The Active Denial System (ADS) uses a beam of millimeter wave (MMW) energy at approximately 95 GHz to induce intolerable heating in the superficial layers of the skin that motivates the targeted subject to escape the beam (repel). At 95 GHz, the penetration depth has been calculated to be approximately 0.3 mm, and thus most of the MMW energy absorption in animals and humans will occur in the skin and cornea. This is significant for the ADS because many of the free nerve endings, which are thought to signal pain and thermal sensation, are located in approximately the first 0.2 mm of the cornea and 0.6 mm of the skin. This fact was key to the development of the ADS bioeffects research plan. The research path used to investigate the safety, efficacy, and utility of the ADS was a deliberate, synchronized line of investigation answering fundamental applied bioeffects questions. The five research areas investigated were (a) eye safety and vision; (b) the risk of thermal injury to the skin; (c) altered pain responses; (d) cancer, fertility, and the risk of birth defects; and (e) whole-body exposures under field conditions. The bioeffects research supports the conclusion that, when used as intended, ADS exposure presents a minimal risk of injury and is effective at producing repel responses. An independent blue-ribbon panel, organized by Pennsylvania State University, reviewed the research plan and subsequent results three times over the course of the program to validate its technical quality and relevance.
KEYWORDS: Active Denial System, Bioeffects, Safety margin, Repel, Eyes, Skin, Fertility

This article summarizes the results from a study on the perception of 94-GHz millimeter wave (MMW) energy by human subjects. The research explored the impact of ambient environmental conditions on MMW energy perception in 10 subjects. The environmental manipulations (ambient air temperature and relative humidity) impacted perspiration during the MMW energy exposures: Local sweating rate differed significantly across the four temperature and humidity combinations. Yet, the four conditions resulted in only a 1% variance in subject estimation of pain threshold. The overall mean estimate of 1241.7 mW/cm² conforms to previous laboratory studies conducted at a fixed environmental setting.
KEYWORDS: Active Denial System, Millimeter wave, Pain threshold, Environmental effects

The Air Force Research Laboratory, 711th Human Performance Wing, Airman Systems Directorate, Bioeffects Division, Radio Frequency Bioeffects Branch has conducted numerous studies intended to safely exploit millimeter wave (MMW) radio-frequency radiation (RFR). Individuals exposed to a MMW beam quickly experience intolerable pain that elicits flight/escape behavior. In situations where potential targets have consumed alcohol, the Air Force needed to examine whether alcohol intoxication impacts the subject response. In the present study, each of nine experimental subjects consumed alcohol and received facial exposures to 94-GHz RFR at three blood alcohol levels (BALs): 0.00, 0.08, and 0.12%. Subjects' faces were exposed five times to each of four energy densities: 0.0, 0.6, 1.0, and 1.4 J/cm². The presence or absence of eye blinks and face averts during exposures was recorded. Skin temperature and aversion response latencies were determined using infrared video records of subject exposures. Although subject BAL during MMW exposures was associated with some statistically significant differences in facial aversion scores, these differences were small in magnitude and their existence probably does not imply that alcohol intoxication substantially alters the degree of effectiveness or the safety margin associated with systems employing MMWs.
KEYWORDS: Active Denial System, Millimeter wave, Alcohol, Intoxication, Pain

The objective of this experiment was to determine the effects of the Active Denial System (ADS) on persons in vehicles and to assess the potential usefulness of the ADS in a vehicle stopping scenario. Experiment 1 measured the time to reaction following ADS exposure onset in a static scenario. Experiment 2 measured the distance at which the vehicle was stopped or steered away from a goal area following ADS exposure onset in a moving vehicle scenario. Additionally, the driver's reaction to the ADS stimulus was measured qualitatively. Overall, the ADS was found to be effective in scenarios where an adequate dose could be delivered (i.e., head-on, lower vehicle speeds, and lower attenuating windshields).
KEYWORDS: Millimeter waves (MMWs), Motor vehicles, Active Denial System (ADS)

This study investigated the effects of 94-GHz exposure on the reproductive organs of the male Sprague Dawley rat (N=120). The scrotal region of each rat (N=36 per group) was sham exposed or warmed by exposure to 94-GHz or infrared (IR) energy. Additionally, 12 other rats had their scrotal regions warmed by warm water immersion to serve as positive control. Each rat in the 94-GHz group was individually restrained in a cylindrical Plexiglas holder and exposed for 10 s at 1 W/cm². Similar surface heating rates were produced by exposure to IR for 10 s at 1.5 W/cm². Blind analyses of sperm motility and morphology (sampled from vas deferens) and sperm production rates (sampled from testes and epididymides) were conducted 6.5, 26, and 52 days post exposure. There were no significant differences among the sham, 94-GHz, or IR exposed animals with respect to sperm production and motility. Morphometric measurements of sperm did not show significant differences among the sham, 94-GHz, and IR exposure groups. Thus, exposure of the scrotal region of Sprague Dawley rats to 94 GHz (10 J/cm²) did not significantly affect sperm production, morphology, or motility.
KEYWORDS: Active Denial System, Millimeter wave, Sperm production, 94-GHz millimeter wave (MMW), Reproduction

This study extrapolates the dose-response relationship for millimeter wavelength radiation-induced thermal injury from previously obtained rodent data to a larger animal model. Based on exposure conditions that cause damage in rats, exposure conditions were chosen that would most likely cause more than superficial burn damage in pig skin (power densities of 2-4 W/cm² and durations of 3-20 s). However, due to structural differences (relative thickness of tissues and density of hair follicles) between rat and pig skin, direct interspecies correlations of burn data are not likely to have statistical significance. Twelve Yucatan mini-pigs were used in this study to establish the probability of developing first- and second-degree burns versus exposure duration at three power density settings (2, 3, and 4 W/cm²) and versus the rise in the mean skin temperature over the exposed area. Additionally, the study examines the effects of repeated exposures to an area, and the time required between exposures to return to pre-exposure temperatures. The results of the study indicate that the damage to the skin from the millimeter wave exposures is a purely thermal effect.
KEYWORDS: Active Denial System, Skin burn threshold, Millimeter wave, Radio-frequency (RF) injury

This article describes the use of carbon-loaded Teflon (CLT) as a dosimeter for 94 GHz millimeter wave (MMW) radiation. The fundamental principle underlying the applicability of CLT as a MMW dosimeter is that the rate of the temperature rise of CLT sheet is proportional to the incident MMW power density. By calibrating the temperature to the power density response of the CLT to a National Institute of Standards and Technology (NIST) traceable power meter coupled to WR-10 open-ended waveguide, field measurements of 94 ± 2 GHz radiation using CLT can be made to within 2.2% of the NIST power meter over the range of 0.5 to 12 W/cm². Additionally, using a sufficiently large CLT sheet enables one to obtain information about the beam shape and observe any interference effects in the region of interest. Alignment of the sheet relative to the beam path is significantly less critical than measurements using an open-ended waveguide. These characteristics are highly desirable for biological experiments involving MMW exposures and make CLT a useful dosimeter for our laboratory.
KEYWORDS: MMW dosimetry, CLT, Active Denial System, power density, beam shape, 94 GHz