Miniaturization of GPS patch antennas based on novel dielectric ceramics Zn(1−x)MgxAl2O4 by sol–gel method

Abstract

The need for miniaturization and weight reduction of GPS patch antennas has prompted the search for new microwave dielectric materials. In this study, a sol–gel method was used to prepare Zn(1−x)MgxAl2O4 thin films and fabricate GPS patch antennas at a low annealing temperature (700 °C). X-ray diffraction (XRD) patterns, field emission scanning electron microscopy images, Fourier transform infrared spectra, and optical band gap analyses confirmed the nanostructure of (Mg/Zn)Al2O4. The XRD patterns displayed the characteristic peaks of (Mg/Zn)Al2O4 with a face-centered cubic structure. Mg addition decreased the crystallite size, surface morphology, and lattice parameters of the resultant films, evidently affecting their density and dielectric constant (ɛ r ). Based on the material investigated and microwave antenna theory, GPS patch antennas were fabricated using Zn(1−x)MgxAl2O4 and then studied using a PNA series network analyzer. The fabricated patch antennas with different ɛ r ceramics decreased in size from 12.5 to 10.8 cm2. The patch antennas resonated at a frequency of 1.570 GHz and provided a return loss bandwidth between −16.6 and −20.0 dB; their bandwidth also improved from 90 to 255 MHz. The GPS patch antenna fabricated from Zn0.70Mg0.30Al2O4 showed an excellent combination of return loss (−20.0 dB), small size (10.8 cm2), and wide bandwidth (255 MHz). Therefore, addition of Mg improves antenna performance and decreases the dimensions of the device.