- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[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) - Miniaturization of Quad Port Helical Antenna for Wireless 5G Massive MIMO Application
摘要： A novel technique for the miniaturization of a quadrifilar helical antenna (QHA) with four independent ports, including for use in multiple-input multiple-output (MIMO) systems and other wireless communication systems. With the addition of one or more conductive components, a QHA may be achieved that has a more compact size, improved radiation patterns, sufficiently wide impedance bandwidth. Design is applied at 2.1-2.7 GHz.
关键词： 5G Wireless,quad antenna,Massive MIMO,wide band
更新于2025-09-23 15:23:52
-
The impact of out of band emissions: A measurement based performance comparison of UF-OFDM and CP-OFDM
摘要： Long Term Evolution (LTE) networks, along with their recent releases, rely on the cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform as the foundation. However, high sidelobes, synchronization problems and spectral efficiency constraints of CP-OFDM cannot meet future requirements of cellular network design targets. At this point, universal filtered orthogonal frequency division multiplexing (UF-OFDM) emerges as a strong candidate. Equipped with the advantages of using filters, UF-OFDM provides additional design flexibility to address the fundamental problems of CP-OFDM. In this study, the effect of adjacent channels that causes interference between different frequency channels because of out-of-band (OoB) emissions on UF-OFDM performance is investigated by performing real-time tests on software defined radio (SDR) nodes with multiple reception paths. Frequency domain carrier frequency offset (CFO) and symbol timing offset (STO) correction techniques are used. By the application of the same correction approaches to CP-OFDM, these two waveforms are evaluated in terms of signal to noise ratio (SNR), bit/symbol error rate (BER/SER) and error vector magnitude (EVM). Test results indicate that, based on lower OoB emissions, UF-OFDM uses the spectrum more efficiently and provides better results than CP-OFDM in congested environments.
关键词： synchronization,CP-OFDM,out-of-band emissions,software defined radio nodes,UF-OFDM
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Field Observations of Temporal Variations of Surface Soil Moisture: Comparison with Insar Sentinel-1 Data
摘要： In this paper we summarize the results of an experiment aiming to compare soil moisture estimates obtained by Sentinel-1 interferometric data with in-situ measurements. The study area, located close to Lisbon in Companhia das Lezirias, Portugal is characterized by a flat topography, large agricultural areas and sparse vegetation. In a test site, four soil moisture sensors were deployed and soil moisture was measured (at a depth of 5 cm) for a period of 7 months in an hourly basis. For the same interval of time and with a temporal resolution of 6 days C-band Sentinel-1 SAR images were interferometrically processed and coherence, phase and phase triplet images were derived. The in-situ soil moisture measurements have been used to predict the analytical interferometric phases, coherences and phase triplets and compared with the measured interferometric phases in both VV and VH polarimetric channels. As a further analysis, a regression analysis of in-situ soil moisture measurement and Sentinel-1 backscattering images has been carried out.
关键词： soil moisture,C-band,SAR interferometry,Sentinel-1
更新于2025-09-23 15:23:52
-
X/Ku Dual-Band Single-Layer Reflectarray Antenna
摘要： X/Ku dual-band single-layer reflectarray antenna is presented. The proposed reflectarray antenna operates in two separated bands with separate feeds. The reflectarray element is composed of a split ring with two phase delay lines and a phoenix patch. The split ring and phoenix patch are designed for operation at X- and Ku- bands, respectively. The split ring is selected as the lower frequency element because of the large enough internal space. The phase shift of these two elements does not depend on variation of external size, which provides a feasible method for designing dual-band elements. The lower-band phase shift is obtained by changing the rotation angle of the phase delay lines. The movement of the inner loop of phoenix patch provides the required phase shift for the higher band. The proposed element realizes 360° phase shift range in both bands. The reflectarray is fabricated and measured to validate the design. The measured gains are 22.9 dBi at 8.5GHz with aperture efficiency of 40%, and 28.8 dBi at 16GHz with aperture efficiency of 44.8%. Besides, the 1 dB gain bandwidths are 20.5%(7.9GHz-9.7GHz) at lower band and 13.3 %(14.7GHz-16.8GHz) at higher band.
