Research On Modeling Method Of Plasma Sheath Channel

High-speed flying aircraft violently rubbing with the atmosphere on the surface will produce an unsteady plasma sheath.The plasma sheath absorbs and scatters electromagnetic waves,which will can interrupt communication signals in severe cases.At present,it is a promising method to improve communication which adding a magnetic field to the receiving antenna.With a suitable magnetic field strength,electromagnetic waves of a specific frequency can be transmitted through the plasma sheath.Since the plasma sheath is dynamic,the impact on the signal is also dynamic,which will cause a series of communication problems.In order to study the dynamic influence of the plasma sheath on the communication system,the specific work of this paper is as follows:(1)The main characteristic parameters of the plasma sheath are analyzed,and then a dynamic electron density model is established according to the parameters.When the steady-state electron density is obtained during modeling,the time-varying and spatial characteristics of turbulence are added,and the dynamic characteristics of electron density with different intensities are simulated.Finally,the dynamics of the electron density model is used to characterize the dynamics ofthe plasma channel.At the same time,the characteristics of the medium in the plasma were analyzed.(2)The electromagnetic calculation method is used to obtain the calculation result of the electromagnetic wave penetrating the plasma sheath.The Scatter Matrix Method(SMM)and Hybrid Matrix Method(HMM)electromagnetic calculation methods are used to calculate the propagation process of electromagnetic waves in the plasma sheath channel without external magnetic field and external magnetic field.(3)According to the electromagnetic calculation results,the dynamic characteristics of the channel are analyzed.At the same time,the coherence time and the coherence bandwidth under the plasma channel are analyzed.An improved description method of dynamic channel based on Markov chain is realized to realize joint modeling of amplitude and phase under dynamic channel.The Markov chain channel model is used to simulate the communication system,and the dynamic channel characteristics are applied to the baseband signal as a real-time response.The bit error rate results of BPSK(Binary Phase Shift Keying,BPSK)in coherent demodulation method and FSK(Frequency Shift Keying,FSK)in non-coherent demodulation method are calculated.