Browsing by Author "Easum, John A."

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    A Low Cost and Highly Efficient Metamaterial Reflector Antenna
    (Institute of Electrical and Electronics Engineers (IEEE), 2018-03) Gregory, Micah D.; Bossard, Jeremy A.; Morgan, Zachary; Cicero, Cooper S.; Easum, John A.; Binion, John D.; Zhu, Danny Z.; Scarborough, Clinton P.; Werner, Pingjuan L.; Werner, Douglas H.; Griffiths, Scott; Ketner, Matthew; Pompeii, Joshua
    The design of an efficient, metamaterial-based reflector antenna capable of operation at high power is presented. Metamaterial unit cells are comprised of end-loaded dipoles (ELDs) with capacitive lumped elements at their center. Enhanced power handling is realized by mitigating field enhancement through rounded edges and using appropriate high voltage capacitors as loads. The metamaterial is designed to have discrete, configurable reflection phase through choice of capacitor on the ELDs. Unit cells are fabricated and patterned to a square, flat reflector surface and configured for broadside reflection with an offset-fed horn antenna. Simulated and measured radiation patterns of the complete antenna system are presented with excellent agreement. High-power testing verifies the ability of the metasurface to withstand extreme incident electric field strengths.
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    Inverse design of engineered materials for extreme optical devices
    (IEEE, 2018-03) Campbell, Sawyer D.; Zhu, Danny Z.; Nagar, Jogender; Jenkins, Ronald P.; Easum, John A.; Werner, Douglas H.; Werner, Pingjuan L.
    Optical devices based on engineered materials can achieve performances not possible with conventional design methodologies. However, these performances come at the cost of relatively unconstrained design spaces which necessitates the development of efficient optimization algorithms. Furthermore, engineered optical devices, as opposed to classical designs, may possess multifunctional behaviors which places additional demands on the optimization algorithms in order to maximize the performance. To this end, two custom state-of-the-art multi-objective optimization algorithms are presented and their application towards the inverse design of engineered materials for the realization of extreme optical devices is discussed.