Next Generation Spaceborne Wind Scatterometer and CubeSat Antennas: Lightweight 3D Printed Inhomogeneous Lens Antennas and Dual Reflectarray Antennas
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Abstract:Weather radar instruments have shown chronic failure due to moving mechanical parts wearing over time. These current systems achieve a conical beam scan by revolving a parabolic reflector antenna by mechanical means. New designs must avoid moving parts and transition to a full electronic version while maintaining similar performance. Of the few design choices, the Luneburg Lens Antenna comes to mind. This class of inhomogeneous spherical lenses can achieve electronic scanning of a beam through a conical pattern sweep with no scan loss. However, these lenses are too massive and heavy. A more lightweight design which achieves similar pattern performance is necessary.
Our approach to achieving such a design is a shaping algorithm based on geometrical optics (GO) and particle swarm optimization (PSO). The GO is equipped with the capability to trace rays through inhomogeneous media, thus allowing the synthesis of both shape and material. The extra degree of freedom allows one to obtain even thinner, more lightweight lenses, with superior scan performance. The bounding surface and permittivity filling the volume of the lens is parameterized using power series expansions with unknown coefficients. Each set of coefficients defines a unique design for characterization through the GO Analysis routine. By integrating the GO algorithm with the PSO method, the optimum set of coefficients are converged upon quickly. This design meets the goals of light-weight and conically scanned revolving beam via electronic means, thus achieving the original project goals. However, the obtained design specifies a material permittivity variation which is difficult to manufacture. To address this issue, we take advantage of the 3D printing revolution to "print' the resultant complex materials on demand. However, once again, this approach brings its own challenges. Materials must be accurately characterized electromagnetically and evaluated for spaceborne use. We present our analyses of two such materials and highlight the advantages and disadvantages of each material in terms of loss, print quality, and mechanical strength.
Several breadboard models of 3D printed lenses which meet the design goals are presented along with measurement validation. Measurements are performed in both the UCLA plane bi-polar near field and the UCLA spherical near field measurement range.
Also presented is recent work on reflectarray antennas for CubeSat applications. To obtain the design of the reflectarray antenna system, complex computer codes must be developed. These codes are based on the SDMoM employing the Infinite Array Analysis Technique commonly used for periodic structure and phased array analysis.
Bio: Jordan Budhu is a Ph.D. candidate at the University of California Los Angeles (UCLA) under the advisement of Professor Yahya Rahmat-Samii in the Antenna Research, Analysis, and Measurement (ARAM) Laboratory. He received his M.S.E.E. degree with Distinction in 2010 from California State University Northridge under the advisement of Professor Sembiam Rengarajan. In 2006, he won the first place award for his undergraduate senior project. In 2012, he won the Best Poster award at the IEEE Coastal Los Angeles Class-Tech Annual Meeting. In 2010, he was awarded the Eugene Cota-Robles Fellowship from UCLA. He has taught numerous undergraduate courses as first a Teaching Assistant in the 2012-2013 Academic year at UCLA, then promoted to Teaching Associate in the 2016-2017 Academic Year at UCLA, then finally promoted to a Teaching Fellow in the 2017-2018 Academic Year at UCLA. He was also selected to be the Head EE Department TA at UCLA for the Fall 2018 quarter, a position selected to be awarded to a single candidate of nearly 100 TA's in the department. He was also an employee at the NASA Jet Propulsion Laboratory in 2011 and 2012. He is the author of numerous publications in various IEEE antennas and propagation society journals. He is also a member of both IEEE APS and the Bioelectromagnetics Societies.