Papers by Keyword: Micro-Wave

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Authors: Gang Chen, Peng Wu, Song Bai, Zhe Yang Li, Yun Li, Wei Jiang Ni, Yu Zhu Li
Abstract: . Silicon carbide (SiC) SITs were fabricated using home-grown epi structures. The gate is a recessed gate - bottom contact (RG - B). We designed that the mesa space 2.7μm and the gate channel is 1.2μm. One cell has 400 source fingers and each source finger width is 100μm. 1mm SiC SIT yielded a current density of 123mA/mm of drain current at a drain voltage of 20V. A maximum current density of 150 mA/mm was achieved with Vd=40V. The device blocking voltage with a gate bias of-16 V was 200 V. Packaged 24-cm devices were evaluated using amplifier circuits designed for class AB operations. A total power output in excess of 213 W was obtained with a power density of 8.5 W/cm and gain of 8.5 dB at 500 MHz under pulse operation.
Authors: Zhen Yu Li, Hong Sheng Li
Abstract: Plasma Chemical Vapor Deposition ( PCVD ) is an important application in making optical fiber core rod. The resonator is the key part for PCVD application. But the existing resonator have several serious disadvantages: its working is not stable; the size of deposited substrate tube is small(Ø31mm); the deposition rate is low(2.5g/min) and the deposition effect is unsymmetrical; the fabrication of the resonator is very difficult and expensive. Therefore, a new type of resonator, a cylinder resonator, is designed to overcome the above disadvantages. The cylinder resonator supports bigger substrate tube (Max Ø60mm) and higher deposition rate(3.2g/min) than existing ones, while its working is also more stable. Since the structure is more simple, the fabrication is easier and cheaper. The corresponding microwave theoretical method of the new resonator designing is also introduced with the necessary computer simulation, as well as test running. And TE111 mode microwave is the Fundamental Mode of the cylinder resonator. The cylinder resonator has been applied in normal production for 4 years, which is better for bigger size core rod making, improving the optical fiber quality and saving cost. It is estimated, after modification with the cylinder resonator and 10kW microwave generator, a PCVD lathe can yield 30% more rods than before.
Authors: Ji Un Im, Chan Yong Yu, Jeong Yi Yoo, Se Mo Son, Gun Dae Lee, Seong Soo Park
Abstract: Symmetrically and unsymmerically substituted bis-dithiobenzil nickel complexes containing four substituted and unsubstituted methoxy groups were synthesized from a benzoin compound using phosphorous pentasulfide under the conventional thermal and microwave processing. The efficiency of microwave synthesis over the conventional thermal synthesis was illustrated by the yield of bisdithiobenzil nickel complex dyes. The samples were characterized by the means of elemental analyzer, 1HNMR, IR spectroscopy, Uv-vis spectroscopy and DSC.
Authors: Juan Juan Song, Li Tu
Abstract: The comprehensive utilization of fly ash mainly concentrated is in construction engineering channels, road engineering, it used to deal with waste water is full of hope. As this, it can achieve the purpose of using the waste to conduct waste. Fly ash was modified by a microwave radiation. This method was simple and easy to operate . When the dosage of Modified fly ash is 4g, the pH value is 6.2, the mixing time is 50min, the initial concentration of copper solution is 1.85mg/L ,Adsorption rate of modified fly ash on Cu2+ reached 96%.
Authors: Hua Yi Jiang, Xu Wang, Ai Jun Wei, Si Jia Zheng, Fang Liu, Cheng Ji
Abstract: Through comparative experiments of products that treated by microwave, researched on the feasibility of disposing oil sludge with microwave technology, analyzed the influence of different microwave parameters (power of microwave and microwave effect time) on the treatment effect, and theoretically analyzed the mechanism of harmless and resourceful treatment of oil sludge with microwave. The experimental and theoretical studies have shown that, microwave radiation has the characteristic of quickly and efficiently, energy conservation and environmental protection, and superior to traditional heating treatment technology. Microwave thermal effect and non-thermal effect can make heavy hydrocarbon cracking, speed up the process of oil sludge separation for gas phase, liquid phase, and solid phase, and achieve the oil sludge harmless and resourceful treatment.
Authors: Katsufumi Ehata, Shenglei Che, Norimasa Sakamoto
Abstract: Details of a new technique for the permittivity measurement of ceramic powders at microwave frequencies are described. Permittivity of a powder is calculated from the permittivity of liquid medium and that of the slurry made from the liquid medium and the powder. Measured permittivities of BaNd2Ti4O12 ceramic powders vary by processing conditions of the powders. This result is consistent with permittivities of composite substrates made from these powders and a thermosetting resin.
Authors: Michael J. Uren, Martin Kuball
Abstract: Recent work on the thermal and electrical challenges in realizing AlGaN/GaN microwave heterojunction field effect transistors grown on SiC substrates is discussed. Raman thermography has been used to directly measure the self-heating induced lattice temperature rise with dramatically improved resolution and accuracy compared to traditional infrared techniques. It is demonstrated that defects in the SiC substrate can influence the temperature distribution within the active device with potential consequences for reliability. Microwave devices require an insulating GaN substrate material for device isolation. It is shown that the net deep level acceptor concentration has to be accurately controlled to suppress short-channel effects and to achieve radio frequency power efficient operation.
Authors: Takashi Nishida, Takashi Nozaka, Takuya Tsuchikawa, Masahiro Echizen, Hiroaki Takeda, Kiyoshi Uchiyama, Tadashi Shiosaki
Abstract: (Ba,Sr)TiO3 (BST) thin films have been investigated because of significant interest in device applications of their nonlinear dielectric properties such as in frequency tunable devices. We have investigated frequency conversion devices using BST films as new nonlinear devices, such as frequency mixers and multipliers. In this paper, we report the evaluation of nonlinear properties of various capacitors, and the experimental equation of the properties and the equivalent circuit model for frequency converters were established. A frequency multiplier using the BST film capacitor was fabricated, and obvious third harmonic signals could be observed. A conversion efficiency of -20 dB was obtained with a low input power of 0.25 W. Analysis of the converter with an equivalent circuit was also carried out, and the calculated output voltage agreed well with the measured result. The model is expected to be used for the analysis and improvement of conversion devices.
Authors: Ladislau Matekovits, Aldo de Sabata
Abstract: This work numerically explores the relations between the positions and the widths of the frequency bandgaps that occur in some shielded high impedance surfaces and the geometrical dimensions of the structures. The reported parameterized results are useful for design issues and for circuit models conception and validation.
Authors: Zheng Jun Wang, Xiao Ou Jin, Dian Min Sun
Abstract: In order to shorten time-periodic of mix design and verification of cement concrete in the period of construction, and can realize the node control of key procedure of cement concrete structure. The paper obtained and established relationship between super-early-stage strength and compressive strength of 7d, 14d and 28d of cement concrete on based of microwave promoting curdle. The method can realize predication of cement concrete through microwave promoting curdle.
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