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Full-Text Articles in Engineering

Propagation Prediction Over Random Rough Surface By Zeroth Order Induced Current Density, Narayana Srinivasan Balu Nov 2014

Propagation Prediction Over Random Rough Surface By Zeroth Order Induced Current Density, Narayana Srinivasan Balu

Masters Theses

Electromagnetic wave propagation over random sea surfaces is a classical problem of interest for the Navy, and significant research has been done over the years. Here we make use of numerical and analytical methods to predict the propagation of microwaves over random rough surface. The numerical approach involves utilization of the direct solution (using Volterra integral equation of the second kind) to currents induced on a rough surface due to forward propagating waves to compute the scattered field. The mean scattered field is computed using the Monte-Carlo method. Since the exact solution (consisting of an infinite series) to induced current …


Design Of Non-Uniform Linear Array Via Linear Programming And Particle Swarm Optimization And Studies On Phased Array Calibration, Hua Bai Nov 2014

Design Of Non-Uniform Linear Array Via Linear Programming And Particle Swarm Optimization And Studies On Phased Array Calibration, Hua Bai

Masters Theses

For a linear array, the excitation coefficients of each element and its geometry play an important role, because they will determine the radiation pattern of the given array. Side Lobe Level (SLL) is one of the key parameters to evaluate the radiation pattern of the array. Generally speaking, we desire SLL to be as low as possible. For the linear array with uniform spacing, there are some classic methods to calculate the excitation coefficients to make the radiation pattern satisfy the given requirements. For the linear array with non-uniform spacing, linear programming and particle swarm optimization are proposed to calculate …


Design And Evaluation Of An L-Band Current-Mode Class-D Power Amplifier Integrated Circuit, Michael J. Shusta Aug 2014

Design And Evaluation Of An L-Band Current-Mode Class-D Power Amplifier Integrated Circuit, Michael J. Shusta

Masters Theses

Power amplifiers (PAs) convert energy from DC to high frequencies in all radio and microwave transmitter systems be they wireless base stations, handsets, radars, heaters, and so on. PAs are the dominant consumers of energy in these systems and, therefore, the dominant sources of system cost and inefficiency. Research has focused on efficient solid-state PA circuit topologies and their optimization since the 1960s. The 2000s saw the current-mode class-D (CMCD) topology, potentially suitable for today's wireless communications systems, show promise in the UHF frequency band. This thesis describes the design and testing of a high-efficiency CMCD amplifier with an integrated …


Cable Discharge Events (Cde) -- A Modeling And Simulation Perspective, Viswa Pilla Jan 2014

Cable Discharge Events (Cde) -- A Modeling And Simulation Perspective, Viswa Pilla

Masters Theses

"Cable discharge events (CDE) typically occur when a charged cable is connected to an electronic device. Several CDE damages in Ethernet LAN and USB communication interface equipment are reported by the IC manufacturers. CDE differs from other types of ESD such as human body model (HBM), charged device model (CDM) and IEC 61000-4-2 mainly due to faster rise times, longer pulse widths and higher peak currents. Various factors such as cable geometries, charging and discharging mechanisms, and load conditions influence CDE. Several researchers have developed some measurement techniques to understand CDE waveforms. However, there is little information regarding its modeling …


Shielding Effectiveness (Se) Measurement For Maxair Waveguide Panel, Lossy Material Evaluation By Laptop Application, Xiao Li Jan 2014

Shielding Effectiveness (Se) Measurement For Maxair Waveguide Panel, Lossy Material Evaluation By Laptop Application, Xiao Li

Masters Theses

"The first part of the thesis presents the EM shielding effectiveness (SE) measurement of new kind of waveguide panel, MaxAir, which based on metal coating technology. SE Measurement tell the SE performance of MaxAir compared to the traditional metal waveguide panel. In terms of good features such as lower price, less weight, MaxAir could replace traditional waveguide panel in some applications by its SE results. There are two SE measurement methods are performed for MaxAir panel, both of them based on reverberation chamber. Measured SE for several MaxAir panel samples in different cell dimension and coating configuration. By the Measured …