Connected FORA Array Antenna Grouping for Cost Efficiency: Study on Microwave Breast Hyperthermia

In microwave hyperthermia (MH) cancer treatment application, antenna arrays selectively heat cancerous cells to a temperature higher than the body's normal temperature. The administered heating relies on the optimal antenna feeds that maximize the specific absorption rate (SAR) inside the tumor. This paper investigates the heat-focusing performance of grouping the phase and/or amplitude of vertically aligned antenna elements, using 2D PSO optimization. The numerical MH system includes a three-dimensional MRI breast model and a connected array as the MH applicator. The array's structure is curved and it consists of 3 layers and 39 elements ( $3\times 13$ ), which are capacitively coupled fractal octagonal rings (FORA). The results show that the phase parameters need to be individually optimized for superior focusing. Grouped antennas' amplitude optimization provides comparable performance to the individual antenna amplitude optimization. To conclude, using the sub-arrays approach in relation to the amplitude of the antenna array can significantly decrease the number of freedom in the system and the RF background cost, without compromising on performance.