CAD Models for a Boxed Coplanar Waveguide with Multilayered Substrates and Overlays

By the conformal mapping method, CAD-oriented analytical closed-form expressions for the quasi-TEM parameters for a boxed coplanar waveguide (BCPW) with multilayered substrates and overlays are presented. The parameters include the effective dielectric constant, the characteristic impedance, the wavelength of the guided wave, and the capacitance per unit length. All of the formulas obtained in this paper are simple and accurate enough for microwave circuits' designs and are useful for transmission line theory.     

Analysis of Asymmetrical Coplanar Strip Lines with Finite Boundary Substrate

Analytical closed-form expressions for the quasi-TEM parameters for asymmetrical coplanar strip lines (ACPS) with finite boundary substrate are obtained using conformal mapping method. The formulations are CAD-oriented purpose. The calculated results are compared with those obtained for a corresponding ACPS assumed that the substrate is infinite. The analyses are useful for MMIC's designs and transmission line theory.     

A Design of Magic Tee with Coplanar Arms

Magic tee is a widely used component in microwave systems; the four arms of conventional magic tee direct at four different directions, which give inconveniences to the assemblage of a system. In this paper, a broad-wall slot directional coupler and an E-plane dielectric loaded waveguide phase shifter is used to form a magic tee with four arms in the same E-plane. The magic tee is analyzed exactly with mode match method; and the simulated annealing method is used to optimize the performance of the magic tee. Simulation results are presented, which show good performance.     

Buckling of Elastic Thin Films on Compliant Substrates for Determination of Surface Parameters

The buckling of an elastic thin film on a compliant substrate under small perturbation in normal deflection and tangential displacement is studied with the effect of surface energy and interracial slip. It is revealed that Poisson＇s ratio of the soft substrate and the interracial slip can be neglected for film＇s thickness smaller than tens of nanometers. The effect of surface energy nevertheless renders the critical strain for the onset of wrinkling and the wave length dependent on the thickness highly nonlinearly. The potential of using buckling of thin films on compliant substrates for determination of surface parameters has been discussed.     

Computation of Microwave Attenuation on Coplanar Waveguide with Conformal ADI-FDTD Method

A novel Conformal Finite-Difference Time-Domain based on Alternating-Direction Implicit Method(ADI-CFDTD) used to calculate the microwave attenuation on coplanar waveguide(CPW) with complicated cross-section up to 200GHz is presented. This ADI-CFDTD algorithm is the combination of conformal algorithm dealing with the deformed cell with ADI-FDTD, and has unconditionally stable. The difference equations are derived from the Faraday's and Ampere's law. To validate its accuracy and efficiency, as an example, a CPW fabricated on lithium niobate is proposed. Numerical results demonstrate that this new ADI-CFDTD algorithm has more accuracy than that of quasi-static and CFDTD and shows good agreement with experiment data. When frequency is up to millimeter wave band the radiation loss is not negligible in total power loss.     

A New Type of Miniature Ultra-Wideband Band-Pass Filter with Coplanar Waveguide Fed

A novel miniature ultra-wideband (UWB) bandpass filter with coplanar waveguide (CPW) fed is proposed. The size of the filter is reduced largely because of combining the wideband couple gap and parallel-coupled CPW line (not cascading multiple resonator), and the length of realized filter is only 0.42 λ _g0 (λ _g0 is the guiding wavelength at central frequency). The measured insertion loss is less than 2.0 dB, and the group delay variation is less than 0.2 ns within the UWB passband. Basic agreement between the simulated and measured results has been achieved.     

有限时间尺度内分子指向相关的不对称扩散研究

传统的经典扩散理论常常将分子和物体假设为球形,这些分子和物体的扩散是无偏移各向同性的。然而,当我们在纳米尺度去看分子和物体时,这些分子和物体呈现出各种不对称的结构。进一步,当我们观察的时间有限到小于几十纳秒时,我们会看到这些分子和物体的自由扩散表现出与它们的初始方位相关的特性。对于像甲醇分子这样的小分子,在约100 ps的有限时间内,常温下,不对称扩散能占到总扩散的10%左右。这样的不对称扩散丰富了分子的扩散理论,对生命和其他自然界现象的理解具有重要的意义,同时也可能提供一种通过控制分子的方向来驱动分子的方法。     

Asymmetrical free diffusion with orientation-dependence of molecules in finite timescales

Using molecular dynamics simulations, we show that free diffusion of a nanoscale particle (molecule) with asymmetric structure critically depends on the orientation in a finite timescale of picoseconds to nanoseconds. In a timescale of ~100 ps, there are ~10% more possibilities for the particle moving along the initial orientation than moving opposite to the orientation; and the diffusion distances of the particle reach ~1 nm. We find that the key to this observation is the orientation-dependence of the damping force to the moving of the nanoscale particle and a finite time is required to regulate the particle orientation. This finding extends the work of Einstein to nano-world beyond random Brownian motion, thus will have a critical role in the understanding of the nanoscale world.     

Computation of Microwave Attenuation on Coplanar Waveguide (CPW) with Complicated Cross-Section

Using a method of conformal finite-difference time domain (CFDTD), we present the analysis results of attenuation that may occur on the CPW with complicated cross-section up to 200GHz. The CPW is fabricated on lithium niobate which is an anisotropic material. The simulative result is more accurate than that of quasi-static method and shows good agreement with experiment data. It also shows that the radiation loss is not negligible in total power loss when frequency is up to millimeter wave band.     

