Attachment RFR Assessment

This document pretains to SES-LIC-20180202-00083 for License on a Satellite Earth Station filing.

IBFS_SESLIC2018020200083_1333933

                          T E L E C O M M U N I C AT I O N S E N G I N E E R I N G

                   G RAY F RIERSON H AERTIG & A SSOC .
                          4646 S.W. C O U N C I L C R E S T D R I V E                ELECTRONIC MAIL
                            P O R TL A N D , O R E G O N 97239                       gfh@haertig.com
                                         503-282-2989 (Office)
                                          503-807-2989 (Cell)




27 January 2017




                          H UMAN E XPOSURE TO
               N ON -I ONIZING E LECTROMAGNETIC F IELDS




This office has been retained by Community Radio of Northern Colorado, Inc., to
investigate the non-ionizing electromagnetic fields ("NIEF") in the vicinity of a Ku Band
transmit/receive satellite earth terminal in order to determine whether these fields fall
within the guidelines for human exposure spelled out in FCC Office of Engineering and
Technology Bulletin 65, Edition 97-01 ("OET 65"); and to determine whether an
Environmental Assessment needs to be prepared per 47 CFR 1.1307 for reasons of NIEF.

The standard set out in OET 65 is derived from standards promulgated by the
IEEE/ANSI and the NCRP and was developed to limit the time-averaged absorption of
radio frequency power by human beings. OET 65 recognizes two classes of exposure,
"Occupational/Controlled" and "General Population/Uncontrolled." In general the
General Population standard is more restrictive than the Occupational Standard. At the
frequencies of interest here, the General Population/Uncontrolled Standard for power
density is 1,000 µW/cm2 and the Occupational/Controlled Standard is 5,000 µW/cm2.
Separate standards for the electric field strength and magnetic field strength are not
specified. Occupational exposure may be time averaged over 6 minutes and General
Population exposure may be averaged over a 30-minute period.

The subject satellite earth terminal operates at Ku Band frequencies, approximately
14,250 MHz, with a maximum licensed Effective Isotropic Radiated Power of 55.2 dBW.


PAGE 2                                   KUNC UPLINK – NIEF REPORT                           27 JANUARY 2018



         The maximum antenna input power is 4 watts. The antenna is a Prodelin Series 1251.
         This is an aperture antenna consisting of a circular paraboloid reflector of 2.4 meters
         diameter and an offset scalar feed. The gain of the antenna is 49.2 dBi at 14,250 MHz.
         and the calculated aperture efficiency η equals 0.66.

         The antenna is mounted at ground level adjacent to a parking lot. The area is accessible
         to the general public. There are publicly accessible areas within the near field region of
         the antenna, as defined below.

         Section 2 of OET 65 divides the electromagnetic environment relative to aperture
         antennas into four regions; the antenna surface; the near field region; the transition
         region; and the far field (Fraunhofer) region. Section 2 also suggests a series of
         calculations of the power density in each of these regions based on an empirical model
         for determining compliance with the exposure guidelines. While more detailed
         methods of analysis exist, the FCC has determined that the calculations set out in this
         section are of sufficient accuracy and are sufficiently conservative to demonstrate
         compliance with the standards for typical satellite uplinks using circular aperture
         antennas of parabolic cross section.

         Near Field Region
         The equation for the power density in the near field predicts the maximum power
         density that might occur in the near field region without regard to actual location. The
         radius of the boundary of the near field is defined by:

                 D2
         Rnf =
                 4λ


         Where:
         D is the diameter of the aperture antenna in meters and
         λ is wavelength in meters

         Therefore, the near field region of the antenna extends 68.4 meters from the antenna.

         The maximum likely power density in the near field in W/m2 is defined by:

                                 – G R AY F R I E R S O N H A E R T I G & A S S O C . –
                                  T E L E C O M M U N I C AT I O N S E N G I N E E R I N G


PAGE 3                                   KUNC UPLINK – NIEF REPORT                           27 JANUARY 2018




                 16 η P
         Snf =
                 πD2


         Where:
         η is the aperture efficiency of the antenna and
         P is the input power to the antenna in watts

         Substituting, we find that the maximum power density that is likely to occur in the near
         field from the proposed operation is 2.33 W/m2.

         Correcting for units, this is 233 µW/cm2.

         This value is well below the 1,000 µW/cm2 General Population/Uncontrolled exposure
         standard.

         Given a maximum allowable 1,000 µW/cm2 exposure and solving for power in the
         above equation, we find that this facility can operate at up to 17.4 watts antenna input
         power without exceeding the exposure limit. This power corresponds to 61.7 dBW
         EIRP. Operation at power levels above this would require either a more detailed
         analysis of power density levels in the near field or field measurements to ascertain
         compliance with the General Population/Uncontrolled exposure standards in OET 65.



