During the reentry process of a spacecraft, a plasma sheath will attenuate and distort the amplitude and phase of the transmitting electromagnetic (EM) waves, influencing signal reception and measurement accuracy of the direction of wave arrival of the spacecraft-borne array antenna, by which the spacecraft communication and guidance system may be affected. To solve this problem, based on the space distribution characteristics of plasma sheath flow field, an EM simulation model of an array antenna under plasma sheath is established, and EM simulations related to field propagation across plasma sheath and radome are performed. Then, the array signal model is constructed by extracting the field strength data at the array element. Several spatial spectrum estimation methods are conducted to calculate the direction of arrival of an EM wave incident on the array antenna. By comparing the direction of the incoming wave in free space with the estimated direction after propagating through the plasma sheath, the direction-finding error of the spacecraft-borne array under the plasma sheath is obtained, and the cause of the error is analyzed. With compensation information, the results of the proposed method can enable higher target-tracking accuracy for the spacecraft guidance system.

中文翻译：

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等离子护套覆盖航天器阵列天线对到达方向估计的影响

在航天器再入过程中，等离子体鞘层会使发射电磁（EM）波的幅度和相位发生衰减和畸变，影响信号接收和航天器载阵列天线波到达方向的测量精度。航天器通信和制导系统可能会受到影响。针对这一问题，基于等离子体鞘流场的空间分布特性，建立了等离子体鞘下阵列天线的电磁仿真模型，并进行了等离子体鞘和天线罩场传播相关的电磁仿真。然后，通过提取阵元处的场强数据构建阵信号模型。进行了几种空间谱估计方法来计算入射到阵列天线上的电磁波的到达方向。通过将自由空间入射波的方向与通过等离子体鞘层传播后的估计方向进行比较，得到等离子体鞘层下星载阵列的测向误差，并分析了误差产生的原因。有了补偿信息，所提出方法的结果可以使航天器制导系统的目标跟踪精度更高。