A microwave ablation system for treating tissue includes at least first and second antennas, a microwave output stage, and a sensor component. The at least first and second antennas are adapted for insertion into tissue. The microwave output stage is adapted to generate microwave energy and is operatively coupled to at least the first antenna to transmit the microwave energy into the tissue. The sensor component is operatively coupled to the first and second antennas and operatively monitors the microwave energy therebetween.