Corona cage approaches are crucial for research on the corona characteristics of conductors. Calibration is an indispensable task for determining excitation functions, which are used to predict corona performance of long transmission lines through extrapolation from measurements of short lines in corona cages. In this paper, the amplification factor G is calculated through a frequently adopted method, propagation analysis of high-frequency corona current along a short line. Another convenient calibration method, based on distributed parameter equivalent circuits, is established. The results for G obtained through propagation analysis and equivalent circuits are compared. To verify the rationality of calculation parameters in propagation analysis and equivalent circuits, a calibration experiment based on the excitation caused by a simulated monopulse current was performed. The results of the proposed calibration method and the calibration experiment are in good agreement.