Tunable Magnetic Metamaterial Based On Array Of Nanowires With Magnetic Shape Anisotropy For Ultracompact Planar Antennas

Metals are nearly perfect electromagnetic reflectors, causing the electric field component parallel to the surface tonearly vanish. The efficiency of a planar microwave antenna, which senses the parallel component of the incidentradiation, is significantly reduced if installed less than half a wavelength from a metallic surface. To mitigate this, abulky dielectric spacer is inserted between the surface and the antenna, increasing the antenna assembly's weight andvolume. An unstructured ferromagnetic film is impractical as a magnetic spacer for the Ku (12-18 GHz) and K (18-26.5GHz) frequency bands. Such a film would require either a high magnetic field from bulky permanent magnets or asingle crystal material with large magneto-crystalline anisotropy, which lacks thermal stability of its FMRfrequency. We propose developing a novel shape anisotropy magnetic metamaterial based on an array offerromagnetic nanowires. This metamaterial will act as a thermally stable, bias-free, ultra-thin magnetic spacer forplanar antennas operating in the Ku and K bands. This technology will address the US Army's need for ultra-compact, surface-mountable conformal antenna technology. In Phase I, we will develop fabrication process and measure microwave properties of a single-layer one-dimensionalarray. We will determine how these parameters depend on the aspect ratio of the nanowire cross-section, aiming toplace the SAMM FMR frequencies into the Ku and K bands.