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This article presents a compact ultra-wideband (UWB) circular monopole antenna with a frequency-selective surface (FSS) for gain enhancement. The proposed antenna has a circular patch with circular cuts at the edges and is excited by a microstrip feed. The bottom plane is truncated and further modified by two triangular cuts at the sides and one rectangular cut in the middle to improve the radiation characteristics of the UWB antenna. The antenna is designed on an FR-4 substrate with a thickness of 1.6 mm, a relative permittivity of 4.3, and planner dimensions of 30 mm × 30 mm. To improve the proposed antenna's gain, an FSS is designed that consists of periodic unit cells of metal printed on the upper layer of an FR-4 substrate with dimensions of 0.11λ × 0.11λ at the lowest operating frequency of 3.3 GHz. The FSS shows a very low transmission coefficient and linearly reducing reflection phase with increasing frequency over a frequency range of 3.3-10.8 GHz. The gain of the proposed antenna is increased from 3 dB to 8.1 dB at 9 GHz by placing the antenna on the FSS. Moreover, the prototype of the proposed antenna is fabricated, and the experimental results are measured, which show close agreements with simulated results. The FSS-based antenna has directional radiation patterns, making it a potential candidate for groundpenetrating radar and UWB applications. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite solar cells (PSCs) are most promising in yielding stabilized power conversion efficiencies (PCE) as compared to their hybrid organic–inorganic counterparts. However, all‐inorganic PSCs have suffered from low efficiency due to significant charge carrier recombination within perovskite active layer (PAL) bulk and at the carrier selective interfaces (CSI). Boosting the PCE through the remedy to both issues seems to be the only Achilles‐Heal on their way to commercialization. Here, a synergistic approach of liquid‐exfoliated molybdenum disulfide (MoS2) at the PAL (CsPbIBr2)/hole transport layer (NiO) interface to enhance the perovskite grain growth and stabilize the hole transport layer (HTL)/PAL interface against the carrier recombination within the PAL bulk and at the interface is reported. The in‐plane coupling between MoS2 crystal lattice and CsPbIBr2 is strongly revealed through transmission electron microscopy (TEM) results, which favored the van der Waals epitaxial growth of CsPbIBr2 PAL toward the larger crystalline grain sizes, preferential growth along (110), i.e., normal to MoS2, and low trap‐density. Therefore, the PCE of organic‐free CsPbIBr2 PSC is increased to as high as 10.98% under 1‐sun illumination, which is 48% higher than the pristine device (7.38%), which concludes that this strategy can be integrated to other analogous perovskite compositions. [ABSTRACT FROM AUTHOR]

This paper presents a broad-band and broad-angle anisotropic reflective polarization converting metasurface (PCMS) for C- and X-band applications, which is composed of square split ring resonators. Such PCMS can be used in a wide range of applications such as satellite antennas, navigation systems, and biomedical devices, to name but a few. The performance of the presented PCMS is analyzed theoretically, numerically, and experimentally. The results at normal and oblique incidences demonstrate that the PCMS achieves broad-band linear polarization (LP) transformation within an operating bandwidth of 5.3 GHz (5.3–10.6 GHz), covering the C-band and a portion of the X-band. The broad-band performance of the PCMS sustains from 0 ∘ to 60 ∘ . Moreover, the PCMS achieves polarization conversion for circularly polarized (CP) waves in the same bands. The polarization conversion ratio is more than 90 % for both LP and CP incident waves. [ABSTRACT FROM AUTHOR]

Summary: A dual broadband cross‐polarization‐conversion (CPC) metasurface is designed, simulated, fabricated and results are experimentally verified. The designed patch of metasurface unit cell is composed of a triangular loop connected with two arcs at both ends. The metasurface is made of 44 × 44 unit cells arranged periodically on 1.6‐mm‐thick FR4 dielectric substrate, backed by a metallic copper sheet as a reflector surface on the back side of the dielectric substrate. The surface achieves CPC in two bands (7–8.5 GHz) and (13–19 GHz), in the microwave regime. The simulation results show that the polarization conversion ratio (PCR) is almost 90% for both x polarized (TM) and y polarized (TE) electromagnetic (EM) waves. The proposed metasurface is fabricated on 308 × 308 mm2 FR4 substrate plane. The simulated results are validated and are found in close covenant with the measured results. [ABSTRACT FROM AUTHOR]

A wideband polarization converting metasurface (MS) is designed, simulated and measured. The proposed design achieves cross polarization conversion from 10.5 to 16.2 GHz. The MS exhibit the property of polarization insensitivity against variation in the incidence angle (0°‐60°) of electromagnetic waves. The unit cell of the MS is imprinted on dielectric substrate supported by a metal ground plane. The MS transform linearly polarized electromagnetic waves to their orthogonal polarization state, that is, x/y‐polarized waves and vice versa in the 10.5 to 16.2 GHz band. To validate the simulated results, the surface is fabricated and tested. A great similarity is found in the simulated and experimental. [ABSTRACT FROM AUTHOR]