On the Performance of a Miniaturized Reactive Loaded Monopole Antenna for Ex Vivo Catheter Applications

Abstract

In this paper, we propose a miniaturized series L-C loaded monopole antenna for catheter application in microwave ablation systems. Initially, a quarter wavelength long monopole antenna (De-sign1), having length 30 mm (≈ 0.24λ 0 where λ 0 represents the free-space wavelength at 2.4 GHz operating frequency) using series LC loading concept is designed. The initial design is further extended to a miniaturized version (Design2) having length 5 mm (≈ 0.04λ 0 ), showing nearly 83% size reduction compared to its former.Both the antennas are designed and simulated by immersing inside high permittivity egg white phantom (ϵ r = 63.84). Antenna Design 1 and 2 exhibit good impedance matching (S 11 < −12 dB) at and around the operating frequency with uniform monopolar radiation pattern having co-to-cross isolation of nearly 30-35 dB. Further, the in-phantom Specific Absorption Rate (SAR) values for both antennas are evaluated using simulation and verified with the measured SAR values such as 22 W/kg and 19.6 W/kg for Design1 and 2 respectively, using an in-house experimental setup. Moreover, the microwave ablation property of the proposed antennas is studied using simulated transient thermal gradient which translates to ablation zone formation. Here, Design 2 shows the advantage of having a low invasive diameter of 1.5 mm and near unity aspect ratio (AR) for the ablation zone as compared to Design1.

Radio frequency hyperthermia system for skin tightening effect by filled waveguide aperture antenna with compact metamaterials

“…Table 1 presents a comparison between the proposed method and other methods. In the invasive method discussed in ( Ganguly et al, 2023 ), low power was utilized for deep tumor hyperthermia; however, it required a significant amount of time to increase the temperature, which posed a risk to the patient. The noninvasive method discussed in (choi et al, 2014) also employed low power for shallow tumors and reduced the RF effective area by minimizing the radiator size using a meander line.…”

“…Previous studies on radio frequency (RF) hyperthermia therapy have focused on cancer ablation using both invasive methods ( Chiang et al, 2021 ; Kp and Arunachalam, 2022 ; Wang et al, 2022 ; Ganguly et al, 2023 ; Kp and Arunachalam, 2023 ) and noninvasive methods ( Choi et al, 2014 ; Hajuagmadi et al, 2022 ; Mahmoud and Montaser, 2022 ). Most of these studies aimed at generating heat to ablate cancer cells.…”