Study on microwave dielectric properties of corundum type (Mg1−xCox)4Ta2O9 (x=0−0.6) ceramics for designing a microwave low pass filter

This paper reports the study of structural, morphological and microwave dielectric properties of (Mg1−xCox)4Ta2O9 (x=0-0.6) ceramics, sintered at 1300-1400 °C. The grown samples were characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Microwave dielectric properties of these samples were investigated using the TE01δ dielectric resonator method. Our study shows that the dielectric properties are strongly dependent on the compositions, densification and micro-structure of the specimens. Out of these compositions, (Mg0.7Co0.3)4Ta2O9 shows near zero τf with a dielectric constant ϵr~13.79 and a quality factor Qf~56,876 GHz (measured at 8.93 GHz). On a substrate made up of this ceramic, a low pass filter of 2.6 GHz cut-off was simulated using Sonnet Lite software and then fabricated. The measured results show a reasonably good agreement with the simulated results. This dielectric shows ~68% size reduction as comparison to FR4 substrate for the same filter design.