Vol 63, No 11 (2018)

The paper presents a technique for calculating the input impedance of a microstrip radiator placed on a substrate of a chiral metamaterial. A singular integral equation with the Cauchy singularity with respect to the unknown current density distribution on the radiator surface is derived. Dependences of the input impedance on the radiator length for different types of chiral substrates are calculated.

Glucose, sucrose and fructose are typical organic compounds having carbon-hydrogen-oxygen atoms. Their sensing is important in many bio-medical applications. In this paper we present a 2D material-based fiber optic surface plasmon resonance sensor for refractive index sensing of some typical organic compounds. 2D material graphene in combination with active metal gold is used in the sensing region. Fiber core is covered with gold and graphene layer. The sensor is simulated using COMSOL Multiphysics simulation software. To measure the sensing performance of sensor we see the effect of two physical parameters of the sensor, thickness of the Au-metal and graphene layer on the sensing performance. The use of graphene layer enhances the sensitivity of SPR sensor. The angular interrogation method of SPR excitation is used for sensor simulation in COMSOL Multiphysics.

A theory of an integral equation of electromagnetic wave diffraction by a segment of an impedance circular cylinder is developed. The existence and uniqueness theorems are proved. Examples of calculations are presented.

A new method for generation of the output signal of a frequency synthesizer of quantum frequency standards is considered. It is demonstrated that this method provides an opportunity to enhance spectral characteristics of the output signal, expand the range of output frequencies, and reduce the tuning step of the output frequency. A considerable (more than 10%) improvement in the frequency stability of a cesium-133 quantum standard and a 2.4-fold improvement in its temperature coefficient of frequency are reported.

The mitigation of interference is an ubiquitous problem in wireless communication systems for which a number of signal processing techniques have been developed. This problem is made more critical in the presence of an increased numbers of interfering cells, interfering users and antennas, as it is the case in massive MIMO systems. As a consequence, the conventional methods see their performance degrades. In this paper, we propose to incorporate Oblique Projection (OP) with conventional ZF beamforming in the downlink of a massive MIMO communication system and investigate the achievable data rate at the reception. Resulting beamformer uses oblique projection spaces to separate the received signal into two subspaces: the one pertaining to the desired user signal and the other to interference signals, thus achieving a high degree of interference suppression. It is shown that the OP beamforming performs better than Maximum Ratio Transmitting (MRT) and the transmit MMSE beamforming counterparts.

Functioning of an access monitoring and control system is experimentally studied in the presence of electrostatic discharges. Several types of malfunctions of the functional units of the system related to the effect of noise of electrostatic discharge are revealed. Mathematical models are proposed for evaluation of electromagnetic noise in communication lines of the access monitoring and control system in the presence of electrostatic discharge. A few methods for an increase in the noise immunity of the access monitoring and control system in the presence of electrostatic discharge are proposed and analyzed.

Data on applications of polycrystalline diamonds obtained with the aid of chemical vapor deposition in high-power optics and electronics are presented. Specific features of diamond optics of СО₂ lasers, X‑ray mirrors, and heat sinks for high-power electronics are considered.