A microwave cavity with low temperature coefficient for passive rubidium frequency standards

Cavity pulling effect has been fully considered in designing of various atomic frequency standards, but quite often it has been neglected for passive rubidium atomic frequency standards (RAFS). This situation may be acceptable for the commonly used RAFS but it is less so for high performance one. A new type of microwave cavity with low temperature coefficient (TC) was designed with coefficient of 28.2 kHz/°C, which is positive and nearly one order smaller than that of the traditional TE₁₁₁ cavity. Analyses show that the cavity pulling effect of the cavity can be neglected under reasonable temperature stabilization condition. The main cause of the small TC of the cavity was discussed, which is due to the compensation of the positive TC of the dielectric ring in the cavity to the negative TC of the metal part of the cavity