Attachment RadHaz

This document pretains to SES-MOD-20190522-00624 for Modification on a Satellite Earth Station filing.


Radiation Hazard Report                                                           Page 1 of 5


      Analysis of Non-Ionizing Radiation for a 4.5-Meter Earth
                          Station System
This report analyzes the non-ionizing radiation levels for a 4.5-meter earth station system. The
analysis and calculations performed in this report comply with the methods described in the FCC
Office of Engineering and Technology Bulletin, No. 65 first 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 dependant on the situation in which the 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 subreflector 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.

               Table 1. 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

                    Table 2. 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

          Table 3. Formulas and Parameters Used for Determining Power Flux Densities
     Parameter                    Symbol           Formula                 Value          Units
     Antenna Diameter                D               Input                   4.5          m
     Antenna Surface Area          Asurface         π D2 / 4                15.90         m2
     Feed Flange Diameter           Dfa              Input                  20.0          cm
     Area of Feed Flange            Afa             π Dfa 2/4              314.16         cm2
     Frequency                       F               Input                  6175          MHz
     Wavelength                      λ              300 / F              0.048583         m
     Transmit Power                  P               Input                 225.00         W
     Antenna Gain (dBi)             Ges              Input                  46.7          dBi
     Antenna Gain (factor)           G              10Ges/10              46773.5         n/a
     Pi                              π             Constant              3.1415927        n/a
     Antenna Efficiency              η             Gλ2/(π2D2)               0.55          n/a


Radiation Hazard Report                                                           Page 2 of 5




1.      Far Field Distance Calculation

The distance to the beginning of the far field can be determined from the following equation:

     Distance to the Far Field Region                       Rff = 0.60 D2 / λ                   (1)
                                                                = 250.1 m

The maximum main beam power density in the far field can be determined from the following
equation:

     On-Axis Power Density in the Far Field                 Sff = G P / (4 π Rff 2)             (2)
                                                                = 13.390 W/m2
                                                                = 1.339 mW/cm2

2.      Near Field Calculation

Power flux density is considered to be at a maximum value throughout the entire length of the
defined Near Field region. The region is contained within a cylindrical volume having the same
diameter as the antenna. Past the boundary of the Near Field region, the power density from the
antenna decreases linearly with respect to increasing distance.

The distance to the end of the Near Field can be determined from the following equation:

     Extent of the Near Field                               Rnf = D2 / (4 λ)                    (3)
                                                                = 104.2 m

The maximum power density in the Near Field can be determined from the following equation:

     Near Field Power Density                               Snf = 16.0 η P / (π D2)             (4)
                                                                = 31.259 W/m2
                                                                = 3.126 mW/cm2

3.      Transition Region Calculation

The Transition region is located between the Near and Far Field regions. The power density
begins to decrease linearly with increasing distance in the Transition region. While the power
density decreases inversely with distance in the Transition region, 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
calculated in Section 1 is the highest power density the antenna can produce in any of the regions
away from the antenna. The power density at a distance Rt can be determined from the following
equation:

     Transition Region Power Density                        St = Snf Rnf / Rt                   (5)
                                                               = 3.126 mW/cm2


Radiation Hazard Report                                                       Page 3 of 5



4.      Region between the Feed Assembly and the Antenna Reflector

Transmissions from the feed assembly are directed toward the antenna reflector surface, and are
confined within a conical shape defined by the type of feed assembly. The most common feed
assemblies are waveguide flanges, horns or subreflectors. The energy between the feed assembly
and reflector surface can be calculated by determining the power density at the feed assembly
surface. This can be determined from the following equation:

     Power Density at the Feed Flange                     Sfa = 4000 P / Afa                (6)
                                                              = 2864.789 mW/cm2

5.      Main Reflector Region

The power density in the main reflector is determined in the same manner as the power density at
the feed assembly. The area is now the area of the reflector aperture and can be determined from
the following equation:

     Power Density at the Reflector Surface           Ssurface = 4 P / Asurface             (7)
                                                               = 56.588 W/m2
                                                               = 5.659 mW/cm2


