Gigahertz frequency tunable noise suppressor using nickel nanorod arrays and Permalloy films

To suppress noise in electronic devices at gigahertz frequencies, the signal attenuation in the pass-band frequency region must be minimized to enhance the signal integrity without distortion. We designed, fabricated, and evaluated two noise suppression microstructures, one using nickel nanorod arrays in a porous anodic aluminum oxide dielectric and a second structure based on a Ni(80)Fe(20) (Permalloy) film in a microstrip waveguide geometry. Both noise suppression structures function as tunable devices in the microwave range. The devices show signal attenuation at the resonance frequency which is increased more than -20 dB compared with a microstrip line without any magnetic material. At ferromagnetic resonance the power loss in the nanorod structure was 15% higher than that of a Permalloy based device. In the pass-band frequency region the signal attenuation/insertion loss of the nanorod arrays was about 2 dB higher than that of the Permalloy film. It is observed that to get good noise suppression, the signal distortion due to the signal phase shift must also be minimized. The differential phase shift of the Ni nanorod device was similar to 20% smaller than that of the Permalloy film device. We also designed noise suppressors using Ni nanorods by changing aspect ratios (rod lengths of 5-50 mu m and diameter of 200 nm). The noise suppression frequency and the magnitude of signal attenuation in the noise suppressor were increased as the Py element became thicker. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3072824]