Abstract: A microwave antenna suitable for cardiac ablation, in particular for catheter ablation, and a method for making such an antenna. The antenna comprises a transmission line having an inner conductor, an outer conductor, and a dielectric insulator to provide insulation between the inner and outer conductors. An energy emitting antenna element is located at the distal end of the transmission line. The antenna element has an inner conductor which is electrically coupled to the inner conductor of the transmission line, and, around the inner conductor, a sheath of dielectric insulator continuous with the insulator of the transmission line. At its distal end, a hollow metallic cap is electrically connected to the inner conductor, surrounding a length of the insulator.