Attachment Rad Haz

This document pretains to SES-MOD-20100805-01001 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2010080501001_833274

Exhibit Radiation Hazard Report Page 1 of 4 Analysis of Non-Ionizing Radiation for a 6.3-Meter Earth Station This report analyzes the non-ionizing radiation levels for TerreStar’s 6.3-meter North Las Vegas backup Feeder Link earth station. The analyses performed herewith comply with the methods described in the FCC Office of Engineering and Technology Bulletin, No. 65 published in 1985 and revised in 1997 in Edition 97-01. The radiation safety limits used in the analysis are in conformance with the FCC R&O 96-326. Bulletin No. 65 and the FCC R&O specifies that there are two separate tiers of exposure limits that are dependent on whether exposure takes place and/or the status of the individuals who are subject to the exposure. The Maximum Permissible Exposure (MPE) limits for persons in a General Population/Uncontrolled environment are shown in Table 1. The General Population/Uncontrolled MPE is a function of transmit frequency and is for an exposure period of thirty minutes or less. The MPE limits for persons in an Occupational/Controlled environment are shown in Table 2. The Occupational MPE is a function of transmit frequency and is for an exposure period of six minutes or less. The purpose of the analysis described in this report is to determine the power flux density levels of the earth station in the far-field, near-field, transition region, between the sub-reflector or feed and main reflector surface, at the main reflector surface, and between the antenna edge and the ground and to compare these levels to the specified MPEs. Limits for General Population/Uncontrolled Exposure (MPE) Frequency Range (MHz) Power Density ( mW/cm2) 30-300 0.2 300-1500 Frequency (MHz) * (0.8 / 1200) 1500-100,000 1.0 Calculated Limit for General Population/Uncontrolled Exposure (F =12875 ) 1.000 Limits for Occupational/Controlled Exposure (MPE) Frequency Range (MHz) Power Density ( mW/cm2) 30-300 1.0 300-1500 Frequency (MHz) * (4.0 / 1200) 1500-100,000 5.0 Calculated Limit for General Population/Uncontrolled Exposure (F =12875 ) 5.000

page 2 of 4 Formulas and Parameters Used for Determining Power Flux Density Parameter Symbol Formula Value Units Antenna Diameter D Input 6.300 m Subreflector Diameter Dsr Input 98.000 cm Frequency F Input 12875.00 MHz Transmit Power P Input 125.893 W Antenna Gain (dBi) Ges Input 57.000 dBi Antenna Surface Area Asurface π D2 / 4 31.172 m2 Area of Subreflector Asr πDsr2/4 7542.964 cm2 Wavelength λ 299.79245 / F 0.023 m2 Antenna Gain (factor) G 10Ges/10 501187.2 N/A Antenna Efficiency η G λ2 / (π2 D2) 0.694 N/A Far Field Distance Calculation Parameter Symbol Formula Value Units 2 Distance to the Far Field Region Rff 0.60 D / λ 1022.725 m On-Axis Power Density in the Far Field Sff G P / (4 π Rff2 ) 4.800 W/m2 0.480 mW/cm2 Near Field Distance Calculation Parameter Symbol Formula Value Units Extent of the Near Field Rnf D2 / (4 λ) 426.135 m 16.0 η P / (π Near Field Power Density Snf D2) 11.206 W/m2 1.121 mW/cm2 Transition Region Calculation Parameter Symbol Formula Value Units Transition Region Power Density St Snf Rnf / Rt 0.467 mW/cm2 Region between the Main Reflector and the Subreflector Parameter Symbol Formula Value Units Power Density at the Subreflector Ssr 4000 P / Asr 66.760 mW/cm2

Page 3 of 4 Main Reflector Region Parameter Symbol Formula Value Units Power Density at the Main Reflector Surface Ssurface 4 P / Asurface 16.154 W/m2 1.615 mW/cm2 Region between the Main Reflector and the Ground Parameter Symbol Formula Value Units Power Density between Reflector and Ground Sg P / Asurface 4.039 W/m2 0.404 mW/cm2 Summary of Calculations Summary of Expected Radiation levels for Uncontrolled Environment Max Power Hazard Region Symbol Density Assessment Far Field (Rff= 1022.72505528408m) Sff 0.480 mW/cm2 Satisfies FCC MPE Near Field (Rnf = 426.1354397017m) Snf 1.121 mW/cm2 Potential Hazard Transition Region (Rnf < Rt < Rff) St 0.467 mW/cm2 Satisfies FCC MPE Between Main Reflector and Subreflector Ssr 66.760 mW/cm2 Potential Hazard Main Reflector Ssurface 1.615 mW/cm2 Potential Hazard Between Main Reflector and Ground Sg 0.404 mW/cm2 Satisfies FCC MPE Summary of Expected Radiation levels for Controlled Environment Max Power Hazard Region Symbol Density Assessment Far Field (Rff= 1022.72505528408m) Sff 0.480 mW/cm2 Satisfies FCC MPE Near Field (Rnf = 426.1354397017m) Snf 1.121 mW/cm2 Satisfies FCC MPE Transition Region (Rnf < Rt < Rff) St 0.467 mW/cm2 Satisfies FCC MPE Between Main Reflector and Subreflector Ssr 66.760 mW/cm2 Potential Hazard Main Reflector Ssurface 1.615 mW/cm2 Satisfies FCC MPE Between Main Reflector and Ground Sg 0.404 mW/cm2 Satisfies FCC MPE

