** **

** **

** **

**ENERGY CHARACTERISTICS OF A RECTANGULAR WAVEGUIDE
T-JUNCTION INTERACTING WITH A MULTIELEMENT VIBRATOR-SLOT COUPLING STRUCTURE**

*S. L. Berdnik,
V. A. Katrich, V. I. Kiyko, M. V. Nesterenko,
Yu. M. Penkin*

The study of peculiarity of influence of the impedance

insertions on the electrodynamic characteristics of the rectangular

waveguide junctions, which are widely used in the

antenna-waveguide devices, is important for practical applications. A

mathe-matical model for *E*-plane T-junction of

rectangular waveguides with a three-element vibrator-slot coupling structure

was built using approximate analytical solutions of equations for induced

currents by a generalized method of electro-magneto-motive forces. The

distinctive feature of the model is the usage of variable surface impedance

along the monopole axes and constant impedance, distributed over the end wall

of the lateral semi-infinite waveguide. Multiparameter

energy characteristics of the junction in the single-mode waveguides are

presented including the case of meta-material coating the end wall of the

lateral waveguide. The possibility of efficient use of impedance coatings as

control element for power division between the output waveguide junction arms

is shown.

**REFLECTION RESONANCES IN A RECTANGULAR WAVEGUIDE
SECTION WITH A PAIR OF ANTIPODAL RECTANGULAR POSTS**

*L. P. Mospan,
S. A. Prikolotin, А. А. Кirilenko*

Intentional and controllable introduction of

attenuation poles into the frequency responses of frequency-selective devices

is in the great demand in the design of modern filters with complicated

performance. Successful implementation of such an approach is possible using

rectangular waveguide sections with metallic inserts. Here, the scattering

characteristics of such sections with a pair of antipodal rectangular posts as

waveguide units with rotational symmetry are studied. Comparative analysis with

the characteristics of a section with a pair of unidirectional posts is performed.

Spectral theory of open waveguide resonators is used in order to interpret the

resonant phenomena. Within the frames of spectral theory the reflection

resonances formed by such sections are the responses to the excitation of eigen

oscillations of complex frequencies. It is shown that the spectral theory

enables an order of magnitude more accurate (in comparison with the

conventional modal analysis) evaluation for basic parameters of the resonance

reflection, namely its frequency and the quality factor. The results obtained

make preliminary synthesis of frequency selective devices based on such

sections physically transparent and more accurate.

**RADAR**** ****ELEVATION
ANGLES MEASUREMENTS OF LOW-ALTITUDE TARGETS OVER THE SEA BY ROOT-MUSIC**

**METHOD UNDER INTERFERENCE FROM MULTIPATH AND THERMAL**

NOISE

NOISE

**О**

**F DIRECTION FINDER**

*Yu. A. Pedenko*

The work is devoted to improvement of the accuracy of

radar measurements of elevation angles of low-altitude targets above sea level

when using the *root-MUSIC*, which is considered by experts as one of the

means to solve this problem. Unlike previous studies, which take into account

the multipath only, in this study the clutter is complicated by thermal noise

of radar. This allows to evaluate the capabilities of the method and provide

guidance on its application in the conditions close to reality. The study was

carried out by computer simulation. It covered various sea states at which the

conditions from specula to strong diffuse reflection were complied. In the

simulation a wide range of signal/noise ratio was used. The main focus was the

study of effects on measurement errors of a priori parameters of the method:

the signal subspace dimension and the order of autocorrelation matrix of

signals received by a multi-element antenna array. The recommendations of their

choice, allowing to minimize the errors of elevation measurement in different

conditions, have been developed. The results of the study extend the knowledge

of how to improve the methods for measuring the target elevation angle above

the sea.

**RESEARCH ****ON**** THE UNDERLYING SURFACE BY RADIATION OF GLOBAL NAVIGATION SATELLITE SYSTEM**

*V. I. Lutsenko, D. O. Popov, I. V. Lutsenko*

The investigation of the scattering signals features

on the land surface can be used to study the physics of scattering processes,

as well as for the establishment of multipath compensation methods for reducing

positioning errors in global navigation satellite systems. The possibility of

detecting the reflection areas on the underlying surface and estimating their

parameters by using radiation of global navigation satellite systems is shown.

