A minimally invasive, coax-fed microwave ablation antenna with a tapered-slot balun

We present a coax-fed interstitial dipole antenna with a tapered-slot balun for minimally invasive microwave ablation (MWA). The balun is created using two tapered slots in the outer conductor of the feeding coaxial cable. This implementation allows for reducing the overall antenna diameter compared to coax-fed MWA antennas employing conventional coaxial baluns. The tapered balun connects the feed line to a dipole that consists of three segments. One segment is an extension of the inner conductor and constitutes one arm of the dipole. The other two segments are connected to the outer conductor of the coax cable and are located in the tapered slots; these segments constitute the second dipole arm. The tapered balun efficiently chokes the currents excited on the outer surface of the feeding cable and provides a good impedance match between the dipole and the feed line, as demonstrated by simulation and measurement results. The proposed antenna offers a less invasive alternative to conventional MWA antennas.