Showing papers by "David Schurig published in 2013"
••
TL;DR: In this article, an augmented metamaterial absorber that supports magnitude and phase measurement of the incident electric field, within each unit cell, is described, implemented in a commercial printed circuit board process with off-board back-end electronics.
Abstract: We present measurements and analysis demonstrating useful direction finding of sources in the S band (2–4 GHz) using a metamaterial detector. An augmented metamaterial absorber that supports magnitude and phase measurement of the incident electric field, within each unit cell, is described. The metamaterial is implemented in a commercial printed circuit board process with off-board back-end electronics. We also discuss on-board back-end implementation strategies. Direction finding performance is analyzed for the fabricated metamaterial detector using simulated data and the standard algorithm, MUtiple SIgnal Classification. The performance of this complete system is characterized by its angular resolution as a function of radiation density at the detector. Sources with power outputs typical of mobile communication devices can be resolved at kilometer distances with sub-degree resolution and high frame rates.
13 citations
••
17 Oct 2013TL;DR: In this paper, it was shown that negative refractive index materials (a very unique class of metamaterials) can produce a perfect image by focusing propagating waves and enhancing the evanescent waves that dominate in the near field.
Abstract: Summary form only given. Wireless power transfer over short distances is increasingly used to power implanted biomedical devices. A typical power transfer system consists of an external coil outside the body and an internal coil on the implanted device. The efficiency of the wireless power transfer depends on the Q of the constituent coils as well as the coupling. Coupling between the coils is severely limited by the distance between the coils. It was shown by Pendry [1] that negative refractive index materials (a very unique class of metamaterials) can produce a perfect image by focusing propagating waves and enhancing the evanescent waves that dominate in the near field. Since wireless power transfer is achieved by near field magnetic field coupling, using metamaterials can enhance this coupling and thereby increase the range of operation. A theoretical analysis using the point dipole approximation for resonating coils showed that power transfer efficiency increased when an anisotropic negative permeability material was placed between the primary and secondary coils [2].
1 citations