Effect of Ionosphere on the Excitation of Electromagnetic Field at Extremely Low and Lower Frequencies in the Near-Field Zone

Tereshchenko, E. D.; Tereshchenko, P. E.; Sidorenko, A. E.; Grigor’ev, V. F.; Жамалетдинов, А. А.

doi:10.1134/s1063784218060233

Cited by 9 publications

(6 citation statements)

References 4 publications

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“…et al, 1999). The influence of the ionosphere on the spectra of artificial signal magnetic field components was noted in almost all experiments, even at distances close to the source (Tereshchenko et al, 2007(Tereshchenko et al, , 2018. The non-monotonic frequency dependence of the signal amplitude was observed by Ryabov et al (2021) in the recent experiment with the Kola ULF emitter.…”

Section: Plain Language Summarymentioning

confidence: 72%

“…Interpretation of the Earth electromagnetic sounding data by such a source requires taking into account the influence of the ionosphere in order to increase the reliability of the results (Tereshchenko et al., 2007; Zhamaletdinov et al., 1999). The influence of the ionosphere on the spectra of artificial signal magnetic field components was noted in almost all experiments, even at distances close to the source (Tereshchenko et al., 2007, 2018). The non‐monotonic frequency dependence of the signal amplitude was observed by Ryabov et al.…”

Section: Introductionmentioning

confidence: 87%

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Characteristics of ULF Magnetic Fields in the 3D Inhomogeneous Earth‐Ionosphere Waveguide

2022

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We develop an algorithm for calculating the characteristics of the magnetic field of signals in the frequency range of (0.1–20) Hz in the horizontally and vertically inhomogeneous spherical Earth‐ionosphere waveguide. This algorithm involves calculations of the surface impedance of an inhomogeneous ionosphere. The frequency dependences of the amplitude, phase and polarization of the magnetic field generated by a horizontal magnetic dipole were analyzed. It is shown that the horizontal inhomogeneity of the Earth‐ionosphere waveguide can significantly affect the frequency dependence of the amplitude and polarization of the magnetic field, increasing the degree of circular polarization. The horizontal inhomogeneity only slightly influences the results in daytime conditions. The most noticeable difference in the amplitude dependences of the magnetic components and large phase shifts (up to 40°) are observed when the terminator passes through the geodetic line connecting the source and receiver, and in the presence of sporadic layers with a horizontally inhomogeneous structure along the low‐frequency wave propagation path. We compare the calculation results with the magnetic pulsations recorded at Nurmijarvi station during the 2001 campaigns of Kola Peninsula ultra low frequency emitter operation. The obtained results make it possible to qualitatively explain peculiarities of the amplitude and polarization spectra of the artificial magnetic signals recorded in this campaigns that are not explained within the framework of the flat homogeneous waveguide model.

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Section: Plain Language Summarymentioning

confidence: 72%

Section: Introductionmentioning

confidence: 87%

Characteristics of ULF Magnetic Fields in the 3D Inhomogeneous Earth‐Ionosphere Waveguide

2022

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Section: Introductionmentioning

confidence: 83%

“…The possibility of recording artificial ULF signals from ETLs at distances of about 1000-1400 km has been confirmed by numerous experiments [5][6][7][8][9][10]. In almost all the experiments, the impact of the ionosphere on the spectra of the magnetic-field components of an artificial signal was noted even when it was recorded at distances closer to the source [8,9]. However, the ionospheric impact on the propagation and formation of the spectra of artificial ULF signals during the interpretation of experimental data has not been fully understood.…”

Section: Introductionmentioning

confidence: 86%

Features of the Spectra of Ultra-Low-Frequency Magnetic Fields from Horizontal Current Sources: Models of Planar and Spherical Earth–Ionosphere Waveguides

Ermakova

Ryabov

Kotik

2021

Radiophys Quantum El

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We simulate the magnetic field components in the frequency range 0.1-30 Hz from a source such as the horizontal magnetic dipole located in the Earth-ionosphere cavity. Models of uniform spherical and planar waveguides are considered, the advantages of each model are determined, and a comparative analysis of the simulation results is performed. The results of numerical calculations lead to the conclusion about the impact of the IAR (ionospheric Alfvén resonator) and sub-IAR (resonator at altitudes of 80-300 km) on the amplitude spectra of the ultra-low-frequency (ULF) signal. It is also shown that the appearance of strong sporadic layers (with a plasma frequency exceeding 5 MHz at their maxima) along the entire propagation path of ULF fields from the source to the receiver can strongly change the amplitude spectra of artificial signals. A significant increase in the amplitude of the magnetic field at the IAR harmonic frequencies can be observed at night. The sub-IAR effect is responsible for the appearance of a dependence of the amplitude of the magnetic components, which increases with frequency. Phase shifts between the horizontal components of the ULF signal and the spectra of the polarization parameter are also analyzed. It is shown that ionospheric resonators have almost no effect on the phase characteristics of artificial signals in a uniform waveguide approximation, in contrast to the polarization of magnetic ULF fields from a vertical electric dipole. The dependences of the amplitude of the magnetic field of a signal on the distance r to the source and on the direction to the source are also analyzed. It is shown that the dependence of the decay of the magnetic field amplitude with distance can differ significantly from the 1/r 2 law. The radiation pattern is almost isotropic for k 0 r < 1, where k 0 is the wave number in free space. The lines of equal amplitude are stretched along the direction of the current source for k 0 r ≥ 1.

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“…Studying the propagation of radio waves in the super low (SLF) and extremely low frequency bands (ELF) (30-300 and 3-30 Hz, respectively, in the International Telecommunication Union designation) in the anisotropic three-dimensional (3D) Earth-ionosphere waveguide is of interest both from the theoretical standpoint and for the practical use in the radiophysical and geophysical applications. In our previous works [1], [2], we considered the influence of the ionosphere on the low-frequency field in the vicinity of the source, i.e., within distances shorter than or comparable to the waveguide height. It was established that the field structure in this region is mainly determined by the conductivity of the lithosphere.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Ionosphere on the Controlled-Source Field in the Frequency Range Between 0.4 and 95 Hz

Tereshchenko¹

2022

Antennas Wirel. Propag. Lett.

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The paper addresses the effect of the ionosphere on the ELF and lower frequency waves excited in the Earthionosphere waveguide by a controlled source. The experiment carried out on the Kola Peninsula is described and the results of measurements in the frequency range 0.4-95 Hz are presented. Non-monotonic behavior of the magnetic field with time is revealed. It is shown that variations in the magnetic field are related to the state of the ionosphere and depend on the geomagnetic activity. The importance of the effect of the topside ionosphere on the structure of the studied field is discussed.

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Effect of Ionosphere on the Excitation of Electromagnetic Field at Extremely Low and Lower Frequencies in the Near-Field Zone

Cited by 9 publications

References 4 publications

Characteristics of ULF Magnetic Fields in the 3D Inhomogeneous Earth‐Ionosphere Waveguide

Characteristics of ULF Magnetic Fields in the 3D Inhomogeneous Earth‐Ionosphere Waveguide

Features of the Spectra of Ultra-Low-Frequency Magnetic Fields from Horizontal Current Sources: Models of Planar and Spherical Earth–Ionosphere Waveguides

Effect of the Ionosphere on the Controlled-Source Field in the Frequency Range Between 0.4 and 95 Hz

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