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Summary: This paper reports the development of a reflectarray (RA) antenna using overlapping tri‐resonance phase distribution to produce enhanced bandwidth performance in X/Ku band frequencies. The RA with square aperture (24 cm) operating from 11 to 15.8 GHz is constructed using unit cells with concentric Malta cross and square ring developed on Diclad substrate isolated from the ground through a 2.5‐mm air layer. Variation in the concentric element's size along with the length of the delay line connected to the square ring offers a 518° phase range. The distribution of the 529 RA elements is done using the phase variations observed at 12, 13, and 14 GHz. The optimized design of the proposed antenna offers a simulated peak gain of 27.43 dBi at 12 GHz and a 1‐dB gain bandwidth of 38%. The experimental validation of the fabricated prototype exhibits a peak gain of 27.4 dBi at 12 GHz with a sidelobe level (SLL), and cross‐polarization level less than −15.6 dB, and −28 dB respectively, and a 1‐dB gain bandwidth of 37%. The enhanced performance characteristics of the proposed X/Ku wideband reflectarray antenna befit the uplink and downlink operations of fixed satellite services (FSS). [ABSTRACT FROM AUTHOR]

Since its discovery in 1839, research on the synthesis and application of perovskite materials has multiplied largely due to their suitability to be used in the fields of nanotechnology, chemistry and material science. Appropriate changes in composition or addition of other elements or blending with polymers may result in new hybrid and/or composite perovskite materials that will be applied in advanced fields. In this review, we have recapitulated the recent progress on perovskite nanomaterial in solar cell, battery, fuel cell and supercapacitor applications, and the prominence properties of perovskite materials, such as excellent electronic, physical, chemical and optical properties. We discussed in detail the synthesis and results of various perovskite hybrid nanomaterials published elsewhere. We have also discussed the results of various studies on these low dimensional composite nanomaterials in broad sectors such as electronics/optoelectronics, batteries, supercapacitors, solar cells and electrochemical sensors.

We have developed conductive, lightweight, and porous composite of polyvinylidene difluoride by blending with synthesized conjugated terpolymer and graphene for conductive polymer composite applications. The new conjugated terpolymer designated as PEPy-TP is synthesized from 3,4-ethylenedioxythiophene, 1-pyrenecarboxzaldehyde, and heptaldehyde through friedel craft reaction. The synthesized terpolymer PEPy-TP have been blended with polyvinylidene difluoride and graphene nanosheets to form porous composite and has been characterized using XRD, TGA, TG-DSC, DTA, DTG, SEM, EDX, and Dielectric spectroscopy. The porous composite is comprised of varying weight percentages of (1, 3, and 5%) of GNS and 10 wt% PEPy-TP in PVDF. The thermal studies on the porous composites indicated that the decomposition occurred at a temperature around 270 and 470 °C corresponds to the PEPy-TP and PVDF/PEPy-TP/GNS (1, 3, and 5%), respectively. The EDX spectrum of neat PEPy-TP polymer and their porous composites of PVDF/PEPy-TP/GNS (1, 3, and 5%) result clearly shows the presence of all elements, such as C, O, S, and F with an atomic weight percentage also. The PVDF/PEPy-TP/5% GNS porous composites having a tremendous electrical conductivity and the dielectric constant value is 56 at 1 MHz and their conductivity of this polymer porous composites value is determined to be 4.9 × 10−6 S/cm at 100 kHz, respectively. [ABSTRACT FROM AUTHOR]

The design, fabrication, and experimental validation of wideband reflectarray with concentric coupled half‐square rings operating at 26.5 GHz for 5G communication is presented in this paper. The proposed unit cell has a simple square patch enclosed within the coupled half‐square rings. The varying delay line length attached to the outer ring provides a phase variation of 420°. A center‐fed reflectarray antenna constructed with circular geometry (12.6 diameters) using 413 elements offers a measured gain of 27.1 dBi and 51.25% of aperture efficiency at its center frequency. The measured 3‐ and 1‐dB gain bandwidth of 45% and 28.6% along with a side lobe level (SLL) of −17.6 dB are achieved. The measured cross‐polarization level is less than −28 dB. Thus, the proposed wideband reflectarray has evolved into a provocative candidate for applications like base station antennas in earth exploration satellites, mobile base station satellites, and radio astronomy satellites. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of Ag/Au-MnO2 nanoparticles dispersed PVDF nanocomposites having high dielectric properties. The Ag/Au-MnO2 nanoparticles are synthesized by hydrothermal method, and were characterized by XRD, SEM and EDAX spectroscopic techniques. The prepared nanocomposites of Ag-MnO2 nanoparticles and Au-MnO2 nanoparticles dispersed PVDF are characterized using XRD, SEM, TGA, DTA and Electrical properties. The Ag/Au-MnO2 incorporated PVDF nanocomposite shows high dielectric constant, electrical conductivity, and reduction in resistivity when compared to neat PVDF. The high dielectric constant was observed for 3%Ag/MnO2 dispersed PVDF with a value of 3.5 × 10−4 and 2% Au/MnO2 dispersed PVDF showed 1.0 × 10−9 at 1 MHz. [ABSTRACT FROM AUTHOR]

Contemplating the advancements in communication technology, the analysis of the features of reflectarray, transmitarray, and transmit‐reflectarray becomes essential for future adaptability. This article presents a thorough review of such high‐gain antennas, presenting some of the most relevant solutions published by the scientific society in the field of antennas and wave propagation. Several examples of unit cells for array implementation and complete array designs discussed in various literatures are analyzed. The analysis is focused in identifying the unit cell layouts, such as those developed using microstrip patches, frequency selective surfaces, or metamaterials. The analysis is extended to the ways of improving bandwidth, for example, true time delay elements, phase delay lines, meander lines, and so on, and the various methods used to enable reconfiguration, for example, p‐i‐n diodes, varactor diodes, or microelectromechanical systems. In addition, some antennas, which produce bidirectional beams simultaneously, are also discussed. Finally, all the models are compared against each other in order to highlight their benefits and limitations, summarizing their main characteristics, such as the frequency of operation, bandwidth, phase range, gain, aperture efficiency, sidelobe levels, cross polarization levels, and maximum beam‐steering range. [ABSTRACT FROM AUTHOR]