A light, thin and flexible applicator using a microstrip patch array for microwave heating is presented and tested in this work. The applicator is made of a flat silicone rubber bag, inside of which flows cooling water. EM coupling feeding is applied, which has no direct contact between the feed and the patch, to improve durability and reliability when it is repeatedly applied to the uneven surface of the heated portion of the human body. Simulations of SAR distribution are performed using the finite difference time domain (FD-TD) method. Simulated data are compared with the experimental ones using cubic and cylindrical phantom models with single and multielement patch applicators. Simulations of temperature distribution are also performed using the heat transfer equation. Simulated data are compared with the experimental ones using cubic and cylindrical phantom models. The simulated results agree well with the experimental ones. The results obtained here show that the multielement flexible microstrip patch applicator which operates at 430MHz can heat a relatively shallow and widespread area on the human body for hyperthermia treatments.

A semicylindrical microstrip applicator system is proposed and designed, both for microwave heating and for noninvasive temperature estimation, in application to hyperthermia treatment. The experimental results showed that the system functions both as a heating device and as a means of noninvasive temperature estimation. Therefore, electrical switching of these two functions makes the system realize both heating and temperature estimation. These functions reduce the pain of hyperthermia therapy for patients. The system is constructed of a water-loaded cylindrical applicator. Thus, the whole system can be made compact compared to conventional applicators. This improvement allows for various merits, such as realizing a surface cooling effect and decreased leakage of electromagnetic (EM) waves. When the applicator is set as an array arrangement, the system can be used as a microwave heating device. The penetration depth can be varied by adjusting phases of the EM wave radiated from each applicator. The experimental results at 430 MHz showed that semicylindrical microstrip applicators can be expected to be valid for tumor heating at depths within 55 mm. Moreover, by measuring transmission power between the two applicators, the system can be used to estimate temperature inside the medium. The transmission power which was measured in the frequency domain was converted in the time domain. By such a method, temperature distribution was calculated by solving simple simultaneous primary equations. The results of the temperature estimation show that the number of estimated temperature segments which have an error within 0.5 is 28 out of 36. The system can be easily used as a temperature measuring applicator as well as a heating applicator.