Adel D. Akchurin

Field tests of compact ultra-wide-band MMIC amplifiers and multi-element two-stage amplifiers on discrete transistors with lossless transformer feedback as broadband antenna amplifiers of short-pulse ionosonde have been performed. Daytime tests have shown the obvious advantage of discrete transistor amplifiers due to the inherent ability of lossless transformer feedback amplifiers to filter out interference with frequencies above 30 MHz due to the use of numerous ferrite trans-formers between the amplifier stages. Our proposed symmetrical (push-pull) version of the lossless transformer feedback amplifier attenuates strong interference more strongly than the classic unbalanced (single-ended) version of such an amplifier.

This work is devoted to potential sources and mechanisms of the mid-latitude MSTIDs formation based on the analysis and comparison of statistical data in two regions: 1 region near Samara (~ 55 N. 50 E), 2 region near Sevastopol (~ 45 N, 35 E). The data obtained using a dense GNSS receivers network (> 150 pcs.) in the European part of the Russian Federation. The study was carried out using a new statistical method for determining the vertical slopes of the MSTIDs phase front. It was found that summer nighttime MSTIDs over the region near Samara (~ 55 N, 50 E) have the traditional southwest directions of propagation and sloping forward phase fronts, while near Sevastopol (~ 45 N, 35 E) northwest directions with sloping backward phase fronts. We suggest that the influence of Mid-latitude Summer Nighttime Anomaly may be a trigger for the northwestward MSTIDs, as unlike the southwestern MSTIDs, they are observed 10 degrees south and only in the summer months and September. We do not propose the exact mechanism of their formation in this article, however, we note that sloping backward phase fronts of MSTIDs couldn't be form by the GWs with sources in troposphere. The propagation directions of the southwestward MSTIDs near Samara (~ 55 N, 50 E) are consistent with those that are expected for the growth of Perkins instability.

A simple indicator has been introduced to detect weak mid-latitude TIDs in ionograms. This indicator is based on the differential rotation of the cusp part of the trace of the F layer. This approach turned out to be much simpler than the analysis and isolation of various additional traces in the form of cusps and hooks. Such an approach turned out to be more capable for highly noisy ionograms. Processing of 3-month data allowed us to detect clear daily-seasonal variations in the intensity of SSTIDs in autumn observations.

The paper considers an automated system for ionosphere sounding by chirp signals. The experimental scheme for quasi-vertical sounding of the ionosphere is described. It has been experimentally shown that there is no reciprocity in the characteristics of the signal propagation when changing the direction of propagation. This effect is explained by the difference in the phase incursion due to the rotation of the polarization plane. The results of numerical simulation are presented.

Powerful HF radio emission to the Earth’s ionosphere can be a reason of complex phenomena, which leads to the generation of artificial ionospheric turbulence. One of the most important components of turbulence is artificial ionospheric irregularities with a transverse dimension from a fraction of a meter to ten or more kilometers. The investigations of their spectral and dynamic characteristics makes possible to study the instabilities properties caused by the powerful radio wave and to study the features of dynamic processes in the ionosphere, and also to determine the possible influence of artificial irregularities to the different ranges radio waves propagation. Therefore, in August 5 2010, a heating experiment was carried out at the SURA heating facilities. The experiment was carried out during evening hours. Observation of generated irregularities occurred at a distance 170 km from the SURA facility at the observatory of Kazan Federal University (near Kazan) with ionosonde Cyclone. The control system of the ionosonde was set to the fast mode of ionograms recording (1 ionogram per minute), which made it possible to observe variations in the amplitude of reflections from the sporadic E-layer (Es). These variations look like synchronous with the heating time. A possible mechanism of the observed effect is discussed.

The paper deals with the problems of the mid-latitude MSTIDs detection with low intensity of electron density, ΔN/N, using the GNSS transionospheric sounding method. To collect data, a dense network of GNSS receivers located on the territory of the Russian Federation (more than 150 pcs.) has been used. On the basis of the obtained experimental data, the selectivity of the method of transionospheric sounding towards the MSTIDs, depending on the satellite-receiver line-of-sight orientation, is shown. Thus, the use of two-dimensional maps of TEC perturbations allowed to simultaneously observe the MSTIDs signatures using the satellites R03, G18 (which have similar geometric conditions of observation) and not observe them using the satellite R18. Accounting the mutual layout of the satellite-receiver lines-of-sight and phase front of the wave made it possible to form a method for observing the low-intensity midlatitude MSTID.

To determine the degree of connectivity of the electron density disturbance of the MSTID type below and above the F layer peak, a comparison data of the ionosonde and the low-orbit constellation of the Swarm satellites was made. It was found that, in most cases, variations in the critical frequency are close to antiphase behavior with respect to variations in the electron density at the satellite altitude. This means that in the altitude structure of the MSTID, the depletion of the electron density in the bottomside of the ionosphere is replaced by the enhancement at altitudes of 450–500 km and vice versa.

Vertical sounding is a fairly informative method for studying the ionosphere at a relatively small transmitted power. Ones of the incompletely studied phenomena in the F layer are travelling ionospheric disturbances (TIDs). Especially poorly studied is their mid-latitude and medium-scale variety, or MSTIDs, which needs more frequent probing than is customary for network ionosondes. In such a situation, the best option is vertical sounding with short-pulse sounding. The structure of a simple and unattended transmitter with a single tube stage with an output pulse power of 4 kW is described. For swinging of tube stage, a stage of carbide silicon field-effect transistors with a limit operating voltage of ~1000 V is used, which allows the matching between them and the output tube stage to be simplified as much as possible.