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Efficient single and bi-layer absorbers of CaTiO3 micro-cubes and polypyrrole nanotubes composites for enhanced microwave absorption in X and Ku band
, Article Ceramics International ; Volume 48, Issue 9 , 2022 , Pages 11953-11961 ; 02728842 (ISSN) ; Abdelbasset, W. K ; Elkholi, S. M ; Ismail, K. A ; Akhtar, M. N ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The present study is focused on the investigation of the absorption properties of the bi-layer absorber with different thickness and orientation approaches. Improvement in absorption exclusively depends on the various parameters as interfacial polarization, multiple reflections among layers, conduction loss, phase cancellations, and shape anisotropy, etc. By considering these parameters. Calcium titanate micro-cubes CaTiO3 (CTO) and polypyrrole nanotubes (PPy) nanocomposites were prepared and microwave absorption from single layer coaxial absorbers having M1 = CaTiO3+15 wt% polymer and M2 = CaTiO3+30 wt% polymer were determined. Different layer orientations and thicknesses of the bi-layer...
Tunable microwave absorption features in bi-layer absorber based on mesoporous CuS micro-particle with 3D hierarchical structure and nanosphere like NiCo2O4
, Article Ceramics International ; Volume 48, Issue 7 , 2022 , Pages 9146-9156 ; 02728842 (ISSN) ; Dai, F ; Mouldi, A ; Bouallegue, B ; Akhtar, M. N ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
There has been a growing demand for materials with superior absorption capabilities, such as strong absorbing capacity, thin thickness, and light weight, to solve challenges related to EM radiation pollution. While the majority of the research is focused on optimizing material compositions, component microstructure and absorber structure are also critical factors for improving microwave absorption performance. In this research, we show how the microstructure of components and absorber design may increase dissipation features. Solvothermal and hydrothermal methods were utilized for synthesizing mesoporous CuS micro-particles with a 3D hierarchical structure as a dielectric component and...
Design and Implementation of a Passive Ku band phase Shifter in 0.18µm CMOS Process
, M.Sc. Thesis Sharif University of Technology ; Medi, Ali (Supervisor)
Abstract
In this project, a “Ku” band (16.3GHz-17.3GHz) 6-bit phase shifter for realizing a phase array T/R module is designed, implemented and measured in CMOS 0.18μm technology. Design specifications for this block were: RMS phase error should be less than 2.5 degree in bandwidth, better than 12dB loss and better than 16dBm input 1dB compression point. High-pass/low-pass filter structure is used to implement this phase shifter. In order to decrease phase shift error in process and temperature corners, a new structure for one of bits was introduced. This structure is less sensitive to process and temperature corners and furthermore it conSumes less area in layout, but it has more loss variation...
Enhanced microwave absorption performance of BiFeO3 nanopowders coated with Polyindole-PANI co-polymer in ku band frequency
, Article Journal of Magnetism and Magnetic Materials ; Volume 560 , 2022 ; 03048853 (ISSN) ; Alnujaie, A ; Tan Hoi, H ; Tra Giang, H ; Niaz Akhtar, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
It's still a significant difficulty to find microwave absorbers that have outstanding microwave dissipation performance in hostile environments. Herein, the core–shell structure of polyindole-PANI co-polymer@BiFeO3 nanocomposite is successfully prepared via in-situ polymerization method. The introduction of a co-polymer shell on the surface of magnetic BiFeO3 nanoparticles considerably tuned the attenuation constant and impedance matching characteristics. The electromagnetic characteristics and microwave absorption feature of the polyindole-PANI co-polymer@BiFeO3 nanocomposites may be found to be influenced by filler loading content regulation. The sample containing 40 wt% of polyindole-PANI...
Highly reliable 10-W X/Ku-band pHEMT monolithic microwave integrated circuit power amplifier
, Article IET Microwaves, Antennas and Propagation ; Volume 10, Issue 6 , 2016 , Pages 656-663 ; 17518725 (ISSN) ; Mohammadi, E ; Medi, A ; Sharif University of Technology
Institution of Engineering and Technology
2016
Abstract
In this study, a reliable 10 W high-power amplifier (HPA) is presented along with its design procedure. Implemented on a 0.25-μm InGaAs/AlGaAs/GaAs pseudomorphic high electron mobility transistor (pHEMT) process, the designed HPA achieves power added efficiency (PAE) of more than 33% across the 7.8-12.8 GHz band. The proposed two-stage PA provides 15 dB large signal gain with an average small-signal gain of 18 dB. Peak results are achieved at 12.2 GHz with 40.8 dBm output power and 44% PAE. The reliability of the designed HPA is studied in detail along with a thorough discussion of related concerns