Attachment RF_Exposure_Study

This document pretains to SES-LIC-20121214-01103 for License on a Satellite Earth Station filing.

IBFS_SESLIC2012121401103_977264

                               Engineering Statement
                     RADIOFREQUENCY EXPOSURE CALCULATIONS
                                                prepared for
                                     WXII Hearst Television Inc.

        WXII Hearst Television Inc. (“WXII-TV”) is the applicant for a transportable “Ku Band” satellite
uplink license. The following study was conducted to evaluate the proposed facility with respect to the
potential for human exposure to radiofrequency (“RF”) electromagnetic field. Specifically, the study
determined whether exposure to RF electromagnetic field would exceed FCC maximum permissible
exposure limits to the general public and to occupational workers at locations in the vicinity of the uplink
antenna based on data provided by the applicant and representatives of the equipment manufacturers.



Human Exposure to Radiofrequency Electromagnetic Field
        The WXII-TV proposed operation was evaluated using the procedures outlined in FCC OET
Bulletin No. 65 (“OET 65"). OET 65 describes a means of determining whether a proposed facility
exceeds the RF exposure guidelines specified in §1.1310 of the Rules. Under present Commission policy,
a facility may be presumed to comply with the limits in §1.1310 if it satisfies the exposure criteria set
forth in OET 65. Based upon that methodology, and as demonstrated in the following, the transmitting
system under study will comply with the cited adopted guidelines at publicly accessible locations when
procedures described herein are followed.



Public Exposure
        The mechanical design of the mounting equipment is optimized to orient the antenna toward
satellites that are located well above the horizon.      Prevention of public exposure to predicted RF
electromagnetic field in excess of the general population/uncontrolled limit1 depends on adherence to the
following operational guidelines by the WXII-TV technicians.


        As shown below, RF attributable to the WXII-TV uplink antenna at locations outside of the “main
beam” and 2.40 meters or more from the center of the main beam will not exceed the FCC general
population and uncontrolled RF exposure limits. According to representatives of WXII-TV, at its lowest
elevation, the center of the uplink antenna is 5.4 meters above the ground and thus more than one dish-
diameter above head level (2 meters) on level terrain.




1
  The general population/uncontrolled maximum permissible exposure (“MPE”) limit of 1 mW/cm² for 14,250 MHz
is specified in §1.1310 of the Rules.


                                      Cavell, Mertz & Associates, Inc.


                                                Engineering Statement
                                                        (page 2 of 4)

               To assure that no publicly accessible area is within the “main beam” of the uplink antenna, sites
       and satellites will be selected such that the elevation angle of the antenna will always exceed five degrees
       and the main beam is 2.40 meters above the horizon, nearby buildings, and places accessible by the
       public. In unusual cases where this isolation cannot be achieved, WXII-TV will utilize crowd control
       stanchions, cones, and RF exposure warning signs to control access to areas that are known to exceed the
       FCC’s general population uncontrolled MPE limit. These areas will be defined either by measurements
       made by qualified, on-site personnel, or by the calculations described herein.


               Based on data provided by the applicant, the following parameters were used in the study:


                   Antenna Manufacturer                           General Dynamics
                   Antenna Model                                  2.4 DMK
                   Center Transmit Frequency                      14,250 MHz
                   Wavelength at Center Frequency                 0.021 meters
                   Max Average Antenna Input Power                108.87 Watts
                   Antenna Diameter                               2.40 meters
                   Antenna Gain                                   48.8 dBi
                   Antenna Gain Ratio                             75857.8
                   Antenna Aperture Efficiency                    0.591


               The area in the immediate vicinity of the antenna is known as the “near field region.”          In this
       region (up to 68.4 meters in the case at hand), the antenna directional characteristics have not fully
       formed. Therefore, antenna manufacturer “off-axis” discrimination specifications cannot be utilized for
       the purpose of determining potential RF exposure. OET 65 provides a methodology (Equation 13) for
       calculating a “worst case” exposure figure within this region. Additionally, OET 65 specifies that the
       “worst case” power density would be reduced by 20 dB at locations at least one antenna diameter (2.40
       meters) off-axis from the “main beam” of the antenna. In this instance, the predicted off-axis, near field is
       0.057 mW/cm², or 5.7 percent of the general population/uncontrolled limit. Off-axis predicted fields
       reduce commensurately at greater distances from the antenna in the antenna transition region.


