Sol–gel auto combustion processed soft Z-type hexa nanoferrites for microwave antenna miniaturization

Nanoparticles of Z-type hexaferrite, Ba3Co2Fe24O41 and Ba3Co1.9−x−yCuxZnyNi0.1Fe24O41 (where x=0.4, 0.2 and y=0.5, 0.7) were prepared by sol–gel auto combustion method. Electromagnetic properties of the prepared nanoparticles were realized in the frequency range from 1.6 GHz to 4 GHz for the design of miniaturized microwave antennas. Optimized synthesis conditions and the addition of selected dopants have been used to enhance the high frequency electromagnetic properties of low loss Co2Z nanoferrites. The best results obtained were ε′=3.07, μ′=2.59 at frequency 2 GHz and ε′=2.33, μ′=2.94 at frequency 2.5 GHz for the composition Ba3Co1Cu0.2Zn0.7Ni0.1Fe24O41. This is a significant improvement w.r.t. our previously reported results. Electromagnetic results are explained on the basis of relevant existing theories and models. Owing to these electromagnetic properties, in particular the controlled electric and magnetic losses close to zero in the frequency range from 1.6 GHz to 4 GHz, these nanoferrites could be useful to the miniaturization of antennas for mobile handheld wireless communication devices.