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Articles 1 - 4 of 4
Full-Text Articles in Engineering
Propagation Prediction Over Random Rough Surface By Zeroth Order Induced Current Density, Narayana Srinivasan Balu
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
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 …
Beam Steering Control System For Low-Cost Phased Array Weather Radars: Design And Calibration Techniques, Rafael H. Medina-Sanchez
Beam Steering Control System For Low-Cost Phased Array Weather Radars: Design And Calibration Techniques, Rafael H. Medina-Sanchez
Doctoral Dissertations
Phase array antennas are a promising technology for weather surveillance radars. Their fast beam steering capability offer the potential of improving weather observations and extending warning lead times. However, one major problem associated with this technology is their high acquisition cost to be use in networked radar systems. One promising technology that could have a significant impact in the deployment of future dense networks of short-range X-band weather radars is the ``Phase-Tilt Radar'', a system that uses a one-dimensional phase scanned antenna array mounted over a tilting mechanism. This dissertation addresses some of specific challenges that arise in designing and …
Design And Evaluation Of An L-Band Current-Mode Class-D Power Amplifier Integrated Circuit, Michael J. Shusta
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 …