The behavior of the signal levels for different satellites in urban areas is

analyzed. The influence of the reflection area’s characteristics on the

spectrum of the received radiations is considered; the method of determining

their location is proposed.

**R****ADIANT**** S****YSTEM**** ****BASED**** ****ON**** ****COLD**** ****PLASMA**

*V. V. Ovsyanikov*

The actual problem of studying the basic properties and searching for methods

of improving the plasma radiator array, which is similar to the array of metal

or dielectric antennas, has been considered. This problem is not sufficiently

covered in the well-known publications, however, the great interest of

professionals to emitters based on cold plasma is due to the prospect of

creating effective multi-beam scanning selective plasma reconfigurable systems

or the plasma array of radiators (PAR). The article studies the main

electrodynamics parameters of PAR in the microwave range, characterizing it on

the one hand, as the load for the generator (receiver) of electromagnetic (EM)

signal. On the other hand, PAR is tested as transmitter of EM energy from the

point of view of its direction pattern (DP) and the main parameters of

radiation of PAR. When scanning DP beam, impedance distortion of PAR

transmitters and DP deformation are investigated. For comparison, similar

studies were carried out for the same design and configuration of the pattern

antenna (PA) of metal antennas. The studies have been carried out by PAR

modeling and their parameters calculations on computer in software environment

FEKO by integral equation method and method of moments for linear PAR from 4

emitters in the form of loop dielectric tubes filled with cold plasma under

reduced pressure. When studying the self and mutual impedances of the PAR and

metal PA in common mode for the distance between the transmitters 0.5λ_{0}, where λ_{0} is the central wavelength

of the test range, it has been determined that electromagnetic interference

between antennas in PAR is less than in the metal antenna array, and when

reducing the distance between transmitters grating with 0.5λ_{0} – 0.25λ_{0} the relative change in

value of units of the input impedance of each radiator of PAR is twice less

than for a lattice of aluminum, which allows to bring together the radiator of

PAR without a substantial increase in interference between them. From

comparison of DP of radiant systems of PAR and aluminum arrays while scanning,

it is obvious that DP of PAR are less distorted than aluminum array. The

obtained results can be used for calculations and design of plasma array of

radiators.

**PLASMA-BEAM SUPERHETERODYNE FREE ELECTRON LASER WITH H-UBITRON
PUMP WITH NON-AXIAL INJECTION OF ELECTRON BEAM**

*A. V. Lysenko, G. A. Oleksiienko*

A cubic-nonlinear theory of a plasma-beam

superheterodyne free electron laser (PBSFEL) with H-ubitron pump and non-axial

injection of electron beam has been constructed. In the investigated system the

parametric resonance interaction between a space-charge wave and cyclotron wave

is realized. The signal wave saturation levels have been determined. It has

been found that the mode using a slow cyclotron wave has the highest saturation

level among all possible operation modes of the PBSFEL with *H*-ubitron

pump. The injection angle of the beam at which the electromagnetic signal gain

is maximal has been determined. It has been shown that PBSFELs using slow

cyclotron waves are able to create a powerful coherent electromagnetic

radiation in the millimeter wavelength range.

*P. P. Maksymov*

Construction of powerful sources of

electromagnetic oscillations of microwave range is an actual task for creating

modern semiconductor devices. In this paper the creation of powerful sources of

electromagnetic oscillations based on reverse-biased abrupt *p–n*-junctions

of avalanche-generator diodes (AGD) with external signal has been theoretically

grounded. Classification of modes of avalanche-generator diodes has been

carried out. The choice of oscillations generation mode is determined by the

parameters of AGD and input signal. It is shown that coherent, multifrequency

and broadband oscillations are generated in AGD. Power and spectral

descriptions of oscillations of AGD are presented. The research results are of

interest for the developers of powerful diode generators with the required

range, power and spectral characteristics.

