Metamaterial absorbers are devices and surfaces specially designed to absorb electromagnetic energy. These absorbers are of critical interest for many applications, such as radar camouflage, EMI shielding, and antenna design. However, it is challenging to design compact absorbers with broadband performances. Experimental verification is even more difficult with current manufacturing processes. In this work, a hybrid genetic programming (HGP) approach has been used to develop several uniquely patterned broadband metamaterial absorbers with absorption characteristics spanning from 2-18GHz. A simple and efficient fabrication method has been developed for cutting unique and highly detailed patterns from a carbon-loaded polyethylene conductive film. This has then allowed for the experimental verification of several new HGP-developed designs. The metamaterials have features including broadband performance, incident angle stability up to 60°, polarization independence, compact 3-layer design, readily available materials, and a simple fabrication process. This thesis covers the design, fabrication, and experimental verification process for three unique conductive film-based designs. These designs are found to agree well with simulation and demonstrate the effectiveness of the HGP approach and unique metamaterials.

Zion McDowell is an Electrical Engineering M.S student at the University of Hawaii at Manoa. She obtained her B.S in Electrical Engineering from UH Manoa in December 2022. Her current research is under the Hawaii Advanced Wireless Technologies Institute (HAWTI) and focuses on developing advanced metamaterial broadband RF absorbers.