical Receiver
摘要： A fully-integrated S-band high-gain MMIC low noise amplifier (LNA) with differential input and single-ended output is presented and implemented in 0.15-μm GaAs pHEMT for Square Kilometre Array (SKA) astronomical receiver. The low-loss input noise matching network is designed, and the fully on-chip LC balun is introduced between the first stage LNA core and the second stage amplifier to improve overall system noise figure. The 1-dB bandwidth of the LNA covers from 1.5 to 3.7 GHz. The measurement results demonstrate 31.8-dB gain, average in-band noise figure of 0.73 dB with DC power con- sumption of 25 mW. The chip area is 2.5 x 2 mm2. Also, a noise figure measurement method for the 3-port differential-input-to- single-ended-output amplifiers is introduced in this paper.
关键词： differential low noise amplifier,GaAs pHEMT,Square Kilometre Array (SKA),fully- integrated,balun,broadband,S-band
更新于2025-09-04 15:30:14
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A tunable ultra-broadband linear-to-circular polarization converter containing the graphene
摘要： In this paper, a tunable ultra-broadband linear-to-circular polarization converter (LCPC) in terahertz regime containing the graphene is proposed, which are composed of two "I"-shaped gold resonators, a strip-shaped graphene sheet, two dielectric layer and a bottom gold reflector. The proposed LCPC can convert the linearly polarized wave into circularly polarized wave in an ultra-broadband frequency range which can be expanded to the lower frequencies by decreasing the Fermi energy (??f ) of the graphene in terahertz region. When ??f = 0.4 eV, 0.6 eV, 0.8 eV and 1.0 eV, the axial ratio band of the proposed LCPC which is less than 3 dB are covered 0.9248～2.2880 THz, 0.9408～2.2893 THz, 0.9665～2.2803 THz, and 0.9746～2.2780 THz, whose relative bandwidths are 84.86%, 83.49%, 80.93% and 80.15%, respectively. The maximum 3 dB axial ratio band is located at 0.9248～2.2880 THz and its relative bandwidth is 84.86% at the case of ??f = 0.4 eV. The polarization conversion rate curves, reflection phase curves, surface current and electric field diagrams are analyzed to elucidate the physical characteristics of the presented LCPC. In addition, the effect of parameters a, b and c on the axial ratio band are also discussed, respectively. This design offers an effective way to realize the reconfigurable LCPC, and also has enormous potential value in realizing the THz devices.
关键词： Graphene,Ultra-broadband,Tunable line-to-circular polarization converter
更新于2025-09-04 15:30:14
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Vertically symmetric broadband lumped element CMOS directional coupler
摘要： A vertically symmetric lumped element directional coupler (VSLEDC) providing broadband characteristics is proposed. In simulations, the proposed VSLEDC showed a 43.8% broader bandwidth than a horizontally and vertically symmetric lumped element directional coupler under similar design conditions for the same insertion loss. The proposed coupler was implemented in a Global Foundry 130 nm CMOS technology. The overall chip size was 1300 μm × 850 μm. The coupling was designed to be ?10 dB at 1 GHz. The S-parameter measurements showed an absolute bandwidth and a fractional bandwidth of 141.1 MHz and 14.11%, respectively. Within the bandwidth, the insertion loss was 1.6?1.8 dB.
关键词： lumped element,directional coupler,Vertically symmetric,broadband,CMOS
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland, New Zealand (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Tunable Low-Frequency Broadband Dual-Polarized Rasorber
摘要： In this paper, a tunable low-frequency broadband metamaterial (MM) dual-polarized rasorber based on slot arrays has been proposed. The structure consists of one air gap sandwiched between top lossy FSS layer and bottom lossless FSS layer, which exhibits a transmission window at 1.70GHz and a -10dB broadband absorption from 0.75GHz to 3.30GHz while the thickness is less than 10% of the free space wavelength at the lowest operating frequency. A switch between absorber and rasorber can be achieved by turning PIN diodes on/off, respectively. We think the proposed rasorber can be applied in low-frequency band stealth technology. The proposed design could also be easily scaled to other frequencies if necessary.
