无线电信号传播的多相位屏数学模型及数值模拟

Mathematical Modeling and Simulation of Multiple-Phase-Screen in Radio Signal Propagation

采用多相位屏的数学模型,数值模拟无线电信号在大气中的传播过程.利用高分辨率探空气球提供的折射率数据,采用三次样条插值,得到地球大气参数的剖面.在大气球对称假设下,把GPS无线电信号看成是平面波,采用多相位屏数学模型,通过每个相位屏上的输入和输出复信号之间的关系,用快速Fourier变换和快速逆Fourier变换得到复信号在相位屏之间的传播,数值模拟无线电信号在大气中传播过程,最后得到观测屏上的相位角和振幅.在Matlab环境下进行编程和数值计算,对模型进行求解.在低对流层中,由于水汽的增加,电磁波传播条件复杂,超折射和衍射现象逐渐严重,信号难以锁定,大气传播的研究比较困难.多相位屏模型的数值模拟对此区域无线电信号传播较为有效,从而对GPS掩星技术的理论研究和物理反演的实现具有一定的价值.

This paper deals with the multiple phase screen mathematical model and simulation of radio signal propagation in the atmosphere. Under the spherically symmetric assumption, the refractivity of atmosphere is obtained by means of cubic-spline interpolation from radiosonde data. Under the plane-wave assumption, a multiple-phase-screen technique is used to describe the relationship between the complex amplitudes on the input screen and on the output. By means of FFT and IFFT, complex signals propagate between successive phase screens. The phase and amplitude on the observation screen are obtained in numerical simulation using Matlab.