Attachment RadiationHazardStudy

This document pretains to SES-LIC-20100723-00952 for License on a Satellite Earth Station filing.

IBFS_SESLIC2010072300952_830973

E Engineering Report O3b Networks USA, LLC GND-023 8900 Liberty Circle 10 Jun 2010 Englewood, CO 80112 REPORT TITLE: Non-Ionizing Radiation Hazard Analysis PREPARED BY: DATE APPROVED BY: DATE Gary Mattie 10 Jun 2010 Jay Bloom 10 Jun 2010 SCOPE/TEXT (ATTACH ADDITIONAL SHEETS AS REQUIRED) This report analyzes non-ionizing radiation levels for O3b’s 7.3m MEO earth stations. Calculations are performed in accordance with FCC Office of Engineering and Technology’s “Bulletin No. 65 Edition 01-01 Supplement C” with regard to the frequencies and antenna types being used. Maximum Permissible Exposure (MPE) limits at O3b uplink frequencies include two exposure situations with limits as described below. General Population/Uncontrolled Exposure (MPE), averaging window of 30 minutes or less: 1500-100,000 (MHz) = 1.0 mW/cm² Occupational/Controlled Exposure (MPE), averaging window of 6 minutes or less: 1500-100,000 (MHz) = 5.0 mW/cm² This analysis compares MPE limits to the calculated power flux densities at the antenna feed, subreflector surface, main reflector surface, between the edge of the main reflector and the ground, near-field region, transition region, and the beginning of the far field. The results of the analysis is a summary table which describes the power flux densities at key locations and the strategy for limiting General Population and Occupational exposure. Non-Technical Data. Authorized for Export. DISTRIBUTION B. Holz J.Mowat J. Bloom K.Mentasti S. Blumenthal G.Mattie M. Carpenter Non-Technical Data. Authorized for Export. 1 of 6

E Engineering Report O3b Networks USA, LLC GND-023 8900 Liberty Circle 10 Jun 2010 Englewood, CO 80112 1 Formulas and Parameters Used The following data is used throughout the analysis: Parameters Symbol Value Units Notes/Formulas Transmit Power¹ P 447.23 W RH traffic + LH traffic + LH CMD (TT&C) Frequency F 29089 MHz Wavelength λ 0.010 m 299.792458 / F Antenna Diameter Dref 7.300 m Antenna Surface Area Aref 41.854 m² π Dref² / 4 Subreflector Diameter Asub 0.610 m Subreflector Surface Area Asub 0.292 m² π Dsub² / 4 Feed Flange Diameter Dflange 0.137 m Viasat spec Feed Flange Area Aflange 0.015 m² π Dflange² / 4 Antenna Gain Ges 65.66 dBi Viasat Data Antenna Gain G 3681289.736 10^(Ges / 10) Antenna Efficiency η 0.743 G λ² / π² Dref² Pi π 3.142 Note 1: Each of the three uplink paths has a dedicated 500W TWT amplifier and associated amplifier-to-feed losses; the “Transmit Power” indicated is the total RF power at the flange with all three amplifiers operating at maximum drive levels. 2 Density at Feed Flange The maximum power flux density at the surface of the Cassegrain feed flange is as follows: Parameters Symbol Value Units Notes/Formulas Density @ flange 121355.623 W/m² 4 P / Aflange Sflange 12135.562 mW/cm² 3 Density at Subreflector The maximum power flux density at the surface of the Cassegrain subreflector is as follows: Parameters Symbol Value Units Notes/Formulas Density @ subreflector 6121.268 W/m² 4 P / Asub Ssub 612.127 mW/cm² Non-Technical Data. Authorized for Export. 2 of 6

E Engineering Report O3b Networks USA, LLC GND-023 8900 Liberty Circle 10 Jun 2010 Englewood, CO 80112 4 Density at Main Reflector The maximum power flux density at the surface of the main reflector is as follows: Parameters Symbol Value Units Notes/Formulas Density @ Main Reflector 42.742 W/m² 4 P / Aref Ssurface 4.274 mW/cm² 5 Density Between Main Reflector and Ground The maximum power flux density in the area between the edge of the main reflector and the ground is as follows: Parameters Symbol Value Units Notes/Formulas Density, Main Reflector/Ground 10.686 W/m² P / Aref Sground 1.069 mW/cm² 6 Density within the Near Field The Near Field environment for a parabolic reflector antenna is contained within a cylinder with the same diameter as the main reflector which extends to a distance called the Near Field Extent. Power within the Near Field is constant with the following maximum flux density: Parameters Symbol Value Units Notes/Formulas Range to Near Field Extent Rnf 1292.688 m D² / 4 λ Density within the Near Field 31.776 W/m² 16.0 η P / π D² Snf 3.178 mW/cm² 7 Density at Transition Region The Transition Region is the area between the Near Field and Far Field regions where power decreases linearly with distance. The maximum power flux density within the Transition Region is located at the Near Field extent range and is calculated as follows: Parameters Symbol Value Units Notes/Formulas Range to Transition Region Rt 1292.688 m Occurs at near field extent Density @ Transition 31.776 W/m² Snf Rnf / Rt Snf 3.178 mW/cm² Non-Technical Data. Authorized for Export. 3 of 6

