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Reconfigurable rectenna array design with mutual coupling analysis
摘要： This article introduces design of two frequency reconfigurable rectenna arrays, which are in direct current (DC) combining and in radio frequency (RF) combining configurations, respectively, with the mutual coupling analysis. We compare the performances in the conversion efficiency of the two arrays. For the mutual coupling analysis, the coupling coefficient matrix and the active DC patterns of the two rectenna arrays are calculated. By analyzing the mutual coupling, we find that the rectenna array in RF combining can achieve higher and more stable output DC power than that in DC combining. When the receiving antenna element spaces about 0.46λ0 and the rectifying circuit element spaces 0.17λ0, the proposed two-element reconfigurable rectenna array in RF combining configuration achieves measured conversion efficiencies of 69.1% and 64.2% at two operation frequency modes, while simulated efficiency in DC configuration achieves 70.3% and 53.2% when the rectenna element spaces 0.38λ0.
关键词： microwave power transmission,rectenna array,mutual coupling,DC combining,RF combining
更新于2025-09-04 15:30:14
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Potential Multi-Function Cylinder as Wave Attenuator
摘要： An experimental investigation, conducted in unidirectional waves with different wave conditions and model configurations were conducted to assess the wave energy loss on cylinder obstacles. This study presents a significant finding on porous cylindrical model. The basic concept of porous cylinder breakwater is to serve as a pervious barrier where particle movements are more which is more environmental friendly and allow the passage of tidal currents with least disturbance where littoral drift is predominant. For the study, Two sizes of cylinder were used, 100 mm and 200 mm with four different porosities ranging from 0.0625 to 0.48 respectively. The influences of water level, wave steepness, wave number and porosities were studied. The test results shown that when the percentage of porosity decreased, more wave energy was dissipated, this resulted in the decrease in transmitted wave heights. Furthermore, it was also found that lower water level has a significant influence on the loss coefficient at bigger model size with El being more than 0.60 at a water level 0.27 m compared to El being less than 0.40 at water level 0.35 m for similar porosity. Overall, the bigger model (single or double cylinder) with lower porosity (P=6.25% and 14%) showed promising performance in reducing wave height at the lee of the model, having high percentage of wave energy loss, and smaller model has been found to be the least effective wave attenuator model to the same environments among all three models. In a way, cylindrical structure being porous could potentially be used together or alone as a wave dampening structure at mangrove sapling replanting coastal area and/or artificial reefs for fish breeding ground.
关键词： Reflection,Dissipation,Submerged,Transmission,Porous
更新于2025-09-04 15:30:14
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Study of the system responsivity to measure the blackbody's temperature by optical pyrometry from 1200?K to 1570?K
摘要： This work presents a method that has been recently adopted in our laboratory to determine the temperatures of blackbody sources in the range of 1200–1570 K. The system uses a Double Monochromator System (DMS) based on a grating and a prism as dispersion elements. The detection element was a silicon photodiode (Si-MMA), over which the spectral range from 800 nm to 900 nm has been used. Between the blackbody source and the DMS was placed an optical system consists of two convergent lenses. The system responsivity “G ” was determined by the transmission factor of the optical system and the transmission factor of the DMS and the photodiode responsivity. The obtained results showed that the relative uncertainty of the system responsivity “G ” varied from 0.3% to 1.12%. This in turn resulted in a corresponding uncertainty in temperature of about 2.2 K and 4.5 K (k = 1) over the evaluated temperature range. Although this uncertainty level was signi?cantly high compared to those obtained by many other national metrology institutes, it was considered as a step forward in our laboratory to measure high temperatures.
关键词： temperature,detector,pyrometry,optical transmission,system responsivity
更新于2025-09-04 15:30:14
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Super compact and ultra-wideband bandpass filter with a wide upper stopband based on a SCRLH transmission-line unit-cell and two lumped capacitors
摘要： This paper presents a simplified composite right/left-handed transmission-line (SCRLH-TL) unit-cell, which is primarily consisted of a rectangular ring with two grounded vias. Superposing this unit-cell onto a high–low–high step-impedance resonator (SIR) leads to a novel SCRLH-TL multiple-mode resonator (SCRLH-TL MMR). By combining the SCRLH-TL MMR with a cross-shaped defected ground structure (DGS) and using a broadside coupling approach with two lumped capacitors, a highly compact and ultra-wideband bandpass filter was carefully designed and fully investigated. The filter was fabricated by using a conventional PCB process with the substrate of FR4. The measured 3-dB passband ranges from 2.55 through 11.75 GHz with the fractional bandwidth (FBW) of about 129%. The filter exhibits a high selectivity with steep skirt property, and has a wide upper stopband. Its total dimension, including the rectangular substrate with feed lines, occupies only 13.5 mm × 6.0 mm, which is found with the smallest size in comparison to those recently published in the literature.
关键词： lumped capacitors,Ultra-wideband bandpass filter,defected ground structure,simplified composite right/left-handed transmission-line,equivalent circuits
更新于2025-09-04 15:30:14
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Coupling Information Transmission with Window Decoding
摘要： We consider a coupling information transmission modulation format utilized for communication over a multiple-access channel. A multitude of packets is transmitted by a number of sources to a common receiver. Each packet is modulated via simple repetition, interleaving, and an application of a signature sequence. The packets are transmitted with time offsets that initiate coupling of the transmitted signals into a received signal that lends itself to an efficient window-based iterative estimation and interference cancellation decoding. We present the window decoding formulation, a theoretic analysis and numerical results for the achievable sum-rate, gap to the channel capacity and the optimal window size.
