Attachment Exhibit C

This document pretains to SES-MOD-20130613-00493 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2013061300493_1000849

Exhibit_C_Radiation_Hazard_Analysis_Takotna_3.8m.xlsx 3 ANALYSIS OF NON-IONIZING RADIATION FOR A 3.8 METER C-BAND EARTH STATION ANTENNA Completed 06/04/2013 This report analyzes the non-ionizing radiation levels for a 3.8m C-band earth station antenna. The analysis and calculations performed in this report comply with the methods described in the FCC Office of Engineering and Technology Bulletin, No. 65 entitled "Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields" - first published in 1985 and revised in 1997 in Edition 97-01. Bulletin No. 65 specifies that there are two separate tiers of exposure limits that are dependant on the situation in which the exposure takes place and/or the status of teh 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, below. The General Population/Uncontrolled MPE is a function of the transmit frequency and is for an exposure period of thirty (30) minutes or less. The MPE limits for persons in an Occupational/Controlled environment are shown in Table 2, below. The Occupational/Controlled MPE is a function of the transmit frequency and is for an exposure period of six (6) minutes or less. The purpose of the analysis described in this report is to determine the power flux density levels of the earth station ni the far-field, near- field, transition region, between the subreflector or feed and the main reflector surface, and at the main reflector surface and to compare these levels to the specified MPE limits. The results of this analysis are summarized in Table 3 on the last page of this analysis. Table 1. Limits for General Population/Uncontrolled Exposure (MPE) Frequency Range (MHz) Power Density(mW/cm2) 30-300 0.2 300-1500 Frequency (MHz)/1500 1500-100,000 1.0 Table 2. Limits for Occupational/Controlled Exposure (MPE) Frequency Range (MHz) Power Density(mW/cm2) 30-300 1.0 300-1500 Frequency (MHz)/300 1500-100,000 5.0 The following parameters were used to calculate the various power flux densities for this earth station: Location: Takotna Alaska Latitude: 62.98 °N Longitude: 156.06 °W Operating Frequency: 6175 MHz Wavelength (λ) 0.04855 meters Antenna Diameter (D): 3.80 meters Antenna Area (A): 11.34 meters² Transmit Antenna Gain: 46.3 dBi Transmit Antenna Gain (G): 42658.0 numeric Maximum 5° Off Axis Gain: 11.5 dBi Maximum 5° Off Axis Gain (G5°): 14.2 numeric Antenna Efficiency (ƞ): 0.706 numeric Feed Power (P): 200 Watts 1. Antenna/Main Reflector Surface Calculation The power density in the main reflector region can be estimated by Antenna Diameter 3.80 meters Power Density at Reflector Surface, Ssurface = 4P/A Ssurface = 70.54 W/m² Ssurface = 7.05 mW/cm² Ssurface = maximum power density at antenna surface P = power fed to the antenna A = physical area of the antenna 2. Near Field Calculations In the near field region, of the main beam, the power density can reach a maximum before it begins to decrease with distance The magnitude of the on axis (main beam) power density varies according to location in the near-field The distance to the end of the near field can be determined by the following equation: Antenna Diameter 3.80 meters Extent of Near Field, Rnf = D²/4(λ) Rnf = 74.36 meters Rnf = extent of near field Exhibit_C_Radiation_Hazard_Analysis_Takotna_3.8m.xlsx

