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Within the limits of a linear model based on processing of data of direct calibration measurements with semiconductor multisensors, a method of their calibration by standard levels of gas concentration is substantiated for its subsequent application for small concentration levels. On an example of data for nitrogen dioxide, the notion of the normalized surface density of the gas is introduced, and its relationship with the volume concentration is established. On this basis, the feasibility of increase in the sensitivity and selectivity of the multisensor system by several orders of magnitude compared with the existing instrumental methods is substantiated by imitational modeling using mathematical methods of modern algebra and regularization theory.

Results of experimental investigations on radar sensing of inhomogeneous media and objects with the use of both superbroadband (from 0.5 to 17 GHz) multifrequency scanning and supershort nanosecond and subnanosecond radar pulses are considered. It is demonstrated that addition of angular and spatial scanning and subsequent synthesis of a large aperture allow a three-dimensional tomography of low-contrast inhomogeneities to be realized with a spatial resolution of about 1 cm. Examples are presented that confirm a high efficiency of the method for contactless tomography of the forest structure and detection and visualization of infantry mines below a rough sand surface.

An oblique scanning method for subsurface radio tomography is proposed that is aimed at reconstructing the inhomogeneity 3D distribution and discovering out-of-level scatterers under a planar interface. The method is based on synthetic-aperture radar technology and uses data of multiposition sensing by omnidi-rectional antennas elevated over the Earth’s surface. The focusing of the synthetic-aperture radar is based on fast Fourier transformation providing a fast algorithm of 3D reconstruction. The method is verified numerically and in real experiments.

A method of teaching of one of the divisions of electrodynamics devoted to relativity theory is suggested. The presentation is based on the four-dimensional formalism, which allows a number of fundamental physical phenomena to be considered from a unified position. The content is in full conformity with the approved standard programs for students and postgraduates of radio physical and radio technical specialities of universities. The methods can be useful to the teachers, scientific workers, and engineers concerned with other directions and specialities.

Results of experimental investigations into the effects arising in the detection and ranging of the earth's forest cover with the use of pulse ultrabroadband radio-frequency radiation are described. A narrow-beam transmitting and receiving antennas oriented at a sliding angle to the forest canopy were mounted on a special mast at an altitude of 21 m above the ground. A corner-cube reflector was used to align and to calibrate the measurement system. The results obtained are compared with the data of independent biometric measurements.

It has been shown that a full vector measurement of the total field allows one to uniquely distinguish the incident and reflected waves at each observation point without the use of a spatial difference based on an analysis of the polarization structure of the interference pattern which arises during reflection of electromagnetic waves from an intermedia boundary. We have investigated the stability of these procedures with respect to measurement noise by means of numerical modeling.

It's considered the principle possibility of creation the managed reflectors for formulation of given field distribution in the focus area. Reflectors change the reflect ratio in dependence of the external control. The proposed theoretical modeling of such controlled focused device which provides focuse to a specific point in a given distribution of the reflectors. On the basis of numerical simulation it's considered the application of this approach for the solution of the problem of radiotomography.

The research of various parameters influence on the Fresnel reflector focusing properties in particular spatial sizes, the focal point position, etc. is conducted. The version of using a flat Fresnel reflector for receiving ultra-wideband signals with the use of Wiener filtering is suggested.

Subsystems of the design of a complex security system for premises under conditions of large volume of passenger traffic are considered. These subsystems provide video- and thermal imaging control, radio wave tomography, and gas analysis. Simultaneous application of all examined variants will essentially increase the probability of timely prevention of dangerous situations with the probability of false alarm as low as possible. It is important that finally, this will provide protection of population and will facilitate the work of intelligence services.

Nowadays the problem of remote sensing of various objects and people to prevent transportation and storage of weapons, explosives, and other forbidden objects becomes urgent in connection with strengthening security measures on counteraction to terrorism all over the world. Methods based on x-ray, magnetic induction, and radar sensing are developed intensively. Methods of x-ray sensing, as a rule, are applied to lifeless objects; in some countries, irradiation of people even by low-power x-rays is forbidden. Methods based on application of magnetic fields are suitable for detecting metal objects; however, they are inapplicable for detecting dielectric targets such as explosives or ceramic knifes. Radio-wave methods are relatively safe for people and allow any objects, including dielectric ones, to be detected. For this reason, methods of micro-wave radar sensing are developed intensively all over the world.

The possibility of image improvement by increasing its resolution using operations of fragment selection, interpolation,point-spread function reconstruction, deconvolution and regularization is considered. First two operations broaden thespectrum of image spatial frequencies, others remove image blurring and noise. The approach effectiveness is demonstratedon examples of processing the images for different parts ofthe Earth surface, which were taken from the satellites NOAA and"Resurs - MSU". It has been shown that the resolution can increase in not less than 10 times.Keywords: increase of resolution, point-spread function, deconvolution, regularization. 1. INTRODUCTION The increase of space image resolution is connected, first of all, with elimination of its blurring'. The image blurring isinfluenced by many reasons. There are equipment influence (probable disfocussing, blurs, digitizing averaging) andatmospheric influence (refractional and turbulent disturbances). As a first approximation, influence of all the factors can bedescribed by point-spread function (PSF). Generally, the PSF is a local characteristic, not constant and which varies over animage2. Besides solving the problem of increasing an image resolution, the PSF reconstruction is important itself, for instance,for determining the atmospheric conditions. In this paper the method of complete PSF restoration on the initial image is beingproposed. The restoration is fulfilled within the interactive mode on a small fragment with heightened brightness contrast bythe method of least squares. The PSF that found is used for fulfilling the image deconvolution. This operation is carried outusing the Wiener's filtration with regularization that raises the solution stability. In the end the image quality improvementserves as a criterion for the PSF reconstruction correctness. In any case, the resolution will not be better than a pixel of an

The passive remote method of microwave radiometry and its instrumental realization for express diagnostics of radioactive elements in the atmosphere have been discussed. Analysis of the microwave radiation due to ionization and dissociation of atmospheric components interacting with radioactive elements is carried out. The photochemical processes resulting in background microwave radiation power have been discussed. As an example, the results of natural experiment of detecting the atomic hydrogen radiation in the plume of emissions of nuclear cycle processing plants have been presented.

At passive sounding the sources of observable radiation are often distributed casually. In this case the intensity of radiation is main information parameter for the decision of an inverse problem. To reconstruction 2D distribution of own radiation sources density on the basis of angular distribution registration of received radiation intensity the decomposition of known and unknown functions in Fourier series on circular harmonics is applied. In case of poor absorption the problem is reduced to equation of Abel type with Chebyshev polynomials in its kernel. New method is offered, which is based on exponential variable replacement. In this case the initial equation is resulted to the convolution equation that admit the decision by use fast algorithms. Efficiency and stability of the decision have been proved by results of initiation modeling. Opportunity of use of the decision for diagnostics of atmosphere radiating pollution and forest fire moving is shown.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The method of singular regularization for inverse ill-posed solving with entropy choosing the regularization parameter is purposed. As an application the scheme of backscattered microwave tomography of biological tissue with double focusing is considered.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The scattering of a spherical wave by a static irregular dielectric surface, separating two subspaces with dielectric constant close to the permittivity of free space, is investigated by the Kirchhoff method. The irregularities of the surface — large-scale with small angles of inclination, and their heights are distributed according to a normal law. Self-shadowing and the set of spots associated with scattering on such a surface are taken into account. The polarization matrix of second moments of the components of the scattered field is calculated. The dependence of the matrix elements on the statistical parameters of a randomly irregular surface are discussed.