A system for tissue ablation comprises a microwave antenna (110), a microwave energy generator (420) coupled to the microwave antenna and configured to generate microwave energy and an impedance matching network (300) coupled between the microwave antenna and the microwave energy generator to compensate for a difference in the impedances of the tissue and the generator. The matching network includes a series inductor (313) having an input (303) coupled to the generator and an output 9305) coupled to the antenna. A series arrangement of a first capacitor (321) and a first tuning diode (310) is coupled to the input of the series inductor (313). A first inductor (314) hasing an input coupled to a first DC input (307) and an output connected between the first capacitor (321) and the first tuning diode (310).A series arrangement of a second tuning diode (311) and a second capacitor (322) is coupled to the output (305) of the series inductor (313). A second inductor (315) has an input connected to a second DC input (309) and an output coupled between the second capacitor (322) and the second tuning diode (311).