钝头锥目标对太赫兹波背景辐射的反射特性研究

Scattering characteristics of background radiation in THz band by a blunt-nosed cone target

为克服大气衰减对太赫兹波应用距离的限制,充分发挥太赫兹波探测的优势,文中对空气稀薄的对流层顶高度上的太赫兹波辐射传输特性进行了研究,探索太赫兹波在卫星及飞行器平台的应用如被动探测技术等.选择7.147 THz,8.839 THz与10 THz三个频率较高、吸收衰减较小的窗口频率,计算和分析不同频率和海拔高度上大气背景亮度及目标对背景辐射的反射辐射.结果表明,在所有高度上,大气背景在向上方向上的辐射比向下方向上的辐射小,这种趋势在海拔高度高于5 km时更为明显.对于平行与地面放置的钝头锥目标来说,在高于5 km的高度上出现反射辐射的不对称性,反射的辐射在约80°和190°时达到峰值.

The radiative transfer of terahertz wave at the height of the tropopause with thin air is studied in this paper to overcome the limitation of atmospheric attenuation on the application distance and realize the full potential of terahertz wave on passive detection technology.Three window frequencies with small absorption attenuation at 7.147 THz,8.839 THz and 10 THz are selected to calculate the atmospheric background brightness and the reflected radiation of the target to the background radiation at different frequencies and altitudes.The results show that at all altitudes,the upwelling radiation of the atmospheric background is smaller than the downward radiation,and this trend is more obvious when the altitude is higher than 5 km.For a blunt-nosed cone target placed parallel to the ground,the asymmetry of reflected radiation appears at a height higher than 5 km.The reflected radiation peaks are at about 80°and 190°,which depends on the shape of the target and radiation difference between the upper and lower sides.