Active microstrip antennas, or antenna-oscillators (AOs) based on field-effect transistors, make it possible to create small-sized radiation sources in a wide frequency range, including the multi-element arrays with the possibility of power combining. The generation of radiation in the microwave range (5-20 GHz), depending on the conditions, can be single-frequency or multi-frequency, and the generation of noise-like signals was also observed. The combining of the AOs radiation power in the mode of oscillation stochastization is of the specific interest. In contrast to phased arrays, where power summation is achieved under conditions of synchronized monochromatic generators, the interaction of stochastic oscillation generators is a complicated process that leads to a radical change in the overall radiation spectrum. It seems more promising to combine the noise emission spectra and power of independent AOs with adjacent and controlled generation frequencies. In this paper, we study the possibilities to combine the power and emission spectra of a group of AOs, taking into account the possibility of their mutual synchronization.

The results of the development of a small-sized laser fiber fluorimeter in the IR spectral range for a luminescent photodiagnostics of superficial localization tumors are presented. This device, working in conjunction with the “Fluroscan” type pharmaceutical composition based on the 2,4-di(α-methoxyethyl)deuteroporphyrin IX ytterbium complex dipotassium salt, ensures the achievement of high values of the luminescent diagnostic contrast index for a neoplasm/normal tissue. Import substitution of some basic design elements of the developed device, in particular the photodiode module, was carried out with a domestic analogue.

The possibility of noise radiation source development based on microstrip log-periodic antennas integrated with field-effect transistor is investigated. Opportunities for spectrum characteristics tuning, power combining and widening the radiation spectrum of the oscillators are experimentally studied at frequency range 5-7 GHz.

We developed a pilot version of a laser-fiber fluorimeter for luminescence diagnostics of skin and mucous membrane cancers, operating in the near-IR spectral range (9–1100 nm). The main components of the device are considered: a compact semiconductor source of laser radiation, operating at a wavelength of 405 nm; a highly sensitive optoelectronic unit; a laptop with a developed program; and a high-aperture fiber optic probe (numerical aperture up to 0.32). The device, working in conjunction with a pharmaceutical composition of the Fluroscan type based on dipotassium salt of the ytterbium complex 2,4-di(α-methoxyethyl)deuteroporphyrin IX, ensures achievement of high values of the luminescence diagnostic contrast index of neoplasm/normal tissue (up to 50 units).

Microwave solid-state oscillators of noise-like signals are of the great interest for wireless telecommunication systems, imaging systems and electronic warfare. In the paper, the possibility of power combining in the array of three independent noise-like oscillators is investigated. The noise-like oscillators are based on the microstrip log-periodic antennas which are integrated with field-effect transistors. As an active element, NE350184С field-effect transistor with 13.5 dB gain at 12 GHz is chosen. It was previously shown that single-frequency, multifrequency or noise-like generations are possible in the active antennas. The main factors that affect the generation type are the current in the drain-source circuit of the transistor and the distance between the antenna plane and reflecting screen. It is experimentally shown, that using of the noise-like oscillator arrays makes possible the spectrum and power combining, but the construction is not enough stable and reliable.

A portable high-sensitivity device for recording weak luminescence signals in the near infrared (NIR) region (900–1100 nm) has been developed for applications in laser oncofluorometry. The device consists of a housing with optical lenses, interference filters, and a high-sensitivity NIR photodiode module with a preamplifier, protection circuit, and power supply. It is shown that the use of interference filters of the SL 930–1100 type can significantly increase the efficiency of the device. The use of a photodiode module unit with a sensitivity peak near 960 nm, which maximally coincides with the luminescence peak of ytterbium porphyrin complexes, ensures the sensitivity of detecting weak luminescence signals at the level of several fW.

The study investigates the possibility of generating noiselike signals in the centimeter wavelength range using antenna generators built on a log-periodic microstrip antenna integrated with a field-effect transistor. The conditions for the occurrence of noiselike generation are experimentally determined. The possibility of expanding the noiselike spectrum using low-frequency noise modulation is studied. Noiselike generation was experimentally obtained in the centimeter wavelength range with a spectral width of up to 2 GHz.

