Measurement Methods And Scattering Properties Of Radar Earth Echo Study

The scattering coefficient measurement is important for research of radar terrain return. By using of different-band radar scatterometer to measure the scattering coefficient of actual landform, analyzing, ployfitting and modeling of the measurement data, we can create a set of effective scattering coefficient measurement and data fitting methods of radar terrain return. These can provide important information for radar altimeter and clutter suppression.This paper researches the measurement and modeling of the farmland with the 8mm, S and L bands frequency-modulated continuous wave(LFMCW) radar scatterometer in the near-vertical condition. This paper mainly discusses the farmland scattering coefficient measurement method and calibration engineering experimental method, showes the environmental conditions for out-field experiments and studies the modeling of experimental data. By amending the existing model we get a new model for scattering coefficient and incidence angle. This model is well fit for the experimental data.Research to find the scattering coefficient measurement method suitable for our scatterometers is the key to ensure the measurement accuracy and validity. The measurement mechanism of the relative calibration measurement method is introduced. Barrier effect and different window functions'effect on the measurement precision is analyzed by simulation when processing the IF signal of the LFMCW radar digitally. An appropriate window function and the length of FFT is selected according to the requirement of measurement precision of the calibration object. The actual RCS of multiple scatters whose theoretical value is already known is obtained by simulation with the relative calibration method. The simulation results verify the scientificity and efficiency of the measurement method, providing an engineering method for our measurement.The scatterometers must be calibrated to measure the farmland scattering coefficient. This paper introduces a calibration engineering experimental method. The out-field calibration experiment using the metal sphere as the standard calibration object is carried out and the power of the IF signal from the metal sphere return is calculated according to the metal sphere return. The distance calibration is also carried out to determine the precise relationship between the target distance and its IF return signal. The concrete realization of experimental methods are further introduced, including the IF signal acquisition from the target return, the acquisiton of the target distance and the incidence angle. At last the software float chart of this series of the process is shown.Finally, this paper describes the processing of the experimental data for the farmland scattering measurment, which can acquire the scattering coefficient of the farmland. Then the fitting analysis of the farmland scattering coefficient is undertaken, a new model for scattering coefficient and incidence angle is acquired by amending the existing model.