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SPONSORING/MONITORING AGENCY ACRONYM(S)AFRL/RYMH
SPONSORING/MONITORING AGENCY REPORT NUMBER(S)AFRL-RY-WP-TR-2013-0059
DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited.
SUPPLEMENTARY NOTESPAO Case Number 88ABW-2013-1345, Clearance Date 20 March 2013 . Report contains color.
ABSTRACTElectromagnetic media and metamaterials have been explored in frequency regimes ranging from the acoustic to the visible domain over the past decade. Here we present the design of a focusing GRadient INdex (GRIN) lens to operate at RF frequencies that is not polarization constrained. We compare theoretical and experimental results from this lens designed to operate at X-band and fabricated using 3D printing technology. The lens with radially varying refractive index gradient was designed, optimized and analyzed by conducting full-wave simulations finite-element method based software Ansoft HFSS®. The design was fabricated and experimentally results are compared to the performance of the theoretical design.
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SUMMARYElectromagnetic media and metamaterials have been explored in frequency regimes ranging from the acoustic to the visible domain over the past decade. A large part of the design, fabrication and prototyping of such materials has focused on planar structures and devices have been demonstrated primarily for certain propagation directions and/or defined polarization. Here, we present the design of a focusing GRadient INdex (GRIN) lens that operates at radio frequency (RF) frequencies and is not polarization constrained. We compare the theoretical and experimental results from this lens designed to operate at X-band and fabricated using three dimensional (3D) printing technology to implement the effective medium. The lens with radially varying refractive index gradient was designed, optimized and analyzed by conducting full-wave simulations finite-element method based software. The permittivity was estimated by effective medium theory and calculated using HFSS®. The optimized design was used to fabricate the GRIN lens with isotropic, inhomogenous dielectric material. The refractive index was designed to match the theoretical results using mixing ratio of air/voids and a polymer. Further, we used the refractive index profile to predict the rays' trajectories and focus length to compare them to those predicted by the finite element method (FEM) simulations. The field distributions were also analyzed to compare performance of the theor...