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The Effect of Antenna Arrangement on the Aliasing Artifacts in Multi-Static Millimeter Wave Imaging Systems Based on the K-Space Analysis and Signal Processing
, Ph.D. Dissertation Sharif University of Technology ; Shabany, Mahdi (Supervisor) ; Kavehvash, Zahra (Supervisor)
Abstract
Millimeter wave imaging has been used in many applications including security screening and medical imaging. Millimeter wave screening systems are considered a reliable option in the design of surveillance systems, because they feature enough penetration in dielectric materials including clothes, low health- risk and decent resolution. The first generation of such systems are based on mono-static arrays and mechanical scanning. Large mono-static arrays are challenging and expensive to implement, because they require high number of antenna elements to satisfy the Nyquist sampling rate. Moreover, the minimum sampling rate imposes limitations on design and size of antenna elements. So,...
Various coupling configurations on the performance of two-dimensional coupled oscillator arrays
, Article IET Microwaves, Antennas and Propagation ; Volume 11, Issue 3 , 2017 , Pages 426-432 ; 17518725 (ISSN) ; Banai, A ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
Coupled oscillator arrays (COAs) can be used to control the phase distribution across the aperture of an array antenna in such a manner as to affect steering of the beam without the use of phase shifters. Given the various possible planar configurations of COAs, a systematic design approach is necessary. In this study, the authors present a comprehensive comparison of various configurations of planar COAs based on their sensitivity to random errors in their free running frequencies. The parameters considered are (a) the beam pointing error of the array, (b) the locking probability, (c) the side lobe level, and (d) the beam width of the radiation pattern. These results can serve as a design...
Investigation and optimization of SDS and key parameters effect on the nickel electroless coatings properties by Taguchi method
, Article Journal of Coatings Technology Research ; Volume 7, Issue 5 , 2010 , Pages 547-555 ; 15470091 (ISSN) ; Ehteshamzadeh, M ; Ghorbani, M ; Vazifeh Mehrabani, J ; Sharif University of Technology
2010
Abstract
In this research, the influence of anionic surfactant sodium dodecyl sulfate (SDS), pH, substrate finishing, and annealing temperature on the surface morphology and hardness of the electroless nickel phosphorus (ENi-P) coatings were studied. Taguchi's experimental design method was used. Parameters selected in three levels and L9 from orthogonal robust array design were employed. Surface roughnesses of the deposits were measured using a stylus instrument. Scanning electron microscope and x-ray diffraction analysis were implemented to study surface morphologies and phase composition, respectively. Microhardness of the ENi-P deposits was measured using a microhardness tester at three trials...