Showing 9 results for Mirhosseini
S. H Mirhosseini, A. Ayatollahi,
Volume 6, Issue 4 (December 2010)
Abstract
Abstract- A novel low-voltage two-stage operational amplifier employing resistive biasing is presented. This amplifier implements neutralization and correction common mode stability in second stage while employs capacitive dc level shifter and coupling between two stages. The structure reduces the power consumption and increases output voltage swing. The compensation is performed by simple miller method. For each stage an independent common-mode feedback circuits has been used. Simulation results show that power consumption is 2.1 mW at 1V supply. The dc gain of the amplifier is about 70 dB while its output swing is as high as around 1.2V.
M. Khalaj-Amirhosseini, M. Moghavvemi, A. Attaran,
Volume 7, Issue 4 (December 2011)
Abstract
This paper proposes an idea to modify the conventional Wilkinson power dividers to have physically spaced output ports. The well-known internal resistor of Wilkinson power divider is now connected to output ports by two additional transmission lines to create a triangular shape power divider. Several modified power dividers are designed at frequency of 1.0 GHz and one of them is fabricated and measured. The measured results of the fabricated diplexer have very good agreement with the theoretical results.
M. Khalaj Amirhosseini,
Volume 9, Issue 3 (September 2013)
Abstract
In this article, three new green's functions are presented for a narrow strip line (not a thin wire) inside or on a homogeneous dielectric, supposing quasi-TEM dominant mode. These functions have no singularity in contrast to so far presented ones, so that they can be used easily to determine the capacitance matrix of multi-layer and single-layer homogeneous coupled microstrip lines. To obtain the green’s functions, the Laplace’s equation is solved analytically in Fourier integral or Fourier series expressions, taking into account the boundary conditions including the narrow strip. The validity and accuracy of three presented green’s functions are verified by some examples.
H. Rahmanian, S. H Sedighy, M. Khalaj Amirhosseini,
Volume 11, Issue 1 (March 2015)
Abstract
A method for design and implementation of a compact via-less Composite
Right/Left-Handed Transmission Line (CRLH TL) is presented. By introducing a new
circuit model, the CRLH transmission line behavior is studied versus the parameters
variations to achieve the desired characteristic impedance and electrical length. Then a
compact quarter wavelength CRLH transmission line with 70 Ω characteristic impedance is
designed as an example. Finally a very compact four way Wilkinson power divider and a
rat-race coupler are designed and fabricated by using this type of CRLH TL which exhibit
about 75% and 80% compactness, respectively.
Prof. M Khalaj-Amirhosseini,
Volume 11, Issue 4 (December 2015)
Abstract
The ideal analysis of planar diodes in Temperature Limited Region is presented. Two types of relations are obtained for electric potential and electric field distributions one accurate but implicit and the other almost accurate but explicit.
M. Khalaj-Amirhosseini, M. Nadi-Abiz,
Volume 16, Issue 2 (June 2020)
Abstract
Phase Perturbation Method (PPM) is introduced as a new phase-only synthesis method to design reflectarray antennas so as their sidelobe level is reduced. In this method, only the reflected phase of conventional unit cells are perturbed from their required values. To this end, two approaches namely the conventional Optimization method and newly introduced Phase to Amplitude Approximation (PAA) method are proposed. Finally, a reflectarray antenna is designed and fabricated to have a low sidelobe level and its performance is investigated.
M. Khalaj-Amirhosseini,
Volume 17, Issue 1 (March 2021)
Abstract
Linear and planar antenna arrays are synthesized to have maximum directivity for a specified sidelobe level. The directivity is maximized subject to a given SLL. The beamwidth and the zeros of array factor are studied as well as the directivity. Maximum directivity-arrays are compared through some examples with super-directive, uniform, Dolph-Chebyshev and Riblet-Chebychev arrays to find a complete definition of optimum arrays. Also, the optimum value of n-bar is intuitively found for Taylor arrays.
M. Khalaj-Amirhosseini,
Volume 17, Issue 2 (June 2021)
Abstract
Nonuniform Phased Sampling method is proposed to phase-only synthesize the power pattern of both linear and planar antenna arrays. This method modifies the conventional sampling method which is used for amplitude-phase synthesis. This method is based on assigning suitable phases to the sampling points of radiation pattern in order to reach desired amplitude of currents. Some examples are given to verify the effectiveness of the proposed method for both pencil-beam and shaped beam patterns.
M. Khalaj-Amirhosseini,
Volume 18, Issue 3 (September 2022)
Abstract
Linear antenna arrays are synthesized to have maximum directivity for a specified beamwidth. The directivity is maximized subject to a given beamwidth such as null to null or half power one. The excitation currents are obtained using a matrix equation obtained from the Lagrange multiplier method. The performance of the proposed method is studied by means of some examples. The synthesized arrays have the pre-specified beamwhidths and their directivity is close to the number of elements.
