Abstract: An anti-jamming antenna utilizing electromagnetic metamaterials is presented in this paper. The anti-jamming antenna consists of a rectangular waveguide cavity, electromagnetic metamaterials embedded in the bottom broad wall of the cavity and the radiating slots cut on the top broad wall. When the metamaterials perform as perfect electric conductor, the anti-jamming antenna radiates efficiently as a traditional waveguide slot antenna. When the metamaterials perform as perfect magnetic conductor, the anti-jamming antenna reject the propagation of electromagnetic wave in specified interference band, just like a band-stop filter does. The antenna structure is highly integrated with the filter structure for this anti-jamming antenna, so the presented antenna is compact. Simulated and measured results show that the proposed anti-jamming antenna has a good radiation performance in the working band while a strong suppression as high as 40 dB in the interference band.