关键词： reflectarray antenna,single layer,dual band
更新于2025-09-23 15:23:52
-
[IEEE 2018 21st Saudi Computer Society National Computer Conference (NCC) - Riyadh, Saudi Arabia (2018.4.25-2018.4.26)] 2018 21st Saudi Computer Society National Computer Conference (NCC) - Millimeter Wave Switching in Radio over Fiber Networks using Semiconductor Optical Amplifier (SOA)
摘要： 5G wireless communication systems promise efficient spectrum utilization, advanced modulation and access techniques, and high data rate. To obtain these requirements, millimeter wave (MMW) signals and subsystems are the most suitable to be used. The Modules and devices, proposed for these networks, are intended to use the efficient capabilities of photonic technologies. In this paper, a photonics-based millimeter wave switch, for orthogonal frequency division multiplexing (OFDM) signals, is proposed by exploiting the nonlinear effects in semiconductor optical amplifiers (SOAs). This includes four wave mixing (FWM), self-phase modulation (SPM) and cross-gain modulation (XGM). A 10 Gbps/16QAM-OFDM signal carried over 30 GHz MMW carrier is considered for signal switching. Moreover, we studied the up- and down- wavelength conversion schemes, in terms of probe and pump signal’s power. Furthermore, we investigate the effects of SOA’s injection current and wavelength spacing between the two injected beams that enable optical single sideband (OSSB) generation and switching. Simulation results show possibility of transmitting and switching OFDM signal with 1×10-3 and 13 % rms symbol error rate (SER) and error vector magnitude (EVM), at -22 dBm received power. The simulation is carried out using Virtual Photonic Integrated (VPI) software.
关键词： optical single side band (OSSB),orthogonal frequency division multiplexing (OFDM),millimeter waves (MMW),semiconductor optical amplifier (SOA),wavelength conversion,5G
更新于2025-09-23 15:23:52
-
A decoupling method between two tri-band antennas for WLAN/WiMAX applications
摘要： A decoupling method between two tri-band antennas for WLAN/WiMAX applications is presented. A monopole is first designed with tri-band characteristic; three resonating frequencies are generated by three separate resonators. Then, two tri-band monopoles are employed to develop a MIMO antenna system. The resonators of low band can reduce the mutual coupling for two higher bands by suppressing surface wave propagation. Finally, coupling reduction at low band is achieved by a Ω-shaped metal line to neutralize original coupling. The proposed MIMO antenna covers the 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX bands, with the measured mutual coupling lower than ?18 dB.
关键词： multiple-input multiple-output (MIMO) antenna,decoupling method,triple-band
更新于2025-09-23 15:23:52
-
Impact of strained silicon on the device performance of a bipolar charge plasma transistor
摘要： In this manuscript we analyze a unique approach to improve the performance of the bipolar charge plasma transistor (BCPT) by introducing a strained Si/SixGe1?x layer as the active device region. For charge plasma realization different metal work-function electrodes are used to induce n+ and p+ regions on undoped strained silicon-on-insulator (sSOI or SixGe1?x) to realize emitter, base, and collector regions of the BCPT. Here, by using a calibrated 2-D TCAD simulation the impact of a Si mole fraction x (in SixGe1?x) on device performance metrics is investigated. The analysis demonstrates the band gap lowering with decreasing Si content or effective strain on the Si layer, and its subsequent advantages. This work reports a significant improvement in current gain, cutoff frequency, and lower collector breakdown voltage (BVCEO) for the proposed structure over the conventional device. The effect of varying temperature on the strained Si layer and its implications on the device performance is also investigated. The analysis demonstrates a fair device-level understanding and exhibits the immense potential of the SixGe1?x material as the device layer. In addition to this, using extensive 2-D mixed-mode TCAD simulation, a considerable improvement in switching transient times are also observed compared to its conventional counterpart.
