Volume 63, Nº 12 (2018)

The basic principles of operation of the sensors based on molecular-electronic transducers (METs) are described. The review of investigations of physical processes into MET and their operating characteristics are considered. Modern MET manufacturing technologies and the production methods and the new applications of planar microelectronic METs are discussed. An overview of devices and systems based on the METs is given.

In this paper, a second-order, dual-band, band-pass frequency selective surface (FSS) with high selectivity is presented by cascading three-layers of periodic metallic arrays. The unit cell in both two exterior layers is composed of gridded-double square loops (G-DSLs) while the element in the middle layer is consisting of wire grid. The three layers are separated by two thin F4B-2 substrates with dielectric constant of 2.65 + 0.02i. The proposed FSS can provide multi-transmission poles and multi-transmission zeros. There are two transmission poles in each pass-band. The two pass-bands are separated by two transmission zeros. On the upper side of the second pass-band, other two transmission zeros are generated also. These transmission zeros lead to a wide out of band rejection and a fast fall off response on both sides of each pass-band. The simulation is implemented using full wave electromagnetic simulator CST Microwave Studio, the central frequencies of the two pass-bands are 12.7 and 17.4 GHz. In addition, the designed principle is described using equivalent circuit model (ECM). Furthermore, the prototype of the FSS is fabricated and measured. Both simulated and measured results demonstrated that the proposed FSS has the merits of incident angle stability from 0° to 60° for both TE and TM polarizations.

A planar two-dimensional array of TEM horns with partial metallization of the inter-horn space and a metal screen is considered. For an infinite scanning array, an approximate numerico–analytical model based on the integral equation methods is developed. The integral equations are solved by the Bubnov–Galerkin method. The propagation constants and characteristic impedances of the principal modes of such an array are found. The problem of mode propagation along the array and their radiation into free space is solved within the transmission line theory. The numerical results obtained within the approximate theory are compared with the corresponding results of the finite element method (FEM). Using the FEM, a full-wave model of a finite array is developed. The numerical experiment has shown the feasibility of matching finite scanning arrays of TEM horns with a screen in a band with a lower-to-upper frequency ratio of 1 : 10.

In this paper novel miniature ultra wide band circular mono pole antenna with penta band rejection characteristics is proposed. The antenna is fed through a Coplanar Waveguide (CPW) feed. The antenna is designed using RT/ DUROID substrate with permittivity 2.2. In the proposed antenna Concentric Rings with Splitter Bricks (CRSB) are used to achieve band notching characteristics. It will reject the existing WIMAX (Worldwide Interoperability for Microwave Access) from 3.326–3.612 GHz, C band down link frequency from 3.8–4.2 GHz, WLAN application from 5.393–5.822 GHz, X Band downlink Satellite communication application from 7.25–7.733 GHz and ITU band operations from 8.0–8.565 GHz. The Simulations of this antenna are carried out using CST microwave studio suite 2016. Antenna performance parameters like Return loss, Voltage standing wave ratio (VSWR), Radiation efficiency and Gain are evaluated. Radiation pattern of the antenna at different frequencies are observed. This antenna provides good gain and a larger band width over the frequency range 3.1–11.6 GHz.

A method for signal detection via estimation of the noise power in the spectral domain is proposed. The influence of the probability density function of the parameter estimate on the result of operation of the detector under the conditions of prior uncertainty is analyzed. Dependences of the parameter distribution in the case of its known estimate are obtained by the example of the additive Gaussian noise. The results of simulation of detector operation with and without consideration for the influence of the distribution of the parameter estimate are presented.

The Design and implementation of fractional order digital differentiators and integrators is the main objective of this paper. Identify the novel reduced s to z transforms calculated using model order reduction techniques. Thus the transforms are discretized directly using Continued Fraction Expansion (CFE).The designed differentiators and integrators are implemented on Xilinx Spartan 3E field programmable gate arrays (FPGA) and are tested using the sinusoidal, square and triangular waveforms. The practical results agree with the theoretical ones.

The work realizes the sinusoidal quadrature oscillator and biquadratic filter with the same configuration using merely two voltage differencing transconductance amplifiers (VDTAs) as active devices and one grounded resistor and two grounded capacitor as passive elements. Performing the quadrature oscillator, the realized circuit is capable of producing two quadrature voltage outputs with almost equal amplitudes, and an independent electronic control of oscillation condition and oscillation frequency. Operating in voltage-mode biquadratic filter, the circuit can simultaneously generate the bandpass and lowpass filtering functions without any matching constraints. The natural angular frequency and the quality factor of the filter are independently and electronically adjustable. The effects of the VDTA non-idealities are also investigated in detail. Simulation results with TSMC 0.25 μm CMOS technology validate both working functions of the proposed circuit.

Propagation of volume spin magnetostatic waves in meander-shaped ferromagnetic films with vertically and horizontally coupled segments is studied. Conditions under which forward and backward volume magnetostatic waves simultaneously exist in the films are determined. Micromagnetic simulation and expansion in terms of plane waves are used to calculate internal effective magnetic fields and dispersion characteristics of the waves in such structures. Spectra of coupled waves in meander-shaped vertically coupled ferromagnetic films are studied. Prospects for application of the above structures in the development of magnonic elements are analyzed.

An anomalously high photosensitivity of \({\text{Cd}}{{{\text{S}}}_{{{\text{1--}}x}}}{\text{S}}{{{\text{e}}}_{x}}\) granular films observed in the experiment is explained. It is assumed that the charge transfer mechanism based on surface states existing at the granule boundaries can be responsible for an anomalously high photocurrent-to-dark current ratio recently found in the study of the photoconductivity of \({\text{Cd}}{{{\text{S}}}_{{{\text{1--}}x}}}{\text{S}}{{{\text{e}}}_{x}}\) granular films. It has been shown that the current of charge carriers in surface states flowing through the gaps between the granules at a certain film topology can exceed by many orders of magnitude the current associated with tunneling of charge carriers between the granules.

The error exponent of the regular graph-based binary low-density parity-check (LDPC) codes under the maximum likelihood (ML) decoding algorithm in the binary symmetric channel (BSC) is analyzed. Unlike most other papers where error exponents are considered for the case when the length of LDPC codes tends to infinity (asymptotic analysis), the finite length case (finite length analysis) is considered. In this paper, a method of deriving the lower bound on the error exponent for a regular graph-based LDPC code with finite length under ML decoding is described. Also we analyze Dependences of the error exponent on various LDPC code parameters are also analyzed. The numerical results obtained for the considered lower bound are represented and analyzed at the end of the paper.