Design and additive manufacturing of broadband beamforming lensed antennas and load bearing conformal antennas
Date
2019
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Publisher
University of Delaware
Abstract
Graded-Index (GRIN) spherical dielectric lens antennas such as Luneburg lens or Maxwell fish-eye lens are an attractive choice for use as low-cost, wide angle and wideband beamforming and beamscanning elements in a number of military and commercial applications for satellite communication, remote sensing, and radar imaging. When implementing these designs, however, there are many practical challenges involved with the GRIN lens technology. First, the lens's spherical shape complicates the integration of an antenna feed networks such as waveguide, antenna arrays, detectors, and other associated external electronics. Second, practical implementation of such a continuously graded permittivity profile is a challenge and requires a robust fabrication approach to realize graded-index lens structures in a minimum fabrication time with the ability of mass production. To solve the design problem, a modified GRIN lens antenna, where portion of the lens’s spherical surface will be modified into a flat surface, can be integrated with the feed networks in a compatible way. However, this approach requires the optimization and redistribution of permittivity profile inside the lens structures to ensure intended beamsteering and electromagnetic performances. In this thesis, I will describe the detail design methodology of quasi-conformal transformation optics (QCTO) based modified GRIN lens structure design. Electromagnetic structures designed with QCTO technique usually suffer from reflection problems at the planar excitation boundary due to the absence of material’s magnetic response and result in degraded device performance. In the following work, I will be addressing the reflection problems associated with the QCTO approximations and design a novel anti-reflective layer along with the QCTO-enabled modified GRIN lens antennas to mitigate the impedance mismatch problems across the entire planar excitation surface. To solve the graded dielectrics realization problem, I will be using fused deposition modeling (FDM) based additive manufacturing technique to realize continuously graded dielectric lens antennas. In addition, I will demonstrate the use of additive manufacturing to embed the antenna elements within a curved surface load-bearing structure.