Abstract A switched‐beam circular array with ultra‐wideband ridged horn elements is proposed in this letter. To obtain stable radiation patterns in a broadband as well as in a large coverage in the elevation plane, the electromagnetic fields in the ridged horn antenna are analyzed by the mode decomposition method. Based on the analysis, the rear of the ridged horn is cut. Besides, the ridge extension, out of the horn aperture, serves as a transformer from the horn to the free space for the downward radiation caused by the horn aperture asymmetry. The simulated results show that the circular array can obtain omnidirectional beam coverage in the range of θ  = 50°–100° from 2.2 to 5.9 GHz, with the S 11 below −10 dB and the gain higher than 5 dBi. The performance of the proposed antenna is validated by experiments.