When the interferometric global navigation satellite system reflectometry (iGNSS-R) altimeter receives the direct and reflected signals through the digital multibeam phased array antenna, the roll-off of element radiation pattern will cause the scanning loss of directivity. If the scanning loss is neglected, the ocean altimetric precision will be biased with possible consequences for the instrument design. This article carries out the following research on this. First, based on the geometry of iGNSS-R altimetry and the principle of phased array antenna beamformer, the scanning loss model with the elevation angle at the specular point as a parameter is established. Second, this article uses the measured data of the phased array antenna to verify the model, and the result shows that the simulated value is in good agreement with the measured value, with an average deviation of 0.07 dB. Third, taking the GPS L1 signal (full composite) as an example, the model is used to analyze the influence of the scanning loss on the iGNSS-R altimetric precision estimation. The research results show that when the phased array antenna synthesizes four beams for iGNSS-R altimetry, the comprehensive effect of scanning loss on altimetric precision estimation is 0.16 m. The influence of scanning loss should be considered in the future high-precision iGNSS-R altimetry instrument design.

中文翻译：

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在星载 iGNSS-R 海洋测高中量化扫描损失效应的必要模型

当干涉式全球导航卫星系统反射计（iGNSS-R）高度计通过数字多波束相控阵天线接收直接和反射信号时，单元辐射图的滚降会导致扫描方向性损失。如果忽略扫描损失，海洋高度精度将出现偏差，可能对仪器设计产生影响。本文对此进行了如下研究。首先，基于iGNSS-R测高几何学和相控阵天线波束成形原理，建立以镜面点仰角为参数的扫描损耗模型。其次，本文利用相控阵天线的实测数据对模型进行验证，结果表明仿真值与实测值吻合较好，平均偏差为 0.07 dB。第三，以GPS L1信号（全合成）为例，利用模型分析扫描损耗对iGNSS-R测高精度估计的影响。研究结果表明，当相控阵天线合成四个波束进行iGNSS-R测高时，扫描损耗对测高精度估计的综合影响为0.16 m。未来高精度iGNSS-R测高仪设计应考虑扫描损耗的影响。扫描损失对高度精度估计的综合影响为0.16 m。未来高精度iGNSS-R测高仪设计应考虑扫描损耗的影响。扫描损失对高度精度估计的综合影响为0.16 m。未来高精度iGNSS-R测高仪设计应考虑扫描损耗的影响。