Papers by Keyword: Low Loss

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Authors: R.N. Gupta, H.R. Chang, E. Hanna, C. Bui
Authors: Makoto Mizukami, Osamu Takikawa, M. Murooka, Seiji Imai, Kozo Kinoshita, Tetsuo Hatakeyama, M. Tsukuda, W. Saito, I. Omura, Takashi Shinohe
Authors: Yi Liao, Yuan Zhang, Kun Cai, Wei Gao
Abstract: Small radio frequency identification (RFID) tag antennas are generally designed to achieve conjugate matching with capacitive chips at the called tag resonant frequency. An approximate equivalent circuit is proposed to represent the antenna input impedance in low loss dielectric materials. It consists of a shunt conductance considered to be linearly proportional to loss tangent, an input resistance and reactance of antenna in lossless materials. Comparing with the simulated result of full wave numerical tool, the equivalent circuit gives acceptable errors in input resistance and reactance at the tag resonant frequency and nearby. The simple equivalent circuit can be used to reduce the repetitive simulation work for different loss tangent.
Authors: Yun Cai Lu, Wei Li, Peng Wu, Chao Wei
Abstract: Firstly, this paper introduces the development of amorphous alloy transformer. According to the technical characteristics of amorphous alloy transformer and the application of Jiangsu power, the comprehensive evaluation about amorphous alloy transformer from the safety performance, the economic performance and the environmental impact are studied comparing with S11 type, S13 type and S15 type transformer. In the safety performance, overload capacity and over-excitation ability of amorphous alloy transformer is insufficient; in the economic performance, low no-load loss, high efficiency, energy saving effect of amorphous alloy transformer is obvious; in terms of environmental impact, the audible noise level of amorphous alloy transformer is higher than that of conventional transformer, and manufacturers need to study to reduce the noise level. Finally, the application recommends of amorphous alloy transformer is presented based on comprehensive evaluation.
Authors: Anesh K. Sharma, Ashu K. Gautam, D.V.K. Sastry, S.G. Singh
Abstract: This paper presents the design & modeling of distributed MEMS phase shifter for Ka band RF systems. The phase shift can be achieved by periodically placing the MEMS bridge variable capacitors as per Bragg frequency criteria on coplanar waveguide (CPW) using GaAs substrate. The EM & electromechanical simulation are carried out with various structural parameters to optimize the designs. The novelties like low insertion loss, low actuation voltage with distributed actuation pads & separate DC and RF are used to make the design unique. The EM simulations are carried out with HFSS and an insertion loss of -3.49 dB at 36GHz for a total Phase shift of 360 deg. was achieved with return loss of - 20.6 dB over a frequency band 34-38 GHz. The electromechanical simulations are carried to achieve the low actuation voltage of 10.3V. The significance of this study is the realization of the digital phase shifter through DMTL approach.
Authors: Jian Ming Huang, Y. L. Zhou, H. Guo
Abstract: The design and development of novel microelectromechanical systems’ (MEMS) coplanar waveguide (CPW) transmission lines, using microshield and groove, are presented in the paper to operate between 5–60 GHz. The quasi-static capacitances of CPW are calculated using the conformal mapping technique to express the propagation properties, i.e., the characteristic impedance and effective permittivity. Simulation results have shown a considerable loss reduction to levels that compare favorably with the conventional CPW. These transmission lines can be widely used in the development of phase shifters, filters, and antennas, because of their advantages in loss reduction and improvement in the performance.
Authors: Chung Long Pan, Chun Hsu Shen, Wei Cheng Lin, Shin Hung Lin
Abstract: The effects of B2O3 additive on the microstructures, the phase formation and the microwave dielectric properties of MgTiO3–CaTiO3 ceramics were investigated. The sintering temperature of B2O3-doped 0.95MgTiO3–0.05CaTiO3 ceramics can be lowered to due to the liquid phase effect. Formation of second phase MgTi2O5 can be effectively restrained through the addition of B2O3. The microwave dielectric properties are found strongly correlated with the sintering temperature as well as the amount of B2O3 addition. At , 0.95MgTiO3–0.05CaTiO3 ceramics with 10 wt% B2O3 addition possesses a dielectric constant of 18.3, a Q×f value of 20,000 (at 7 GHz) and a value of −6.12 ppm/. In comparison with pure 0.95MgTiO3–0.05CaTiO3 ceramics, the doped sample shows not only a 22% loss reduction but also a lower sintering temperature. That makes it a very promising material to replace the present one for GPS patch antennas.
Authors: Makoto Mizukami, Osamu Takikawa, Seiji Imai, Kozo Kinoshita, Tetsuo Hatakeyama, Tomokazu Domon, Takashi Shinohe
Abstract: A 4H-SiC 600 V class Deep-Implanted gate Vertical JFET (DI-VJFET) is examined. The DI-VJFET exhibited a specific on-resistance of 13 mΩcm2, drain current of 5 A, and a blocking-voltage of 600 V. In this paper, the very high temperature dependence (R.T.~ 400 oC) of the I-V characteristics is measured and the dominant factor of the on-resistance and the blocking-voltage is discussed. Moreover, the switching waveform of SiC DI-VJFET with SiC SBD is measured by using a half bridge, double-pulse circuit with inductive load at R.T. and 200 oC. The turn-off time is 300 ns at an inductance of 4 mH and an external gate resistance of 100 Ω.
Authors: Mo Yang, Jin Cheng Song
Abstract: In this paper, we present the design of a novel hybrid dielectric-metal-dielectric waveguide, which consists of a metal stripe sandwiched between low-high dielectric layers. Its modal characteristics are investigated using the finite element method at the telecom wavelength. Simulations show that the dielectric contrast near the metal stripe results in a strongly confined hybrid plasmonic mode with sub-micron mode size and low propagation loss. The effects of geometrical parameters are analyzed systematically and the properties of directional couplers based on such hybrid waveguide are also investigated. The proposed structure could be useful candidates for various integrated optical devices and enable many applications such as electro-optic modulation, switching, sensing and more.
Authors: Jian Fu Peng, Le Feng Cheng, Li Peng Huang, Jing Jiang, Tao Yu
Abstract: This paper presents an intelligent method of optimized control of DC voltage based on BP Neural network, on account of this presentd method, by collecting parameters of grid voltage and significant frequency of harmonic current, then, construct couples of tranining samples and fully use the advantages of BP Neural network that can discretionarily utlize arbitrary precision to approximate any continuous function, and computing the optimized voltage of DC side, as a result, achieving online adjustment of capcitors voltage at DC side. Futher more, adjusting the hysteresis width automatically according to the voltage variation of capacitor, thus the voltage of DC side can automatically adapt to fluctuation of grid voltage and load current, so that to obtain comprehensive optimum of power loss and compensation performance of power active filter.
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