Radioelectronics and Communications Systems

Design principles of integrated solid-state protective and switching devices at mmWave frequencies

2026-07-17T23:05:10+03:00

The paper addresses the physics of operation of limiting diodes, the main factors that determine the parameters and characteristics of protective devices, and the prospects for their development in the millimeter-wave (mmWave) range. New solutions to problems associated with the development of switching and protective semiconductor microwave devices in the mmWave range are described. The achieved results in solving these problems are confirmed by the creation of new semiconductor devices manufactured in a single technological cycle based on monolithic multi-diode structures, as well as the development of electrodynamic structures of protective devices and switches using packaged diodes, which provide high stability when the product is exposed to mechanical and climatic factors. The designs of switches containing several distributed-type diodes, due to an increase in the effective switching area, have better range characteristics and increased electrical strength (over 10 kW). A new approach to creating packaged diodes containing lumped-type semiconductor structures is proposed, enabling the development of various communication devices with a speed of 5–10 ns across all sections of the waveguide path in the mmWave range.

Phantom-guided adaptive denoising of medical images using enhanced U-Net architecture

2025-09-19T10:08:20+03:00

In this paper, we propose an approach to medical image denoising that combines a deep neural network of the U-Net type with atrous spatial pyramid pooling (ASPP) modules, coordinate layers, and adaptive modulation based on statistical noise parameters obtained from preliminary phantom analysis. This architecture qualitatively accounts for spatial noise patterns and models its intensity across different image regions, thereby enabling better preservation of small structures and contours, even in low-signal areas. To improve reconstruction quality, a combined loss function was also used, including gradient loss, structural similarity index (SSIM), and mean absolute error (MAE). Verifications on real data showed the superiority of the proposed method over state-of-the-art approaches, such as denoising convolutional neural network (DnCNN), flexible feature denoising network (FFDNet), and block-matching and 3D filtering (BM3D), both in terms of quantitative metrics (PSNR increased from 28 to 41 dB, SSIM from 0.5 to 0.97, edge preservation index (EPI) decreased from the range of 1–6.5 to a stable 1, indicating a decrease in structure errors), and in terms of visual reconstruction indicators. The results demonstrate the potential of this method for clinical application and automatic pre-enhancement of digital imaging and communications in medicine (DICOM) images.

Estimation of weather signal parameters based on eigenvectors and eigenvalues of correlation matrix of input influences

2026-07-17T23:16:37+03:00

The safety of aircraft flights largely depends on the quality of measurements of weather formation parameters using the pulsed Doppler weather radars. This paper discusses the features of estimating the width of the Doppler spectrum of velocities of optically unobservable weather formations based on the paired-pulse method. A characteristic feature of such weather phenomena is the low power of radar reflectivity. It is shown that the estimation errors depend on the power ratio of the weather formations themselves and the receiver internal noise. A method for eliminating this dependence is proposed. It is based on representing the correlation matrix of input influences in terms of its eigenvectors, dividing the matrix into signal and noise components, and subsequently reducing the noise component’s influence. The effectiveness of the proposed method is illustrated using simulation modeling results. Analytical expressions have been derived for the distribution density of the absolute and relative estimation errors of the spectrum width of Doppler velocity fluctuations within the components of weather formations.

Transmission line resonators for bandpass filters with increased selectivity

2026-07-17T23:35:15+03:00

The paper presents a synthesis of two stepped-impedance resonators (SIR) that provide band-pass filters (BPF) with increased frequency selectivity. Two antiresonant frequencies of these resonators ω_p1 and ω_p2, which are the poles of their input admittance Y_in, are located close to each other and equidistant from the working resonant frequency. These frequencies generate transmission zeros (TZ) in BPFs with parallel-type resonators near the passband, thereby increasing filter selectivity. Both resonators operate at higher resonant frequencies corresponding to 3λ/4 and 5λ/4 oscillations. This allows the use of these resonators at very high frequencies without reducing their length. The main properties of the synthesized SIRs and the features that enable the simplification of the design process for BPFs based on them are established. The prospects for using the synthesized SIRs in coaxial filter designs are noted. Examples of calculations and frequency responses of SPFs with synthesized resonators and high-frequency selectivity are presented.