Effect of Plasma Sheath Covering Spacecraft-Borne Array Antenna on Direction-of-Arrival Estimation

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.