An ablation catheter with an anchoring tip extension includes an elongated flexible tubular member adapted to be inserted into a vessel in the body of a patient. A transmission line is disposed within the tubular member, and a transducer is coupled to the transmission line for generating an electric field sufficiently strong to cause tissue ablation. An anchoring tip extension, which is located at the distal end of the catheter, lodges into the wall of a cardiac chamber and serves to anchor the catheter both during an ablation procedure and during the process of conforming the catheter to the wall. In one preferred embodiment, the catheter includes a shape memory wire. In another embodiment, the transmission line of the catheter is a co-axial cable, and the transducer is a helical antenna coil that is adapted to radiate electromagnetic energy in the microwave frequency range. Methods for manufacturing and using such ablation catheters are also described.