- 标题
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- 实验方案
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Tellurene Photodetector with High Gain and Wide Bandwidth
摘要： Two-dimensional (2D) semiconductors have been extensively explored as a new class of materials with great potential. In particular, black phosphorus (BP) has been considered to be a strong candidate for applications such as high-performance infrared photodetectors. However, the scalability of BP thin film is still a challenge, and its poor stability in the air has hampered the progress of the commercialization of BP devices. Herein, we report the use of hydrothermal-synthesized and air-stable 2D tellurene nanoflakes for broadband and ultrasensitive photodetection. The tellurene nanoflakes show high hole mobilities up to 458 cm2/V·s at ambient conditions, and the tellurene photodetector presents peak extrinsic responsivity of 383 A/W, 19.2 mA/W, and 18.9 mA/W at 520 nm, 1.55 μm, and 3.39 μm light wavelength, respectively. Due to the photogating effect, high gains up to 1.9 ×103 and 3.15×104 are obtained at 520 nm and 3.39 μm wavelength, respectively. At the communication wavelength of 1.55μm, the tellurene photodetector exhibits an exceptionally high anisotropic behavior, and a large bandwidth of 37 MHz is obtained. The photodetection performance at different wavelength is further supported by the corresponding quantum molecular dynamics (QMD) simulations. Our approach has demonstrated the air-stable tellurene photodetectors that fully cover the short-wave infrared band with ultrafast photoresponse.
关键词： air-stable,two-dimensional (2D),wide bandwidth,tellurene,photodetector,high gain
更新于2025-09-12 10:27:22
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Switch fault diagnosis for boost DC–DC converters in photovoltaic MPPT systems by using high-gain observers
摘要： Open- and short-circuit faults (OSCFs) in boost dc–dc converters for photovoltaic (PV) maximum power point trackers (MPPTs) imply an inefficiency after fault is triggered, which affect the security and profitability of PV projects. Hence, fault detection and isolation (FDI) techniques have become an important issue for PV technology. In this study, a model-based FDI technique is proposed to boost dc–dc converters in PV MPPT systems. As is well-known, major issues of model-based FDI techniques have always been parametric uncertainty and no-modelled dynamics. This study focuses on how to mitigate these shortcomings by applying a high-gain observer (HGO) as a residual generator. A striking feature of HGO's is that exponential stability is still guaranteed for bounded disturbances (or faults). As demonstrated in this study, under an integral control action in the closed-loop control system, OSCFs are characterised for ever-growing signals, enabling the suggested FDI scheme. Also, the FDI proposal is decoupled from PV current (irradiance changes) and load variations, thereby avoiding false alarms. Moreover, the output-injection gain and thresholds are selected such that the fault diagnosis is achieved in eight switching cycles, enabling a fast and reliable diagnosis. Experimental results are illustrated to validate the FDI scheme proposed in this study.
关键词： photovoltaic MPPT systems,boost dc–dc converters,parametric uncertainty,fault detection and isolation,no-modelled dynamics,high-gain observers
更新于2025-09-11 14:15:04
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A Ka-Band 3D-Printed Wideband Stepped Waveguide Fed Magneto-Electric Dipole Antenna Array
摘要： A novel millimeter-wave aperture-coupled magneto-electric (ME) dipole antenna with a low-profile metallic geometry is proposed based on the three-dimensional (3D) printing technology. An impedance bandwidth of 53.7%, a gain up to 10.8 dBi, and stable unidirectional radiation patterns with the cross polarization of less than -38 dB are achieved by the antenna. Its operating mechanism and design process are studied in detail as well. In order to widen the bandwidth of the millimeter-wave full-corporate H-plane air-filled waveguide feed network, a wideband H-plane stepped waveguide T-junction with a compact size is then investigated, which has a bandwidth of about 50% for the reflection coefficient of less than -20 dB. By combining the presented radiating element with the feed network, an 8 × 8 ME-dipole array is designed, printed and tested in the Ka-band. An enhanced bandwidth of 31%, symmetric radiation patterns with the cross polarization of less than -35 dB, and a gain varying from 25.5 to 28.5 dBi are obtained experimentally. The proposed design demonstrates the advantage of utilizing the 3D printing method to improve the operating characteristics of the millimeter-wave antenna array and is attractive for the emerging wideband millimeter-wave wireless applications.
