Abstract: Monopulse tracking is widely used in tracking middle or low orbit satellite communication antenna. The cutoff frequency and the voltage maximum position of the differential mode of the single-slot corrugated horn is studied. Based on the differential mode signal, an L/S dual-band corrugated horn with monopulse tracking ability in L-band is designed. The measured results demonstrate that the horn has good matching performance and symmetric radiation pattern in L/S band. Besides, the differential signal coupled from the corrugated horn is able to fulfill the monopulse tracking in L-band. It is indicated that the corrugated horn antenna satisfies the requirements in application.