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Theoretical analysis of RF pulse termination in nonlinear transmission lines
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 66, Issue 11 , 2018 , Pages 4757-4764 ; 00189480 (ISSN) ; Hashemi, S. M. A ; Farzaneh, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Nonlinear transmission lines (NLTLs) are passive networks with the capability of modulating baseband pulses. These networks are used for generating RF pulses at high-power levels. NLTLs have a unique performance in high-power RF pulse generation among all the generators based on the solid-state technology. A high-power rectangular pulse is injected to the line, gradually evolved into an oscillatory pulse while propagating through the network, and finally, in the form of a high-power RF pulse, is delivered to the load. Properly terminating an NLTL, in order to transfer the maximum available RF power to the load, is an important problem. In this paper, an accurate analysis is presented, which...
Performance analysis of an optical beam-forming network with custom microwave CAD tools
, Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010, Isfahan ; 2010 , Pages 100-104 ; 9781424467600 (ISBN) ; Akbari, M ; Sharif University of Technology
Abstract
Next generation wideband and ultra-wideband radar antenna arrays need efficient true-time delay networks for array control. Optical beam-forming networks have been considered as a promising solution in such arrays. Performance analysis of optical beam-formers is thus quiet necessary. In this paper signal to noise ratio and dynamic range of simple optical beam-forming structures are investigated with a custom microwave CAD tool. Two structures with optical and RF power combining methods are discussed. With the proposed devices' parameters, the optical combining method shows better performance for low and moderate optical powers
Study of surface plasmon resonance of Cu@Cu2O core-shell nanoparticles by Mie theory
, Article Journal of Physics D: Applied Physics ; Volume 42, Issue 1 , 2009 ; 00223727 (ISSN) ; Vesaghi, M. A ; Shafiekhani, A ; Sharif University of Technology
2009
Abstract
Cu@Cu2O core-shell nanoparticles on a-C : H thin films are prepared by co-deposition of RF-sputtering and RF-PECVD. Samples with different copper concentrations are grown. The copper content of films increases with reduction in initial pressure and rises with increasing RF power. When the Cu/C ratio reaches 0.5, the surface plasmon resonance (SPR) peak that is a signature of the formation of Cu nanoparticles appears in visible spectra of these films. X-ray photoelectron spectroscopy (XPS) characterization indicates that the surface of the copper nanoparticles oxidizes when they are exposed to air. The results are indicative that the shell of the nanoparticle is mainly the Cu 2O phase that is...