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- Title
SOFT-FOCUSING IN ANISOTROPIC INDEFINITE MEDIA THROUGH HYPERBOLIC DISPERSION.
- Authors
Wheeland, S.; Amirkhizi, A. V.; Nemat-Nasser, S.
- Abstract
Materials that exhibit negative refraction may have many novel applications. We seek to evaluate the possibility of soft-focusing of microwave signals using a medium with an indefinite (hyperbolic) anisotropic permittivity tensor. We fabricated a 147 mm thick and 220 mm wide Styrofoam sample with an embedded array of 12-gauge brass wires of 6.35 mm lattice spacing. Two single-loop antennas were used to approximately generate a transverse magnetic (TM) point source and the associated detector. Using an Agilent 8510C Vector Network Analyzer (VNA), the frequency spectrum was scanned between 7 and 9 GHz. Relative gain or loss measurements were taken at equal spatial steps behind the sample. A scanning robot was used for automatic scanning in the x, y, and z directions, in order to establish the focusing patterns. The signal amplitudes measured in the presence and absence of the sample were compared. The robot was controlled using LabVIEW, which also collected the data from the VNA and passed it to MATLAB for processing. A soft focusing spot was observed when the antennas were placed in two different symmetric configurations with respect to the sample. These results suggest a method for focusing electromagnetic waves using negative refraction in indefinite (hyperbolic) anisotropic materials.
- Subjects
NEGATIVE refraction; MICROWAVES; SIGNAL processing; PERMITTIVITY; ANTENNAS (Electronics); FREQUENCY spectra; SCANNING systems
- Publication
Progress in Electromagnetics Research, 2012, Vol 132, p389
- ISSN
1070-4698
- Publication type
Article
- DOI
10.2528/pier12080207