Attachment Western Arc Request

This document pretains to SES-MOD-20181030-03759 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2018103003759_1563944

Exhibit B Radiation Hazard Analysis

GCI Ambler 3.6m Radiation Hazard Study ANALYSIS OF NON-IONIZING RADIATION FOR THE GCI C-BAND 3.6M EARTH STATION ANTENNA IN AMBLER, ALASKA Completed 10/4/2018 This report analyzes the non-ionizing radiation levels for the GCI 3.6m C-band earth station antenna employed at the Ambler, Alaska site. 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: Ambler, Alaska Latitude: 67.086558 °N Longitude: 157.857875 °W Operating Frequency: 6000 MHz Wavelength (λ) 0.04997 meters Antenna Diameter (D): 3.60 meters Antenna Area (A): 10.18 meters² Transmit Antenna Gain: 45.9 dBi Transmit Antenna Gain (G): 38904.5 numeric Maximum 5° Off Axis Gain: 11.5 dBi Maximum 5° Off Axis Gain (G5°): 14.2 numeric Antenna Efficiency (ƞ): 0.759 numeric Feed Power (P): 400 Watts 1. Antenna/Main Reflector Surface Calculation The power density in the main reflector region can be estimated by: Antenna Diameter 3.60 meters Power Density at Reflector Surface, Ssurface = 4P/A Ssurface = 157.19 W/m² Ssurface = 15.72 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: Page 1 of 3

GCI Ambler 3.6m Radiation Hazard Study Antenna Diameter 3.60 meters Extent of Near Field, Rnf = D²/4(λ) Rnf = 64.84 meters Rnf = extent of near field D = maximum dimension of antenna (diameter if circular) λ = wavelength The maximum near-field, on-axis, power density is determined by: Antenna Diameter 3.60 meters On Axis Near Field Power Density, Snf = 16ƞP/πD² Snf = 119.36 W/m² Snf = 11.94 mW/cm² The maximum near-field, 5° off-axis, power density is determined by: Antenna Diameter 3.60 meters Power Density at 5° Off Axis Snf 5°= (Snf/G)*G5° Snf 5°= 0.0044 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 3.60 meters Distance to the Far Field Region, Rff = 0.6D²/λ Rff = 155.63 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 3.60 meters On-Axis Power Density in the Far Field, Sff = (P)(G)/4π(Rff)2 Sff = 51.13 W/m² Sff = 5.11 mW/cm² The maximum far-field, 5° off-axis, power density is determined by: Antenna Diameter 3.60 meters Power Density at 5° Off Axis Sff 5°= (Sff/G)*G5° Sff 5°= 0.0019 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 radiator Rff = distance to beginning of far field Page 2 of 3

GCI Ambler 3.6m Radiation Hazard Study 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 3.60 meters St= (Snf*Rnf)/R St 5° = (Snf 5°*Rnf)/R St= 11.94 mW/cm² St 5° = 0.0044 mW/cm² 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 1.8m Earth Station Antenna 1. Antenna Surface Ssurface= 15.72 Potential Hazard Potential Hazard 2. Near Field Snf= 11.94 64.8 Potential Hazard Potential Hazard 3. Far Field Sff= 5.11 155.6 Potential Hazard Potential Hazard 4. Transition Region St= 11.94 Potential Hazard Potential Hazard 5. Near Field 5° Off Axis Snf 5°= 0.0044 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° = 0.0044 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 not been exceeded in any region for this installation. Further, it should be noted that General Population/Uncontrolled MPE limit is always satisifed at angles 5° off of boresite or greater for all antenna apertures. As these earth station antennas will never be operated with elevation angles 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 even if the transmitter is upgraded at a later date to a larger size. GCI will post appropriate RF Radiation Hazard placards and other signage in the areas near these antennas and/or will restrict access to the antenna by means of fencing or other appropriate devices. Finally, the transmitter will be disabled during maintenance activities in the areas where the Occupational MPE is exceeded in order to protect personnel from exposure. Andrew F. Rzeszut (10/4/2018) Senior Staff Engineer GCI Communication Corp. Page 3 of 3



Document Created: 2018-10-09 18:03:04
Document Modified: 2018-10-09 18:03:04
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