关键词： bipolar charge plasma transistor (BCPT),mole fraction,cutoff frequency (fT),current gain (β),collector breakdown voltage (BVCEO),strained Si layer,band gap lowering
更新于2025-09-23 15:23:52
-
Synthesis and optical band gap determination of CuO nanoparticles from salen-based infinite coordination polymer nanospheres
摘要： A symmetric bi-carboxylic acid functionalized salen-type ligand was used as organic linker to prepare a Cu-based infinite coordination polymer. The analytical data demonstrated that the proposed structure contains one bi-carboxylic acid salen type ligand and two copper cations in each monomeric unit. One of the Cu2+ cations is coordinated by N2O2 site of salen ligand and the other one acts as node to connect metal-organic linkers to each other. The reasonable formation mechanism for coordination polymer formation proposed which shows the formation of nanoparticles from intertwined oligomer chains. The prepared coordination polymer was used as a good precursor to synthesis copper oxide nanoparticles with larger band gap relative to bulk CuO.
关键词： CuO,salen-type ligand,ICP,band gap,nanoparticles
更新于2025-09-23 15:23:52
-
Sharp increase in the density of states in PbTe upon approaching a saddle point in the band structure
摘要： PbTe is a leading mid-range thermoelectric material with a zT that has been enhanced by, amongst other methods, band engineering. Here we present an experimental study of the Hall effect, quantum oscillations, specific heat, and electron microprobe analysis that explores the evolution of the electronic structure of PbTe heavily doped with the 'ideal' acceptor Na up to the solubility limit. We identify two phenomenological changes that onset as the electronic structure deviates from a Kane-type dispersion at around 180 meV; a qualitative change in the field dependence of the Hall effect indicative of an increase in the high-field limit and a change in the Fermiology, and a sharp increase in the density of states as a function of energy. Following consideration of three possible origins for the observed phenomenology we conclude that the most likely source is nonellipsoidicity of the L pocket upon approach to a saddle point in the band structure, which is evidenced directly by our quantum oscillation measurements. Comparison to density functional theory calculations imply that this evolution of the electronic structure may be a key contributor to the large thermopower in PbTe.
关键词： band structure,PbTe,Hall effect,density of states,thermoelectric,quantum oscillations
更新于2025-09-23 15:23:52
-
Hyperspectral band selection for soybean classification based on information measure in FRS theory
摘要： Soybeans and soy foods have attracted widespread attention due to their health benefits. Special varieties of soybeans are in demand from soybean processing enterprises. Because of the advantage of rapid measurement with minimal sample preparation, hyperspectral imaging technology is used for classifying soybean varieties. Based on fuzzy rough set (FRS) theory, the research of hyperspectral band selection can provide the foundation for variety classification. The performance of band selection with Gaussian membership functions and triangular membership functions under various parameters were explored. Appropriate ranges of parameters were determined by the number of bands and mutual information of subsets relative to the decision. The effectiveness of the proposed algorithms was validated through experiments on soybean hyperspectral datasets by building two classification methods, namely Extreme Learning Machine and Random Forest. Compared with ranking methods, the proposed algorithm provides a promising improvement in classification accuracy by selecting highly informative bands. To further reduce the size of the subset, a post-pruning design was used. For the Gaussian membership function, a subset containing eight bands achieved an average accuracy of 99.11% after post-pruning. As well as classification accuracy, we explored stability of band selection algorithm under small perturbations. The band selection algorithm of the Gaussian membership function was more stable than that of the triangular membership function. The results showed that the information measure (IM) based band selection algorithm is effective at obtaining satisfactory classification accuracy and providing stable results under perturbations.
关键词： Soybean classification,Information measure,Band selection,Fuzzy rough set,Hyperspectral imaging
更新于2025-09-23 15:23:52