Optimization of a dual concentric conductor antenna for superficial hyperthermia applications.

Dual concentric conductor antennas (DCCs) have been proposed as effective radiators for microwave hyperthermia applications, due to simplicity of construction from flexible printed circuit board (PCB) material. With proper design, the power deposition (SAR) pattern is uniform across the DCC. The effect of a single antenna can be combined in conformal nonphased arrays to form a region of nearly flat temperature distribution over a large area down to 1-1.5 cm depth. In the past, DCC antenna performance was analyzed using in-house FDTD software. Recently available electromagnetic simulation software provides reduced simulation time, increased accuracy and a user friendly interface with the ability to sweep design parameters to achieve critical optimization goals. More detail on antenna loading conditions provides enhanced design accuracy by accounting for second order effects neglected in previous modeling. In particular, recent design efforts have focused on improving antenna efficiency and reducing losses and reflections in the feedline network. A second challenge involves measurement of antenna properties in conditions more similar to the treatment environment, since temperature and loading condition affect antenna radiation and thus design requirements. We present the challenges of both antenna design and characterization, along with preliminary results of recent design improvements.