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91.
In an electronic device, the current supplied to the electrodes is related to different types of processes inside the device:
current density, change in spontaneous polarization, and change in dielectric properties. Two expressions for the electrode
current are derived: one is based on the time derivative of the Shockley-Ramo theorem, the other on the time derivative of
the dielectric tensor. This result is illustrated for a switching liquid crystal device and a two-dimensional flux tube. 相似文献
92.
Noureldin M. Ibrahim Ismail H. A. Fattah Mahmoud H. Ahmed 《Fiber and Integrated Optics》1994,13(4):373-379
A design for a 3-dB single-mode Y-junction has been developed and investigated by the beam propagation method with a purpose of decreasing radiation loss in the case of power dividers. The design has two aspects. The first introduces a general design of the boundaries of the 3-dB Y-junction. The second aspect is the replacement of a strip of the guiding material with a lower refractive index near the branching vertex. The design is optimized for low radiation loss, so the output power is increased by 42% over a conventional design. 相似文献
93.
94.
为提高宽带高功率微波辐射天线的总体功率容量和增益,研究了2×2宽带高功率贴片天线阵列的阵元互耦特性、馈电功分器设计及对宽带电磁脉冲的辐射特性。阵元采用宽带高功率双层贴片天线,分析了阵元反射和互耦系数随阵元间距的变化关系,结合增益变化曲线,选取阵元间距为30 cm。优化设计了1分4的同轴功分器,采用阻抗渐变方法,提高了功分器的带宽,使其在224~415 MHz时的反射系数小于0.1。模拟了带功分器的完整天线阵,结果表明天线阵带宽达到了57.4%,280~390 MHz频带范围内的增益大于12 dB,在360 MHz时达到最大增益14.23 dB,对中心频率320 MHz,带宽10%的宽带电磁脉冲辐射效率为868%,峰值功率增益大于11 dB。 相似文献
95.
Transmittance investigation on capacitive mesh on thick dielectric substrates as output windows for optically pumped terahertz lasers 下载免费PDF全文
This paper reports that an output window for optically pumped terahertz (THz) laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate (approximating to 5 mm thick).Unlike the conventional process of depositing a gold film approximating to 100 nm on negative photoresist using electron-beam evaporation,a nickel film approximating to 1.5 μm thick is directly deposited on the clean surface of dielectric substrate using magnetron sputtering and then a positive photoresist is spun onto the nickel metal surface at 6000 r for 60 s.A transmittance spectrum of the output window in a certain frequency range (say,from zero to 1 THz) has been obtained by using THz time domain spectroscopy.Moreover a transmittance spectrum simulated numerically has also been estimated with respect to the output window using the transmission-line model (TLM) containing attenuation component from dielectric substrate.The simulation results show that the TLM can explain well the experimental curve in a certain frequency range from zero to 1 THz.Thus it is demonstrated that the improved optical component can be efficiently used as both output coupler and output window for optically pumped THz lasers. 相似文献
96.
V. V. Azharonok I. I. Filatova V. D. Shimanovich L. N. Orlov 《Journal of Applied Spectroscopy》2001,68(5):831-837
Using methods of emission spectroscopy, we have determined the gaskinetic temperature fields of planar highfrequency capacitive discharge plasma in N2/CO2/He gas mixtures depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture. It is shown that the dominant contribution to the neutral component heating in the center of the discharge chamber is made by the processes of V–T relaxation of vibrationally excited molecules N2(X
1, V) and CO2(X
1, V), whereas in the zones near the electrodes an important role in the heating is played, along with the V–T relaxation of the N2(X
1, V) and CO2(X
1, V) molecules, by the processes of deactivation of the metastable states A
3 of the N2 molecule. 相似文献
97.
98.
介观含时电容耦合电路中压缩的产生及其在有限温度下的量子涨落 总被引:1,自引:0,他引:1
从电容和电感随时间变化的介观电容耦合电路的经典运动方程出发,在给定初始条件下,精确求解了电荷和电流涨落的时间演化规律,并考虑了温度对涨落的影响。在这样的电路中可以产生压缩,并将压缩参数与电路中的物理量联系了起来。 相似文献
99.
A novel 35GHz 3dB power divider using coupled transmission line is presented. Unlike conventional Wilkinson divider circuit, only the 50 transmission lines are used in the design. The impedance matching can be achieved by coupled transmission line even mode characteristic impedance. The predicated and measured performances agree well. 相似文献