**THREE-CHANNEL PHASE METERS BASED ON THE AD8302
AND FIELD PROGRAMMABLE GATE ARRAYS FOR
HETERODYNE MILLIMETER WAVE INTERFEROMETER**

*A. V. Varavin, G. P. Ermak, A. S. Vasilev, A.
S. Fateev, N. Varavin, F. Zacek, J. Zajac*

The paper presents the results of research

and development of two types of phase meters for heterodyne two-wave

“unambiguous” interferometer designed to measure the plasma density in tokamak *COMPASS.* The aim of this work is the creation of a phase meter capable of measuring fast

phase changes of each probing wave, and their phase difference. Plasma is

probed by two microwave signals with different wavelengths propagating along

identical paths to meet each other. Each analyzed signal acquires a certain phase

shift φ_{1} and φ_{2}, and the “unambiguous” interferometer

determines the difference (φ_{1}–φ_{2}). The phase measurement is carried out by using

three-channel phase meters: a phase meter based on the pairs of the *AD*8302

and a phase meter based on field programmable gate arrays (*FPGA*). The

proposed circuit decisions and algorithms of signal processing allow to measure

phases in the range 0…360° in real time.

*Z. А. Maizelis*

For detecting and establishing the nature

of frequency noises in the oscillating system, it is very important to separate

different types of noises. For determination of characteristics of the

frequency noise it is necessary to study statistical properties not of actual

coordinate and its derivative, but of complex coordinate of oscillator. Its

moments do not depend on the amplitude noises that often can prevail in the

system. The growing interest in noises of frequency is related to the fact that

they determine the loss of coherence of vibrations in many systems, from the

devices based on Josephson contacts, to the nanomechanical resonators. The

knowledge of statistical characteristics of frequency noises inevitably present

in the devices of information read-out in quantum computers will allow correct

processing of the information in them. Here the influence of the telegraph

unbalanced noise of frequency on properties of electromechanical resonator is

studied. It is shown that the dependencies of the higher cumulants contain

features, which allow to separate the effects related to the presence of noise

of frequency. The results may be useful in the theory of nanomechanical

resonators, in processing the data, obtained in the radio-technical devices and

devices, based on Josephson contacts, in quantum computers, in the estimation

of precision of atomic clock.

**RECONSTRUCTION OF IMAGES WITH LARGE NON-UNIFORM
INCREMENTS**

*S. I. Melnyk, S. S. Melnyk*

In recent years, the range of tasks related

to the study of structures image elements of which are beyond the resolution of

matrix type sensors is becoming wider. Thus, the problem of their

reconstruction by applying algorithmic and information image processing

techniques is relevant. The problems emerging when observing objects whose

dimensions do not exceed several pixels of matrix of recorders have been

considered. It is shown that motion of the object relative to the matrix and

the use of multiple consecutive frames allow to improve the fidelity of shape

and true size of the object. This measurement information can be represented as

integrals along the trajectories on a three-dimensional lattice of space-time

pixels. The reconstruction of a heterogeneity function of pixels through the

use of the controlled motion of the test object and methods of computer

tomography. The possibility of determining the relative velocity of the object

in each of the frames using the blind method has been shown. The algorithm of

reconstructing images with large non-uniform increment during their arbitrary

and controlled relative motion has been elaborated.

*V. P. Ruban*

The estimation of synchronization

instability becomes actual in GPR due to the fact that this phenomenon affects

the accuracy of recording and reproducing the received signal forms and,

accordingly, the efficiency of use of digital signal processing algorithms. The

existing method for estimation of jitter of the GPR receiver using errors of

the converted signal amplitude is not universal and should be corrected for the

case of converter with incomplete charging of the storage capacitor. Simulation

of the stroboscopic conversion with instability of sampling interval for cases

of full charging (when the evaluation method gives correct results) and

incomplete charging of the storage capacitor has been done in this paper. The

relationship between the forms of probabilistic distribution of jitter and

errors of amplitude after stroboscopic conversion has been analyzed. The jitter

values originally specified in the simulation and the ones calculated

(reconstructed) by a known method also have been analyzed. According to the

simulation results, the limits of applicability of this method were determined.

It is shown that the direct application of the jitter evaluation method which

is right for the converter with a full charging gives incorrect estimates for

the one with incomplete charging of storage capacitor. Due to this, the signal

amplitude recovery procedure which allows obtaining a correct estimate of the

jitter of synchronization of GPR receivers operating in the mode of incomplete

charge storage capacitor has been suggested.