Comparison of simulated and experimental results from helical antennas within a muscle-equivalent phantom

Miniature microwave helical antennas for use in thermal therapy applications are usually investigated using muscle-equivalent phantoms. In this paper, an alternative method using an electromagnetic solver based on the finite integration technique is used to simulate a range of 915 MHz helical antennas within a medium with the dielectric properties of muscle. By avoiding the stair-casing effect associated with many solvers, this method enables accurate simulations of non-orthogonal geometric objects such as helical antennas to be achieved. The effects of coil-spacing and insertion depth on the SAR distribution produced by the antennas were characterized and showed good agreement with previously published results obtained using a muscle phantom and a thermographic camera. The simulations confirm that the performance of helical antennas depends on insertion depth. Modification of the coil density demonstrated improvement of the return loss characteristics and changes to the resulting SAR profile.