The possibility of using millimeter-wave (MM) satellite communication lines in the Arctic to ensure reliable and high-speed communication is considered. The main problem for the application of MM waves is the possible meteorological conditions for the propagation of radio waves in the cold. Vertical profiles of meteorological data for a pair of islands in the Arctic Ocean were used to calculate molecular absorption on a possible link. A very simple model of attenuation of radio waves in rain on such a line is proposed. The satellite orbits for calculating the line attenuation margin were assumed as in the existing satellite system Gonets operating at frequencies of 300/400 MHz. The results of calculations show that satellite communications in the MM band are possible in the Arctic.

Abstract—The article describes an algorithm for calculating the characteristics of the passage of low-frequency electromagnetic waves through the magnetoactive plane-stratified lower ionosphere. The algorithm is based on numerical integration of wave equations for the case of a plane wave incident on the ionosphere from below, taking into account the plasma’s ionic composition. As an illustration, the basic characteristics of passage of waves in the 0.05–1 kHz frequency range are calculated. It is shown that the power transmission coefficient of these waves is quite large, ranging from 0.2–0.4 for most of the frequencies used. It is shown that in the daytime near a frequency of ~300 Hz, the transmission coefficient in the daytime has a maximum and is approximately double the nighttime values.

Based on the results of numerical calculations of the intensity of the low-frequency (LF) electric field of an emitter in the form of a loop antenna installed on board an artificial Earth satellite, this quantity was compared with the strength of the field demodulated in the lower ionosphere, perturbed by the radiation of a high-power high-frequency (HF) transmitter (HAARP station, Alaska). It is shown that the onboard low-frequency transmitter with a power of ~1 kW is able in the lower ionosphere to provide approximately the same field strength as the HAARP demodulator with an average power consumption of the HF transmitter of 3.6 MW.

Artificial power low frequency transmitters are widely used as wave sources in the Earth-ionosphere waveguide and in the ionosphere and the magnetosphere for active experiments, for navigation and communication especially with underground or under water objects.In such projects the correct choice of type and placement of the radiating device is especially important.It is well known that earth located electric dipole is relatively non-effective low frequency source because of high earth conductivity in this frequency range.The HAARP project was recently developed particularly for creating an effective low frequency source situated in low disturbed polar ionosphere.Such a source is a result of nonlinear process of demodulation of modulated high frequency emission from a ground based power transmitter.This multistage process seems to have a relatively low efficiency.In this work we try to compare an electric field strength of the HAARP 'virtual' low frequency source with a field value of an onboard loop antenna in 1…10 kHz frequency range.The loop field calculations were carried out in linear cold plasma approximation.For excluding of plasma resonances singularities we use a model of the 'finit size' circular electric current source.It is shown that the loop field spatial distribution is extremely non uniform and is highly different from corresponding distribution in free space.It is also shown that onboard loop transmitter of ~1 kW power is capable to give approximately the same low frequency electric field strength in the low ionosphere as whole HAARP station.

ОСЛАБЛЕНИЕ ЭЛЕКТРОМАГНИТНЫХ ВОЛН В НИЖНЕЙ ИОНОСФЕРЕ В ШИРОКОМ ИНТЕРВАЛЕ ЧАСТОТ ОТ 1 кГц ДО 10 МГц А. В. Мошков, В. Н. Пожидаев Институт радиотехники и электроники им.В.

The possible distribution of the field strength of the low-frequency demodulated radiation of the high-power transmitter of the HAARP station (Alaska, USA) over the Earth surface in the Earth–ionosphere waveguide has been numerically simulated. It has been shown that, owing to the extremely weak electromagnetic coupling between the ionosphere and the waveguide in the case of an ionospheric source, the strengths of the electric and magnetic fields of the waveguide waves are relatively low and are at the level of the low-frequency noise even in the immediate vicinity of the center of the distribution. It has been confirmed that, in order to detect such a signal and measure its parameters, it is necessary to use special procedures for processing data from ground-based receivers.

Numerical simulation of propagation of a demodulated beam of low-frequency electromagnetic waves at low latitudes in the presence of latitudinal gradients of the equatorial anomaly has been performed under the condition that the signal is recorded in the vertical direction, for example, with the use of sounding rockets. It has been shown that the wave beam has small spatial dimensions and, therefore, the amplitude distribution of the electromagnetic field in this beam is nonuniform owing to the interference effects under competitive action of the plasma density gradients and plasma anisotropy in the presence of a nonuniform geomagnetic field. Under these measurement conditions, the measurements usually conducted with the use of the instruments carried by an Earth satellite may become insufficient.

The limits of applicability of terahertz band radiowaves for creating communication lines in the Earth’s atmosphere have been shown in a well-argued manner for the first time. It has been shown that the extension of the lines for near-ground paths will be comparatively small due to the properties of the atmosphere.

Features of propagation of low-frequency electromagnetic waves in the low-latitude ionosphere are considered in the case when such waves are generated by means of demodulation of the radiation of a high-power short-wave ground transmitter in the lower ionosphere. Calculations are performed in the ray approximation based on a simplified model (developed specially for the case under study) of the anomaly of the low-latitude equatorial electron density. It is demonstrated that latitude gradients of the equatorial anomaly may result in both additional focusing and defocusing of the beam of demodulated low-frequency waves.

A method for calculating the angle of Faraday rotation of the polarization plane in the ionosphere is developed for P-band synthetic-aperture radars. In combination with the methods for processing of radar signals, this approach allows elimination of the ambiguity of this angle. The method uses the model of the geomagnetic field based on expansion into spherical harmonics. It is shown that the use of the conventional dipole model in the vicinity of geomagnetic anomalies may result in substantial errors.

Рассмотрены параметры рефракции радиоволн в условиях Арктики. Учтены особенности как тропосферы, так и ионосферы в этом районе. Показано, что в приполярных районах отсутствуют какие-либо существенные отличия в величинах углов рефракции относительно других областей. Расчеты проводились численно с использованием точных формул для рефракции. Определено соотношение между углами истинной и полной рефракции.

The radio-wave refraction parameters are analyzed under the Arctic conditions. The features of the troposphere and ionosphere of this zone are taken into account. It is demonstrated that the refraction angles of near-polar regions has no substantial differences from those of other regions. Calculations are performed numerically with the use of exact formulas for refraction of electromagnetic wave. The relationship between true and total refraction angles is derived.