Showing 7 results for Kashani
F. Hojjat Kashani, A. A. Lotfi Neyestanak, K. Barkeshli,
Volume 1, Issue 2 (April 2005)
Abstract
A modified circular patch antenna design has been proposed in this paper, the
bandwidth of this antenna is optimized using the genetic algorithm (GA) based on fuzzy
decision-making. This design is simulated with HP HFSS Program that based on finite element
method. This method is employed for analysis at the frequency band of 1.4 GHz- 2.6 GHz. It
gives good impedance bandwidth of the order of 15.5% at the frequency band of 1.67GHz-
1.95GHz and 10.6% at 2.23GHz- 2.48GHz. It means that impedance bandwidth increases above
4.9% than the impedance bandwidth of ordinary circular patch antennas and band width rise
from 1.78GHz- 1.98GHz (10.6%) to 1.67GHz- 1.95GHz (15.5%) and 2.23GHz- 2.48GHz
(10.6%). The antenna fabricated with two slots on circular patch antenna. The measured results
of the optimized antenna validate a high compatibility between the simulation and the
measurements.
F. Hojjat Kashani, Salimnejad,
Volume 2, Issue 2 (April 2006)
Abstract
The development of numerical techniques now permits us to analyze complex
structures such as dielectric resonator filters and planar passive elements for coplanar
monolithic microwave integrated circuits. In this paper, we describe a novel method for
designing dielectric resonator filters. Then a Chebychev band pass filter is designed by
coaxially placing high-Q TM01Q dielectric resonators in a cutoff circular waveguide. In the
present work, discussions are made regarding high-Q resonators and inter-resonator
coupling.
A. Hajiaboli, Hodjat-Kashani, M. Omidi,
Volume 3, Issue 3 (October 2007)
Abstract
This paper presents a novel implementation of an electromagnetically coupled
patch antenna using air gap filled substrates to achieve the maximum bandwidth. We also
propose an efficient modeling technique using the FDTD method which can substantially
reduce the simulation cost for modeling the structure. The simulated results have been
compared with measurement to show the broadband behavior of the antenna and the
accuracy of the proposed modeling technique. The measured results show a 16% of
VSWR<2 bandwidth which is considerable considering the inherent bandwidth limitations
in microstrip antenna technology.
B. Ghafary, F.d. Kashani, E. Kazemian,
Volume 9, Issue 1 (March 2013)
Abstract
The effects of aberration on the Bit-Error-Rate (BER) and reliability of free- space optical (FSO) communication links are investigated. Based on aberrated divergent rectangular partially coherent flat-topped beam formula on the receiver plane and considering the atmosphere losses due to absorption and scattering, numerical values for Power In Bucket (PIB), Signal to Noise Ratio (SNR) and BER are calculated. Using above mentioned values, the effects of source parameters on link reliability is described. The results are illustrated by graphs obtained by calculation and simulation.
F Dabbagh Kashani, M R Hedayati Rad, E Kazemian,
Volume 9, Issue 4 (December 2013)
Abstract
Study of the beam propagation behavior through oceanic media is a challenging subject. In this paper, based on generalized Collins integral, the mean irradiance profile of Gaussian laser beam propagation through ocean is investigated. Power In Special Bucket (PIB) is calculated. Using analytical expressions and calculating seawater transmission, the effects of absorption and scattering on beam propagation are studied. Based on these formulae, propagation in ocean and atmosphere are compared. The effects of some optical and environmental specifications, such as divergence angle and chlorophyll concentration in seawater on beam propagation by using mean irradiance, PIB and analytical formula of oceanic transmission are studied. The calculated results are shown graphically.
F. Dabbagh Kashani, M. R. Hedayati Rad, E. Kazemian, A. Kahrizi, M. R. Mahzoun,
Volume 10, Issue 1 (March 2014)
Abstract
In this paper, we investigate the effects of auto-tracking subsystem together with different beam divergences on SNR, BER and stability of FSO communication links. For this purpose we compute the values of power, SNR and BER on receiver, based on analytic formula of Gaussian beam on receiver plane. In this computation the atmospheric effects including absorption, scattering and turbulence are considered. Using mentioned computed values, the laser link stability and its reliability in presence of auto-tracking subsystems are evaluated. The results of simulation and computation are shown with the help of figures and tables.
A. Halvaei Niasar, E. Boloor Kashani,
Volume 10, Issue 3 (September 2014)
Abstract
In this paper, one-cycle control (OCC), as a constant-frequency PWM control strategy for current control of a six-switch brushless dc (BLDC) motor drive is investigated. Developed current regulator is a unified controller and PWM modulator. Employing the one-cycle control strategy, decreases the torque ripple resulted from the conventional hysteresis current controllers and therefore, the vibration and acoustic noise of the drive are reduced. Total operations of the system control and OCC strategy are realized by a low-cost general-purpose AVR microcontroller (Atmega8) that leads to a low-cost, high performance BLDC motor drive. Computer simulations using Matlab simulator, have been presented to show the good characteristics of this solution. Furthermore, experimental works show the excellent behavior of developed BLDC drive and agreement with simulation results.
