Chapter 6 Modeling and Testing RF Meta-Atom Designs for Rapid Metamaterial Prototyping Russell P. Krones, Derrick Langley, Peter J. Collins, and Ronald A. Coutu Jr. Abstract Metamaterials offer custom electromagnetic properties not easily found elsewhere. In this investigation, we look at fabrication methods to reduce time and cost for metamaterials. These designs are compared against analytical modeling, and verified with experimental radio frequency (RF) testing. This paper discusses two models used to represent meta-atoms as lumped circuit elements to establish a resonant frequency. The analytic model is compared with a finite element method (FEM) modeling simulation to determine the capacitance and inductance of the meta-atom and establish a resonant frequency for the comparison. These modeling methods help to determine the resonant frequency before it can be experimentally verified. In this research, we experimentally show the resonant response at 2.57 GHz. In addition, various Metamaterial configurations are tested to capture effects for focusing and blocking electromagnetic waves. The best focusing response occurred at 2.57 GHz with a null of 21 dB with silver inkjet printed meta-atoms supported with FR4 material. The best blocking response occurred at 2.76 GHz with a null of 92 dBwith silver inkjet printed meta-atoms supported with FR4 material. The experimental measurements provide characterization for the resonant response, and extraction of electromagnetic material properties which enhances the fundamental understanding for metamaterials. Keywords Meta-atom • Metamaterial • Radio frequency • Resonant response • RF measurement 6.1 Introduction The term metamaterials (MTMs) describes a broad area of devices with many specific definitions sharing a few common elements. Ciu et al. describe a MTM as “a macroscopic composite of periodic or non-periodic structure, whose function is due to both the cellular architecture and the chemical composition” [1]. This definition shows the broad spectrum of topics within MTM research. To narrow this definition, Ciu et al. also state that the cell size needs to be less than the “subwavelength” if an MTM is to be regarded as an effective medium [1] or homogeneous matter. This caveat also plays an important role in the measurement of these materials. Making the assumption of a homogeneous medium leads to isotropic material equations; for these, a more simplified closed form solution exists to calculate the constituent electromagnetic (EM) properties. Once the constituent properties are derived (permittivity and permeability) the material can be fully described, including the electric and magnetic field interactions, the reflection and refraction, and the complex impedance. Therefore, this investigation focused on designing and measuring radio frequency (RF) MTM structures. Then, from the RF measurements, constituent EM material properties were derived. R.P. Krones • D. Langley (*) • P.J. Collins • R.A. Coutu Jr. Air Force Institute of Technology, 2950 Hobson Way, Bldg 641, Wright-Patterson AFB, OH 45433, USA e-mail: Derrick.Langley@afit.edu Disclaimer: The views expressed in this article are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the U.S. Government. B.C. Prorok et al. (eds.), MEMS and Nanotechnology, Volume 8: Proceedings of the 2014 Annual Conference on Experimental and Applied Mechanics, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-07004-9_6, #The Society for Experimental Mechanics, Inc. 2015 45
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