Showing papers in "Radiophysics and Quantum Electronics in 1989"

A radiometry method of determining the subsoil temperature profile and depth of soil freezing

Abstract: We present results from theoretical and experimental studies into the possibilities of thermal probing of soil by means of a superhigh-frequency radiometry method. A special measurement method has been developed to eliminate the effect of the reflective and scattering characteristics of the soil on radio emissions. Subsoil temperature profiles have been reproduced on the basis of measurement data from thermal radio emissions under summer and winter conditions at wavelengths of 0.8, 3, 9, and 13 cm, and the daily dynamics of soi! temperature were investigated. Methods have been developed for the determination of the extent to which the soil is frozen, and the accuracy of these methods was 15-20%.

Hybrid modes of open waveguide cavities (numerical and analytical investigation)

Abstract: We see that the behavior of the spectral curves near regions of mode interaction can be reconstructed by determining the set of Morse critical points and the expansion (3). If these curves are augmented with corresponding asymptotes of the form Re ϰ(L) → ν n /2πθL≫1, Im ϰ(L) → 0 fairly detailed information can be obtained about the behavior of the eigenfrequencies of the investigated structure. This approach is most effective in cases where mode interaction can be expected beforehand on the basis of general considerations when the sequence of excitation of the OWC and the energy-converting properties of its boundaries are known. By solving Eq. (4), we can predict unambiguously whether such interaction will take place and, if so, for what geometrical and frequency parameters. Once the coordinates of the Morse point are known, the structure of the field can also be effectively and deliberately varied without any appreciable change in the OWC geometry.

Synchronization of stochastic oscillations of parametrically excited nonlinear oscillators

Abstract: (1) ~ 2 = ~ , ~ = -k ,~--x2(1 + q cos o+x~ ) + c~(y,--y2), o=~, which individually (for C I = C 2 = 0) exhibit stochastic dynamics for determined values of the parameters. Here k I, k 2 are the dissipation loss coefficients, q, ~ are the pump amplitude and frequency, C I, C 2 > 0 are the coupling parameters. It was discovered that by increasing the coupling parameter (C I = C a = C) from zero, the proprties of the oscillators' stochastic oscillations evolve similarly to the evolution of the oscillations of interacting independent oscillators with one degree of freedom. That is, they possess all of the charcteristic attributes of what is called \"synchronization\".

Using millimeter radio waves to probe the earth's atmosphere

Abstract: We analyze the unique features involved in employing millimeter radio waves to investigate and monitor the earth's atmosphere by means of radio transmissions involving the use of two satellites. We discuss the absorption of radio waves in the atmosphere along the path of the two satellites, depending on the wavelength and the time of year. Signal attenuation is analyzed in the absorption lines of water vapor, oxygen, and in the millimeter transmission range. It is demonstrated that radio transmission probes using the millimeter waves makes it possible to investigate the altitude distribution of moisture, density, and cloud cover.

Electrodynamic theory of regular finned-dielectric structures

Abstract: Finned-dielectric structures form the direction-guiding systems in the EHF band in which a plane-parallel uniform dielectric layer guides the wave, while thin metallic fins enhance the concentration of the energy from a working wave in a portion of the line that is restricted in breadth. We examine two variants of a finned-dielectric line in this study: one with fins of various heights and one that has been inverted. For purposes of analysis we have used a system of four integral equations relative to the tangential components of the field; the algebraization of this system is accomplished by the Galerkin method. The characteristics of the fundamental and higher wave types are derived by a numerical method, and we offer both an analysis and a classification of these.