Novel temperature-stable ceramics for microwave dielectric resonators and microstrip substrates

Ceramics comprising homogeneous single-phase zirconate solid solutions of suitable composition have very low temperature coefficients of permittivity, low-frequency permittivities of 30¿40 and low losses. Dielectric resonators give Q values up to 4000 and permittivities of 28¿35 at 4¿5 GHz. The effective permittivity measured on a microstrip ring resonator on a calcium-zirconate substrate shows the dispersion predicted theoretically; the effective permittivity increases from 17 to 23 over the frequency range 1¿12 GHz and gives 28.1 as the calculated real value of the permittivity of the substrate. The measured Q value of 200 indicates negligible dielectric losses compared with the I2R losses.