Attachment Exhibit C

This document pretains to SES-MOD-20130415-00324 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2013041500324_993356

Spacenet Services License Sub, Inc. Application for a Modification of Earth Station Authorization E891044 Exhibit C - Radiation Hazard Study When applying for a license to construct and operate, modify, or renew an earth station, it is understood that the applicant must certify whether grant of the application will have significant environmental impact as defined in the Federal Communications Commission's (FCC) rules, 47 C.F.R. § 1.1307. In this report Spacenet analyzes the maximum radiofrequency (RF) levels emitted from the satellite communications antenna described below. The reference document for this study is OET Bulletin No.65, Edition 97-01, Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, August 1997. 1. Antenna Near-Field Power Density Calculation The extent of the near-field is defined by the following equation1: Rnear = (Dantenna)² / (4λ) where: Rnear = extent of the near-field (in meters) Dantenna = diameter of the antenna main reflector (in meters) λ = wavelength of the RF transmit frequency (in meters) The maximum on-axis power density within near-field is defined by the following equation2: Snear = {(16h Pfeed) / [π(Dantenna)²]} / 10 where: Snear = maximum on-axis power density within the near-field (in milliwatts per square centimeter) h = antenna aperture efficiency Pfeed = maximum power into antenna feed flange (in watts) Dantenna = diameter of the antenna main reflector (in meters) 1 See OET 65 page 27 formula (12). 2 See OET 65 page 28 formula (13). The right side of the equation is divided by 10 so that the power 2 spectral density units on the left side will be mW/cm . Page 1 of 7

Spacenet Services License Sub, Inc. Application for a Modification of Earth Station Authorization E891044 Exhibit C - Radiation Hazard Study 2. Antenna Far-Field Power Density Calculation The distance to the beginning of the far-field region is defined by the following equation3: Rfar = [0.6(Dantenna)²] /λ where: Rfar = distance to beginning of far-field (in meters) Dantenna = diameter of the antenna main reflector (in meters) λ = wavelength of the transmit frequency in (meters) The maximum on-axis power density within the far-field is defined by the following equation4: Sfar = [(Pfeed Gantenna) / 4π(Rfar)²] / 10 where: Sfar = maximum on-axis power density in the far-field (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Gantenna = antenna main beam gain at AF transmit frequency (in numeric value) Rfar = distance to beginning of far-field (in meters) The on-axis power densities calculated from the above formulas represent the maximum exposure levels that the system can produce. Off-axis power densities will be considerably less. 3. Antenna Transition Region Power Density Calculation The on-axis power spectral density for the transition region is defined by the following formula5: Str = Snear Rnear / R where: Str = maximum on-axis power density in the transition region (in milliwatts per square centimeter) Snear = maximum on-axis power density in the near-field (in milliwatts per square centimeter) 3 See OET 65 page 29 formula (16). 4 See OET 65 Section 2, page 19, formula (3) and page 29, formula (18). The right side of the equation is 2 divided by 10 so that the power spectral density units on the left side will be mW/cm . 5 See OET 65 page 34, formula (17). Page 2 of 7

Spacenet Services License Sub, Inc. Application for a Modification of Earth Station Authorization E891044 Exhibit C - Radiation Hazard Study Rnear = is the distance that defines the end of the near field region. R = is the distance within in the transition region between the near field and far field regions. Since the distance within the transition region “R” will always be greater than the distance to the end of the near field region “Rnear” then Str ≤ Snear. 4. Antenna Feed-Flange Power Density Calculation The maximum power density at the antenna feed-flange is defined by the following equation6: Sfeed = 1000{[4(Pfeed)] / {[π(Dfeed)²] / 4}} where: Sfeed = maximum power density at the antenna feed-flange (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dfeed = diameter of the antenna feed-flange (in centimeters ) 5. Antenna Sub and Main Reflector Power Density Calculation The maximum power density in the main reflector region of the antenna is defined by the following equation7: Santenna = {[4Pfeed] / {[πD² / 4}} / 10 where: S = maximum power density in the antenna sub or main reflector region (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) D = diameter of the antenna sub or main reflector (in meters) 6. Power Density Calculation between the Antenna Main Reflector and the Ground 6 The formula is multiplied by 1,000 on the right side of the equation to change the units from watts on the right side of the equation to milliwatts on the left side. 7 See OET 65 equation (11) which is “S = 4 P / A”, where “A” is the area of the reflector and for a circular 2 reflector A = π (Dantenna ) / 4. The formula is divided by 10 on the right side to change the units from meters and watts on the right side of the formula to cm and mW on the left side. Page 3 of 7

