Matching permeability and permittivity of Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 ferrite for substrate of large bandwidth miniaturized antenna

Abstract

Nickel zinc cobalt indium ferrite of nominal composition Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 was synthesized by a co-precipitation technique. The effect of sintering temperature on structural and electromagnetic properties was studied over the frequency range of 10 MHz to 6 GHz. The crystallite size increases from 45 to 60 nm, with an increase in sintering temperature from 800 to 1000 °C. The relative permeability (μr) and relative permittivity (er), both varies between 5 and 8 with sintering temperature and remains consistent up to 700 MHz, but ferrimagnetic resonance frequency reduces from 900 to 700 MHz. For sintering temperature of 900 °C, almost matching value of permeability and permittivity equals to 5.5 and 5.3 respectively were obtained up to 700 MHz. The loss tangent are found to be of the order of 10−2 in the same frequency band. Matching values of er (~5.3) and μr (~5.5) are very effective in proper impedance matching of substrate material with free space. Analysis in High frequency structural simulator verifies that the synthesized magneto-dielectric material based antenna can miniaturize size (~65 %), lowers reflection losses (RL) by 15 %, higher −10 dB RL bandwidth (8–12 %) and higher voltage standing wave ratio bandwidth (9–13 %) at resonant frequency of 450 MHz. The observed matching values also result in higher gain and radiation efficiency. Hence, the excellent electromagnetic properties obtained in our investigation for the suitably sintered Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 ferrite shows a lot of potential to be used as a substrate material in miniaturizing microstrip antenna for futuristic electronic devices.