Study On Field Strength And Delay Of Low Requency Ground-Wave

Low frequency ground-wave propagation with stability, small attenuation, far transmissiondistance and other advantages, is widely used in navigation, time, frequency and remotecommunication, broadcasting, underground communication and detection etc. It is veryimportant for the timing and navigation precision correction to the accurately predictionpropagation attenuation and phase delay of long wave along the uneven ground.At present, long wave along the uneven ground propagation calculation mature methods areJ. R. Wait method and Millington method. J. R. Wait method is strictly surface wave formula,but it is necessary to introduce more multiple integral with more segmented. So bring a lot ofdifficulties to numerical calculation in practical. In this thesis, using software to realized the anyfrequency ground wave field strength and secondary phase factor computation. Using thesoftware can easily predict LF. Millington empirical formula is quite convenient, but it isempirical formula, calculation accuracy less than the J. R. Wait method. In practicalapplications we generally use the Millington empirical formula to replace the J. R. Wait method.Scholars and experts concerned problem if Millington empirical formula to replace J. R. Waitmethod meets the application requirements. In this paper, through the calculation andcomparison, the final numerical results showed that the Millington empirical formula to replacethe J. R. Wait method to meet the application requirements.The existed low frequency wave forecasting methods are relevant to surface wavepropagation path, so it is inevitably affected by many irresistible factors that suddenweather(rain, snow) effect; wave propagation terrain path; value conductivity with the sides ofwave path regional conductivity very difference. This paper based on the wave theory formulaand numerical calculation, boldly put forward the "carrier frequency distortion" concept andbriefly explores the predicted new method of LF that use of" frequency distortion". Currently,this new method is simple and rough exploratory discussion only on theoretically. Complexityof practical implementation and application accuracy issues still need to do further study byexperts.