Spacenet Services License Sub, Inc. Application for a Modification of Earth Station Authorization E891044 Exhibit C - Radiation Hazard Study The maximum power density between the antenna main reflector and the ground is defined by the following equation: Sground = {Pfeed / {[π{(Dantenna)²] / 4}} / 10 where: Sground = maximum power density between the antenna main reflector and the ground (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dantenna = diameter of the antenna main reflector (in meters) 7. Calculation of Radiation Levels and FCC Standards Spacenet understands that a licensee must ensure that people are not exposed to harmful levels of radiation. Spacenet plans to utilize the 3.7 meter ASC Signal antenna with Gregorian optics in fixed installations with up to 100-watt transmitters. The transmitters will be operated at full output power. The preceding formulas were used to calculate the power densities shown on the following page. The Commission’s maximum permissible exposure (MPE) limits at the transmit frequency band for the earth stations included in this application are provided in the table set forth below. Maximum Permissible Exposure (MPE) Limits at 14,000-14,500 MHz Power Averaging Density Time Exposure Criteria (mW/cm2) (minutes) Reference OET 65 page 67 general population/uncontrolled 1 6 Appendix A exposure Table 1 (A) OET 65 page 67 occupational/controlled exposure 5 30 Appendix A Table 1 (B) Page 4 of 7

Spacenet Services License Sub, Inc. Application for a Modification of Earth Station Authorization E891044 Exhibit C - Radiation Hazard Study Radiation Hazard Calculations – 3.7 meter ASC Signal Antenna Antenna IDs 1&2 Antenna main reflector diameter 3.7 m Feed flange diameter 17.4 cm Sub-reflector diameter 48.0 cm RF transmit frequency 14.250 GHz Maximum power into antenna feed-flange 100 watts Main-beam antenna transmit gain 52.6 dBi Antenna aperture efficiency 0.6% Antenna main reflector surface area 10.75 m² Feed flange surface area 237.8 cm² Sub-reflector surface area 1,809.6 cm² Wavelength at RF transmit frequency 2.1 cm Distance to beginning of far-field region 391 m Distance to extent of near-field region 163 m 2 Maximum on-axis power density in far-field 0.95 mW/cm Satisfies MPE Limits Maximum on-axis power density in near-field 2 Satisfies controlled MPE 2.22 mW/cm (see note 2) Limits Maximum power density at feed-flange 2 1,682 mW/cm Potential Hazard (see note 1) Maximum power density at sub-reflector 2 221 mW/cm Potential Hazard (see note 1) Maximum on-axis power density in transition 2 221 mW/cm Potential Hazard region (see note 1) Maximum power density at main reflector 2 Satisfies controlled MPE 3.72 mW/cm (see note 2) Limits Maximum power density between main 2 0.93 mW/cm Satisfies MPE Limits reflector and ground Note 1: Feed flange, sub-reflector and transition region power density exceeds both uncontrolled MPE limit 2 2 of 1 mW/cm and controlled MPE limit of 5 mW/cm Note 2: 2 Satisfies controlled MPE limit of 5 mW/cm , but is a potential hazard for uncontrolled MPE limit of 1 2 mW/cm Page 5 of 7

Spacenet Services License Sub, Inc. Application for a Modification of Earth Station Authorization E891044 Exhibit C - Radiation Hazard Study 8. Conclusion The calculations provided in this exhibit indicate that MPE limits are exceeded in certain areas of the 3.7 meter earth stations with 100-watt transmitters which are the subject of this application. The 3.7 meter ASC Signal antenna is a Gregorian design that utilizes a feed horn, sub-reflector and main reflector. The 3.7 meter antenna exceeds the MPE limits for occupational/controlled and general population/uncontrolled exposure at the feed horn, sub-reflector, in the area between the feed horn and sub-reflector and the area between the sub-reflector and main reflector (transition regions). The MPE limit for general population/uncontrolled exposure is exceeded at the antenna reflector and in the near field region, but the MPE limit is met for occupational/controlled exposure. All 3.7 meter fixed antennas will be installed such that the area where the MPE is exceeded will not be readily accessible to humans. Additionally, all transmissions will be terminated whenever the technical staff is required, for maintenance or other activities, to occupy the regions where potentially hazardous power density levels can exist. The 3.7 meter fixed earth stations will have an automatic shut-off mechanism that will terminate transmissions if the outbound receive signal is lost. Page 6 of 7

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Document Created: 2013-04-15 17:25:25
Document Modified: 2013-04-15 17:25:25
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