A microwave antenna assembly comprises a feedline (20) including an inner conductor (50), an outer conductor (56), and an inner insulator (52) disposed therebetween. A radiating portion (18) including a dipole antenna (40) is coupled to the feedline. An inner fluid feed member (106) is disposed around the outer conductor (56) in electro-mechanical contact therewith, the inner fluid feed member having a plurality of fluid lumens (107) defined therein. An outer fluid feed member (108) is disposed around the inner fluid feed member (106) in electro mechanical contact therewith, the outer fluid feed member having a plurality of fluid lumens (111) defined therein. A slidable outer jacket (102) is disposed about the radiating portion and the feedline.
