Yinghong Wen

A Compact Uniplanar Rat-Race Coupler with Arbitrary Power Division Ratio and Harmonics Suppression

In this paper, a miniaturized planar rat-race coupler is proposed to achieve arbitrary power division ratio and harmonic suppression performance simultaneously. It consists of six enhanced T- shaped line sections. The T-shaped lines can be equivalent to arbitrary electrical length lines rather than the conventional λ/4 lines. The explicit design formulas are derived and the characteristic impedances variations with the freedom variable are discussed. Simulated and experimental results show the harmonic suppression to be over �35 dB, while maintaining the conventional performance at the fundamental frequency. The circuit area of the prototype is only 30.8% of the conventional coupler.

An investigation of the total radiated power of pantograph arcing measured in a reverberation chamber

Pantograph arcing is the main electromagnetic interference source in electric railways. A series of measurements of the radiated power of pantograph arcing has been taken in a reverberation chamber by using a laboratory replica designed to simulate the arcing pantograph. The radiated power properties are investigated in different resolution bandwidths, arc gap lengths and train speeds. The results show that pantograph arcing is a broadband signal compared to GSM-R bandwidth; the radiated power decreases when the arc gap gets bigger or the speed of train goes higher.

Coupling Analysis for Wires in a Cable Tray Using Circuit Extraction Based on Mixed-Potential Integral Equation Formulation

The China high-speed trains use cable trays to neatly arrange the cables running through the distributed systems. On one hand, they protect cables against external electromagnetic interference and reduce external radiation from the cables. On the other hand, the cable trays create waveguide structures that affect the coupling among cables inside the cable trays. To simplify coupling analysis for cables going through a cable tray, a lumped circuit model was built using admittance blocks extracted from a mixed-potential integral equation (MPIE) formulation. In the MPIE formulation, either the half-free space or the waveguide dyadic Greens function was used depending on the region where the cables were. A test case was investigated. Results by the proposed circuit model were validated by measurement and full-wave simulation results.

A new method of on-site radiated emission measurement of train based on Blind Source Separation

In this paper, we present a new method of on-site radiated emission measurement of train. This method is based on Blind Source Separation(BSS) which the prior knowledge of the source signals and transmission channels are unknown. By processing the received multi-channel mixed data, the source signals can be extracted only via two hypothetical conditions (statistical independence and non-gaussianity) in the complex electromagnetic environment under the influence of background noise and interference signal. It has been verified by the simulation that this method can effectively weaken the influence of external interference and improve the accuracy of the measurement which has great value to ensure the safe operation of train.

Simulation of electromagnetic environment inside railway

The environment inside of train is heavily polluted by electromagnetic noise from the railway system itself. These electromagnetic noise may do harmful to passengers and interrupted the communication devices. Aiming at analysis of electromagnetic environment inside railway, the shielding efficiency of enclosure will be researched at first. The electromagnetic field distribution around the cabinet is given in this paper. Then, a simulation model of environment inside train is set up to analyze electromagnetic field of different position in the train. The result shows that the maximum field strength is decreasing with the increase of the distance from disturbance source. At the same frequency, typical electromagnetic fields variation tendency are different according to position.

An anti-interference method for radio signals based on matching pursuit algorithm

Since the GSM-R (Global System for Mobile communications-Railways) antenna located on the train roof is very close to the catenary, it often receives electromagnetic transient disturbance due to sliding contact between the pantograph and the catenary. In order to suppress this transient noise and improve the reliability of communication, a transient noise suppressing method for radio signals based on matching pursuit algorithm is proposed. Firstly, An over-complete atomic library that matches only the transient noise in the mixed radio signal is constructed to implement the sparse decomposition of the transient noise. Then, the optimal matching atomic search of the transient noise is proceeded in the atomic library. In this paper, the GMSK modulation signal in GSM-R system is used as the radio signal to be denoised from the transient noise. The simulation results show that this method can effectively deal with the transient noise denoising problem of the radio signal with a high accuracy result and a low distortion of the radio waveform which keeps the original characteristics of the radio signal, the bit error rate of the radio signal polluted by transient noise is significantly reduced after the processing of the algorithm proposed.

An EMC safety assessment model to analyze complex system in high speed railways

This paper presents a safety assessment model with regard to electromagnetic compatibility (EMC) fault suitable for estimating the EMC failure probability (EMC FP) of the complex system facing uncertain electromagnetic environment. First, the model is successfully applied to decompose the complex system into different independent subsystem and equipment. Then the practical EMI scenario is modeled as different typical EMC problem, such as the Plane Wave Coupling and Crosstalk respectively. After that the fault tree analysis (FTA) is proposed to use in combination with electromagnetic topology (EMT) calculating the EMC FP of the system. A focus is put on the practical case of the Desktop Management Interface (DMI) system. In this context, a system-level EMC safety assessment model has been applied to solve EMC FP by uncertainty analysis in high speed railways with the complex electromagnetic environment.

A Novel Method for Calculating the Radiated Disturbance From Pantograph Arcing in High-Speed Railway

Pantograph arcing is a key electromagnetic disturbance source to affect train control system in high-speed railway. Since the characteristics of pantograph arcing are related to train speed, it is necessary to investigate effective numerical modeling and measurement method. However, due to the uncontrollable train speed during onsite measurement, it is difficult to study the radiated disturbance from arcing in the corresponding speed and repeat the same measurement. Therefore, a method that combines numerical modeling and reverberation chamber measurements for calculating the radiated disturbance from pantograph arcing in a high-speed railway is proposed. Numerical models of train and sensitive equipment are built to calculate the coupling coefficient in CONCEPT II. And a new measurement procedure in reverberation chamber using pulse signal as the reference source is proposed based on a speed-controllable laboratory replica to measure the total radiated power of pantograph arcing. Then, the radiated disturbance from pantograph arcing to the sensitive equipment is achieved with the coupling coefficient and the total radiated power of arcing. The method is verified by laboratory experiments. This method can solve the uncontrollable train speed problem during on-site measurement and improve the repeatability of measurement.