Determining the attenuation function of the Earth’s wave field for reception on different heights of the aircraft flight. Abstract.

Abstract. Formulas derived from Kirchhoff's integral equation are offered for calculations of an attenuation function of the Earth’s wave field taking into consideration the height of the signals reception for geometrically and electrically inhomogeneous radio paths. Comparative calculations of an attenuation function are carried out by the method of integral equations and on the normal waves row for reception at different heights in the LF range. It is shown that field intensity measurements on a board of the aircraft when flying at an altitude up to 200 meters don’t differ from measurements on the Earth's surface. An estimation of the impact of perturbations in the form of geometric inhomogeneity as Gaussian hill on a process of the radio wave propagation taking into account the different heights of the reception at the 100 kHz frequency is given. Experimental works in the far North region near Chersky town were carried out. Measurements of the surface impedance and the electromagnetic field intensity from the aircraft above a flat radio path Chersky-Chokurdakh, and over a mountainous radio path Chersky-Pevek at the frequency of 257 kHz that is the airport homing station were carried out. The estimation of accuracy of calculations of the field of the Earth’s wave by the local electrical characteristics of underlying high-latitude media taking into account geometric inhomogeneities and the height of the receiving signal is given. The processing of measurement results of electromagnetic field intensity from the aircraft showed a good correlation with the calculated data.

Key words: Earth’s wave field, an attenuation function, surface impedance, terrain relief, height of signal reception.

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