Interstitial 915 MHz microwave antennae employing helical slow wave structures

Flexible interstitial microwave antennas have been developed using helical slow-wave structures to produce controlled hyperthermia in deep-seated tumors. The antenna is composed of an optimized multipitch helical coil placed over the exposed Teflon-coated center conductor and soldered to both the center conductor at the tip and the shield. Unlike conventional dipole antennas, this structure is not insertion-depth sensitive, exhibits beyond the tip heating, and can produce controlled heating patterns of various lengths which do not extend to the skin surface. Active heating lengths of up to 12 cm have been produced to date.<>