A microwave ablation system configured for use in luminal network, comprising: a microwave energy source ; a microwave ablation catheter configured to receive microwave energy from the microwave energy source; an extended working channel configured to provide passage for the catheter; a locatable guide catheter having a distal tip including a position sensor positionable through the extended working channel and configured to navigate the extended working channel adjacent the target tissue ; and at least one imaging modality for confirming placement of the ablation catheter within target tissue; wherein the microwave ablation catheter comprises: a coaxial cable connected at a proximal end of the coaxial cable to a microwave energy source and at a distal end of the coaxial cable to a distal radiating section, the coaxial cable including inner and outer conductors and a dielectric positioned therebetween, the inner conductor extending distally past the outer conductor and in sealed engagement with the distal radiating section; and a balun formed in part from a conductive material electrically connected to the outer conductor of the coaxial cable and extending along at least a portion of the coaxial cable, the conductive material having a braided configuration and covered by at least one insulative material. a microwave energy source ; a microwave ablation catheter configured to receive microwave energy from the microwave energy source; an extended working channel configured to provide passage for the catheter; a locatable guide catheter having a distal tip including a position sensor positionable through the extended working channel and configured to navigate the extended working channel adjacent the target tissue ; and at least one imaging modality for confirming placement of the ablation catheter within target tissue; wherein the microwave ablation catheter comprises: a coaxial cable connected at a proximal end of the coaxial cable to a microwave energy source and at a distal end of the coaxial cable to a distal radiating section, the coaxial cable including inner and outer conductors and a dielectric positioned therebetween, the inner conductor extending distally past the outer conductor and in sealed engagement with the distal radiating section; and a balun formed in part from a conductive material electrically connected to the outer conductor of the coaxial cable and extending along at least a portion of the coaxial cable, the conductive material having a braided configuration and covered by at least one insulative material. a coaxial cable connected at a proximal end of the coaxial cable to a microwave energy source and at a distal end of the coaxial cable to a distal radiating section, the coaxial cable including inner and outer conductors and a dielectric positioned therebetween, the inner conductor extending distally past the outer conductor and in sealed engagement with the distal radiating section; and a balun formed in part from a conductive material electrically connected to the outer conductor of the coaxial cable and extending along at least a portion of the coaxial cable, the conductive material having a braided configuration and covered by at least one insulative material. <EOS>