An MR-compatible printed Yagi-Uda antenna for a phased array hyperthemia applicator

Magnetic resonance (MR) thermometry guided hyperthermia has a strong potential to make the heat delivery to the tumor more selective. For head and neck hyperthermia, the Hypercollar was developed that allows focused, tumor-conformal, heating. To replace current dose assessment using invasive probes, an MR compatible Hypercollar is being designed. The conducting backplane of current patch antennas make MR imaging impossible. In this study, we developed a printed Yagi-Uda antenna for the 433 MHz ISM band that is inherently MR compatible. Proper design makes it very small in dimensions and allows it to work without a backplane. Parameter studies using simulation tools were performed to validate its properties under clinical conditions. Subsequently, a prototype was manufactured and reflection coefficient was measured and compared to simulations. Simulations and measurements show a good agreement and indicate that the antenna meets with the investigated specifications.