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

• Published in: IEEE access Vol. 11; pp. 14667 - 14676
• Main Authors: Ganguly, Debarati, Dash, Jogesh Chandra, Sarkar, Debdeep
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ablation; Antenna design; Antenna measurements; Antenna radiation patterns; Antennas; Aspect ratio; Capacitors; Catheters; clinical modality; Design; Diameters; hyperthermia; Impedance; Impedance matching; Loaded antennas; Microwave ablation; Microwave antennas; Microwave measurement; miniaturized; Monopole antennas; Monopoles; Phantoms; reactive loaded; Thermal simulation; Transient analysis
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2023.3243642

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 (Design1), having length 30 mm (<inline-formula> <tex-math notation="LaTeX">\approx 0.24\lambda _{0} </tex-math></inline-formula> where <inline-formula> <tex-math notation="LaTeX">\lambda _{0} </tex-math></inline-formula> 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 (<inline-formula> <tex-math notation="LaTeX">\approx 0.04\lambda _{0} </tex-math></inline-formula>), showing nearly 83% size reduction compared to its former.Both the antennas are designed and simulated by immersing inside high permittivity egg white phantom (<inline-formula> <tex-math notation="LaTeX">\epsilon _{r} </tex-math></inline-formula> = 63.84). Antenna Design 1 and 2 exhibit good impedance matching (<inline-formula> <tex-math notation="LaTeX">{S_{11} < -12} </tex-math></inline-formula> 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.