Features of reflection at limiting range of one-hop radio-waves propagation from Es layer

Sporadic E layer has essential influences on propagation of radio waves in decametric range, both expanding range of working frequencies, and shielding reflection of radio waves from overlying ionosphere. In report considered reflection of radio waves from Es layer on a line Cyprus-Kazan in the extent of 2600 km, at range of propagation limiting one-hop reflection for heights of arrangement of layer. Researches were spent by method of LFM sounding. The explanation of received results on expansion of usable range made on the basis of modeling reflections from spatial gradients of density of electronic concentration in Es layer. © 2011 IEEE

Determination of sporadic e radio wave propagation parameters based on vertical and oblique sounding

© 2015 COSPAR. Published by Elsevier Ltd. All rights reserved. Sporadic E layer is often determined for HF radio communication. We have to deal with oblique radiowave propagation in the radio practice. The limiting frequencies at oblique propagation depend heavily on the transmitter power and the receiver sensitivity. The reason for this, as in the case of vertical propagation, is the dependence of Es reflection coefficient, ρEs (reflection loss R(dB)), on Es operation frequencies. This paper describes the characteristics of HF Es propagation in relation to foEs obtained from ionospheric vertical observations. It was found that characteristics of Es propagation depend on the type and height of the Es layer. Also the foEs diurnal variation at definite R(dB) was detected. This investigation allows improving the prediction of limiting frequencies for HF radio propagation

Modeling and experimental observations of radio wave propagation by reflection from the Es-layer at short radio-lines

© 2014 IEEE. These The effects of focusing and defocusing at radiowave propagation through the Es-layer are frequently obtained. The large-scale cloud structure of Es layer was used to explain the effects of radiowaves focusing and defocusing by VS[1], as well as estimation of energy loss at oblique propagation[2]. Note, however, that this model can be used with a threshold level of registration not less than -35-40dB, because at lower levels the signal can be obtained by reflecting from electron density gradient and by scattering from the small-scale irregularities of the layer

Observation of irregularities dynamics by vertical and quasi-vertical sounding

© 2014 IEEE. Based on comparative analysis of the A and H plots collected from the ionograms of vertical and quasi vertical sounding you can get information about spatial and temporal changes. The ionosonde sensitivity to irregularities ΔN / N ∼510, sensing period 1 minute, distance between ionosondes 30 km. It is allows to investigate fast-flowing (with periods of 5-20 min) and small-scale irregularities of the ionosphere

Optimal conditions and the dynamics of quantum memory for spatial frequency grating resonators

The dynamics of the interaction between microcavities connected to a common waveguide in a multiresonator quantum memory circuit is investigated. Optimum conditions are identified for the use of quantum memory and a dynamic picture of the exchange of energy between different microcavities is obtained

The effect of the large-scale structure of the Es layer on limiting frequencies at oblique incidence

The results of experimental determinations of the correction coefficient K to the parameter M for converting the vertical-sounding frequency parameters of the Es layer into oblique-incidence limiting frequencies are reported. The measurements were made on the Moscow-Kazan path using a digital ionospheric sounder operating in the variable-frequency oblique-incidence sounding mode. Vertical-incidence sounding was performed on the path midpoint simultaneously with the oblique-incidence measurements. The coefficients K were determined by computing the ratios of the experimentally determined parameters M to the corresponding computed parameters M0 for specular signals reflected from the Es layer at a height of 110 km. The resulting distribution of the coefficient K can be fully interpreted in terms of the cloud model of the Es layer with the parameters inferred from the temporal variations in the blanketing frequency fbEs. The signal-amplitude dependence of the coefficient K is found to differ during daytime and nighttime hours. The corresponding differences for signal levels below -30 dB can also be interpreted in terms of the gradient and scattering Es layer models. Copyright © 2001 by MAIK "Nauka/Interperiodica"

Orbital structure of a meteoric complex in a vicinity of the Earth's orbit by Kazan meteor radar. Types of meteor orbits

© 2018 Elsevier Ltd The orbital structure of a meteoric complex in a vicinity of the Earth's orbit is substantially defined by conditions of its observation from the Earth. Orientation of aerials of Kazan meteor radar varied each 15 min to the North, East, South and West – the directions to provide the maximal review of northern celestial hemisphere together with the Earth's rotation. Nevertheless, the antiapex area of celestial sphere was practically inaccessible due to influence of the physical factor of small radar sensitivity to meteors with velocities less than 18 km/s. On the contrary, the meteor streams in which movements are backward compared to the Earth's movement, are quite observationally accessible. In the given work, the data of meteor radar observation from August to November of 1986 are resulted. The conditions of observation have defined some types of orbits: internal orbits with aphelion distance Q∼1 AU and with a wide spectrum of perihelion distances and external orbits with perihelion distance q∼1 AU and with a wide spectrum of aphelion distances. The majority of all observed orbits are close to circular orbits for which Q∼1 AU and q∼1 AU. Three-dimensional maps of meteor microstream distribution and numbers of meteors in them by perihelion, by aphelion distances and by inclinations are constructed. Orbital parameters of the most significant meteor streams that have been found out are presented