         Transition Region
         Power density in the transition region is expressed as a percentage of the maximum
         near field power density proportional to the ratio of the distance to the boundary of the
         near field to the distance of interest from the antenna. This ratio is always less than one,
         therefore the power density in the transition region is always less than the maximum
         power in the near field region.

         Therefore fields in the transition region are well below the General Public/Uncontrolled
         exposure standard.


                                 – G R AY F R I E R S O N H A E R T I G & A S S O C . –
                                  T E L E C O M M U N I C AT I O N S E N G I N E E R I N G


PAGE 4                                  KUNC UPLINK – NIEF REPORT                           27 JANUARY 2018




         Far Field Region
         The power density at the boundary between the transition region and far field region is
         the same whether calculated by the transition region formula or the far field region
         formula and the power density decreases with the distance squared in the far field
         region. Therefore, the power density in the far field region is always less than in the
         transition region and therefore less than in the near field region.

         Therefore fields in the far field region are well below the General Public/Uncontrolled
         exposure standard.




                                – G R AY F R I E R S O N H A E R T I G & A S S O C . –
                                 T E L E C O M M U N I C AT I O N S E N G I N E E R I N G


PAGE 5                                   KUNC UPLINK – NIEF REPORT                           27 JANUARY 2018



         Antenna Surface
         The maximum power density at the surface of the antenna is defined by:

                     4P
         Ssurface
                    = A


         Where:
         A is the surface area of the reflector (as a conservative approximation this is
             surface



              taken as being equal to the aperture area of the reflector).


         With an antenna input power of 4 watts, the maximum power density at the surface of
         the dish is 3.53 W/m2. Correcting for units, this is 353 µW/cm2.

         This value is well below the 1000 µW/cm2 general public/uncontrolled MPE standard.



         Region Between Reflector and Feed
         The point of highest power density in this region will occur at the face of the feed horn.

         The power density at the face of the feed assembly is defined by

            4P
         S = A
          feed




         Where:
         A is the aperture area of the feed horn
             feed




         The Prodelin feed assembly has an aperture area of .0283 m               2




         Therefore the power density at the face of the feed horn is equal to 565.0 W/m .             2




         Correcting for units this is 56,500 µW/cm .     2




         This value exceeds both the general public/uncontrolled and occupational/controlled
         exposure standards by a considerable amount.


                                 – G R AY F R I E R S O N H A E R T I G & A S S O C . –
                                  T E L E C O M M U N I C AT I O N S E N G I N E E R I N G


PAGE 6                                  KUNC UPLINK – NIEF REPORT                                 27 JANUARY 2018




         The applicant will erect signage in the vicinity of the antenna warning workers that the
         maximum permissible exposure standard is exceeded in areas between the feed
         assembly and the reflector. The applicant will institute a lock-out/tag-out procedure to
         be followed during maintenance of the antenna.



         Conclusions
         At no place accessible to the general public is the General Population/Uncontrolled
         exposure standard exceeded;

         The Occupational/Controlled standard is exceeded only in a very limited area near the
         face of the feed assembly;

         Access to this area can be controlled and safety procedures instituted to prevent
         exposure to NIEF which exceeds the Occupational/Controlled exposure standard;

         This facility does    not    significantly        affect     the    environment    as   defined   in
         47 CFR §1.1307(b);

         And the preparation of an Environmental Assessment is, therefore, not required.




                                – G R AY F R I E R S O N H A E R T I G & A S S O C . –
                                 T E L E C O M M U N I C AT I O N S E N G I N E E R I N G


PAGE 7                                   KUNC UPLINK – NIEF REPORT                           27 JANUARY 2018



         I, Gray Frierson Haertig, hereby affirm that:


         I am principal of Gray Frierson Haertig and Assoc.;


         This firm has been retained by Community Radio of Northern Colorado, Inc., to
         investigate the NIEF levels in the vicinity of a receive/transmit satellite earth terminal
         and to prepare this report for submission to the Commission;


         All materials contained herein, unless otherwise attributed, have been prepared by
         myself;


         All statements made herein, unless otherwise attributed, are true to the best of my
         knowledge and reflect the actual facts of the matter;


         I am a Broadcast Engineer of 50 years experience, and my qualifications are a matter of
         record with the Commission.



         Respectfully submitted this 27 day of January 2018,
                                          th




                   Gray Frierson Haertig




                                 – G R AY F R I E R S O N H A E R T I G & A S S O C . –
                                  T E L E C O M M U N I C AT I O N S E N G I N E E R I N G



Document Created: 0810-04-18 00:00:00
Document Modified: 0810-04-18 00:00:00

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