Abstract: By building the microwave cavity model, the tuning procedure for microwave cavity in the compact cesium atom clock was simulated by using Ansoft HFSS 12.0. There was the curve relationship between cavity resonance frequency and the length in the tuner microwave of the rod tuner. The result shows that, with increasing the length of rod tuner in the tuner microwave, the cavity resonance frequency is decreased, when the radius of rod tuner is a constant, and the length of rod tuner is changed within a certain range. With increasing the radius of rod tuner, the range of cavity resonance frequency is increasing, meanwhile the influence of length on the cavity resonance frequency is increasing at the transition frequency of cesium atom. We suggest the optimal radius of rod tuner on the basis of the result in order to provide the basis for the structure and principle analysis of cavity in compact cesium atom clock and theoretical guidance for the cavity design and manufacture.

Key words: Cesium atom clock, Microwave cavity, Resonance frequency, Simulation