Exhibit_C_Radiation_Hazard_Analysis_Takotna_3.8m.xlsx 3 D = maximum dimension of antenna (diameter if circular) λ = wavelength The maximum near-field, on-axis, power density is determined by: Antenna Diameter 3.80 meters On Axis Near Field Power Density, Snf = 16ƞP/πD² Snf = 49.77 W/m² Snf = 4.98 mW/cm² The maximum near-field, 5° off-axis, power density is determined by: Antenna Diameter 3.80 meters Power Density at 5° Off Axis Snf 5°= (Snf/G)*G5° Snf 5°= 0.0017 mW/cm² Snf= maximum near-field power density Snf 5° = maximum near-field power density (5° off axis) ƞ= aperture efficiency P= power fed to antenna D= maximum dimension of antenna (diameter if circular) 3. Far Field Calculations The power density in the far-field region decreases inversely with the square of the distance The distance to the beginning of the far field region can be found by the following equation: Antenna Diameter 3.80 meters Distance to the Far Field Region, Rff = 0.6D²/λ Rff = 178.46 meters Rff = distance to beginning of far field D = maximum dimension of antenna (diameter if circular) λ = wavelength The maximum main beam power density in the far field can be calculated as follows: Antenna Diameter 3.80 meters 2 On-Axis Power Density in the Far Field, Sff = (P)(G)/4π(Rff) Sff = 21.32 W/m² Sff = 2.13 mW/cm² The maximum far-field, 5° off-axis, power density is determined by: Antenna Diameter 3.80 meters Power Density at 5° Off Axis Sff 5°= (Sff/G)*G5° Sff 5°= 0.0007 mW/cm² Sff= power density (on axis) Sff 5°= power density (5° off axis) P= power fed to antenna G= power gain of antenna in the direction of interest relative to an isotropic radiato Rff = distance to beginning of far field 4. Transition Region Calculations The transition region is located between the near and far field regions. The power density decreases inversely with distance in the transition region, while the power density decreases inversely with the square of the distance in the far-field region. The maximum power density in the transition region will not exceed that calculated for the near-field region. The power density in the near field region, as shown above will not exceed: Antenna Diameter 3.80 meters St= (Snf*Rnf)/R St 5° = (Snf 5°*Rnf)/R St= 4.98 mW/cm² St 5° = 0.0017 mW/cm² Exhibit_C_Radiation_Hazard_Analysis_Takotna_3.8m.xlsx

Exhibit_C_Radiation_Hazard_Analysis_Takotna_3.8m.xlsx 3 Table 3 Summary of Expected Radiation Levels Calculated Maximum Distance to Maximum Permissible Exposure (MPE Region Radiation Level (mW/cm² Region (m) Occupational General Population 2.4m Earth Station Antenna 1. Antenna Surface Ssurface= 7.05 Potential Hazard Potential Hazard 2. Near Field Snf= 4.98 74.4 Satisfies MPE Potential Hazard 3. Far Field Sff= 2.13 178.5 Satisfies MPE Potential Hazard 4. Transition Region St= 4.98 Satisfies MPE Potential Hazard 5. Near Field 5° Off Axis Snf 5°= 0.0017 Satisfies MPE Satisfies MPE 6. Far Field 5° Off Axis Sff 5°= 0.00 Satisfies MPE Satisfies MPE 7. Transition Region 5° Off Axis St 5° = 0.0017 Satisfies MPE Satisfies MPE 7. Conclusions Based on the above analysis, it is concluded that the OET/FCC Radiofrequency Electromagnetic Fields guidelines for Maximum Permissible Exposure (MPE) have been exceeded in the region(s) specified in Table 3. However, it should be noted that General Population/Uncontrolled MPE limit is always satisifed at angles 5° off of boresite or greater. As this earth station antenna will never be operated with an elevation angle of less than the minimum specified in 47 C.F.R. Ch. 1 §25.205 (namely 5°), then the MPE associated with the General Population/Uncontrolled limits will always be satisied. GCI will post appropriate RF Radiation Hazard placards and other signage in the areas near these antennas and will restrict access to the antenna by means of fencing or other appropriate devices. Finally, access to the antenna surface, as well as the region between the feedhorn and the antenna surface will be restricted to qualified personnel and the transmitter will be disabled during maintenance activities in these areas to protect personnel from exposure. Andrew F. Rzeszut RF Senior Staff Engineer GCI Communication Corp. Exhibit_C_Radiation_Hazard_Analysis_Takotna_3.8m.xlsx


Document Created: 2013-06-04 08:44:27
Document Modified: 2013-06-04 08:44:27
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