地基GNSS-R功率测量应用中的天线方向性影响分析

全球导航卫星系统反射信号遥感技术（global navigation satellite system reflectometry，GNSS-R）地基功率测量应用中，信号接收天线对于背向同极化和各向交叉极化信号的抑制并不理想.为了分析天线方向性对于目标信号相关功率测量的影响，以右旋圆极化（right hand circular polarized，RHCP）直射信号接收天线和左旋圆极化（left hand circular polarized，LHCP）反射信号接收天线为例，建立了实际天线接收信号的相关功率模型，确定了实际信号相关功率的概率分布以及数字特征，在仿真信号相关功率的数字特征的基础上计算了相关功率的相对偏差和离散系数并进行了分析.结果表明:天线方向性的不理想会造成目标信号相关功率测量误差，RHCP天线方向性仅在低卫星高度角范围内对直射目标信号相关功率测量有较大影响，而LHCP天线方向性在整个卫星高度角变化范围内都对反射目标信号相关功率测量有显著影响. 

Antenna Directivity Effect Analysis for Ground-Based GNSS-R Power Measurement Applications

In ground-based global navigation satellite system reflectometry (GNSS-R) power measurement applications, signal-receiving antennas could not perfectly suppress the co-polarized signal from backwards and the cross-polarized signal from both forwards and backwards.In order to analyze the influence of the antenna directivity on the correlation power of the target signals, a right hand circular polarized (RHCP) antenna and a left hand circular polarized (LHCP) antenna were used to receive the direct signal and reflected signal, respectively. The correlation power models of the signals received by the actual antennas were firstly established, and then the probability distribution and numerical characteristics of the actual signal correlation powers were determined successively. Based on simulating the numerical characteristics, the relative deviations and variation coefficients of the correlation powers were calculated and analyzed. Simulation results show that the actual antenna directivity can cause errors in the correlation power measurement of target signals. The RHCP antenna ’s directivity has a considerable impact on measuring the correlation power of direct target signal in the low elevation angle range, while the LHCP antenna ’s directivity significantly affects the measurement of reflected signal correlation power in entire elevation range.