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Author
Title Compact Antennas and Arrays for Unmanned Air Systems
URL
Publication Date
Degree MS
Degree Level masters
University/Publisher Brigham Young University
Abstract A simple and novel dual-CP printed antenna is modelled and measured. The patch antennais small and achieves a low axial ratio without quadrature feeding. The measured pattern showsaxial ratio pattern squinting over frequency. Possible methods of improving the individual element are discussed, as well as an array technique for improving the axial ratio bandwidth. Three endfire printed antenna structures are designed, analyzed, and compared. The comparison includes an analysis of costs of production for the antenna structures in addition to their performance parameters. This analysis concludes that cost of materials primarily reduces the size of antennas for a given gain and bandwidth. An antenna stucture with an annular beam pattern for down-looking navigational radar is proposed. The antenna uses sub-wavelength grating techniques from optics to achieve a highly directive planar reflector which is used as a ground plane for a monopole. A fan-beam array element is fabricated for use in a digitally steered receive array for obstacle avoidance radar. The steered beam pattern is observed. The element-dependent phase shifts for a homodyned signal in particular are explored as to their impact on beam steering.
Subjects/Keywords unmanned air vehicles; unmanned air systems; dual circularly polarized antennas; printed circuit board antennas; planar antennas; digital beam steering; antenna arrays; sub-wavelength; grating; electromagnetic orientation; sense-and-avoid radar; Electrical and Computer Engineering
Language en
Rights License: http://lib.byu.edu/about/copyright/
Country of Publication us
Format application:pdf
Record ID oai:scholarsarchive.byu.edu:etd-5296
Repository byu
Date Retrieved
Date Indexed 2019-12-30

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…4x1 Vivaldi array. This fixed-feed, four-Vivialdi-element array achieves a fan beam at endfire from the board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Measured return loss for the Vivaldi array. It is matched from 8.5 GHz to…

…extreme steering angles, strong side lobes are seen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8 Simulated peak gain over steering angle for a narrow band signal. The 4x4 array has an additional 6 dB of gain forward…

…looking and a 3-dB steering range of 90◦ in simulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9 The narrow band, simulated side lobe levels for the array, representing the gain of the main lobe minus the largest side…

…lobe’s gain at a given steering angle. They are more than 8 dB over the full 90◦ steering range. This means that a target at a given range and angle will appear over four times as bright as its image at steering angles where it is in a side lobe…

…6.10 The narrow band, simulated 3-dB beam width of the steered beam. This beam width determines how wide targets appear to the radar because as the beam is steered the target remains in the beam over a steering range equal to the beam width. Targets at…

…the edges of the steering range will appear wider than those directly in front of the UAV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.11 The simulated radar image for four targets. Note that each target has weaker ‘ghost images…

…where it appeared in the side lobe of the steered beam, especially near the edge of the angular steering range. . . . . . . . . . . . . . . . . . . . . . . . . . . 6.12 This is a radar image like that in Figure 6.11, except that the homodyning dispersion…

board (PCB) antennas, which are light-weight, planar, compact, and inexpensive. They also have an inherently high aperture efficiency and therefore translate board area to directivity at a high rate of return. These antennas also rely heavily…

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