关键词： stepped waveguide,wideband,Millimeter-wave,3D printing,magneto-electric (ME) dipole,high-gain
更新于2025-09-11 14:15:04
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High-Gain Electrically Large Air-Cavity-Backed Patch Antenna Element and Array
摘要： In this work, single high-gain patch antenna element with electrical large property (ELP) based on TM30 mode is presented. Stable field distribution of the TM30-mode is maintained by using one TE20-mode substrate integrated waveguide (SIW) slot-coupling feed structure. Furthermore, air-cavity-backed structure and metal pins are introduced to expand the antenna bandwidth. The ELP element resonates at 22GHz with simulated -10dB impedance bandwidth of 6.9% and maximum gain of 14.2 dBi. Then in order to correct the asymmetrical field distribution in TE20-mode SIW, differential feed technology is introduced in array design. The feeding network consists of two TE10-TE20 mode planar transducers and one anti-phase power divider. The working principle and design procedure of the ELP array are given in detail accordingly. Finally, a 2×2 ELP array is optimized and fabricated for verification. The measured results show that the array antenna has -10dB impedance bandwidth of 9% and maximum gain of 18.9 dBi. Furthermore, it owns merit of excellent radiation performance with high aperture efficiency of about 90%.
关键词： high-gain,Array antenna,high-order mode,millimeter-wave,high-aperture efficiency,mode-transducer,electrically large property (ELP),differential feeding network
更新于2025-09-10 09:29:36
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Magneto-Electric Dipole Antenna (MEDA)-Fed Fabry-Perot Resonator Antenna (FPRA) With Broad Gain Bandwidth in Ku Band
摘要： One planar Fabry-Perot resonator antenna (FPRA) with broad gain bandwidth is proposed in this paper. Magneto-electric dipole antenna (MEDA) is used as the feeding antenna providing good impedance matching and stable radiation pattern over the whole Ku band. Then gain enhancement is realized by loading with one partially reflective surface (PRS), which consists of a single dielectric slab with two-dimensional patches array on both surfaces. Unlike the sharply negative phase slope of conventional cover designs, the proposed one produces a much gentle reflective phase gradient with both negative and positive phase slopes. Thus the gain property of the MEDA is obviously improved along the whole band. One prototype is fabricated for verification and the results show that the proposed antenna has a wide impedance bandwidth, which is 56.25% for S11<-10dB, ranging from 11.5 GHz to 18.7 GHz. It possesses a 3-dB gain bandwidth of 35% from 12.3 GHz to 17.2 GHz with a peak gain of 11.2 dBi at 14 GHz. Compared with the unloaded type, gain enhancement of about 1.5~5 dBi is achieved. Due to the advantages of simple structure and broad gain bandwidth, this method is a good option to design antennas in satellite communication systems in future.
关键词： Fabry-Perot resonator antenna (FPRA).,Broadband high gain,magneto-electric dipole antenna (MEDA)
更新于2025-09-10 09:29:36
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A 400-GHz Wideband High-Gain Quartz-Based Single-Layered Folded Reflectarray Antenna for Terahertz Applications
摘要： Compact high-gain antennas are highly desired in the high speed terahertz (THz) wireless system, especially for the space limited application such as the high speed inter-link inside the high density wireless communication base station. To this end, a 400-GHz folded reflectarray (FRA) antenna with high gain, high aperture efficiency and compact profile is proposed in this paper. It is composed of a feed source, a single-layered reflectarray using a lithography process on quartz, and a wire-grid polarizer implemented by the printed-circuit-board (PCB) technology. A 3-D printed fixture is used to assemble all parts together. In order to design accurately the THz electromagnetic properties of the supporting dielectric materials are extracted by using a THz time-domain spectrometer system. Then, a single-layered phasing element, made up of a pair of orthogonally I-shaped structures with an open square ring, is proposed and designed based on the extracted material characteristics. Both phase compensation and polarization conversion can be realized by the proposed unit cell. A reflectarray is designed by using the proposed phasing element with the conventional array synthesizing theory, and a THz grid polarizer is designed with strips on a 0.127 mm Taconic TLY-5 substrate. The THz grid is placed in front of the THz feed and the reflectarray, which is fully reflective to the feed and transparent to the reflectarray. All components of the FRA antenna have been fabricated and assembled. Experiments show that the FRA prototype has a peak gain of 33.66 dBi at 400 GHz with an aperture efficiency of 33.65%, and a 3-dB gain bandwidth of 16% (357-421 GHz).
