Effect on the Propagation Characteristics of the Electromagnetic Waves by the Second-order Radiation of the Moving High-speed Train
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Abstract
The effect on the propagation characteristics of the electromagnetic waves by the second-order radiation of the moving high-speed train is analyzed in this paper. Two Lorentz transformations, one from the stationary reference coordinate system to the moving system and the other vice versa, are employed to derive the theoretical model for analysis of the propagation characteristics of the vertical polarized plane time-harmonic waves, which is oblique incidence to the train. The calculation results show that for the transmitting wave reflected by the moving high-speed train, two main signals can be received. One is at the transmitting frequency and the other is at the second-order radiated frequency. The frequency spectrum between these tw ofrequencies are much larger than which is introduced by the Doppler shift. The frequency and the reflection angle of the reflected wave are no longer equal to the frequency and the incident angle of the incident wave. The changed reflection frequency and angle are related to the train's velocity, the incident angle and the azimuth angle of the incident wave. The frequency shift is mainly decided by the y-component of the train's velocity. It has nothing to do with x-component of the train's velocity. The reflection angles will be smaller than the related incident angles when the train goes along -y direction. The reflection angles will be larger than the related incident angles when the train goes along +y direction. The reflection angle will become larger and larger with the increase of the incident angle and the y-component of the train's velocity. The induced current density and the charge density on the surface of the train are increased with the train's velocity, and the induced charge is much smaller than the induced current.
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