Numerical Simulations of Backward-to-Forward Leaky-Wave Antenna with Composite Right/Left-Handed Coplanar Waveguide

A composite right/left-handed （CRLH） coplanar waveguide （CPW） structure and its leaky-wave antenna （LWA） with continuous backward-to-forward scanning applications are proposed. The structure of the CRLH transmission line （TL） is composed of split-ring resonators （SRRs） for left-handed （LH） series capacitance and short-circuited stubs connected between the CPW central signal line and the ground for LH shunt inductance, while the unavoidable right-handed （RH） parasitic effects series inductance and shunt capacitance are generated by wave propagation through the host transmission line. The dispersion relations are calculated and compared with the equivalent circuit model method and 3D full-wave simulations, which can be used to determine the physical dimensions of the CRLH-CPW, such as in the balanced CRLH-TL case. As a main example, a CRLH-CPW-LWA operating from 1.67 GHz to 1.80 GHz with the dispersion characteristics of the balanced CRLH-TL case shows continuous leakage frequency band （fast wave region） from LH （phase constant β 〈0, .67〈f〈1.74 GHz） to RH （β〉0, 1.74〈f〈1.80 GHz） state through the transition frequency point （β=0, f=1.74 GHz）, whereas conventional LWAs operated in RH state only provide forward scanning capabilities （β〉0）.     

Multilayer neural network with randomized learning: Model and applications

A randomized annealing-simulation scheme for learning by a multilayer neural network is examined. The fractal properties of the learning trajectories in the phase space of the network are studied. It is proposed that the learning temperature be controlled by the phenomenological characteristics of the trajectory. The errors of generalization of a multilayer perceptron and of the method of splines in time-series prediction are compared. It is shown that for nonsmooth functions that generate a stochastic time series, a neural network is preferable to a spline for the same number of parameters. The learning scheme is used to construct a cybernetic neural-network model of the phenomenon of magnetic implosion as well as for fault classification in the coolant system of a nuclear-power-plant reactor.Russian Federal Nuclear Center-All-Russian Scientific-Research Institute of Engineering Physics, Snezhinsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 9, pp. 1084–1103, September, 1994.     

SiO2溶胶及其静电自组装薄膜的制备

采用HCl催化、NH3 ·H2 O催化、HCl与NH3 ·H2 O分步催化三种途径制备了SiO2 胶体 ,用透射电镜观察了胶体粒子的形貌 .用静电自组装 (ESAM)法制备了聚电解质PDDA与SiO2 胶体粒子的有机 /无机复合光学薄膜 .实验结果表明 ,用HCl催化制备的SiO2 透明溶胶不适合于用ESAM法制备薄膜 ,用HCl与NH3 ·H2 O分步催化以及用NH3 ·H2 O单独催化制备的SiO2 胶体适合于用ESAM法制备光学薄膜 .薄膜的透射电镜微观察结果表明 ,以HCl与NH3 ·H2 O分步催化的SiO2 胶体制备的PDDA/SiO2 薄膜为连续结构 ,NH3 ·H2 O单独催化的为颗粒堆积 .研究了薄膜透光率与薄膜层数的关系 ,考察了薄膜的机械强度 .结果显示 ,以NH3 ·H2 O单独催化的SiO2 胶体制备的光学薄膜的增透效果较好 ,但耐机械擦伤强度较弱     

Theory of Reflective X-Ray Multilayer Structures with Graded Period and its Applications

Journal of Russian Laser Research - We report a theory of reflective X-ray multilayer structures with a graded (slowly-varying) period based on the coupled-wave method and quasiclassical asymptotic...     

Experimental Verification of Left-Handed Metamaterials Composed of Coplanar Electric and Magnetic Resonators

We verified experimentally left-handed metamaterials （LHM） composed of coplanar electric and magnetic resonators. A typical LHM sample composed of coplanar resonator unit cells was fabricated, investigated and tested. The experimental results show that the tested sample has a left-handed band of width 1.4 GHz in the X band. The experimental results agree quite well with the simulation ones. Moreover, both the simulation and experimental results show that the LHM under study can automatically achieve good impedance-matching in the left-handed band.     

Wetting Transitions of Thin Multilayer Films with Opposite Surface Fields

Wetting transitions of very thin three-dimensional ferromagnetic Ising films with opposite surface fields are studied by using a self-consistent duster method. The main result is that the wetting transitions of a thin film depend on the thickness L of the film. When L is small the quasiwetting is suppressed and only the layering exists; while as L ≥ L_C (L_C = 20 in our model), both the quasiwetting and the layering can be observed. The question of critical-point shift in the thin film is also discussed.     

COmparison of Some Basic Plasma Parameters and Discharge Characteristics of Planar Magnetron Sputtering Discharges in Argon and Neon

A comparative investigation is carried out of the discharge characteristics (current-voltage characteristic and dependence of the running voltage on the gas pressure at constant discharge current), as well as of some plasma parameters (electron temperature, floating potential and plasma potential) and densities of the ion current extracted to the substrate, for discharges in neon and argon in a planar magnetron system for sputtering with a graphite target.     

Properties of Defect Modes in Periodic Lossy Multilayer with Negative-Index-Materials

Employing the characteristic matrix method, this study investigates transmission properties of onedimensional defective lossy photonic crystals composed of negative and positive refractive index layers with one lossless defect layer at the center of the crystal. The results of the study show that as the refractive index and thickness of the defect layer increase, the frequency of the defect mode decreases. In addition, the study shows that the frequency of the defect mode is sensitive to the incidence angle, polarization, and physical properties of the defect layer, but it is insensitive to the small lattice loss factor. The peak of the defect mode is very sensitive to the loss factor, incidence angle, polarization, refractive index, and thickness of the defect layer. This study also shows that the peak and the width of the defect mode are affected by the numbers of the lattice period and the loss factor. The results can lead to designing new types of narrow filter structures and other optical devices.