Backgrounds of adaptive Fourier transform and analytical wavelet transform have been briefly described in comparison with traditional Fourier transform using a time window. As an example, all three transforms are used to analyze quasiperiodic wave-like processes in the ionosphere, which accompanied the passage of the solar terminator and rocket launch from the Plesetsk site. The advantages of adaptive Fourier transform and analytical wavelet transform as compared to traditional Fourier transform, which make it possible to reliably detect wave-like disturbances against a background of noise at a signal-to-noise ratio not less than 0.1, have been demonstrated.

On the basis of the author's long-term experimental and theoretical studies, the concept that the Earth–atmosphere–ionosphere–magnetosphere system (EAIMS) is a complex, open, dissipative, nonlinear dynamical system whose most important property is a trigger mechanism for energy release has been validated, and the basic aspects of the system paradigm are described. Highly energetic phenomena in the system are shown to give rise to a complex cluster of processes and to reconstruction in the subsystem coupling. Active experiments in the EAIMS have established the limitations of the linear description of the subsystem response to large energy inputs, determined the possibility of the onset of large-scale and global-scale perturbations from local and localized energy releases, and also revealed and identified the types of waves transferring these disturbances. Most of the highly variable processes in the EAIMS have been found to be accompanied by energetic particle precipitation from the magnetosphere at middle latitudes. A few remote sensing techniques have been used to study the dynamic processes operating in the EAIMS and to confirm the basic aspects of the system paradigm.

A circularly polarized antenna base on the transparent conformal polarization-conversion metasurface is proposed. The designed meta-surface unit is an ellipse rotating 45 degrees with a rectangular slot. The three metasurface cells are arranged in a group and rotated 90 degrees around the feed antenna. The metasurface is printed on transparent and conformal PET while also possessing low-profile characteristics. By using this method, polarization conversion of the antenna is achieved without damaging the original antenna structure, thus extending the circular polarization bandwidth of the antenna. The simulated and measured results show that the -10 dB bandwidth of the antenna is 3.9-4.7 GHz, the axial ratio is less than 3 dB. The meta-surface effectively expands the circular polarization bandwidth of the antenna from 100 MHz to 800 MHz. The radiation efficiency of the antenna exceeds 60%, and the peak gain is more than 5 dBi. The radiation patterns show that the antenna has right-handed polarization characteristics and obvious directional radiation characteristics. The meta-surface design effectively broadens the circular polarization bandwidth of the antenna, making it suitable for circularly polarized communication systems operating in the C-band frequency range.

An analysis was conducted of time variations in geomagnetic field components on the day of the Chelyabinsk meteorite event (February 15, 2013) and on control days (February 12 and 16, 2013). The analysis uses the data collected by magnetic observatories in Novosibirsk, Almaty, Kyiv, and Lviv. The distance R from the explosion site to the observatories varies in the range 1200–2700 km. The flyby and explosion of the Chelyabinsk cosmic body is found to have been accompanied by variations mainly in the horizontal component of the geomagnetic field. The variations are quasi-periodic with a period of 30–40 min, an amplitude of 0.5–2 nT for R ≈ 2700−1200 km, respectively, and a duration of 2–3 h. The horizontal velocity of the geomagnetic field disturbances is close to 260–370 m/s. A theoretical model of wave disturbances is proposed. According to the model, wave disturbances in the geomagnetic field are caused (a) by the motion of the gravity wave generated in the atmosphere by the falling space body and (b) by traveling ionospheric disturbances, which modulate the ionospheric current at dynamo altitudes. The calculated amplitudes of the wave disturbances are 0.6–1.8 nT for R ≈ 2700−1200 km, respectively. The estimates are in good agreement with the observational data. Disturbances in the geomagnetic field level (geomagnetic pulsations) in the period range 1–1000 s are negligible (less than 1 nT).

Observation results are presented for the lower and upper ionosphere disturbances accompanying the passage and explosion of the Chelyabinsk space body. The effects near the meteoroid’s path are investigated from the total electron content variations detected by GPS radio receivers. The ionosphere observations at distances of ∼2000-300 km are based on the ionosonde data and the phase and amplitude measurements for a radio signal at 66.67 kHz on the route from Moscow to Kharkiv. Manifestations are found both of acoustic and gravity waves following the passage and explosion of the space body. Their connection with the passage of the Chelyabinsk meteoroid is discussed.