Page 4 of 4 Summary of Results The results of analyses shown above for the 6.3 meter antenna indicate that the maximum power density in the near field exceeds the FCC’s safety limit by 0.1 mW/cm2 for uncontrolled environments. The antenna is located within a fenced area limited to individuals who work at the site. Visitors can enter through a locked gate with a key card which must be obtained at a separate building which requires identification before providing the key card. Visitors are advised not to enter the area of the antennas without being accompanied by staff. In addition, there are hazard signs in and around all areas near the antennas. The region between the main reflector and the subreflector exceeds the limit by 65.76 mW/cm2, however no personnel are permitted in this area during any transmissions. Besides monitoring visitors, the antenna elevation angle to the satellite is at 30.4° in a direction not looking towards any buildings or towers. At this elevation angle, there no one could get close to the actual transmitted beam. As the frequency for transmission is at Ku-Band, the beam is 0.26°. CERTIFICATION OF PERSON RESPONSIBLE FOR PREPARING THE ENGINEERING INFORMATION SUBMITTED IN THIS EXHIBIT I hereby certify that I am a technically qualified person responsible for the preparation of engineering information contained in this filing, that I am familiar with Part 2, 25 and 101 of the Commission’s rules, that I have prepared or reviewed the engineering information submitted in these reply comments, and that it is complete and accurate to the best of my knowledge. I am a registered Professional Engineer. My seal is attached. By: __ Philip A. Rubin, P.E. President RKF Engineering, LLC Washington, DC


Exhibit Radiation Hazard Report Page 1 of 4 Analysis of Non-Ionizing Radiation for a 9.3-Meter Earth Station This report analyzes the non-ionizing radiation levels for TerreStar’s 9.3-meter North Las Vegas Feeder Link earth station. The analyses performed herewith comply with the methods described in the FCC Office of Engineering and Technology Bulletin, No. 65 published in 1985 and revised in 1997 in Edition 97-01. The radiation safety limits used in the analysis are in conformance with the FCC R&O 96-326. Bulletin No. 65 and the FCC R&O specifies that there are two separate tiers of exposure limits that are dependent on whether exposure takes place and/or the status of the individuals who are subject to the exposure. The Maximum Permissible Exposure (MPE) limits for persons in a General Population/Uncontrolled environment are shown in Table 1. The General Population/Uncontrolled MPE is a function of transmit frequency and is for an exposure period of thirty minutes or less. The MPE limits for persons in an Occupational/Controlled environment are shown in Table 2. The Occupational MPE is a function of transmit frequency and is for an exposure period of six minutes or less. The purpose of the analysis described in this report is to determine the power flux density levels of the earth station in the far-field, near- field, transition region, between the sub-reflector or feed and main reflector surface, at the main reflector surface, and between the antenna edge and the ground and to compare these levels to the specified MPEs. Limits for General Population/Uncontrolled Exposure (MPE) Frequency Range (MHz) Power Density ( mW/cm2) 30-300 0.2 300-1500 Frequency (MHz) * (0.8 / 1200) 1500-100,000 1.0 Calculated Limit for General Population/Uncontrolled Exposure (F =12875 ) 1.000 Limits for Occupational/Controlled Exposure (MPE) Frequency Range (MHz) Power Density ( mW/cm2) 30-300 1.0 300-1500 Frequency (MHz) * (4.0 / 1200) 1500-100,000 5.0 Calculated Limit for General Population/Uncontrolled Exposure (F =12875 ) 5.000

