Microwave Radiation Characteristics And Detection Method Research In Aerial Target Detection

Microwave radiation detection technology uses the thermal radiation of target to detect target. In the cold sky, air targets because of their high-temperature thermal radiation and the reflection background radiation from the ground, become significant heat targets, and can be easily detected by the microwave radiometer.Synthetic aperture microwave radiometers can instantaneous image without scanning and achieve high spatial resolution by adopting the technique of aperture synthesis.And synthetic aperture microwave radiometers hold the same favorable concealment and survival ability, and are applicable for most weather conditions and battlefield environment in day and night. So it becomes the new research focus of passive detection.Based on the mechanism of microwave radiation, the study of the radiation characteristics is carried out on three aspects:aerial target, the atmosphere and background, synthetic aperture microwave radiometer. An integral microwave radiation signal model is presented. And the background suppression and target detection method for aerial target detection using synthetic aperture radiometer is researched. Main works are given below:The radiation characteristics of the body and exhaust gas of aerial target is analyzed. The analytical expression of the radiation brightness temperature is presented. According to the different Feature of isotropic and anisotropic absorbing material, equivalent transmission line method and physical optics method is used to derivate the analytical expression separately.The radiation characteristics of clear sky and complex weather (clouds, fog, and rain) are researched. The microwave spectral characteristics models of clear sky and complex weather are analyzed. A sectionalized microwave propagation algorithm for long distance detection based on exponential-layered spherical atmosphere is presented by considering the atmospheric refraction and the earth curvature. Several microwave radiation images of typical complex weather are obtained by compute simulation.An integral microwave radiation brightness temperature model is built using ray tracing method. The performance of metal targets and invisible targets detection using synthetic aperture microwave radiometer is analyzed. The influence of complex weather (clouds, fog, and rain) is analyzed.The statistical distribution model based on inversed images is built. The method for calculating the detection probabilities of inversed images is presented. The formula for calculating the maximum distance of detecting target by synthetic aperture radiometer is deduced.According to the characteristics of synthetic aperture radiometer single frame image, a small target detection method based on nonparametric statistics is presented. The rank analysis method is introduced to describe the edge transition texture. And the target and background is separated by the different characteristics of their rank correlation.