Amplitude Spectra of Reflection Type Atmospherics

Abstract

The waveforms of reflection type atmospherics were Fourier analysed using an electronic digital computer, to yield composite spectra as well as the individual amplitude spectra of different orders of sky wave, in the frequency range 1-20kc/s. The spectral peak frequency is found to decrease with increasing order of ionospheric reflections, the rate of decrement being more for the first few reflections then decreasing with higher orders of reflection.Assuming the ionosphere as a sharply bounded homogeneous medium and the ray theory to hold good, theoretical curves for the shift in peak frequency with the order of ionospheric reflection, for various source distances have been drawn. Experimental results are found to be in fair agreement with the theoretical deductions. The variation of spectral peak frequency of the composite spectra with propagation distance of atmospheric has also been explained.