Hyperthermia is a cancer therapy that necrotizes cancerous tumors with heat. Functional Hyperthermia (soft-heating hyperthermia) is one type that implants small elongated elements inside the body. The element generates heat induced by a high-frequency magnetic field produced by exciting coils and is therefore a less-invasive method.
  The most heat is generated when the element's major axis is parallel to the direction of the incoming magnetic field. However, a single coil can be excited in a constant direction. Therefore, an exciting system to generate multidirectional magnetic fields is needed. We developed this exciting system using two coils and two frequencies. The combination of two frequencies and an easy way of estimating the heating value were examined. The profiles of various combinations of these two frequencies were measured and as a result, we found the heating value was much the same, if the sum of the two frequencies was the same. Using a single solenoid coil and the magnetic field of strain waveform enabled us to successfully of and easily estimate the heating value.