磁窗减缓等离子体对天线性能的影响

飞行器以高超声速再入大气层返回地球时，飞行器周围形成等离子体鞘套，等离子体会影响电磁波的传播特性，严重时通信甚至完全中断。从理论上分析了外加磁场时电磁波与等离子体的相互作用机理，提出了利用永磁体和螺旋天线一体式的设计方式，即磁窗天线，并研究了在等离子体环境中螺旋天线和磁窗天线的性能，仿真结果表明，利用永磁体和螺旋天线一体式设计的磁窗天线，可以减弱等离子体对天线性能的影响，这为解决飞行器再入通信中断问题提供了一种有效途径。

Influence of magnetic window for mitigating on antenna performance in plasma

The communication blackout caused by the plasma sheath around a hypersonic vehicle flying in atmosphere is a problem to aerospace vehicles. When a vehicle enters the communication blackout phase, it loses all communication including GPS signals, data telemetry, and voice communication. The communication blackout becomes an even more critical issue with development of re-entry vehicles missions. During such missions, the communication loss caused by radio blackout introduces significant problems related to the vehicles safety. This paper analyzes the interaction of electromagnetic waves with plasma in an external magnetic field in theory. The external magnetic field can improve the transmission of electromagnetic waves in plasma from the theoretical analysis. The magnetic window antenna which is designed by integrating the permanent magnet and the helical antenna is proposed. The performance of the helical antenna and magnetic window antenna in plasma is studied. The simulation results show that using the magnetic window antenna can weaken the influence on the antenna performance in plasma. The magnetic window antenna makes it possible for electromagnetic waves to spread in plasma. This provides another way to solve the problem of spacecraft re-entry blackout.