Hyperthermia treatment (HT) is a thermal treatment which uses non-ionizing electromagnetic radiation, like microwaves, to rise the temperature in the tumor region (where cells reach 42/44°C) creating tissue damage. Recent studies show that HT can sensitize cancer cells to both chemotherapy and radiotherapy treatments, increasing their efficacy without providing new dose exposition. During HT, it is crucial to limit the heating process only in the tumor site while maintaining the temperature values in the surrounding healthy tissues around the physiological level. For internal cancers, phased antenna arrays are properly designed to focus the electromagnetic radiation on the tumor region, avoiding hotspots, i.e., dangerous overheated regions far from the tumor site, which could be harmful especially in the treatment of head and neck (H&N) cancers.