Abstract: A novel antenna operating at two very different frequencies based on high-order mode of circular ring slots has been proposed. The antenna is realized by loading two closed circular ring slots on two arms of bow-tie antenna respec- tively. Fundamental mode of circular ring slots usually obtained by loading opened circular ring slots, while high-order mode is obtained by using closed circular ring slots. By using high-order mode of circular ring slots, two very different frequencies are realized and the performance at high frequency is insured. For the antenna, the frequency ratio can be more than 3:1. Both simulation and experiment show that the proposed antenna has good performance. Through the development of the novel antenna, the kind of multi-band antenna is enriched, and a feasible structure and method is provided for realizing high performance antenna at two very different frequencies.