Temperature distribution produced in models by three microwave applicators at 433.92 Megahertz

Temperature distributions produced in phantom models by diathermy applicators operating at a frequency of 433.92 MHz, a frequency not approved for diathermy by Federal Communication Commission regulations, and an experimental cooled contact applicator operating at an assigned frequency of 915 MHz were compared. The specially designed direct contact applicator with surface cooling elevated deep muscle temperatures as effectively as the 'Rundfeldstrahler' operating at the lower frequency in spite of the better penetration of the energy at the lower frequency. The 'Pyrodor' and the 'Langfeldstrahler', the largest of the applicators operating at 433.92 MHz, do not appear to offer any advantage over existing diathermy equipment. The highest temperatures produced with these applicators were at the fat muscle interface.