Characteristics of EHF Wave Propagation in Hypersonic Plasma Sheaths Magnetized by Dipole Magnetic Fields  
[PERSON]  
1 School of Resources Environment, Nanchang University, Nanchang 330031, China; [EMAIL_ADDRESS]  
[PERSON]  
3 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China; [EMAIL_ADDRESS]  
[PERSON]  
2 School of Information Engineering, Nanchang University, Nanchang 330031, China;  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China; [EMAIL_ADDRESS]  
[PERSON]  
2 School of Information Engineering, Nanchang University, Nanchang 330031, China;  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China;  
33 School of Physics and Materials Science, Nanchang University, Nanchang 330031, China  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China  
33 School of Physics and Materials Science, Nanchang University, Nanchang 330031, China  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China  
33 School of Physics and Materials Science, Nanchang University, Nanchang 330031, China  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China  
33 School of Physics and Materials Science, Nanchang University, Nanchang 330031, China  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China  
33 School of Physics and Materials Science, Nanchang University, Nanchang 330031, China  
33 Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China  
33 School of Physics and Materials Science, Nanchang University, Nanchang 330031, China
state-to-state model is one of the above-mentioned four models, focusing on the role of molecular vibration in the plasma's evolution [10]. Previous studies have shown that EHF (extremely high frequency) communication could be a potential solution to the blackout problem [11; 12]. Many models have been developed to study the propagation characteristics of EHF waves in hypersonic plasma sheaths. For example, in the frequency domain, EHF wave propagation in a plasma sheath was modeled with the scattering matrix method (SMM) [7; 13] and the Wentzel-Kramers-Brillouin (WKB) method [14; 15]. In the time domain, wave propagation used to be modeled with the finite difference time domain (FDTD) method [4; 16]. Previous studies have shown that EHF waves propagating in plasma sheaths used to suffer from severe attenuation [4; 12], which could make the wave very weak by the time it reaches the receiver. Such attenuation is led mainly by the high-density plasma and the collisions between free electrons and neutral particles [17]. On the other hand, the bit error rate (BER) for an EHF communication system is also influenced by the parameter of the plasma sheath [18]. In addition, the EHF signal propagations are influenced by many flight conditions, e.g., the atmospheric conditions surrounding the vehicle [19], the flight speed [20], the angle of attack (AOA) [21], and the shape of the vehicle [22]. In other words, the characteristics of EHF wave propagation in plasma sheaths is dynamic, which is always varying with time. In order to mitigate the communication blackout effectively, it is necessary to reduce the EHF wave attenuation in plasma sheaths. Some previous studies have shown that the EHF signal attenuation could be significantly reduced by introducing an external magnetic field near the onboard EHF antenna [16; 23; 24; 25]. Nevertheless, previous studies that modeled EHF wave propagation in magnetized plasma sheaths were based on the linear electron motion equation. The magnetic field near the onboard antenna is more likely to be generated by a coil, which means it would be a dipole field. Whether there are other dissipation mechanisms for EHF waves in plasma sheaths magnetized by dipole fields has not yet been sufficiently studied.