Influential parameters on electromagnetic properties of nickel-zinc ferrites for antenna miniaturization

Electromagnetic properties of nickel-zinc ferrites based materials make them potential candidates for applications linked to telecommunications. In the present study, nanosized particles of spinel ferrite Ni0.5Zn0.3Co0.2Fe2O4 were prepared by coprecipitation method. An optimized material is obtained after adequate heat treatment and partial filling of the porosity by epoxy resin. This material lies between ceramic and composite medium (with porosity close to 40%), and shows almost constant complex permeability and permittivity in the frequency range from 0.1-0.7 GHz, and equal to similar to 3.5-j0.15 (loss tangent similar to 0.04) and similar to 4-j0.2 (loss tangent similar to 0.02), respectively. The refractive index n is close to 3.75. These electromagnetic properties, in particular the low levels of losses, show that this material could be useful to the design of miniaturized antennas in the VHF-uhf (300-700 MHz) range of frequency. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3356235]