超视距雷达工作在短波波段,通过电离层的折射,可探测到常规雷达无法探测到的地平线以下的远距离目标。但雷达电波经电离层折射,探测结果必然受到电离层的影响,其主要特征之一是回波谱中常伴随多普勒(Doppler)频移。文中简单描述电离层Doppler频移的产生机制,并在已预测电离层信道参数的基础上利用数字射线追踪技术对E层、F2层的高频天波Doppler频移进行预测。

The Over-the-Horizon Radar(OTHR) operates in shortwave band(3-30 MHz).It uses sky-wave refracted by the ionosphere to detect targets at distances an order of magnitude greater than that of conventional microwave radar limited by the line of sight.Since radar wave is refracted by ionosphere,so the result of detection must be affected by ionosphere,whose main characteristic is that the spectrum of sea echo is associated with Doppler shift.The mechanism of ionospheric Doppler shift is briefly described in this paper,and the HF sky-wave Doppler shift of E layer and F2 layer are predicted using the numerical ray tracing technique based on some predicted ionosphere channel parameters.

TN958

国家自然科学基金项目