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The Accuracy of Radio Direction Finding in the Extremely Low Frequency Range
Author(s) -
Mlynarczyk Janusz,
Kulak Andrzej,
Salvador Jacobo
Publication year - 2017
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/2017rs006370
Subject(s) - physics , radio propagation , refraction , radio wave , standard deviation , amplitude , angle of arrival , optics , great circle , acoustics , atmospheric noise , angle of incidence (optics) , computational physics , geodesy , geology , telecommunications , infrasound , antenna (radio) , mathematics , computer science , statistics , quantum mechanics , astronomy
Abstract In this work, we study the accuracy of direction finding in the extremely low frequency (ELF) range using a newly installed broadband receiver equipped with two active magnetic antennas. The main natural source of ELF radio waves is lightning. In this work, we analyzed 1000 atmospheric discharges at distances of up to 5000 km from the receiver. We identified the most important factors influencing the accuracy of the angle of arrival: the deviation of the radio waves propagating through the day‐night terminator zone and the signal‐to‐noise ratio resulting from local electromagnetic noise and Schumann resonance background. The obtained results clearly show that the accuracy of estimating the direction of arrival is very high (an average error of 0.1° with the standard deviation of 2.3°) when the signal‐to‐noise ratio is large (the amplitude of the magnetic field component above 100 pT), except for short periods in the local morning and evening, when the day‐night terminator is present on the propagation path of the direct wave. For the day‐night propagation paths, the refraction angle was larger than the incidence angle, and for the night‐day propagation paths, the refraction angle was smaller than the incidence angle, which is consistent with theory. Using our analytical ELF radio propagation model allowed us to explain the obtained results.