Effects of Variable Spot Size on Human Exposure to 95 GHz Millimeter Wave Energy

Abstract : The report documents two studies that were conducted to quantify human behavioral responses to 95-GHz millimeter wave (MMW)exposures employing differing beam sizes and power densities. Previously, the speed of the repel response was found to be dependentupon the power density and spot size on the target, but the exact form of this function was unclear. To provide clarity of the repeleffect function, we investigated two experimental paradigms. Experiment 1 examined the repel times of stationary subjects atcombinations of three MMW power densities and five spot sizes. Experiment 1 results confirmed that repel times decreased withincreasing beam size, although the strength of this relationship varied with power density. Experiment 2 investigated the extent towhich the Experiment 1 relationships between beam size and repel time could be extrapolated to moving subjects. Subjects wererequired to throw balls into a net while being targeted by the MMW beam. Results indicated similar performance at the four largestspot sizes tested, and better subject activity performance (i.e., decreased MMW effectiveness) at the smallest spot size.