title: Thresholds of microwave-evoked warmth sensations in human skin.
abstract: We measured thresholds for microwave-evoked skin sensations of warmth at frequencies of 2.45, 7.5, 10, 35, and 94 GHz. In the same subjects, thresholds of warmth evoked by infrared radiation (IR) were also measured for comparison. Detection thresholds were measured on the skin in the middle of the back in 15 adult male human subjects at all microwave (MW) frequencies and with IR. Long duration (10-s), large area (327-cm2) stimuli were used to minimize any differential effects of temporal or spatial summation. Sensitivity increased monotonically with frequency throughout the range of microwave frequencies tested. The threshold at 94 GHz (4.5 +/- 0.6 mW/cm2) was more than an order of magnitude less than at 2.45 GHz (63.1 +/- 6.7 mW/cm2), and it was comparable to the threshold for IR (5.34 +/- 1.07 mW/cm2).
authors.affiliation: Systems Research Laboratories, Inc., Brooks AFB, Texas 78235, USA. blick@rfr.brooks.af.mil
authors.forename: D W
authors.initials: DW
authors.lastname: Blick
authors.forename: E R
authors.initials: ER
authors.lastname: Adair
authors.forename: W D
authors.initials: WD
authors.lastname: Hurt
authors.forename: C J
authors.initials: CJ
authors.lastname: Sherry
authors.forename: T J
authors.initials: TJ
authors.lastname: Walters
authors.forename: J H
authors.initials: JH
authors.lastname: Merritt
mesh_terms: D000328:Adult; D004307:Dose-Response Relationship, Radiation; D006358:Hot Temperature; D006801:Humans; D007259:Infrared Rays; D008297:Male; D008872:Microwaves; D008875:Middle Aged; D012684:Sensory Thresholds; D012867:Skin / Q000528:radiation effects*; D012879:Skin Physiological Phenomena; D013997:Time Factors