E Engineering Report O3b Networks USA, LLC GND-023 8900 Liberty Circle 10 Jun 2010 Englewood, CO 80112 8 Density at Beginning of the Far Field The Far Field region is the range at which power decreases inversely with the square of the distance. The maximum power flux density within the Far Field region occurs at the Far Field Boundary and is calculated as follows: Parameters Symbol Value Units Notes/Formulas Range to Far Field Boundary Rff 3102.452 m 0.6 D² / λ Density @ Far Field Boundary 13.612 W/m² P G / 4 π Rff² Sff 1.361 mW/cm² 9 Range to Far Field General Population Exposure Limit In addition to the power flux density calculations at key locations, it’s valuable to locate the specific range at which MPE limits are reached to aid in managing exposure control. The following calculation show the range at which the Far Field General Population MPE limit occurs: Parameters Symbol Value Units Notes/Formulas Range to 1 mW/cm² 4107 m Range to General Population Limit 10.001 W/m² 1.000 mW/cm² Non-Technical Data. Authorized for Export. 4 of 6

E Engineering Report O3b Networks USA, LLC GND-023 8900 Liberty Circle 10 Jun 2010 Englewood, CO 80112 10 Non-Ionizing Radiation Summary Flux Densities & Exposure Limits General Population Exposure Limit = 1.0 mW/cm² Occupational Exposure Limit = 5.0 mW/cm² Region Symbol Level Units Hazard Assessment Density @ Antenna Flange Sflange 12135.562 mW/cm² Exceeds General Population Exposure limit Exceeds Occupational Exposure limit Density @ Subreflector Ssub 612.127 mW/cm² Exceeds General Population Exposure limit Exceeds Occupational Exposure limit Density @ Main Reflector Ssurface 4.274 mW/cm² Exceeds General Population Exposure limit Does not exceed Occupational Exposure limit Density Between Main Reflector Sground 1.069 mW/cm² Exceeds General Population Exposure limit and Ground Does not exceed Occupational Exposure limit Max Density @ Near Field Extent Snf 3.178 mW/cm² Exceeds General Population Exposure limit Does not exceed Occupational Exposure limit Max Density @ Transition Region St 3.178 mW/cm² Exceeds General Population Exposure limit Does not exceed Occupational Exposure limit Density @ Beginning of Far Field Sff 1.361 mW/cm² Exceeds General Population Exposure limit Does not exceed Occupational Exposure limit Range to Key Points and General Population Exposure Limit Avoidance Methods Distance from Antenna Symbol Value Units Protection Method Antenna Immediate Area Fencing and Signage, no public access Range to Near Field Extent Rnf 1292.688 m Main lobe offset greater than 1 diameter Range to Far Field Boundary Rff 3102.451 m Main lobe offset greater than 1 diameter Range to 1 mW/cm² MPE Limit 4107 m Main lobe offset greater than 1 diameter 11 Conclusion The above analysis confirms the presence of hazardous power flux densities at the O3b Gateway terminal which will require physical and operational protections to manage General Population and Occupational exposure. The O3b Gateway Antennas at the Sunset Beach, Hawaii facility will be enclosed in a fence designed to control access to the antenna area for RF safety, physical safety, and security purposes. The size of the enclosed area will consider the RF hazards, moving antenna 'swept volume', and the surrounding terrain. In addition to fencing, the area will contain signage which clearly states the standard Radiation Hazard warning. O3b will ensure antenna tracking geometry maintains angular limits which equates to at least one antenna diameter of separation between the antenna's main beam and nearby buildings and other occupied areas where the calculated General Population MPE levels may be exceeded. Finally, each antenna contains two safety features to protect operators and maintenance personnel: Non-Technical Data. Authorized for Export. 5 of 6

E Engineering Report O3b Networks USA, LLC GND-023 8900 Liberty Circle 10 Jun 2010 Englewood, CO 80112 1. All High Power Amplifiers are automatically inhibited at elevations of <5 degrees 2. Each antenna has an “Emergency Stop” safety switch located at the base of each structure. Personnel with access to the antenna area will be trained to ensure that HPA's are off and system motion is disabled via the Emergency Stop switch before working in the vicinity or on the antenna systems directly. Non-Technical Data. Authorized for Export. 6 of 6


Document Created: 2010-07-23 08:58:25
Document Modified: 2010-07-23 08:58:25
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