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利用位于夸贾林靶场的罗依-纳幕尔岛上的L、S和C波段雷达同时对小入射余角(<0.1°)雷达后向散射进行了一系列的测量。利用各种波形,以连续的1.26km的步长,记录了海情为3级和5级、距离从8km到60km时的相干数据。本文详细地介绍了入射余角很小、距离大大超过视距时的新的频谱测量结果。这些测量结果证明了来自视距之外的雷达回波的相干性,而且证明了净空对小入射余角海杂波数据的扰动的存在和影响。证明相干性是因为在60km的距离内存在着有意义的多卜勒频谱的缘故。可以看出,逆风谱在整个测量范围内是双峰的。一个分量以风速运动,另一个分量以接近1/4的风速运动。文中分别对每一个分量在逆风方向上的主极化和垂直极化作了分析。每一种极化的速度较慢的分量大致相等,而速度较快的分量相差10dB。速度较快的分量可看作是由同质的、各向同性的物体的折射率波动即净空的扰动引起的后向散射。文中把以高分辨率数据观测到的遮挡情况与一些新近的小入射余角后向散射模型的预测情况进行了比较。
A series of measurements of backscatter at a small incident coma angle (<0.1 °) were simultaneously conducted using the L, S and C-band radars on Royale-Napier Island at Kwajalein. Using various waveforms, the coherent data at sea level 3 and level 5 and distances from 8 km to 60 km were recorded in a succession of 1.26 km steps. This paper introduces in detail the new spectrum measurement results when the incident residual angle is very small and the distance greatly exceeds the line of sight. These measurements demonstrate the coherence from radar echoes beyond line-of-sight and demonstrate the existence and impact of headroom on the perturbation of small-incident co-angular clutter data. Proof of coherence is due to the existence of a meaningful Doppler spectrum at a distance of 60 km. It can be seen that the inverse wind spectrum is bimodal over the entire measurement range. One component moves at wind speed and the other component moves at nearly 1/4 wind speed. The main polarization and vertical polarization of each component in the upwind direction are analyzed respectively. Each of the slower components of polarization is roughly equal, while the faster components differ by 10 dB. The faster component can be thought of as the backscattering caused by the refractive index fluctuations of homogenous, isotropic objects, ie the perturbation of the headroom. In this paper, the occlusion observed with high-resolution data is compared with the prediction of some recent small-angle backscatter backscatter models.