Design and Fabrication of a Radio Frequency GRIN Lens Using 3D Printing Technology
Final rept. 1 Mar 2012-1 Mar 2013
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH SENSORS DIR
Pagination or Media Count:
Electromagnetic 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 andor 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 HFSSregistered. 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 airvoids 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 theoretical design to the fabricated lens and were found to be in good agreement with each other.
- Radiofrequency Wave Propagation