ГЕНЕРАЦИЯ ШУМОПОДОБНОГО ИЗЛУЧЕНИЯ СВЧ ДИАПАЗОНА В ОДНОМЕРНОЙ РЕШЕТКЕ МИКРОПОЛОСКОВЫХ АНТЕНН-ГЕНЕРАТОРОВ

A layer of vegetation above the surface of the soil absorbs the microwave radiation emitted by the soil and some objects under the vegetation canopy. This paper explores the microwave propagation process within the vegetation layer and evaluates the respective attenuation coefficients. For this purpose, an experimental laboratory test bench is constructed which is based on the special rectangular camera-waveguide with the transmission and reception of broadband antennas. This allows the study of the dependence of the attenuation coefficient on the 0.8–10 GHz frequency range and the water content in different types of vegetation. Evaluations of attenuation coefficients are achieved on a wide range of frequencies for deciduous and coniferous forests, which separate the branches and trunks as canopy fragments. These experimental results are important because they can fulfill the requirement for verification and validation of existing theoretical models that describe the attenuation effect of microwave propagation in vegetation canopy. In addition, the development of a simple empirical model based on the results obtained can give a brief indication of their importance.

Аннотация.В работе рассмотрены вопросы моделирования экспериментального комплекса из девяти измерительных установок на

A layer of vegetation over the soil surface absorbs microwave radiation emitted from the soil and some objects located under the vegetation canopy. This paper investigates the microwave propagation process within the vegetation layer and evaluate the attenuation coefficients. For this purpose, laboratory experimental test bench is synthesized. It is based on the special rectangular camera-waveguide with transmission and receiving wide band horn antennas and allows the study of the attenuation coefficient dependence on the frequency of 0.8-10 GHz range and water content in the different vegetation elements. Evaluations of attenuation coefficients are implemented over a wide frequency range for deciduous and coniferous forests with separation consideration of the branches and trunks as the canopy fragments.

We consider some peculiarities of the behavior of thermal and radio thermal (microwave radiation) characteristics of the atmosphere during prestorm situations in water areas monitored directly and remotely. The objects of research are (a) a region of the SMKF1 station (Sombrero Key) in the Florida Straight in August 2005 and (b) Golubaya Bay in the Black Sea (Gelendzhik, the territory of the Southern Branch of the Shirshov Institute of Oceanology, Russian Academy of Sciences) in September 2010, several days before an intensive storm. Using meteorological and satellite microwave radiometric data, we have studied some common and specific features in the behavior of surface air temperature and humidity, surface fluxes of sensible and latent heat, total heat and water vapor content of the atmosphere, and microwave radiation characteristics of the “water surface-atmosphere” system during time periods preceding the approach of Hurricane Katrina to the region of SMKF1 and development of the sea storm near the Golubaya Bay. In both cases the effect of the accumulation of the latent heat of water vapor in the atmosphere was observed during the prestorm periods (of several days).

Рассмотрены особенности поведения тепловых и радиотепловых (СВЧ-излучательных) характеристик атмосферы в акваториях, контролируемых контактными и дистанционными средствами в предштормовых ситуациях. Объекты исследования: а) район станции SMKF1 (Sombrero Key) Флоридского пролива накануне прихода в этот район мощного тропического циклона Катрина в августе 2005 г.; б) Голубая бухта Черного моря (г. Геленджик, территория филиала Института океанологии им. П.П. Ширшова РАН) в сентябре 2010 г. накануне интенсивного шторма. На основе метеорологических и спутниковых СВЧ-радиометрических данных проведено изучение общих и отличительных признаков в поведении температуры и влажности приводного воздуха, приповерхностных потоков явного и скрытого тепла, полного тепло- и влагосодержания атмосферы, а также СВЧ-излучательных характеристик системы “водная поверхность–атмосфера” в периоды времени, предшествующие приближению циклона Катрина к району станции SMKF1 и развития морского шторма в районе Голубой бухты. В обоих случаях в предштормовой период времени (несколько суток) наблюдался эффект “накачки” атмосферы энергией в виде скрытого тепла, содержащегося в водяном паре.

Methods for measuring the reflection coefficient for flat samples in a free space at millimeter, centimeter, and decimeter waves are described. The efficiency of these methods in measuring real samples of a two-layer structure based on chiral elements is demonstrated. Good agreement between the experimental results obtained by different methods is shown experimentally.