A microwave ablation cable assembly including a first coaxial cable having a first diameter, an inner conductor, an outer conductor and a dielectric formed between the inner and outer conductors, a second coaxial cable having a second diameter, and inner conductor, an outer conductor, and a dielectric formed between the inner and outer conductor, and a transition between the first and second coaxial cables having an inner conductor and outer conductor and a dielectric formed between the inner and outer conductors where the inner conductors of the first and second coaxial cables and the transition are in electrical communication and the outer conductors of the first and second coaxial cables and the transition are in electrical communication.
