The frequency response of a superconducting transmission line

A two-element equivalent circuit for the surface impedance of a superconductor is considered in approximations of the frequency response of a superconducting transmission line. It is shown that the model yields good approximate agreement with more rigorous derivations applied to classical or anomalous normal conductivities, as well as to nonlocal conduction effects.     

Nonlinearity in fiber transmission

Procedures are presented for estimating critical powers for nonlinear optical processes in single-mode fiber transmission systems. Crosstalk due to Raman gain in multiplexed systems can appear at powers of a few mW. The effects of self-phase modulation and stimulated Brillouin scattering can appear around 100 mW while typical stimulated Raman threshold powers are a few watts.     

Field solution of a type-II superconducting thin-film planarasymmetric transmission line in the mixed state

By using the electrodynamic field equations for a type-II superconductor in the mixed state, a sinusoidal wave solution is derived for an asymmetric high-T_c superconducting transmission line in the presence of vortices. This solution can be used to numerically demonstrate the dependence of the slow mode propagation on the temperature, frequency, and static magnetic field. The effects of vortices on propagation characteristics in a superconducting strip line are thus elucidated     

Wide-band superconducting microstrip delay line

This paper describes the design, fabrication, and testing of a novel microstrip superconducting delay line. The structure of the delay line is a double-spiral meander line. The device is patterned from a YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//(YBCO) thin film deposited on both sides of a 2-in-diameter LaAlO/sub 3/ substrate with a thickness of 0.25 mm. It exhibits low insertion loss up to 20 GHz. At 10 GHz, the measured attenuation is 0.031 dB/ns at 30 K, 0.049 dB/ns at 60 K, and 0.118 dB/ns at 77 K. The magnitudes of the ripples are below 2 dB across the entire band. The total delay at low frequency is approximately 29 ns.     

Modeling of planar quasi-TEM superconducting transmission lines

Design oriented modeling of high-temperature superconducting thin-film microwave circuits is difficult when film thickness is on the order of the penetration depth of the fields. Involved formulas for loss, phase velocity and characteristic impedance can be derived from the Bardeen-Cooper Schrieffer (BCS) theory of superconductivity. The parameters required by these formulas do not correspond to readily measurable observables that depend on the manufacturing process of the superconductor. An application of the phenomenological loss equivalence method in modeling the microwave behavior of planar quasi-TEM superconducting transmission lines is presented. Measured and modeled S-parameters of a superconducting coplanar waveguide lowpass filter agree to within 0.3 dB in magnitude and 0.5 radians in phase. Extracted values for the penetration depth and the real part of the conductivity of the superconducting film are within 10% of the findings of other researchers     

Compact superconducting coplanar meander line filters

Novel slow-wave coplanar waveguide (CPW) filters using high temperature superconductor (HTS) films are presented. Both half-wavelength and quarter-wavelength resonators are used in the filter topology. The miniaturisation is achieved using meander structure and interdigital grounding lines. A 3-pole Chebyshev bandpass filter has been designed, fabricated and studied. The untuned experimental results are in very good agreement with the simulated responses.     

Hyperbolic RC transmission line

The hyperbolic RC transmission line, defined by r = r0 sech2x and c = c0 cosh2x, is a new class of RC nonuniform line whose rc product is a constant. This line can be used to make quantitative comparisons of the performance of the three general shapes of nonuniform RC lines with a constant rc product.     

Feasibility of electric power transmission by DC superconducting cables

The electrical characteristics of dc superconducting cables of two power ratings were studied: 3 GW and 500 MW. Two designs were considered for each of the two power ratings. In the first design, the SUPPLY stream of the cryogen is surrounded by the high-voltage high-temperature superconductor cylinder. The RETURN stream of the cryogen is on the grounded side of the system. In the second design, both the SUPPLY and the RETURN streams of the cryogen are on the grounded side of the cable. Two electrical characteristics of these cables were studied: 1) fault currents and 2) current harmonics. It was concluded that neither the fault currents nor the current harmonics pose any problems in the operation of the dc superconducting cables.     

