Evanescent-mode applicators (EMA) for superficial and subcutaneous hyperthermia

Evanescent-mode waveguide aperture applicators are proposed for hyperthermic treatments of superficial and subcutaneous tissues. They consist of air-filled waveguide segments that work below the cutoff frequency and therefore support only evanescent transverse modes. These are excited by radiators of suitable symmetry and configuration to produce modal heating fields of selected cross-sections. This field emerges from the waveguide active aperture and enters the tissue to be heated through an air gap. These devices work in a very large range of frequencies and are extremely simple to manufacture, even with a variety of cross-section sizes and shapes, because of their air-filled feature. This enables good heating field flexibility with improved penetration to be obtained. Their operation is safe and practical also on irregular and curved tissue surfaces.