Attachment Exhibit B

This document pretains to SES-MOD-20170908-00993 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2017090800993_1272518

                                             Comtech Mobile Datacom Corporation
                                                                  Exhibit B, Page 1
                      ROUS (E090027) Modification Application – September 8, 2017



                           Radiation Hazard Study – Item 28

                         Comtech Mobile Datacom Corporation
                            Mobile Earth Station Terminal

                                       Introduction

Comtech Mobile Datacom Corporation (“CMDC”) designs, manufactures, and is licensed
to operate Mobile Earth Station Terminals (“MESs”) in spectrum allocated to the Mobile
Satellite Service under the Federal Communications Commission (“FCC”) guidelines of
Part 25, Title 47 of the Code of Federal Regulations. This Radiation Hazard Study
demonstrates that CMDC’s MESs meet FCC guidelines for RF exposure.

                                       Background

Completion of a routine environmental analysis for RF exposure (as described in FCC
Office of Engineering and Technology Bulletin 65 (“Bulletin 65”)) due to emissions from
the MES is one of the requirements to modify the existing blanket license.

Bulletin 65 identifies two parameters relating to equipment type and usage that determine
the appropriate testing methods and limits.

First, devices may be classified as either Mobile or Portable. A Mobile device is
intended for use in other than fixed locations and should be separated from the user or
bystanders by at least 20 centimeters. Portable devices are intended to be operated within
20 centimeters of the user or bystander.

Second, the exposure must be deemed Occupational/Controlled Exposure or General
Population/Uncontrolled Exposure. Occupational/Controlled Exposure applies where
persons are exposed due to their employment or when they have been made aware of the
potential for exposure and are able to exercise control over their exposure. Cases where
the general public is exposed or where workers are not fully aware of the potential for
exposure or are unable to exercise control over the amount of their exposure fall into the
General Population/Uncontrolled Exposure category.

CMDC MESs fit into the Mobile and General Population/Uncontrolled Exposure
categories. As such, the permissible radiation level may be determined using either
Maximum Permissible Exposure or Specific Absorption Rate techniques. CMDC elects
to use a Maximum Permissible Exposure analysis using the limits for General
Population/Uncontrolled Exposure for frequencies above 1500 MHz shown in section B
of the table below.


                                             Comtech Mobile Datacom Corporation
                                                                  Exhibit B, Page 2
                      ROUS (E090027) Modification Application – September 8, 2017




                                     Analysis Method

A Maximum Permissible Exposure analysis will be done using the methods described in
Bulletin 65 and the source-based time-averaging methods described in Title 47 of the
Code of Federal Regulations Part 2.1091.

The source-based averaging allows scaling of the exposure level based on the inherent
duty cycle of the MES. CMDC’s MESs are limited to a maximum transmission duty
cycle of 52% (a 1.552 second transmission burst every 3.0 seconds).

Bulletin 65 offers several methods for calculating the RF Power Density. Three of these
methods seem appropriate for this analysis.

First, the equations below will predict the power density in the antenna far field and will
overstate the density in the near field.


                                             Comtech Mobile Datacom Corporation
                                                                  Exhibit B, Page 3
                      ROUS (E090027) Modification Application – September 8, 2017




Second, the power density may be determined for an antenna close to a ground plane.
The following equation provides this result based on 100% reflection from the ground
plane. The power density determined by this method will be four times that of the
density determined in the far field.




Third, the Environmental Protection Agency has recommended a more realistic
approximation of those results in a power density increase of 2.56 above the far field
case.


                                             Comtech Mobile Datacom Corporation
                                                                  Exhibit B, Page 4
                      ROUS (E090027) Modification Application – September 8, 2017



This method seems most representative of the typical operating conditions for CMDC’s
MESs and is the method adopted for this analysis.

                                          Analysis

The separation distance required to produce an RF power density less than one milliwatt
per square centimeter will be calculated for all possible antennas. The calculations will
be done for the maximum antenna input power of 6 dBW and for a maximum duty cycle
of 52 %. The antennas that are available for use are characterized in the table below.

       Antenna                                        Antenna Size        Antenna
                                   Type
         ID                                             (meters)         Gain (dBi)
          1                 Quadrafilar Helix             0.15              2.9
          2                 Quadrafilar Helix             0.15              4.8
          3                      Patch                    0.06              4.0
          4                 Quadrafilar Helix             0.15              5.0
          5                 Quadrafilar Helix             0.27              3.9
           6                      Patch                    0.18              3.7
           7                     Patch                    0.18                6
           8                     Patch                    0.19               3.7
           9                Quadrafilar Helix             0.27               3.9
          10                Quadrafilar Helix             0.27               3.9
          11                 Circular Patch              0.1524              4.5
          12                Quadrafilar Helix             0.15               2.9
          13                Quadrafilar Helix             0.15               4.8
          14                     Patch                    0.06               4.0
          15                Quadrafilar Helix             0.15               5.0
          16                Quadrafilar Helix             0.27               3.9
          17                     Patch                    0.18               3.7
          18                     Patch                    0.18                6
          19                     Patch                    0.19               3.7


                                             Comtech Mobile Datacom Corporation
                                                                  Exhibit B, Page 5
                      ROUS (E090027) Modification Application – September 8, 2017



Using the maximum power into the antenna of 6 dBW, a duty cycle of 52% and the
antenna gains from the table above; the minimum separations to achieve one milliwatt
per square centimeter power densities are calculated and listed in Table B below.


                                                   Separation distance for 1 mW
         Antenna
                                Type               per square centimeter Power
           ID
                                                           Density (cm)
             1            Quadrafilar Helix                     29
             2            Quadrafilar Helix                     36
             3                 Patch                            33
             4            Quadrafilar Helix                     37
             5            Quadrafilar Helix                     32
             6                 Patch                            31
             7                 Patch                            41
             8                 Patch                            31
             9            Quadrafilar Helix                     32
            10            Quadrafilar Helix                     32
            11             Circular Patch                       41
            12            Quadrafilar Helix                     29
            13            Quadrafilar Helix                     36
            14                 Patch                            33
            15            Quadrafilar Helix                     37
            16            Quadrafilar Helix                     32
            17                 Patch                            31
            18                 Patch                            41
            19                 Patch                            31


The typical CMDC MES is installed on the top surface of a land vehicle, ship, or aircraft.
Distances to operating personnel and the general population will be greater than the
separation distances calculated above.

The table below indicates the typical CMDC MES mounting location for various
applications and the minimum distance necessary to prevent a hazard to operators and the
general population.


                                              Comtech Mobile Datacom Corporation
                                                                   Exhibit B, Page 6
                       ROUS (E090027) Modification Application – September 8, 2017



                  Typical
                 minimum          Minimum distance necessary    Minimum distance necessary
Application     installation       to prevent hazard (cm) for    to prevent hazard (cm) for
              separation from            9-ASDR/INT                    10-ASDO/INT
                people (cm)
Trucking             90                        58                             28
  Rail              300                        58                             28
Container           200                        58                             28
 Boats             >300                        58                             28
Aviation             75                        58                             28


                                                                Minimum distance necessary
                                Typical minimum installation
       Application                                              to prevent hazard (cm) for all
                                separation from people (cm)
                                                                       other antennas
        Trucking                             90                              41
          Rail                              300                              41
        Container                           200                              41
         Boats                             >300                              41
        Aviation                             75                              41


                                          Conclusion

  The preceding analysis shows that the CMDC MESs meet the FCC guidelines for RF
  exposure.



Document Created: 2017-09-08 12:30:28
Document Modified: 2017-09-08 12:30:28

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