关键词： multiple-access channel,coupling information transmission,iterative estimation,window decoding,interference cancellation
更新于2025-09-04 15:30:14
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Joint user and relay selection for relay-aided RF/FSO systems over Exponentiated Weibull fading channels
摘要： In this paper, we investigate the performance of joint user and relay selection scheme for a multi-user relayed network over mixed radio-frequency (RF) and free space optical (FSO) system. In this set-up, the non-line-of-sight (NLOS) RF link is modeled with Rayleigh fading whereas the LOS FSO path is modeled with Exponentiated Weibull (EW) distribution. We assume that the multiple users at source terminal communicate with the destination over multiple decode and forward relays which are located at the rooftops of the buildings to provide a perfect LOS path. In the proposed scheme, all users send pilot signals to the destination through relay terminals and the latter jointly selects the best user and relay based on the maximization of the end-to-end signal-to-noise ratio (SNR). To quantify the performance of the proposed scheme, closed form outage and error probability are derived. Moreover, asymptotic analysis is performed to obtain important system parameters including fading severity, number of users and relays in the system. Finally, Monte-Carlo (MC) simulations are carried out the verify the performance of the considered scheme.
关键词： Exponentiated Weibull fading channel,Joint user and relay selection,Free space optical communication,relay aided transmission
更新于2025-09-04 15:30:14
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Formation mechanism of twin structures in p-type (Bi0.25Sb0.75)2Te3 thermoelectric compound
摘要： The formation mechanism of twin structures in p-type (Bi0.25Sb0.75)2Te3 compound was examined using high-resolution transmission electron microscopy (HR-TEM) and computer simulations. The results shown that the formation of twins is analogous to the twinning mechanism via synchronized activation of Shockley partial dislocations commonly observed terminating {111} growth and annealing twins in face centered cubic (FCC) metals. The f1010g boundary, as an incoherent twin boundary (ITB), is mobile due to its lower shear stress compared to that of the coherent {0001} twin boundary; thickness of the twin region can be reduced or increased according to the direction of the movement.
关键词： Twin structure,Interfacial step,Transmission electron microscopy (TEM),(Bi, Sb)2Te3 thermoelectric compound
更新于2025-09-04 15:30:14
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Entanglement, nonclassical properties, and geometric phase in circuit quantum electrodynamics with relativistic motion
摘要： In this work, we study qualitatively the nonclassical properties, nonlocal correlation, and geometric phase in a superconducting qubit system connected to a transmission line resonator (TLR) within a circuit quantum electrodynamics setup, where the modulation of the coupling strength can imitate the harmonic motion of the superconducting system at relativistic speeds. We analyze the effects of the relativistic motion on these quantum quantifiers under the influence of the physical parameters implicated in the whole quantum system state. Furthermore, the relationship between the different quantifiers is explored. Our results may open new perspectives to understand and explore the relativistic phenomena on the comportment of the quantum quantifiers for new applications in superconducting quantum technologies.
关键词： E. Nonclassical properties and correlation,B. Superconducting qubit system,A. Solid state systems,C. Transmission line resonator,D. Circuit quantum electrodynamics
更新于2025-09-04 15:30:14
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Hybrid transmission of unicast and broadcast signals without optical filter for WDM systems
摘要： This paper proposes and experimentally demonstrates the hybrid transmission of unicast and broadcast signals without using optical filters for the WDM systems. The dual-wavelength generated from a laser source are modulated by a phase modulator (PM) with a broadcast signal. Then, the central carriers and side-bands are separated by using a polarization beam splitter (PBS) and modulated with unicast data using Mach-Zender modulator (MZM). After combining side-bands (broadcast data) and central carriers (unicast data) using PBS, the hybrid data are transmitted through 25 km single mode fiber (SMF) to the remote node (RN). By probably adjusting the polarization controller (PC), the central carriers and side-bands are separated by PBS into two orthogonal polarization states. After transmission over 25 km SMF, the measured bit error rate (BER) curves and eye diagrams show that the performance of the proposed system is excellent to simultaneously transmit both unicast and broadcast signals. Moreover, only two modulators are required, which is cost-effective and also FBG or optical filter is not required due to sensitivity to temperature that decreases the system stability.
关键词： Wavelength-division-multiplexing (WDM) system,Hybrid signal Transmission,Optical filter,Broadcast signal,Unicast signal
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 Flexible 2.45 GHz Rectenna Using Electrically Small Loop Antenna
摘要： We present the concept and design of a compact flexible electromagnetic energy-harvesting system using electrically small loop antenna. In order to make the integration of the system with other devices simpler, it is designed as an integrated system in such a way that the collector element and the rectifier circuit are mounted on the same side of the substrate. The rectenna is designed and fabricated on flexible substrate, and its performance is verified through measurement for both flat and curved configurations. The DC output power and the efficiency are investigated with respect to power density and frequency. It is observed through measurements that the proposed system can achieve 72% conversion efficiency for low input power level, -11 dBm (corresponding power density 0.2 W/m2), while at the same time occupying a smaller footprint area compared to the existing work.
关键词： energy harvesting,flexible rectenna,wireless power transmission
更新于2025-09-04 15:30:14