Attachment RADIATION HAZARD STU

This document pretains to SES-LIC-20080701-00870 for License on a Satellite Earth Station filing.

IBFS_SESLIC2008070100870_650745

    RADIATION HAZARD STUDY

                              SITE: University Of Mississippi




University Of Mississippi has evaluated the radio frequency environment in
and around the proposed earth station and found it to be safe for continuous
exposure of operating personnel and the general public.

Only the internal antenna structure, specifically the area between the
feedhorn and the dish, shows a radio frequency environment that is
considered excessive for continuous exposure of personnel. This area is
sufficiently high above ground level that it cannot accidentally be entered
without the aid of mechanical equipment.

The supporting calculations that are submitted as part of this study show
that the proposed earth station is environmentally safe, not only based on
the criteria published in the Occupational Safety and Health Act (OSHA), but
also in the light of recent recommendations for stricter control of radio
frequency radiation.

1.0    Station Parameters

                             Antenna Diameter (D) =        1.5 M

                             Operating Wavelength (λ) =     .021 M

                             Antenna Gain (G) =           45.5 dBi

                             Transmitter RF Power (P) = 200.0 W

2.0    Summary of Results

       RF Power Density - Centerline of Near Field = 27.18 mw/cm²

       RF Power Density - Far Field =                 13.8 mw/cm²

       *RF Power Density - Edge of Near Field = 0.27 mw/cm²

       *RF Power Density - Behind Antenna = 0.040 mw/cm²

*      The density levels denoted by an asterisk are representative of the
       maximum radiation environment in or around the proposed earth station
       to which the general public may be exposed.




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3.0   Near Field Evaluation

      The earth station antenna that will be employed for this service is
      designed to focus nearly all of the radiated radio frequency energy
      into a cylindrical beam with a diameter only slightly larger than that
      of the antenna dish. Any intrusion into this beam would impair the
      performance of this earth station. This broadcaster has, therefore,
      selected a site location for the antenna that will insure that the beam
      of principle radio frequency radiation is clear of any obstructions,
      buildings, etc. and cannot accidentally be entered by the general
      public.

3.1   The near field cylindrical projection extends to a distance (d) that is
      defined by the following relationship:

                          d(nf)= D²/4λ

                          d(ff)= .6D²/λ

      For the proposed antenna, the near field extends, therefore, to a
      distance of:

                          26.8 meters

      And the far field extends, therefore, to a distance of:

                          64.3 meters

3.2   The maximum radio frequency power density within this near field
      cylinder is a function of the antenna diameter and transmitter power as
      follows:

                          W(nf) = 9.6P/πD²

      For the proposed earth station, the maximum power density in the near
      field was computed not to exceed:

                          27.18mw/cm²

3.3   At the edge of the near field cylindrical beam, 0.7 antenna diameter
      removed from its center, the power density is attenuated at least 20 dB
      to 1/100th of the maximum near field power. The power along the
      outside edge of the beam will, therefore, not exceed:

                          0.27 mw/cm²




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4.0   Far Field Evaluation

      Beyond the near field region, the cylindrical beam begins to

      spread gradually into a slightly tapered cone in accordance   with the
      published radiation pattern for the proposed         antenna. The
      specified antenna gain is realized and the       radiated power density
      decreases proportionally to the        inverse square of distance from
      the antenna.

4.1   For the purpose of determining the maximum power density within the far
      field, this broadcaster has conservatively assumed that the full
      antenna gain is already realized at the limit of the near field
      cylindrical region. The radio frequency power density in the far field
      region is given by:

                             W(ff) = PG/4πd²

      For the proposed earth station, the maximum radiated power at the point
      of transition between the near field and far field regions was computed
      not to exceed:

                              13.68 mw/cm²

5.0   Off-Axis Evaluation

      The proposed antenna meets or exceeds the performance specifications
      under part #25 of the FCC rules. The off-axis gain of this antenna is,
      therefore, - 10dBi or less in any direction more than 48° removed from
      the centerline of the main beam.

5.1   The off-axis power density may be conservatively evaluated using the
      far field method of computation:

                             W (OA) = 0.1P/4πd²

      Assuming a distance of 2 meters from the antenna, the density was
      calculated to be:

                             0.040 mw/cm²




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6.0   Summary

6.1   The computed values for near field projection distance, RF power
      density at the centerline, RF power density in the far field, RF power
      density at the edge of the near field, and RF power density behind the
      antenna are furnished by the Engineering Department.

6.2   Radiation calculations verify that the actual levels, which are
      accessible to the general given the system design, do not exceed the
      OSHA maximum of 5mw/cm² with-in the off-axis access areas of the
      system.


                        TECHNICAL CERTIFICATION


      I hereby certify that I am the technically qualified person responsible

for preparation of the engineering information contained in this

Application; that I am familiar with the applicable Rules of the Commission;

that I have either prepared or reviewed the engineering information

submitted in this application; and that it is complete and accurate to the

best of my knowledge.



                                By: Bram Flynn



                                Name:Bram Flynn



                                Title:Owner



                                Company: Bram Flynn & Associates




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Document Created: 2008-07-01 09:21:27
Document Modified: 2008-07-01 09:21:27

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