@article{oai:nagoya.repo.nii.ac.jp:00019703,
 author = {佐尾, 和夫 and SAO, Kazuo},
 issue = {1-2},
 journal = {空電研究所報告},
 month = {Mar},
 note = {In order to illustrate the wave-forms of atmospherics with the knowledge of pulses radiated from the origin and theories of propagation of V.L.F. waves, investigations of the frequency spectra obtained with the aid of frequency analyses were proposed. In this paper the author analysed a number of smooth type wave-forms of atmospherics and tried to investigate the characteristics of frequency spactra. The relation between a wave-form and its frequency spectrum is represented by an expression of the form. (The equation is omitted) where G(t) is the wave-form, S (ω) is the amplitude-frequency spectrum and φ(ω) is the phasefrequency spectrum. However, because of the difficulties of the computation of Fourier transform expressions, the author prepared an analog computer. In the consideration of wave-forms of received atmospherics there are two problems to be considered; first the discharge current wave-froms of lightning strokes, secondly attenuation characteristics of propagation paths. When we consider a lightning discharge as a source of an atmospheric, and assume that a vertical cloud-to-ground lightning stroke is a vertical aerial, we know well that the received electric field is proportional to the current of the aerial. Therefore some curves of various types of discharge currents reported by Norinder and Dahle were selected, and their frequency spectra were obtained. Furthermore, frequency spectra of received wave-forms of atmospherics are described concering the following points. a) Frequency spectra of the received wave-forms of atmospherics radiated from the similar region at about the same time. b) Differences between frequency spectra derived from wave-forms with long duration and those with short duration. c) Frequency spectra derived from the complicated wave-forms. But it is not our purpose to clarify here the characteristics of propagation paths employing the frequency spectra of received atmospherics with precise sferics fixes; the author, therefore, has as yet no information as to what is involved in the propagation of V.L.F. waves.},
 pages = {19--25},
 title = {空電波形の周波数分析研究（第1報）},
 volume = {8},
 year = {1958}
}