An ablation device, comprising a feedline including an inner conductor having a distal end, an outer conductor coaxially disposed around the inner conductor, and a dielectric material disposed between the inner conductor and the outer conductor, a dielectric layer coaxially disposed around at least a portion of the outer conductor and extending distally beyond a distal-most end of the inner conductor, and a first balun disposed around at least a portion of the outer conductor and including an electrically-conductive layer coaxially disposed around a proximal portion of the dielectric layer.
