Vol 61, No 2 (2016)

An algorithm of calculation of the directivity, energy, and polarization radiation characteristics of an arbitrarily oriented thin impedance vibrator located above a rectangular screen is developed on the basis of the asymptotic solution to the 3D problem of diffraction of the field of the electric vibrator by a perfectly conducting rectangular screen. The asymptotic expressions for the current of an impedance vibrator having the electric length 0.4 ≤2l/λ ≤ 0.6 are applied. The asymptotic solution is obtained on the basis of the method of the uniform geometric diffraction theory. The aforementioned characteristics are studied in the whole observation space in the far zone. The effects of the thickness and length of the vibrators and the effects of the distances from the screen on the resonance values of the distributed surface impedance and the corresponding radiation characteristics are shown. The resonance vibrator’s radiation characteristics that depend on the screen dimensions are analyzed. The amplitude and polarization patterns of a horizontal vibrator located above a square screen having optimal dimensions are calculated.

Design versions of the phased array antenna (PAA) of an object coordinate meter are considered. The array antenna forms the sum radiation pattern and two difference patterns ensuring measuring of the object angular coordinates. The problem of the phase-only synthesis of the PAA sum amplitude pattern with a given shape is solved under the condition of keeping the angular orientation of direction-finding nulls of difference patterns in the pattern scanning direction. Design relationships are derived and a pattern synthesis method based on numerical minimization of a nonlinear functional is described. Synthesis examples are presented.

The problem of digital wavelet filtering of noisy data is considered. The results are comparatively analyzed when the threshold function is specified in different ways for wavelet transformation coefficients. The influence of the choice of the wavelet basis on the efficiency of the noise removal is studied. It is shown that the minimum filtering error is in most cases provided when the soft variant of the threshold function introduction is introduced.

Spoofing and jamming are two kinds of significant interferences in Global Navigation Satellite System (GNSS). When they coexist in GNSS propagation environment, interference suppression becomes more difficult. Conventional power inversion (PI) algorithm can reject jamming effectively, but has different influences on repeat spoofing when the different numbers of elements are used in an antenna array. Nevertheless, repeat spoofing still has the capability of deception after being processed by the PI algorithm. In the paper, different influences have been analyzed and a blind adaptive anti-interference algorithm is proposed based on negative diagonal loading technique. The proposed method can adaptively reject spoofing and jamming simultaneously without estimating the direction-of-arrivals (DOAs) of them, and ensure that authentic satellite signal can be acquired by the GNSS receiver without other treatment of repeat spoofing. Simulation results show the effectiveness of the new method.

An equivalent circuit of a joining two-port is proposed. The two-port provides for the stability and convergence of the results of semi-natural modeling of a partitioned linear dynamical system to the results of numerical modeling of the integral original system. The functional properties of the obtained two-port are investigated. It is shown that the obtained results are coupled with the well-known results in the decomposition methods and system modeling by parts. It is supposed that the obtained two-port is one of the simplest hypostases of the Poincare–Steklov operator.

Thin solid layers that are formed upon heating of the gaseous trimethylbismuth–isopropylselenide–hydrogen system on the (0001) Al₂O₃ and singular and vicinal (100) GaAs surfaces are studied. The conditions for deposition of metal Bi and phases of Bi₄Se₃, BiSe, and topological insulator Bi₂Se₃ using the MOCVD method are determined. Pure metastable phase BiSe is obtained for the first time. Bi₂Se₃ films with a thickness of no less than 200 nm, a relatively low volume concentration of 3 ×10¹⁸ cm^–3, and a high mobility of carriers at 300 K (1000 cm² V^–1 s^–1) are fabricated.

It is shown that a more efficient use of microwave energy of a source operating into a nonstandard load is possible. As an example, a magnetron operating into a microwave-oven chamber is discussed. Calculation of a matching device with the variation in the amount of food placed in the oven chamber taken into account is presented. The improvement in matching has been experimentally validated by a physical model.

Microwave circulators based on magnetic nanocomposites made of opal matrices are mathematically simulated and experimentally studied. Mathematical models are based on the solution of the 3D diffraction problems using the projection method and the decomposition computational algorithm that employs autonomous units with magnetic nanoinclusions and virtual Floquet channels. The computational algorithm developed using the projection method with effective parameters of the magnetic nanocomposite is used to calculate the S parameters of the scattering matrix of the microwave Y circulator based on the opal-matrix magnetic nanocomposite. The S parameters (real loss, isolation between arms, and reflection coefficient) of the Y circulator are measured for several nanocomposites made of opal matrices with magnetic nanoparticles (Co_0.5Zn_0.5Fe₂O₄ and Ni_0.5Zn_0.5Fe₂O₄) and compared with the parameters of the circulator based on magnesium–manganese ferrite in a frequency interval of 14–18 GHz. The simulated results are compared with the experimental dependences.