Radiation Hazard UHF band

1136-EX-ST-2013 Text Documents

BlackSky Global, LLC

2013-12-19ELS_144212

RKF Engineering Solutions, LLC 1229 19th St. NW, Washington, DC 20036 Phone 202.463.1567 Fax 202.463.0344 www.rkf-engineering.com Radiation Hazard Report – UHF-Antenna This report analyzes electro-magnetic non-ionizing radiation which would accompany the operation of the Black Sky UHF earth station antenna (manufactured by M2 Antenna Systems and known as Model 450CP34-Yagi) which will be used to uplink UHF signals to their two satellites. The antenna will be located at Tukwila, WA. where the site elevation is 15.9m AMSL. The antenna will be transmitting at UHF (435-455MHz). This report provides calculations which are used to determine the transmission power density in the “Far Field”, the “Near Field”, the “Transition Region” and nearby ground. Accordingly, we use the “Maximum Permissible Exposure” limits published by the FCC OET 65 Bulletin for the General Population/Uncontrolled Exposure and the limits for the Occupational/Controlled Exposure. The results of the calculations meet the FCC’s requirements. Far Field Analysis The calculation for the Far Field location includes the actual distance to where the far field begins, followed by a calculation of the power density at that location. Near Field Analysis The power flux density will be at its highest value the whole length of the Near Field area. We evaluate end of the Near Field, followed by the maximum power density in that area. Transition Area In the Transition area between the Near and Far Fields, the power density decreases inversely with the square of the distance. Area from the Antenna to nearby Ground The power density in this area will be determined by calculation of the nearby ground area. Conclusions The following page provides the details of each analyzed area. The results of the calculations demonstrate that the Black Sky UHF antenna will meet all required values of power density.

UHF Power Density UHF Power Inputs Units Calculations Density Units UHF Antenna diameter 2.54 m Far Field dist 5.80644 m UHF Gain 16 dBi On-Axis Power Density Far Field 0.939658941 W/m^2 39.8107170 UHF Gain 6 0.093965894 mW/cm^2 UHF EIRP 24.15 dBW Power UHF 8.15 dBW Near Field Dist 2.41935 m Frequency (UHF) 450 MHz Near Field Power Density 2.193577486 W/m^2 0.66666666 Wavelength UHF 7 m 0.219357749 mW/cm^2 0.27787552 Antenna efficiency UHF 9 Power in Watts 10 W Transition Dist 4.112895 m UHF Antenna Surface 5.06707479 Area 1 m^2 Transition Region Power Density 1.290339697 W/m^2 0.12903397 mW/cm^2 Antenna/Ground 1.973525241 W/m^2 0.197352524 mw/cm^2


Document Created: 2013-12-19 13:17:46
Document Modified: 2013-12-19 13:17:46
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