Microstrip Dielectric Patch Antenna Fabrication and Characterization Using Ultra Low Permittivity and Low Temperature Co-Fired LiAlSiO4 Ceramics

LiBxAl1-xSiO4 (x = 0.02 to 0.1) ceramics were prepared by conventional solid-state method with a reduction in sintering temperature by up to 250-475 oC. The relative permittivity was significantly decreased by εr = 3.3-3.7, one of the lowest ever reported values among crystalline ceramics, while maintaining exceptional quality factors (Q×f = 25,000-28,000 GHz) and low temperature coefficients of resonance frequency (τf = -23 ~ -16 ppm/oC). Furthermore, these LiBxAl1-xSiO4 ceramics possess a low density (~2.3 g/cm3), making them highly promising for lightweight microwave devices. The potential application of LiB0.1Al0.9SiO4 ceramics in LTCC was assessed based on their ability to achieve low densification temperature and exhibit chemical compatibility with silver electrodes. A microstrip patch antenna with an operating frequency of 6.68 GHz, featuring high efficiency (91.88%) and wide bandwidth (400 MHz), has been designed and fabricated from LiB0.1Al0.9SiO4 ceramics substrate, which provides a good application prospect for advanced wireless systems. The development of these ultra-low permittivity dielectric ceramics opens new potential to revolutionize the field of microwave dielectric ceramics.