arXiv subjects

Mahyar Mehri Pashaki

Publications and source records attributed to Mahyar Mehri Pashaki.

3 recordsLinked to original sources

arXiv2026

Circuit-Based Dispersion Analysis of Periodic Cross-Shaped Unit Cells with Dirac Characteristics

In this paper, the dispersion behavior of periodic cross-shaped unit cells is investigated with emphasis on Dirac-type dispersion using an equivalent circuit modeling approach. Two unit-cell geometries, including a simple cross structure and a modified configuration with a central patch, are analyzed using full-wave eigenmode simulations and scattering-parameter-based dispersion extraction. An equivalent circuit model is developed to capture the dominant coupling mechanisms and accurately reproduce the dispersion characteristics near the $Γ$-point. The results demonstrate that the proposed circuit model exhibits good agreement with full-wave simulations and provides a physically intuitive framework for analyzing stopband behavior and mode degeneracy. Furthermore, the limitations of S-parameter-based dispersion extraction in the presence of low-Q radiative modes are highlighted.

eess.SY↗

arXiv2025

A Corrugated All-Metal Vivaldi Antenna for 5G Phased Array Applications

In this paper, a corrugated Vivaldi phased array antenna in the 28 GHz frequency band is proposed for 5G communication applications. The presented configuration features an all-metal antipodal antenna structure with a broad bandwidth ranging from 26 to 30 GHz and beam steering capabilities from -30 to +30 degrees. The proposed antenna consists of a 4x4 array configuration, where each element has dimensions of 6.46x6.46x14.25 mm, resulting in an overall antenna structure with dimensions of 25.84x25.84x14.25 mm. The corrugation method is applied to minimize surface currents, resulting in a reduction in interelement mutual couplings. Therefore, the return loss in the array structure for central elements is decreased, and the antenna gain and radiation efficiency are improved. Moreover, the improved radiation efficiency allows for higher power transmission and reception from an antenna, resulting in potentially higher data rates and better performance.

eess.SP↗

arXiv2025

Confocal Ellipsoidal Reflectors with Phased Array Vivaldi Antenna Source for Imaging Systems

In this paper, an on-axis dual-reflector confocal ellipsoidal structure is presented for near-field imaging systems. In the proposed structure, the backscattered electromagnetic wave problem, known as the blockage effect, is reduced considerably using an elaborate design of the sub-reflector and precise alignment of the reflectors. The proposed geometry is analyzed, followed by a design example for the stand-off distance of 2 m. The blockage reduction characteristic is verified using ray-tracing simulation. Next, the scanning performance of the structure is investigated utilizing a Vivaldi phased array antenna as the source designed at the central frequency of 28 GHz. The full-wave simulations proved a field-of-view (FoV) of approximately 40 cm. Furthermore, tuning the proposed reflectors configuration standoff distance is examined with a point source. The ray-tracing simulations showed that stand-off distance can be easily changed up to tens of centimeters with just a few centimeters of source point lateral displacement.

physics.optics↗