6.      Region between the Reflector and the Ground

Assuming uniform illumination of the reflector surface, the power density between the antenna and
the ground can be determined from the following equation:

     Power Density between Reflector and Ground           Sg = P / Asurface                 (8)
                                                             = 14.147 W/m2
                                                             = 1.415 mW/cm2


Radiation Hazard Report                                                         Page 4 of 5



7.     Summary of Calculations

           Table 4. Summary of Expected Radiation levels for Uncontrolled Environment
                                            Calculated Maximum
                                       Radiation Power Density Level
Region                                              (mW/cm2)               Hazard Assessment
1. Far Field (Rff = 250.1 m)                    Sff         1.339            Potential Hazard
2. Near Field (Rnf = 104.2 m)                   Snf         3.126            Potential Hazard
3. Transition Region (Rnf < Rt < Rff)           St          3.126             Potential Hazard
4. Between Feed Assembly and                    Sfa      2864.789            Potential Hazard
    Antenna Reflector
5. Main Reflector                               Ssurface    5.659             Potential Hazard
6. Between Reflector and Ground                 Sg          1.415            Potential Hazard

            Table 5. Summary of Expected Radiation levels for Controlled Environment
                                           Calculated Maximum
                                          Radiation Power Density
Region                                        Level (mW/cm2)               Hazard Assessment
1. Far Field (Rff = 250.1 m)                   Sff         1.339            Satisfies FCC MPE
2. Near Field (Rnf = 104.2 m)                  Snf         3.126            Satisfies FCC MPE
3. Transition Region (Rnf < Rt < Rff)          St          3.126            Satisfies FCC MPE
4. Between Feed Assembly and                   Sfa      2864.789             Potential Hazard
    Antenna Reflector
5. Main Reflector                              Ssurface    5.659             Potential Hazard
6. Between Reflector and Ground                Sg          1.415            Satisfies FCC MPE

It is the applicant's responsibility to ensure that the public and operational personnel are not
exposed to harmful levels of radiation.



8.     Conclusions

Based on the above analysis it is concluded that the FCC MPE guidelines have been exceeded (or
met) in the regions of Table 4 and 5. The applicant proposes to comply with the MPE limits by one
or more of the following methods.


Means of Compliance Uncontrolled Areas

This antenna will be located in a fenced area. The area will be sufficient to prohibit access to the
areas that exceed the MPE limited. The general public will not have access to areas within ½
diameter removed from the edge of the antenna.

Since one diameter removed from the main beam of the antenna or ½ diameter removed from the
edge of the antenna the RF levels are reduced by a factor of 100 or 20 dB. None of the areas
exceeding the MPE levels will be accessible by the general public.


Radiation Hazard Report                                                           Page 5 of 5


Radiation hazard signs will be posted while this earth station is in operation.

The applicant will ensure that no buildings or other obstacles will be in the areas that exceed the
MPE levels.


Means of Compliance Controlled Areas

The earth stations operational will not have access to the areas that exceed the MPE levels while
the earth station is in operation.

The transmitters will be turned off during antenna maintenance.



The applicant agrees to abide by the conditions specified in Condition 5208 provided below:

Condition 5208 - The licensee shall take all necessary measures to ensure that the antenna does
not create potential exposure of humans to radiofrequency radiation in excess of the FCC
exposure limits defined in 47 CFR 1.1307(b) and 1.1310 wherever such exposures might occur.
Measures must be taken to ensure compliance with limits for both occupational/controlled
exposure and for general population/uncontrolled exposure, as defined in these rule sections.
Compliance can be accomplished in most cases by appropriate restrictions such as fencing.
Requirements for restrictions can be determined by predictions based on calculations, modeling or
by field measurements. The FCC's OET Bulletin 65 (available on-line at www.fcc.gov/oet/rfsafety)
provides information on predicting exposure levels and on methods for ensuring compliance,
including the use of warning and alerting signs and protective equipment for worker.



Document Created: 2019-05-22 11:14:46
Document Modified: 2019-05-22 11:14:46

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