Attachment Western Arc Waiver

This document pretains to SES-MOD-20181030-03740 for Modification on a Satellite Earth Station filing.


        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




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                                                          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.




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

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