Page 2 of 4 Formulas and Parameters Used for Determining Power Flux Density Parameter Symbol Formula Value Units Antenna Diameter D Input 9.300 m Subreflector Diameter Dsr Input 118.000 cm Frequency F Input 12875.000 MHz Transmit Power P Input 128.825 W Antenna Gain (dBi) Ges Input 60.200 dBi Antenna Surface Area Asurface π D2 / 4 67.929 m2 Area of Subreflector Asr πDsr2/4 10935.884 cm2 Wavelength λ 299.79245 / F 0.023 m2 Antenna Gain (factor) G 10Ges/10 1047128.548 N/A Antenna Efficiency η G λ2 / (π2 D2) 0.665 N/A Far Field Distance Calculation Parameter Symbol Formula Value Units Distance to the Far Field Region Rff 0.60 D2 / λ 2228.659 m On-Axis Power Density in the Far Field Sff G P / (4 π Rff2 ) 2.161 W/m2 0.216 mW/cm2 Near Field Distance Calculation Parameter Symbol Formula Value Units Extent of the Near Field Rnf D2 / (4 λ) 928.608 m 16.0 η P / (π Near Field Power Density Snf D2) 5.045 W/m2 0.505 mW/cm2 Transistion Region Calculation Parameter Symbol Formula Value Units Transition Region Power Density St Snf Rnf / Rt 0.210 mW/cm2 Region between the Main Reflector and the Subreflector Parameter Symbol Formula Value Units Power Density at the Subreflector Ssr 4000 P / Asr 47.120 mW/cm2

Page 3 of 4 Main Reflector Region Parameter Symbol Formula Value Units Power Density at the Main Reflector Surface Ssurface 4 P / Asurface 7.586 W/m2 0.759 mW/cm2 Region between the Main Reflector and the Ground Parameter Symbol Formula Value Units Power Density between Reflector and Ground Sg P / Asurface 1.896 W/m2 0.190 mW/cm2 Summary of Calculations Summary of Expected Radiation levels for Uncontrolled Environment Max Power Region Symbol Densityl Hazard Assessment Far Field (Rff= 2228.65936083447m) Sff 0.216 mW/cm2 Satisfies FCC MPE Near Field (Rnf = 928.608067014363m) Snf 0.505 mW/cm2 Satisfies FCC MPE Transition Region (Rnf < Rt < Rff) St 0.210 mW/cm2 Satisfies FCC MPE Between Main Reflector and Subreflector Ssr 47.120 mW/cm2 Potential Hazard Main Reflector Ssurface 0.759 mW/cm2 Satisfies FCC MPE Between Main Reflector and Ground Sg 0.190 mW/cm2 Satisfies FCC MPE Summary of Expected Radiation levels for Controlled Environment Max Power Region Symbol Density Hazard Assessment Far Field (Rff= 2228.65936083447m) Sff 0.216 mW/cm2 Satisfies FCC MPE Near Field (Rnf = 928.608067014363m) Snf 0.505 mW/cm2 Satisfies FCC MPE Transition Region (Rnf < Rt < Rff) St 0.210 mW/cm2 Satisfies FCC MPE Between Main Reflector and Subreflector Ssr 47.120 mW/cm2 Potential Hazard Main Reflector Ssurface 0.759 mW/cm2 Satisfies FCC MPE Between Main Reflector and Ground Sg 0.190 mW/cm2 Satisfies FCC MPE

Page 4 of 4 Summary of Results The results of the analyses shown above for the 9.3 meter antenna indicate that the maximum power density exceeds the FCC’s safety limit for uncontrolled environments in only one area, the region between the main reflector and the subreflector where it exceeds the limit by 46.12 mW/cm2, however no personnel are permitted in this area during any transmissions. The antenna is located within a fenced area limited to individuals who work at the site. Visitors can enter through a locked gate with a key card which must be obtained at a separate building which requires identification before providing the key card. Visitors are advised not to enter the area of the antennas without being accompanied by staff. In addition, there are hazard signs in and around all areas near the antennas. Besides monitoring visitors, the antenna elevation angle to the satellite is at 30.4° in a direction not looking towards any buildings or towers. At this elevation angle, there no one could get close to the actual transmitted beam. As the frequency for transmission is at Ku-Band, the beam is 0.18°. CERTIFICATION OF PERSON RESPONSIBLE FOR PREPARING THE ENGINEERING INFORMATION SUBMITTED IN THIS EXHIBIT I hereby certify that I am a technically qualified person responsible for the preparation of engineering information contained in this filing, that I am familiar with Part 2, 25 and 101 of the Commission’s rules, that I have prepared or reviewed the engineering information submitted in these reply comments, and that it is complete and accurate to the best of my knowledge. I am a registered Professional Engineer. My seal is attached. By: __ Philip A. Rubin, P.E. President RKF Engineering, LLC Washington, DC


Document Created: 2010-08-04 16:32:38
Document Modified: 2010-08-04 16:32:38
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