Abstract: Examples of a probe for microwave ablation are disclosed. The probe comprises a feed coaxial cable and an antenna that has a cylindrical outer housing with a predetermined diameter and a predetermined length defining a cavity therein and a radiating conductor positioned within the cavity with a matching stepped portion. The antenna further comprises a dielectric material placed in the cavity between the radiating conductor and the outer housing of the antenna to increase the mechanical strength of the probe as well as to improve the power coupling to the tissue to be ablated. The design of the coaxial cavity of the antenna with radiating conductor with a stepped portion fitted into dielectric materials increases antenna's mechanical strength to withstand higher temperatures and reduces an energy reflected back to the feed coaxial cable due to a good impedance match between the antenna and the feed cable such that antennas with smaller length can be used to fit curved paths.