Impedance matching of electrically small antenna with Ni-Zn ferrite film

Abstract

We demonstrate that a partial loading of Ni0.5Zn0.5Fe2O4 (Ni-Zn ferrite) film remarkably improves impedance matching of electrically small Ba3Co2Fe24O41 (Co2Z) hexaferrite antenna. A 3 μm thick Ni-Zn ferrite film was deposited on a silicon wafer by the electrophoresis deposition process and post-annealed at 400°C. The fabricated Ni-Zn ferrite film has saturation magnetization of 268 emu/cm3 and coercivity of 89 Oe. A partial loading of the Ni-Zn ferrite film on the Co2Z hexaferrite helical antenna increases antenna return loss to 24.7 dB from 9.0 dB of the Co2Z antenna. Experimental results show that impedance matching and maximum input power transmission to the antenna without additional matching elements can be realized, while keeping almost the same size as the Co2Z antenna size. © The Korean Magnetics Society. All rights reserved.