Yu. B. Bashkuev

Experimental proof of the existence of a surface electromagnetic wave

Results of experiments for the observation of surface electromagnetic waves (SEWs) in the decameter range (10 and 15 MHz) excited by a vertical dipole and propagating above the ice-coated surface of a salt lake over a distance of up to 1.2 km are considered. It is shown that the SEW decays much more weakly than the “ground” ray. An analysis of the field of radiation from the vertical dipole reveals the presence of a wave with an amplitude decaying with the distance R approximately as 1/R1/2, which corresponds to the SEW divergence. The absolute values of the radiation attenuation function |W| are significantly greater than unity and reach |W| ≈ 2, which also corresponds to the SEW. Experimental data on the SEW damping agree with the results of numerical calculations of the electromagnetic field in the system under consideration.

Formation of circular rings on the snow-covered ice field of Lake Baikal

Satellite images taken from the ice surface of Lake Baikal show dark rings 7–8 km in diameter. Physically, this phenomenon can be explained by the emission of warm natural gas from the sedimentary thickness on the Lake Baikal bed. When the natural gas ascends toward the surface, it cools down but has time to heat ambient cold water. This gives rise to toroidal convection around the site of natural gas emission in the water column. Convection carries the warmed water to the surface (to the lower surface of ice) clear of the natural gas column. The heat reaches the upper surface of ice by means of heat conduction, where snow starts intensely melting. As a result, a thaw hole in the form of a ring arises on the snow-covered ice.

Effect of the cryolithic zone electrical properties on the medium-frequency surface wave at high latitudes

Result of the measurements of the cryolithic zone electrical properties by the radio impedance sounding method are presented. The surface impedance and geoelectric section of the Arctic permafrost have been determined. The experiments have been performed near Cherskii in the continental zone. The surface wave attenuation function is considered. The accuracy of the surface wave field calculations at high latitudes has been estimated based on the local electrical characteristics of the underlying cryogenic medium. The effect of the Arctic Ocean on the operating zone of navigation and communication facilities in the kilometer wave band has been experimentally estimated.

The Transmission and Reflection Coefficients of an Electromagnetic Wave for a Gradient Dielectric Layer

A gradient dielectric layer is considered. In the layer, permittivity ɛ(z) depends on coordinate z as follows: ɛ(z) = ɛLa4/(z − a)4 (a being the gradientness parameter). For this layer, reflection and transmission coefficients rr and rt are determined. It is found that, in a wide frequency range, the considered gradient layer has amplitude- and phase-constant reflection and transmission coefficients and can serve as a low-pass filter in radio devices involved in the transmission of wideband signals.

Spatial characteristics of radiation from lightning discharges

The results of measurements of levels of electric and magnetic radiation fields from lightning discharges are presented. Lightning discharges occurred in the region of the terrestrial surface bounded by a sector of ∼90° with a radius of ∼30–300 km. A power spatial dependence of the electromagnetic radiation field components of lightning discharges is established. The results of measurements are interpreted using fractal geometry methods.

Restoration of a two-layer geoelectric section in the coastal area of Lake Baikal

Radioimpedance measurements are taken at two sites on ice in the coastal area of Lake Baikal. From these full-scale measurements for a water-bottom soil system, a two-layer geoelectric section is restored; namely, the resistivities of a water layer and bottom soil are determined and the thickness of the water layer is measured. For example, the following values are obtained at one of the sites: water resistivity ρw = 120 Ω m, bottom soil resistivity ρb = 1400 Ω m, and depth h = 5.5 m. These values are in agreement with published data. The suggested method or geoelectric section restoration is applicable to a thin water layer near the coast.

Electromagnetic waves over stratified media in natural conditions

Experimental data of the radio wave propagation over high inductive structure “ice-salt water” in the decameter range of a field radiated by vertical dipole on a distance of up to 1.2 km are considered. It is shown that the surface electromagnetic waves (SEW) were attenuated less than the “ground” ray. An analysis of the field of radiation from the vertical dipole reveals the presence of a wave with the amplitude decaying with the distance R approximately as 1/R1/2, which corresponds to the SEW divergence. The absolute values of the radiation attenuation function |W| are significantly greater than unity and reach |W|=2, which also corresponds to the SEW. Experimental data on the SEW damping agree with the results of numerical calculations of the electromagnetic field in the system under consideration.

Way of detecting an electromagnetic earthquake precursor

A way of detecting an electromagnetic earthquake precursor is suggested. Detection is carried out with a device composed of a vertical electrical antenna and a toroidal magnetic antenna located on the Earth’s surface. It is shown that the detector is the most sensitive to the radiation of an electrical dipole inside the lithosphere that is oriented normally to the Earth’s surface. Such a pattern allows one to detect electromagnetic precursors by the method suggested.

Characteristics of the electromagnetic wave field far away from the radiation source

A solution to the Sommerfeld problem of the far (in terms of wavelengths) field of a vertical electrical dipole placed at the interface between two media has been found. The characteristics of a surface electromagnetic wave that propagates over a medium with highly inductive surface impedance δ have been determined. The spatial characteristics of the wave are expressed through the real and imaginary parts of impedance δ. It has been proved that the surface electromagnetic wave is the major contributor to the electromagnetic field of the ground wave in the case of highly inductive radio paths.

Electrometric method to determine the surface impedance of an ice–sea water bilayer system

An electrometric method to determine the surface impedance of an ice–sea water bilayer system is suggested. The complex impedance (its magnitude and phase) of this system is determined at very low, low, and medium frequencies from electrometric, rather than radio, measurements. For the ice–sea water system, it is sufficient to determine the conductivity and thickness of a water sample from drilling data.