关键词： terahertz,3-D printing,high-gain,material characteristics,quartz substrate,single-layer,Folded reflectarray antenna,THz time-domain spectrometer
更新于2025-09-10 09:29:36
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Photogating and high gain in ReS <sub/>2</sub> field-effect transistors
摘要： Two-dimensional layered transition metal dichalcogenides have shown much promise due to their remarkable electro-optical properties and potential use as photodetectors. We observed photogating in our few-layered (3–4 layers) ReS2 field-effect transistors (FETs) in which varying the incident optical power shifted the FETs’ threshold voltage. The photogating effect produced a significant gain in the electrical response of the FETs to incident light as measured by the responsivity (R) and external quantum efficiency (EQE). We obtained a maximum R of 45 A/W corresponding to an EQE of ～10 500% in a four-terminal measurement of the photoconductivity in the ON-state. We attribute both the photogating and the observed gain to the influence of charge traps. An estimate of the device gain based on our observations is calculated to be 5 × 104. Published by AIP Publishing.
关键词： photodetectors,high gain,charge traps,ReS2,field-effect transistors,photogating
更新于2025-09-10 09:29:36
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RCS Reduction and Gain Enhancement for the Circularly Polarized Array by Polarization Conversion Metasurface Coating
摘要： High-gain, the ultra-wide band circularly polarized (CP) array with low radar cross section (RCS) is proposed based on (UWB) polarization conversion metasurface (PCM) coating. A chessboard-like coating is formed by a mess of arrow-shaped PCM elements which have UWB and high polarization conversion ratio. The coating is distributed beneath the dipoles and behaving as a reflector. With the PCM beneath each dipole, the CP radiation is achieved and enhanced in a low profile by the radiating wave and the reflected wave, which have equal amplitude and 90° phase difference. With the chessboard-like coating, the incident wave is converted into the equal amplitude and out-of-phase reflected waves, which will cancel each other to reduce the backward scattering. The performances of the array are validated by both simulations and measurements. The results show that the left-hand CP radiation is achieved in 11.25 GHz to 12.31 GHz with the RCS being reduced for more than 4.8 dB in 10.5 GHz to 35.1 GHz.
关键词： high gain,circular polarization,low profile,radar cross section (RCS),polarization conversion metasurface (PCM)
更新于2025-09-09 09:28:46
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A Miniaturized and High Gain Double-Slot Vivaldi Antenna Using Wideband Index-Near-Zero Metasurface
摘要： In this paper, a wideband, miniaturized, and high gain double-slot Vivaldi antenna is proposed. First, a corner cutting technique is adopted to broaden the frequency band. Second, a pair of defected ground slots are added to the edges of the antenna to extend the low-end frequency limitation from 2.27GHz to 1.15 GHz, which provides a great design freedom. Third, a novel unit cell of an index-near-zero metasurface is proposed in our design. The unit cell is a two-stub-loaded split-ring resonator, which has a compact size, a wide frequency band, and a good reflection coefficient. The gain of the double-slot Vivaldi antenna is improved over a wide frequency band by the inclusion of the index-near-zero metasurface in the aperture, without changing the overall dimensions or compromising the whole frequency band performance of the antenna. Finally, to verify the design method, an ultra-wideband double-slot Vivaldi antenna with defected ground slots and metasurface was fabricated and measured. The circuit has an overall size of 0.76 λg × 0.41 λg × 0.005 λg. The modified antenna exhibits a measured gain of 0.7–14 dBi over the frequency band of 1.13–12 GHz.
关键词： index-near-zero,Vivaldi antenna,Defected ground slot,high gain,metasurface
更新于2025-09-09 09:28:46
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Metamaterial-Inspired Self Polarizing Dual Band Dual-Orthogonal Circularly Polarized Fabry-Perot Resonator Antennas
摘要： This study presents a Fabry-Perot resonator antenna (FPRA) with dual-band dual-orthogonal circular polarization. The whole FPRA consists of a linearly polarized microstrip patch antenna and a chiral metamaterial superstrate. The linearly polarized microstrip antenna serves as the feed system, while the chiral metamaterial (CMM) superstrate has the function of polarization transformation. The CMM also works as a partial reflective sheet to form an FPRA. Ray-tracing method in the circular base is introduced to describe the mechanism of this type of FPRA. Furthermore, the procedure of controlling the frequency ratio of two bands is discussed as well. An antenna prototype is fabricated to validate the simulated results. In the frequency band from 7.24 GHz to 7.36 GHz, the proposed FPRA produces right-handed circularly polarized wave. However, left-handed circularly polarized wave is achieved when the frequency ranges from7.96 GHz to 8.14 GHz. The realized gains reach 12.98 dBic at 7.28 GHz and 13.25 dBic at 8 GHz, respectively.
关键词： Fabry-Perot resonator antenna,dual-orthogonal circular polarizations,dual-band,chiral metamaterial,high gain,self-polarizing
更新于2025-09-09 09:28:46