               In the “far field” region of the antenna (in this case, starting at a distance of 164.3 meters from the
       antenna), the antenna directional characteristics have formed and the off-axis power density can be
       readily calculated using “off-axis” antenna discrimination specifications. At locations greater than five

                                             Cavell, Mertz & Associates, Inc.
2012141DGR


                                                    Engineering Statement
                                                            (page 3 of 4)

       degrees off-axis from the “main beam,” the manufacturer of the proposed antenna specifies a minimum
       side-lobe attenuation of 34.3 dB.2 Again using the methodology detailed in OET 65, this “off-axis”
       attenuation is predicted to result in a power density of 0.0009 mW/cm², or 0.09 percent of the general
       population/uncontrolled limit.


       Controlled Access Area Exposure

                  Access to the vicinity of the antenna will be limited and restricted to authorized, trained
       personnel. Using data provided by the applicant, the potential for RF exposure to occupational workers
       was evaluated. As described previously, the maximum predicted off-axis, “near field” power density is
       0.057 mW/cm², which is 1.14 percent of the controlled limit. As the operator will generally be posted at
       locations at ground level or within the truck itself, it is anticipated that actual exposure will be
       substantially less than the above “worst case” prediction.



                  With respect to worker safety, it is believed that based on the preceding analysis, excessive
       exposure would not occur provided that adequate physical separation is established. As mentioned
       previously, detailed operator policy will be employed protecting workers from excessive exposure when
       work must be performed where high RF levels may be present. Such protective measures may include,
       but will not be limited to, restriction of access to areas where levels in excess of the guidelines may be
       expected, or the complete shutdown of facilities when work or inspections must be performed in areas
       where the exposure guidelines would otherwise be exceeded. On-site RF exposure measurements may
       also be undertaken to establish the bounds of safe working areas. The applicant will coordinate exposure
       procedures with all pertinent facilities.



       Conclusion

                  As demonstrated herein, excessive levels of RF energy will not be caused at publicly accessible
       areas by strictly following the policy detailed herein. Consequently, neither members of the general
       public nor occupational staff will be exposed to RF levels in excess of the Commission’s guidelines.
       Whenever necessary to assure compliance, access to the vicinity of the uplink antenna will be restricted
       and controlled through the use of crowd control stanchions, cones, and conspicuous RFR warning signs as
       part of an overall RF safety program. The above study presumes that the subject antenna is the sole


       2
           According to the manufacturer, the antenna meets the minimum off-axis specification detailed in FCC Rule
            §25.209(a)(2) or 32-25 Log(θ) dBi.


                                                 Cavell, Mertz & Associates, Inc.
2012141DGR


                                               Engineering Statement
                                                       (page 4 of 4)

       source of RF energy at the uplink site. In the case of multiple emitters, further analysis or measurement is
       necessary to assure compliance.



       Certification

               The undersigned hereby certifies that the foregoing statement was prepared by him or under his
       direction, and that it is true and correct to the best of his knowledge and belief. Mr. Ryson is a senior
       engineer in the firm of Cavell, Mertz & Associates, Inc.




                                                                       Daniel G. Ryson
                                                                       December 5, 2012


       Cavell, Mertz & Associates, Inc.
       7732 Donegan Dr.
       Manassas, VA 20109-2686
       (703) 392-9090




                                             Cavell, Mertz & Associates, Inc.
2012141DGR



Document Created: 2012-12-05 15:43:10
Document Modified: 2012-12-05 15:43:10

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