Zinc Aluminate-Based Composite Nanoparticles for Microwave Applications

This paper reports the sol-gel preparation of ZnAl₂O₄ (ZA) and ZnAl₂O₄-TiO₂ (ZAT) dielectric ceramic nanoparticles for fabricating prototype microstrip patch antennas. The prepared nanoparticles were polycrystalline in nature with their crystallite sizes of 9.4 and 11 nm, along with average grain diameters of 16 and 12 nm corresponding to samples ZA and ZAT. Dielectric properties were investigated using an LCR meter, which endorsed enhanced dielectric permittivity and decreased dielectric loss. Finally, prototype microstrip patch antennas named AZA and AZAT were fabricated using the prepared nanoparticles, and their performances were evaluated. Both antennas exhibited resonant peaks in the frequency range from 6.4 to 6.5 GHz. The antenna AZAT showed a return loss of -37.07 dB with a voltage standing wave ratio (VSWR) of 1.02 compared to the return loss of -19.42 dB, and a VSWR of 1.24 corresponds to AZA. The AZAT antenna's improved return loss can be regarded as the increased dielectric permittivity and reduced tangent loss of the ZAT sample. Furthermore, the ZAT antenna evidenced increased/decreased forwarded/reflected power decreased reflection coefficient and an optimal VSWR value compared to that of the AZA antenna.