This paper presents a thin and wideband frequency selective surface FSS absorber. The suggested unit cell consists of a circular ring loaded with lumped resistors for improving the absorption bandwidth. The absorber has a compact unit cell size of 0.23 × 0.23 , where is the wavelength at the operating frequency of 3 GHz. The design and optimization of the reflectivity were performed using CST Microwave Studio. The influences of the design parameters, were investigated to optimize the performance of the absorber. The simulation results show reflectance of less than -10 dB across the frequencies from 2.39 GHz to 8.07 GHz (108.6% fractional bandwidth) with a thickness of . Verification of the obtained results was carried out using the HFSS software. The proposed design offers large bandwidth, polarization insensitivity, a single layer, and 4 resistors that make it as an attractive solution for various electromagnetic absorption problems.  

In this study, we present a multi-band, ultra-wideband (UWB) compact monopole patch antenna tailored for radar and wireless communication applications. The proposed antenna is capable of operating across the UWB frequency range, specifically from 4.1 to 4.7 GHz and 6.6 to 10.2 GHz. It also incorporates a tunable configuration that effectively filters out target signals from WLAN frequencies, including both 2.4 GHz and 5 GHz Wi-Fi bands. This fre-quency range encompasses the C and X bands, supporting a diverse set of applications such as satellite communications, weather radar systems, terrestrial microwave links, defense tracking, vehicle speed monitoring for law enforcement, and 5G mobile communications—a cornerstone technology for the Internet of Things (IoT). The antenna demonstrates an impedance bandwidth of 1.1 GHz (S11 < -10 dB) at the WLAN band, with 21% fractional bandwidth, and 3.5 GHz at the X-band, with 40% fractional bandwidth. Measured peak gains are 6.5 dBi for the WLAN band and 2.5 dBi for the X-band, with favourable S11 levels, omni-directional radiation patterns, and consistent gain across both bands. Experimental results confirm highly the array’s significant advancements in multi-band performance, making it suitable for communication applications. diverse wireless The optimized compact antenna design was realized by fabricating a prototype using a copper metallic structure printed on an FR4 epoxy substrate with precise dimensions of 40 mm × 28 mm × 1.6 mm. 

This paper presents a novel design of a Ka-band circularly polarized aperture-coupled microstrip antenna employing a truncated 2×2 patch array configuration for satellite and wireless applications. The uniqueness of the proposed work lies in the integration of truncated patches with strategically engineered aperture slots on a multi-dielectric substrate, enabling the excitation of two orthogonal modes with equal amplitude to achieve robust circular polarization. Unlike conventional designs, a single microstrip feed line has been utilized to efficiently couple energy to the truncated patch array through the apertures, thereby simplifying the feeding network and reducing complexity. The novelty of this antenna topology is demonstrated through its enhanced impedance bandwidth, excellent axial ratio performance, uniform surface current distribution, and improved realized gain across the Ka-band spectrum, surpassing many existing approaches. The antenna exhibits compact size, lightweight structure, and wide operational frequency coverage while maintaining optimum return loss, VSWR, and radiation characteristics. Full-wave simulations followed by fabrication and its validation confirm the design’s reliability. The innovative multi-dielectric, aperture-truncated array configuration not only ensures superior performance but also provides a novel structural approach for next-generation satellite and wireless systems.

This study explores the impact of incorporating dielectric-coated plasmonic metal nanoparticles into hybrid organic-inorganic halide perovskite solar cells to enhance solar absorbance. The results reveal that metal-dielectric core-shell nanoparticles significantly boost absorption efficiency by 1.4 to 1.7 times. The metal core enhances optical absorption through localized surface plasmon resonance, while the dielectric shell prevents exciton recombination by isolating the metal. A comparative analysis involving Au@SiO2 and Cu@SiO2 nanoparticles confirms the superior light-trapping capability of copper-based structures. Simulations indicate that absorbance improvements depend not only on the dielectric’s refractive index but also on coating thickness. High refractive index shells show more consistent performance enhancements than their low-index counterparts. Additionally, Cu@dielectric nanoparticles exhibit greater chemical and thermal stability compared to other metal cores, making them ideal for long-term applications. Their lower material cost also promotes affordability, especially in resource-limited regions. These findings provide valuable insights into optimizing plasmonic designs for improved light harvesting in perovskite solar cells. The research supports the development of efficient, stable, and cost-effective solar energy solutions, contributing to the broader adoption of renewable energy technologies.