PhD candidate
Ali Foudazi
"Small UWB Planar Monopole Antenna With Added GPS/GSM/WLAN Bands"
A small-size microstrip-fed multi-band planar monopole antenna is presented. The base of the proposed antenna covers the UWB frequency range. To create a multi-band antenna, several narrow strips, acting as resonance paths, can be integrated with the base antenna. It is shown that by removing the centre part of the base antenna, without distorting the UWB behavior, quarter-wavelength strips can be added to the notched region. This will not affect the dimension of the base antenna. The designed quad-band antenna has a substrate size of 16 mm × 22 mm and covers the frequency bands of GPS, GSM, WLAN and UWB.
"Triboelectric Charging Between Display Glass Panels and Dissipative/Insulative Rollers"
The underlying cause of most electrostatic discharge is tribocharging. Thus, understanding tribocharging is essential to assess the likelihood of damages as they might occur in the production of Liquid crystal display (LCD) screens. In this paper, a study of triboelectric charge build-up between the glass and rollers during the glass transfer process in display panel manufacturing is presented. A roller conveyor system was fabricated and two types of rollers materials, insulative and dissipative, with radii of 30 and 90 mm, were considered. To measure the triboelectric charge of the glass, a Faraday cup with an elevator system was mounted on the apparatus. Various parameters including transfer velocity, acceleration/deceleration, and relative humidity were investigated.
"Aperture-Coupled Microstrip Patch Antenna Fed by Orthogonal SIW Line for Millimeter Wave Imaging Applications"
A new microstrip patch antenna feeding technique for millimeter wave imaging applications is proposed. The technique utilizes a substrate integrated waveguide (SIW) line that orthogonally feeds the patch antenna through a coupling aperture. Measurement and simulation results for rectangular patch antenna are presented showing good agreement with 9% bandwidth (|S11| < -10 dB). The aperture-coupled rectangular patch antenna provided 5.5 dBi gain and 72% efficiency at the design frequency. Finally, the antenna is used for nearfield and wideband SAR imaging to demonstrate the potential of the proposed antenna for imaging at millimeter band.
"Pattern synthesis for multi-feed reflector antennas using invasive weed optimisation"
A new optimization method for pattern synthesis of multi-feed reflector antennas is presented. By using an invasive weed optimization (IWO) algorithm, shaped beam antennas are designed. The results of the IWO algorithm for the synthesis of cosecant squared and contoured beam patterns are presented and compared with particle swarm optimization algorithm results. The far-field radiation patterns of reflector antennas, fed by a linear and planar array of conical horn antennas, are provided by a physical optics and the error between desired and provided radiation patterns is calculated by a RMS method. The results show that the IWO algorithm, which provides good convergence, is stable and adaptive-to-change for different boundary conditions in pattern synthesis applications.
"Evaluation of steel fiber distribution in cement-based mortars using active microwave thermography"
The non-uniform distribution of steel fibers in fiber-reinforced cement-based mortars (FRCMs) can lead to heterogeneous properties of hardened material with direct impact on mechanical properties. Among various nondestructive testing techniques, the active microwave thermography (AMT) has shown good potential for inspection of cement-based materials. AMT utilizes combination of microwave energy to generate controlled and localized heating and uses commercially-available infrared cameras to capture surface thermal images in realtime. Utilizing AMT, four FRCM samples made with different steel fiber volumes ranging from 0 to 3 % were investigated to evaluate the feasibility of this method for detecting and quantifying fiber distribution. Full-wave coupled electromagnetic-thermal numerical modeling was also conducted to evaluate the effect of dielectric properties, fiber depth, and fiber clumping on surface thermal profile.
