Aftab Ahmad

The goal of this research is to formulate and numerically solve an accurate theoretical full-wave model that describes the wave propagation characteristics in different optical structures containing DNG materials. A comprehensive mathematical analysis will be performed from physical as well as device points of view. Several time-frequency techniques to represent material properties will be investigated and evaluated.

It is also the objective of this research to diversify the applicability of DNG materials in novel optical structures and devices by considering alternative methods of obtaining the double negative characteristics. A rigorous numerical simulation of the model is another objective. The numerical tool will be used to investigate the effects of the playing parameters in the problem.

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F Alkhuraish

Investigate and analyze novel designs of low profile microstrip antennas for the wireless communications applications. The designs utilize the EBG concept and the microstrip technology. The work also aims at the formulation of an accurate EM model for the wave propagation in EBG-based structures. In particular metal as well as dielectric properties will be accommodated. The mathematical model will be solved numerically using the full-wave FDTD method with extended capabilities. The FDTD simulator will be used to analyze a number of interesting microstrip antenna structures. Experimental data will be collected, as much as possible, to validate the theoretical results.

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The finite-difference time-domain (FDTD) method is used to model the response of microstrip patch antennas on magnetized ferrite substrates. The proposed FDTD model utilizes the Auxiliary Differential Equation (ADE) approach to represent the frequency dependent permeability tensor in the time domain equations. The resulting 3D full-wave numerical model is tested and verified against experimental data showing very good agreement. This model, being efficient, stable and robust, is expected to assist in the design and characterization of wideband ferrite-based antenna structures.

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The main objective of the project is to develop a comprehensive simulator to analyze and design optically controlled devices. The simulator should be capable of 1) accurately representing the physics of the device 2) accommodating all inhomogenities involved 3) properly representing different applied sources and forces 4) having provision for different types of analysis and investigations 5) predicting and giving insight into underlying physical effects as well as circuit-level calculations.

The large wealth of information the simulator provides should assist in enhancing existing system designs and pave the way for advanced structures and systems.

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The effects of electrode spacing on the optical response of illuminated MESFETs are analyzed. The analysis targets various optical performance factors including terminal photocurrent peak value, peak-time and discharge time. Whereas photocurrent peak value increases nonlinearly with electrode spacing, it was found that increasing the electrode spacing has a profound effect on the ability of the device to flush-out the optically generated carriers and hence more output delays are generated. A figure-of-merit has been defined to quantify the overall spacing effects. The simulation results show that optimum electrode spacing can be achieved.

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