  Electromagnetic metamaterials at microwave frequencies are well established
in industry and research. Recent work has shown how a specific kind of metallic
metamaterial can contribute towards improving the performance of the feedhorn
antennas used in radio astronomy and satellite telecommunications. In this
article, we justify this argument, finding an innovative type of meta-ring of
remarkable manufacturability with a potential to improve the state of the art
in these fields. A pioneering meta-horn antenna formed of meta-rings is then
fabricated and characterized in the laboratory, showing an excellent feature on
an octave bandwidth, especially in terms of cross-polarization, a key figure of
merit in both radio astronomy and telecommunications; and also side-lobe level,
return-loss and gain.
