The Polarimetric Analysis And The Feasibility Study Of Interference Rejection For Schumann Resonance

Schumann resonance is an electromagnetic oscillation propagating between theearth and the ionosphere cavity around the world, which is formed by naturalphenomena such as thunderstorm and lightning inspirtion. Schumann resonancewave transmission model is researched in this paper, including uniform cavity andasymmetric cavity analytical model. Meanwhile, the polarization analysis utilizingthe actual ELF magnetic data of Schumann resonance signal is proposed. Basedon the analysis results, the possibility of polarization filtering is discussed in thepaper as well.First of all, the analytical model to simulate the Schumann resonance wave isadopted in the paper, choosing the electric dipole source of Williams form asexcitation source of Schumann resonance wave in the meantime. Under the idealcondition that global conductivity is invariable and the ionosphere is isotropic, theanalysis formula of Schumann resonance wave is formulated within Maxwell’sequations, the transmission model equation of schumann resonance wave is builthereafter. The simulation result shows that the harmonic frequency of Schumannresonance wave is10.6Hz,18.5Hz,26.8Hz and33Hz in the ideal condition. By themeans of changing the location of radiation sources and the radius of the earth, wecan draw a conclusion that the harmonic frequency of Schumann resonance wave isrelated to the size of the earth. On the basis, in view of the two models in thepractical condition:(1) day-night case;(2)the conductivity mutation on one positionof the earth case, the analysis of the two cases is proposed in detail. In the model ofdat-night case, since the conductivity is different between day and night, theperturbation technology is used to modify the ideal conductivity model. In themodel of conductivity mutations case, the ELF magnetism data received by receivepoint is composed of two parts: one is direct wave, the other is the scattering wavefrom interference point to the receive point.Secondly, the concept of polarization is studied. The concept of fivepolarization descriptors and their characteristics are expounded respectively. Thegeneration of Schumann resonance wave is expounded in detail in the paper. Then,global source model is divided into three thunderstorms thunder storm sources.Furthermore, the Schumann resonance wave data collected from Yongsheng, Tongsai, Qiaojia, Mangshi and Weihai observatory is used to conduct polarizationanalysis, including the polarization direction, polarization plane, axial ratio andsome other parameters. The observation results and simulation results are comparedas well.Finally, in view of some common interference of observation data, thepolarization characteristic is analysed. Based on this, the feasibility of polarizationfiltering restrain interference is discussed. From the analysis, the conclusion isconducted as follows: in the situation that only the magnetic field exists without theelectric field, because of the low signal to noise ratio, especially the lack of priorknowledge of the independence Schumann resonance signal and jamming signal, itis not suitable for the polarization when the signal and jamming in the polarizationdirection or frequency is similar.