Microwave coaxial antenna for cancer treatment: Reducing the backward heating using a double choke

In this paper, we focus on the so-called backward heating problem, which appears when coaxial-type antennas are used to treat certain types of cancers. The aim of this study is to reduce the surface currents propagating along the outer conductor of the antenna that lead to a higher Specific Absorption Rate (SAR) and overheat the healthy tissues. Our study shows that the use of a double-choke can lead to a lower SAR compared to the case of a single one. We also demonstrate that the use of a periodic structure does not help to further improve the SAR-level along the antenna.