The Effect On The Shortwave Transmitting Field Of The Electrified Railway's Radio Disturbance

In recent years, because of the increase of the transportation of both travelers and goods, the electrified reconstructions for some important high railway are being progressed. The electrified railway has been increasingly used in many countries, due to the advantage of its great power and little pollution to the environment. In fact, it is indispensable in modern transportation. However, there are also some problems, because the energy consumed by the train is the alternating current of large amplitude supplied by the contact system. When the train is running, the contact system can not always keep contact with pantograph pan due to many factors. Thus, the disturbance pulse with large amplitude may be generated when the pantograph pan is off the contact system. Usually, this kind of pulse has a wide frequency spectrum, which can interfere with radio equipments nearby. There are many factors associated closely with it, such as the speed of the train, the type of the train, the type of the contact system and pantograph, the characteristic of the ground near the railway, and so on. That's why many scholars devoting to the problems in recent years. Lots of conclusions are given, but many problems remain unanswered.In the thesis, the effect on the shortwave transmitting field nearby of the electrified railway's radio disturbance were analyzed. First, the radio disturbance of the electrified railway were measured and much measurement data were obtained; And then a model of radio disturbance of the electrified railway and a model of a fixed shortwave transmitting antenna were set and analyzed by the FEKO program. FEKO is a kind of widely used simulation software, which is suitable for simulating the problems of electric large size. Then some characteristic of the radio disturbance of the electrified railway (the frequency range is from 3MHz to 30MHz) and the characteristic of the shortwave transmitting antenna were obtained. Especially, the transverse propagation characteristic of the radio disturbance of the electrified railway and the directivity of the transmitting antenna were analyzed.At last, comparisons were done between the measurement data and the simulated data. The comparison result shows that the models and the simulations are correct; Also comparisons were done between the data obtained by the theoretical formula and the simulated data. It is concluded that the data was well matched in the measurement distance. At the end of the thesis, the effect on the transmitting field of the electrified railway's radio disturbance were investigated based on the simulated results.