Magneto Tuning of a Ferrite Dielectric Resonator Antenna Based on LiFe5O8 Matrix
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LiFe5O8 (LFO) spinel-like material has been studied for use in ferrite resonator antennas (FRAs). Antenna parameters such as gain and return loss were greatly affected when an external magnetic field was applied to the FRA. The temperature coefficient of the resonant frequency (τ f ) for the FRA presented a value of − 482.16 ppm/°C. The magnetic hysteresis results showed that the LFO was a soft ferrite, considering the values of the remanent magnetization (Mr = 5.95 emu g−1), coercive field (0.76 mT), and saturation magnetization (32.15 emu g−1). The magnetodielectric resonator presented a tuning effect in the resonant frequency as a function of the external magnetic field. The antenna bandwidth was also affected by the presence of the magnetic field. LFO is a soft ferrite with applications in microwave circuits, antennas, and devices for operation at microwave frequencies due to its magnetization and demagnetization properties. Impedance study revealed increasing conductivity from room to higher temperature with low activation energy (0.36 eV).
KeywordsFRA LFO hysteresis spectroscopy impedance τf
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Financial support from the Brazilian Agency for Scientific and Technological Development CAPES and the US Air Force Office of Scientific Research (AFOSR, FA9550-16-1-0127) is gratefully acknowledged.
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