A low loss NiZnCo ferrite, prepared using a hydrothermal method, for antenna applications

Abstract

In this paper, a novel low-loss NiZnCo ferrite prepared by a hydrothermal method has been developed for miniaturization and performance enhancement of mobile handset antennae. XRD analysis revealed that in weakly alkaline solution, H+ ions generated in the reaction process result in an acid-alkali imbalance. In a strongly alkaline solution, Fe(OH)3 readily loses water to generate α-Fe2O3 and is no longer able to act as a nucleation skeleton. With powders prepared at pH = 10, the ceramic samples consisted of a pure phase, with compact and uniform microstructure, leading to relatively high permeability, very low dielectric constant, and with low losses. A miniaturization factor of about 6.2 and normalized impedance of about 1 were obtained for the developed substrate ferrite when used in a helical antenna operating in the terrestrial digital multimedia broadcasting (T-DMB) band for a mobile handset.