Radioelectronics and Communications Systems

Varactor controlled X-band passive RIS optimization

Hlib Zadorozhnyi, Finn-Niclas Stapelfeldt, Dmytro Vasylenko, Vadim Issakov — Mon, 27 Nov 2023 00:00:00 +0200

Reconfigurable intelligent surface (RIS) is one of the possible solutions to overcome challenges that bring up the 6G communication networks. Unit cell design for RIS is similar in many aspects to the design of artificial magnetic conductors (AMC) because both have a common nature of changing the phase of the reflected wave. However, RIS is aimed at controlling the angle of reflection to maintain requirements for the radiation pattern similar to phased antenna arrays such as low side lobes and beamwidth. The paper reviews the criteria for optimizing RIS: unit cell dimensions, phase span, frequency bandwidth, and loss. An optimization algorithm is proposed for the proper accounting of RIS optimization criteria. A new X-band unit cell is designed using the proposed optimization algorithm.

Diffused oscillation spectra in dielectric materials

Yuriy Poplavko, Dmytro Tatarchuk, Yuriy Didenko, Dmytro Chypehin — Mon, 27 Nov 2023 00:00:00 +0200

Dielectric spectroscopy is widely used in research on electronic materials. When processing experimental data, relaxation models are often used to obtain the parameters of the researched material. However, we should prefer the oscillator methods to study composite materials with resonance components, crystals, and polycrystals, whose structure is multi-domain or characterized by high disharmony. In this paper, we consider a dielectric dispersive oscillator model in detail. Primary attention is paid to the case of an oscillator with very high attenuation. It is determined that the main feature of resonance dispersion is the presence of a minimum in the frequency dependence of a real part of the permittivity.

5G cellular network coverage with KUD-based SC deployment

Mon, 27 Nov 2023 00:00:00 +0200

This work analyzes the effect of positioning small cells (SC) on an existing heterogeneously scattered macro cellular (MC) network. The impact of SC deployment based on the planned blend of K-means and user density (KUD) algorithms on an existing MC network is explored. With an application of the Cox process, heterogeneous and uneven distributions of 50 and 100 users were generated for investigation. The simulated outcomes and plotted graphs illustrate a gradual increment in the average user throughput, sum rate, and energy efficiency with the overlaying of 8 SCs using the proposed KUD algorithm in an existing MC.

Dual-polarization Yagi antenna for meter wavelength range

Mon, 27 Nov 2023 00:00:00 +0200

The article presents the results of the development and experimental study that characterize the prototype of dual-polarization Yagi-Uda antenna for the meter wavelength range, which receives/transmits and selects electromagnetic energy in two orthogonal planes of linear polarization without additional mechanical (electromechanical) intervention. The antenna is designed to be part of the command radio line equipment for receiving and transmitting telemetry information in digital format with high-speed flying objects that can rotate around the longitudinal axis and change their polarization during flight.

Thermostable sensor-converter of optical radiation with frequency output based on single-junction transistor oscillator

I. M. Vikulin, Oleksandr Nazarenko — Mon, 27 Nov 2023 00:00:00 +0200

The paper considers the effect of temperature on an optical radiation sensor based on an oscillator with single-junction (SJT) and field-effect (FET) transistors, the output signal of which is the frequency proportional to the radiation intensity. Under the impact of temperature, the parameters of transistors change, causing frequency instability in the temperature. For thermal stabilization of the output signal, a second FET2 with the opposite sign of the current dependence on temperature and adjustable thermal sensitivity is connected in parallel to the first FET1. As a result, the temperature effects of all three transistors on the generation frequency are mutually compensated, and the output frequency is thermally stabilized.