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Adaptive spatial resolution in fast, efficient, and stable analysis of metallic lamellar gratings at microwave frequencies
, Article IEEE Transactions on Antennas and Propagation ; Volume 57, Issue 4 PART 2 , 2009 , Pages 1115-1121 ; 0018926X (ISSN) ; Mehrany, K ; Sharif University of Technology
2009
Abstract
The technique of adaptive spatial resolution is for the first time applied in fast and efficient Fourier-based analysis of metallic lamellar gratings at microwave frequencies. Inasmuch as the ultrahigh-contrast permittivity profile of these structures is likely to incur numerical instabilities, the continuity condition is heedfully imposed on the transverse electromagnetic fields and an elegant, unconditionally stable matrix-based strategy is proposed to rigorously analyze the microwave transmission of these structures. © 2009 IEEE
Parallel-plates-based dirac leaky wave antennas
, Article IET Microwaves, Antennas and Propagation ; Volume 15, Issue 15 , 2021 , Pages 1877-1890 ; 17518725 (ISSN) ; Memarian, M ; Ahmadian, M ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
In this work, the authors experimentally show Dirac Leaky Wave Antennas (DLWAs) at upper microwave frequencies. For the first time, DLWAs are implemented using simple Parallel plate waveguide (PPW) technology, while yielding desirable radiation features and continuous beam scanning through broadside, as well as extremely low profile, with significant ease of fabrication, making them well suited for Ku band applications such as satellite communication, radar and emerging fifth-generation (5G). A planar Dirac photonic crystal in PPW is shown with a closed bandgap and linear dispersion around broadside. In this work, 1D and 2D PPDLWAs are designed that provide scannable fan and pencil beams,...
Imaging Through a Scattering Medium Using Microwave Frequency
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
Radio waves can penetrate through walls and various scattering environments, allowing us to communicate with mobile phones within buildings or use wireless waves to transfer data from one room to another despite physical obstacles. Radio signals, especially at lower frequencies, are highly effective in traversing such environments. However, the ability to penetrate walls does not imply the ability to "see through" them. In this thesis, we focus on examining the development and improvement of imaging techniques in the presence of walls. The aim is to present the concept of imaging through walls in a comprehensible manner for researchers and enthusiasts, facilitating the development and...
Structural and magnetic evaluations of rare-earths (Tb, Pr, Ce, Gd, Y)-doped spinel ferrites for high frequency and switching applications
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 6 , 2021 , Pages 7692-7703 ; 09574522 (ISSN) ; Akhtar, M. N ; Baqir, M. A ; Ahmad, A ; Khallidoon, M. U ; Farhan, M ; Khan, M. A ; Sharif University of Technology
Springer
2021
Abstract
NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and...
Structural and magnetic evaluations of rare-earths (Tb, Pr, Ce, Gd, Y)-doped spinel ferrites for high frequency and switching applications
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 6 , 2021 , Pages 7692-7703 ; 09574522 (ISSN) ; Akhtar, M. N ; Baqir, M. A ; Ahmad, A ; Khallidoon, M. U ; Farhan, M ; Khan, M. A ; Sharif University of Technology
Springer
2021
Abstract
NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and...
An ultra-broadband direct demodulator for microwave FM receivers
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 59, Issue 8 , August , 2011 , Pages 2131-2139 ; 00189480 (ISSN) ; Banai, A ; Sharif University of Technology
2011
Abstract
A new broadband frequency discriminator is introduced for demodulating the frequency modulated signals in the microwave frequency range. Direct demodulation with no need for tuning the center frequency of the resonance circuits is the most important advantage of the proposed technique. This technique uses the in-phase/quadrature demodulation, in some manner, without using any additional local oscillator for down conversion. Simulation of the proposed demodulator has been done with Advanced Design System software to evaluate and predict the system behavior. A setup based on the proposed method was designed and implemented in order to verify the accuracy of the theory. We tested the proposed...