Mathematical modeling of disprersive distortions of the wideband chirp signal during its propogation in the ionospheric radiochannel
Theoretical description of the chirp ionosonde operation has been made. Ionosonde registers spectrum sequence of window received-signal sampling. Mathematical modeling of dispersive distortions of spectra registered has been carried out.
On the shape of measured spectra of the ionosphere sounding by an FMCW signal under dispersion case
Abstract A theoretical description is given to the ionosonde operation configuration in the mode of sounding the decametric radio channel by the frequency-modulated continuous wave (FMCW). A preprocessing of the received signal is carried out using the frequency-compression method. It is shown that the result derived from processing an individual time sample is mathematically equivalent to a sounding of the radio channel by a complex-valued narrow-band impulse signal. The group delays of this signal determines maximum in the recorded spectrum. We give the formula for calculating the form of the recorded spectrum at ionospheric soundings by the FMCW signal subject to the dispersion. A formula for calculating the spectral width due to the dispersion is obtained. A comparison is made with experimental data.
Microwave source with enhanced radiation power based on orbitron MASERs
We have proposed the design of high power microwave source in a vacuum tube based on the theory of negative mass instability. The proposed source does not operate based on a slow-wave structure but instead makes use of accelerated charged particles. In our structure, an electron emitter injects the charged particles into to the cavity. Emitted particles move around the anode, which leads to electron acceleration and emission of electromagnetic waves with a specific frequency. In this paper, we have enhanced the output power and frequency of microwave source by variation of particles initial energy and the number of anodes incorporating their specific arrangement and applied voltages. Working at room temperature, compactness, wide bandwidth, and tunability of output frequency are among the advantages of the proposed source.