Study On Characteristic Of Electromagnetic Wave Propagating Through Ionosphere And Microwave Absorbing Properties Of Carbonaceous Material

The refraction is the main characteristic when electromagnetic wave propagation through ionosphere and the characteristic is mainly determined by the free electrons in ionosphere. And we know that how far the electromagnetic wave propagation through ionosphere rest with the frequency and the electron concentration. In this paper the relationship between the refractive index(n), the electron concentration (Ne) and the altitude(h) is analyzed, the numerical simulations are taken on the refractive index and the electron concentration relating to the altitude. We contrast the simulative altitudinal profile of critical frequency and the actual altitudinal profile of critical frequency by measured. And at the high ionosphere, the simulations are basically in agreement with the actual measurements; but at the lower ionosphere E and the higher ionsphere F2, there are errors between the simulations and the measurements by reason of nonlinear relationship. The relationship between the absorption loss in the ionosphere and the effective frequency(f+fH) is analyzed. The effective frequency affect how much decibel the ionosphere can absorb,the effect of the absorption loss on the high effective frequency is much little. The relationships between other things and the absorption loss are also analyzed.In this paper, the microwave absorbing properties of multi-walled carbon nanotubes and expanded graphite composites is analyzed. The results show that maximum absorption of the Multi-walled carbon nanotubes is about-21.7dB at10.4GHz, and which of the Large Inner Diameter-thin walled Carbon Nanotubes is-17.6dB at11.2GHz. the microwave absorbing properties of expanded graphite composites is bad.