Microwave Imaging Radar Reflectometer Receiver System Utilizing Digital Beam Forming PDF Download

Author: Fengqi Hu
Publisher:
ISBN: 9780355149494
Category :
Languages : en
Pages :

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Book Description
In recent years, the exponentially increasing energy requirements and the serious environmental problems caused by traditional fossil sources have drawn tremendous attention to the development of alternative energy sources. One of the most promising candidates is nuclear fusion energy. To study the fundamental physical phenomena inside the confined hot plasma of which the temperatures are in excess of 100 million Kelvin, advanced imaging systems are being developed with millimeter wave imaging systems of particular importance. The Microwave Imaging Reflectometry (MIR) developed at UC Davis is an active radar imaging system used to measure the electron density fluctuations. In the currently employed system, carefully designed optical lenses are used to shape the probing beam so that it would impinge upon the plasma cutoff surface with normal incidence. On the receiver side, another set of lenses are used to collect and further shape the beam to form an image of the cutoff surface. The focusing is done by motor controlled lenses, which not only take up more space but also are slow to adjust compared to many plasma times of interest. Phased array synthesis offers the ability to change the shaping and steering of the beam electronically for fast-tracking and remote tuning without the need for bulky lenses. Based on where in the system the phase shifting is performed, there are two major categories of phased array. One is the analog phased array where the beam shaping and steering are done in the analog domain with analog phase shifters. The other approach is digital beamforming where the amplitude scaling and the phase shifting are realized by mathematical operations in the digital domain. Compared to its analog counterpart, digital beam forming could be done much faster with great flexibility. The focus of this dissertation is the utilization of digital beam forming to realize high speed focusing with greater flexibility. The beam shaping, focusing/de-focusing, beam steering and beam translation with digital beam forming are demonstrated with a simplified W-band receiver system. The possibility of a V-band system-on-substrate with on-board LO feed is also explored.