Additively-Manufactured All-Dielectric Microwave Polarization Converters Using Ceramic Stereolithography

Abstract

We report a class of all-dielectric, additively-manufactured polarization converters with tailored temporal frequency responses within the Ku and Ka microwave bands (15 -40 GHz). These multi-layer devices consist of cascaded, subwavelength, high-contrast gratings with different fill fractions and orientations, providing control over the effective anisotropic properties of each layer. In design, the subwavelength gratings are modeled as homogeneous anisotropic layers. This allows the overall metastructure to be treated as a stratified dielectric medium. Therefore, it can be analyzed and optimized using plane-wave transfer matrix techniques that fully account for multiple reflections between layers. Using this cascaded grating geometry, a variety of high-efficiency microwave polarization converters can be realized with broadband, multiband, or multifunctional behavior. The transmissive metastructures do not require anti-reflection layers since impedance matching is incorporated into their design. Three example devices based on alumina/air gratings have been monolithically fabricated using ceramic stereolithography: a broadband reflective half-wave plate, a broadband isotropic polarization rotator, and a dual-band linearto-circular polarization converter.

Phase Gradient Metasurface Assisted Wideband Circularly Polarized Monopole Antenna

“…The above discussed metasurfaces are fabricated as printed layers. The elements in a few metasurfaces are also fabricated using dielectric material (called as dielectric metasurfaces) [34,35] or all metal [36] patches, which are application specific. The inference from the above designs is that the axial ratio is achieved with much effort, complex feeding techniques, and more strip loading methods.…”