关键词： slot arrays,metamaterial,low-frequency,broadband,rasorber,PIN diodes,tunable,FSS,dual-polarized
更新于2025-09-04 15:30:14
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Compact High-Efficiency Broadband Metamaterial Polarizing Reflector at Microwave Frequencies
摘要： A compact highly efficient broadband microwave polarizing reflector, employing a quasi-2-D metamaterial composed of a single layer of square split-ring resonators, is presented and its performance is reported. Numerical and experimental results show a cross-polarization average polarization conversion ratio of greater than 90% for normal incident linearly polarized waves over a frequency range of 8.2–23 GHz. Due to multiple resonances occurring over this frequency range, the polarizing reflector presents both broadband performance and high polarization conversion efficiency. Transfer matrix and equivalent surface impedance theory and modeling are discussed to explain the physical underpinnings of the reflector’s multiresonance behavior. These physical mechanisms are further analyzed by examination of simulated surface current distributions. The reflector is expected to be employed in applications where the control of the signal polarization is of central importance.
关键词： transfer matrix,polarization converter,Broadband,equivalent surface impedance
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Compact broadband dual-polarized antenna element for 2G/3G/4G base station applications
摘要： A novel broadband and slant ±45? dual-polarized antenna element with compact structure is presented in this paper for LTE700/CDMA800/GSM900 bands applications. The proposed antenna mainly comprises of two pairs of orthogonal dipoles, four couples of baluns, an octagonal pedestal and two kinds of plastic fasteners. A square aluminum sheet is placed between adjacent dipoles to widen the impedance bandwidth of the antenna. Simulated and measured results show that the proposed antenna element has a wide impedance bandwidth of 31.60% with VSWR < 1.6 from 698 to 960 MHz at both ports. High port-to-port isolation (< ?25 dB) and stable radiation pattern with horizontal half-power beam width (HPBW) of 65?±6.4? are achieved within the whole working band. The antenna is suitable for existing 2G/3G/4G base station applications.
关键词： broadband antenna,dual-polarized antenna,base station applications
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Broadband Metamaterial Based Radar Absorber
摘要： In this article, a layer broadband metamaterial radar absorber is presented. Under normal incidence, it achieves at least 90% of absorption from 5.6 GHz to 9.1 GHz for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations. The structure is 12.7 times thinner than the wavelength at the center frequency. In order to understand the absorption mechanism, the three near unity absorption peaks at 8.87, 7.16 and 8.82 GHz have been used to study the electric and magnetic fields.
关键词： Low Profile,Metamaterial,Broadband,Radar Absorber
更新于2025-09-04 15:30:14
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Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films
摘要： Optical switches offer higher switching speeds than electronics, however, in most cases utilizing the interband transitions of the active medium for switching. As a result, the signal suffers heavy losses. In this article, we demonstrate a simple and yet efficient ultrafast broadband all-optical switching on ps timescale in the sub-bandgap region of the a-Se thin film, where the intrinsic absorption is very weak. The optical switching is attributed to short-lived transient defects that form localized states in the bandgap and possess a large electron-phonon coupling. We model these processes through first principles simulation that are in agreement with the experiments.
关键词： electron-phonon coupling,optical switches,interband transitions,all optical broadband switching,first principles simulation,amorphous selenium thin films,ultrafast defect dynamics,sub-bandgap region,transient defects
更新于2025-09-04 15:30:14
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Anomalous carrier transport model for broadband infrared absorption in metals
摘要： We derive a model for accurately reproducing the broadband infrared optical response of common engineering metals. Here we use “broadband infrared” to refer to wavelengths beginning at 1 μm and extending to approximately 100 μm or more. The model generalizes the Drude theory to account for sources of anomalous intraband absorption. This is accomplished by modeling these sources as elements of disorder that introduce diffusive perturbations into the local ?eld. In the stationary setting, the memory kernel description of the ?eld relaxation leads to a fractional derivative with an order that corresponds to the memory decay strength. We demonstrate that this model is fully consistent with the Drude theory and that the semiclassical theory is recovered under requisite assumptions on the ?eld relaxation or radiative wavelength. The anomalous model component is shown to reproduce empirically observed anomalous absorption that has been traditionally corrected by models possessing empirical components that have not been formally derived. Results are presented for several common metals for which the proposed model accurately reproduces the data over the entire modeled bandwidth. A comparative analysis con?rms that the proposed model represents a robust, high ?delity alternative to previously proposed models that do not capture the observed physical response over the extended infrared range.
关键词： broadband infrared,anomalous intraband absorption,fractional derivative,Drude theory,memory kernel
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Graphene Based Absorber Using LTJEC FDTD
摘要： A terahertz absorber using graphene is simulated using Laplace transform current density convolution finite difference time domain method. An absorber with approximately unity absorption is designed with a graphene ribbon array and a graphene sheet. The numerical results are presented to validate the proposed structure and demonstrate that the graphene sheet is an appropriate material to develop a broadband absorber.
关键词： Graphene,Broadband absorber,Finite difference time domain method,Laplace transform
更新于2025-09-04 15:30:14