传输线的反射干扰

在数字信号处理系统中,时钟信号和数字信号传输因传输始端和终端阻抗不匹配而引起反射干扰,使传输信号的波形出现上冲、下降和振荡。为了抑制这种因阻抗不匹配引起的反射,本文首先从产生这种反射的原因和造成的重大危害分析,提出了反射干扰这一亟待解决的问题;接着从传输线的阻抗特性以及阻抗匹配原理出发,提出了始端和终端阻抗匹配原则,最后给出了几种减小和抑制反射干扰的方法,实践证明使用阻抗匹配这一方法在减小反射干扰是十分有效的。     

硅基微机械微波传输线的制备与特性分析

介绍了三种硅基微机械波传输线：矩形波导、V型槽及W型槽共平面波导,及其三种传输线的制备工艺流程。分析认为,制备方法不同,导致传输线结构、特性阻抗、插入损耗等特性亦不同。     

Semiconductor photodetection-active transmission line analog

Semiconductor detection of optical frequency (or less) signals makes use of the photoelectric effect and may be readily characterized by active transmission lines. This letter briefly describes the semiconductor photodetection analog.     

Codes for digital line transmission

Some ternary line codes using alternative codeword sets are described; it is shown that, compared with the currently accepted 4B3T codes, some reduction in redundancy can be achieved without increasing the digital-sum variation.     

输电线路智能地线管控系统的研制与应用

为了提高输电线路智能地线管控能力,构建输电线路智能地线管控系统,提出基于虚拟同步控制的输电线路智能地线管控系统,建立了矢量控制下输电线路智能地线管控等效电路模型.采用T型等效电路分析的方法进行输电线路智能地线管控的系统稳定性特征分析,求得输电线路智能地线管控的优化参数结构模型.基于虚拟同步控制方法,进行输电线路智能地线...     

Analysis of a MEMS transmission line

A microelectromechanical system (MEMS) sound waveguide is considered as a transmission line for RF signals. We analyze a device geometry of a straight one-dimensional microsize silicon rod, where a longitudinal acoustic wave is generated and detected using capacitive transducers. Linear, isotropic, and nondispersive acoustic-wave propagation is assumed. Based on the calculation of the electromechanical impedance, an electrical equivalent model is derived for the acoustic transmission line. A numerical example and a comparison to measured properties of a MEMS-transmission-line resonator shows that the characteristic impedance level of the waveguide is typically high, which causes challenges for matched termination. Solutions to overcome the matching problems are discussed.     

Low-loss open transmission line: the open ring line

A new low-loss line, the open ring line, is described. The aluminium-alloy structure consists of equally spaced rings held by a rod of the same metal. The measured attenuation for the hybrid dipolar mode is less than 5 dB/km below 1.8 GHz.     

An exponentially tapered transmission line antenna

The analysis and design of an exponentially tapered transmission line antenna is presented. The exponentially tapered transmission line is designed to operate such that it has radiator characteristics at high frequency and serves as a matching section at low frequency. The NEC-2 is used to model the antenna at frequencies ranging from 500 MHz to 1 GHz to obtain the input impedance and the desired radiation pattern     

Scattering parameter and bit error rate characterization of hightemperature superconducting coplanar transmission lines

We report the gigahertz experimental results of time and frequency performance on YBCO high temperature superconductor (HTS) and gold coplanar transmission lines. An on-wafer direct probing measurement system was used to collect data at cryogenic temperatures on both YBCO and gold coplanar lines. The insertion loss of the 6-cm lines at a frequency of 3.0 GHz was measured to be -0.12 dB for the superconducting line compared to -10.7 dB for the gold line at 80 K. Error rate and eye-diagram measurements were performed on the packaged lines and show the correlation between the insertion loss of the line and the attenuation of a Pseudo Random Bit Sequence (PBRS). The superconducting line measured at 77 K had a BER rate of less than 10^-11 at a data rate of 3 Gb/s. The measured eye height was 350 mV for the YBCO compared to 100 mV for a gold line at 3 Gb/s and a temperature of 77 K for the packaged 6-cm lines