Ex-Vivo Performance of A Multiband Catheter Antenna Suitable for Percutaneous Tumor Ablation at 2.4 GHz

A multiband reactive loaded quarter-wavelength monopole antenna designed as a catheter applicator working at and around ISM bands with center frequencies at 1.38 GHz, 2.4 GHz, and 5.2 GHz is proposed herein for microwave ablation of superficial and deep-seated tumors. The design, conceived from the standard techniques of series inductive or shunt capacitive loading of monopole antenna for better impedance matching, has been improvised herein for high permittivity percutaneous applications for providing flexibility and tunability in catheter antenna design. It comprises a quarter wavelength monopole
$(L=\lambda/4=30\ \mathbf{m} \mathbf{m})$
loaded with a helical coil and a parallel plate capacitor connected in series and this whole ensemble is enclosed in a biocompatible parylene catheter tube
$(\epsilon_{r}=3)$
. The series reactively loaded catheter antenna portrays a peak gain varying over 1.38-2.25 dBi with uniform monopole type radiation at all the aforesaid frequencies of operation thereby producing a spheroid ablation zone intended to ablate near spherical hepatic and renal tumors.