Attachment Att. B -RF Statement

This document pretains to SES-MOD-20160125-00086 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2016012500086_1123900

                           RADIATION HAZARD STUDY

                              SITE: KPHO-TV




KPHO 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) =        2.4 M

                             Operating Wavelength (λ) =     .021 M

                             Antenna Gain (G) =           48.9 dBi

                             Transmitter RF Power (P) = 100.0 W (max)

2.0   Summary of Results

      RF Power Density - Centerline of Near Field = 4.55 mw/cm²

      RF Power Density - Far Field =                  1.93 mw/cm²

      *RF Power Density - Edge of Near Field = 0.05 mw/cm²

      *RF Power Density - Behind Antenna = 0.017 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:

                          68.40 meters

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

                        164.16 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:

                          4.55 mw/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:

                         0.046 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:

                               1.93 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:

                             0.017 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.




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Document Created: 2016-01-25 13:45:01
Document Modified: 2016-01-25 13:45:01

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