A Microwave Ablation Antenna Based on Substrate-Integrated Coaxial Line

This letter presents a planar, low-cost microwave ablation antenna operating at 2.45 GHz with the minimal cross-sectional area. The proposed antenna can produce local spherical ablation zones by double dipole structure, which is fed through substrate-integrated coaxial line (SICL) without a balun. The input impedance of the double dipole structure, which is in fact extensions of the outer and inner conductors of the SICL, is very low. SICL is mismatched with the double dipole structure when designed as the smallest cross-sectional area. Impedance matching is achieved through a microstrip line cascaded with SICL. A prototype of the antenna is fabricated and the measured results show good agreement with the simulations. An ablation experiment in the porcine liver tissue confirms the capability of the antenna with the minimal cross-sectional area in generating localized ablation zones. The proposed antenna can be manufactured through mature and cheap printed circuit board technology, serving as a promising commercial candidate for minimally invasive ablation.