Research on frequency-temperature compensated sapphire-SrTiO3 loaded cavity for hydrogen maser

To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO
3
is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TEoll mode of a sapphire loaded cavity associated with two small rings of SrTiO
3
with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SrTiO
3
dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from −58.8 kHz/K to −8.2 kHz/K and the quality factor is 40248.