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Author: Fengqi Hu Publisher: ISBN: 9780355149494 Category : Languages : en Pages :
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.
Author: Fengqi Hu Publisher: ISBN: 9780355149494 Category : Languages : en Pages :
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.
Author: Meijiao Li Publisher: ISBN: 9781369796506 Category : Languages : en Pages :
Book Description
Phased Antenna Array (PAA) technology with its compact structure, high gain, low side-lobes, and electronic beam steering and shaping capability is desirable for both military and civilian applications. Due to the dramatic growth of commercial demands and technology advances, PAA have begun to play an increased role and have achieved significant development in many new applications in civilian areas. In this dissertation, PAA technology has been developed for a specific application – Fusion Plasma Imaging Radar Reflectometric Diagnostics. Fusion energy with its self-sustainability and environmentally friendly nature stands out to be the clean and inexhaustible energy that humanity has dreamed about for a long time. Plasma Imaging Radar Reflectometric Diagnostics is a technology to remotely detect the plasma density fluctuations in fusion plasmas which helps scientists to better understand fusion and make the clean energy available sooner. In this dissertation, a Phased Array Transmitter System based on digitally controlled phase shifter technology, a wide band double-sided print bow-tie antenna, and a 16-element V-band array have been developed. Both the transmitter system and the V-band antenna array were designed, fabricated, and measured. Electromagnetics simulations were performed using both CST STUDIO SUITE® and HFSS. A low-cost, 28 GHz Phased Array Transmitter System with digitally controlled beam forming technology has been demonstrated. The 8-element PAA transmitter systems are fabricated on a low-cost PCB substrate to avoid the extra loss caused by connection of different circuit pieces and for easier integration and simpler circuit structure. By using wideband, double-side printed bow-tie antennas, and digitally controlled phase shifters together with frequency up-converter components, the systems can provide more than 40 degrees beam scanning ranges with high resolution of 1 degree, which satisfies the requirements for the microwave imaging reflectometer (MIR) system proposed for the NSTX-U fusion device at Princeton Plasma Physics Laboratory. The technology is scalable to larger arrays and higher frequencies and should have a broad range of applications.In the wide band V-band antenna design, a 46 GHz to 76 GHz double-sided printed bow-tie antenna with an elliptical lens was designed, implemented using low cost RO4003C substrate, and experimentally characterized. The antenna shows a gain of 16 dBi, and -15 dB side lobe ratio. In antenna array design, it is well known that a spacing of no more than a half wavelength between nearby antennas is desired to avoid grating lobe influence. As the dimensions of the designed antenna’s width are less than half of a wavelength (0.36 [lambda]), it is feasible to keep the space between each element in the array equal to half of a wavelength. Therefore, the designed antenna can also be used in antenna arrays or phased antenna array systems. To demonstrate the idea, a 16-element double-sided printed bow-tie array was designed, fabricated, and tested. The theoretical and measured far-field patterns agree well. With its compact structure, high gain, low side-lobes, and easy integration capability, it should be successfully applied to V-band (60 GHz) Phased Array Systems and will be specifically used for Plasma Imaging Radar Reflectometric Diagnostics applications.
Author: Arindam Sengupta Publisher: ISBN: Category : Beamforming Languages : en Pages : 128
Book Description
Wideband beamforming is an essential requirement for several areas of importance, such as radar, cognitive radio and wireless communications. Emerging ultra-wideband (UWB) systems demand rapid electronic steerability, and multiple beams, while maintaining a relatively constant far-field beamwidth. Traditional phased-array based coherent summing approaches generally fail to comply with the requirements of the UWB systems, and implementing such architectures on a hardware level is computationally intensive. Moreover, digital signal processing (DSP) of wideband signals require sophisticated front-ends for pre-processing stages, followed by analog-to-digital converters (ADCs) operating at a very high frequency of operation. In this study, a novel approach to mitigate the ADC requirements is explored, by using both microwave channelizers and sub-sampling ADCs. The microwave channelizer splits the incoming wideband signals into narrower bands, which are then digitized using subsampling ADCs. The resulting signals are simultaneously down-sampled and down-converted. This approach is investigated for a planar manifold-type microwave channelizer, integrated with multi-dimensional filters, to aid 2-D and 3-D wideband directional beamforming systems. The proposed 3-D architecture was investigated for focal plane array (FPA) applications, in order to exploit the high gain of a parabolic dish reflector, while achieving support for multiple electronically scanned beams, by replacing existing horn antennas with an FPA placed at the focal point of the dish. Such architectures, with the aid of the recently proposed frustum shaped filters, find many applications in radar, radio astronomy and other microwave imaging techniques. A novel 2-D bio-inspired spatially band-pass multi-beam filter, from the 1-D electrical equivalent of a mammalian cochlea, is explored. The proposed architectures were evaluated for performance under various scenarios involving wideband directional interference, off-dish interference and additive white Gaussian noise (AWGN), and were found to demonstrate significant noise rejection and subsequent desired signal enhancement. VLSI architectures for three high-precision fast division algorithms are presented. Such architectures are of extreme importance for several fields, that require real-time high-precision fast computations, such as, digital signal processing, information theory, cryptography, graph theory, and next generation of computational devices.
Author: United States. National Aeronautics and Space Administration. Scientific and Technical Information Division Publisher: ISBN: Category : Astronautics Languages : en Pages : 504
Author: Publisher: ISBN: 9781423572381 Category : Languages : en Pages : 605
Book Description
This handbook is designed to aid electronic warfare and radar systems engineers in making general estimations regarding capabilities of systems. It is not intended as a detailed designer's guide, due to space limitations. Portions of the handbook and future changes will be posted on an internet link.
Author: F. Cap Publisher: Springer ISBN: 3709127009 Category : Science Languages : en Pages : 287
Book Description
This book presents the contents of a CISM Course on waves and instabilities in plasmas. For beginners and for advanced scientists a review is given on the state of knowledge in the field. Customers can obtain a broad survey.
Author: Fengqi Hu
Author: Fengqi Hu
Author: Meijiao Li
Author: Arindam Sengupta
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Author: 
Author: United States. National Aeronautics and Space Administration. Scientific and Technical Information Division
Author: 
Author: 
Author: 
Author: F. Cap