Design of a small sapphire loaded dielectric cavity for a space-borne hydrogen maser

Abstract

For a space-borne hydrogen maser frequency standard, it is severely required to reduce the size and weight without degrading its excellent frequency stability. To meet these requirements, a small sized microwave cavity with high quality factor is necessary. In this paper, TE₀₁₁ mode of a small sapphire loaded dielectric cavity for a space-borne hydrogen maser is analyzed and its design principle is discussed. The analysis shows that the frequency stability is optimized when the ratio of the outer diameter of the dielectric tube to the inner diameter of the cavity cylinder is about 0.5. The weight of the physics package is minimized when the diameter and the height of the cavity cylinder are equal to each other. The diameter or the volume of the cavity cylinder is determined by the frequency stability required in the application program.