1.65 letter 2014-12.

Section 1.65 Notification submitted by O3b Limited

1.65 Notification re Updated Rad Haz for 1.8m

2014-12-11

This document pretains to SES-LIC-20141001-00781 for License on a Satellite Earth Station filing.

IBFS_SESLIC2014100100781_1070876

LAW OFFICES GOLDBERG, GODLES, WIENER & WRIGHT LLP 1229 NINETEENTH STREET, N.W. WASHINGTON, D.C. 20036-2413 HENRY GOLDBERG (202) 429-4900 JOSEPH A. GODLES TELECOPIER: JONATHAN L. WIENER (202) 429-4912 DEVENDRA (“DAVE”) KUMAR e-mail: ________ general@g2w2.com HENRIETTA WRIGHT website: www.g2w2.com THOMAS G. GHERARDI, P.C. COUNSEL ________ THOMAS S. TYCZ* SENIOR POLICY ADVISOR *NOT AN ATTORNEY December 11, 2014 Marlene H. Dortch Secretary Federal Communications Commission 445 12th Street, SW Washington, DC 20554 Re: O3b Limited FCC File No. SES-LIC-20141001-00781 (Call Sign E140101) Dear Ms. Dortch: Pursuant to Section 1.65 of the Commission’s rules, 47 C.F.R. § 1.65, O3b Limited (“O3b”), by its counsel, hereby provides a complete radiation hazard report for the operation of 1.8m antennas that is proposed in the above-referenced application. Because of an oversight, the last page of the 1.8m radiation hazard report was not included previously. Please contact the undersigned if you have any questions. Respectfully submitted, Joseph A. Godles Counsel to O3b Limited

Radiation Hazard Study - GDST1.8M, 1.8 m Antenna RADIATION HAZARD STUDY When applying for a license to construct and operate, modify, or renew an earth station, it is understood that licensees must certify whether grant of the application will have significant environmental impact as defined in the Federal Communications Commission’s (FCC) rules, 47 C.F.R., Section 1.1307. In this report SES Government Solutions, Inc. (“SES-GS”) analyzes the maximum radiofrequency (RF) levels emitted from the satellite communications antenna described below. The reference document for this study is OET Bulletin No. 65, Edition 97-01, Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, August 1997. I. Antenna Near-Field Power Density Calculation The extent of the near-field is defined by the following equation: Rnear = (Dant)2 / (4O) where: Rnear = extent of the near-field (in meters) Dant = diameter of the antenna main reflector (in meters) O = wavelength of the RF transmit frequency (in meters) The maximum on-axis power density within near-field is defined by the following equation: Snear = {(16KPfeed) / [S(Dant)2]} / 10 where: Snear = maximum on-axis power density within the near-field (in milliwatts per square centimeter) K = antenna aperature efficiency Pfeed = maximum power into antenna feed flange (in watts) Dant = diameter of the antenna main reflector (in meters) Page 2

II. Antenna Far-Field Power Density Calculation The distance to the beginning of the far-field region is defined by the following equation: Rfar = [0.6(Dant)2] / O where: Rfar = distance to beginning of far-field (in meters) Dant = diameter of the antenna main reflector (in meters) O = wavelength of the RF transmit frequency in (meters) The maximum on-axis power density within the far-field is defined by the following equation: Sfar = [(Pfeed Gant) / 4S(Rfar)2] / 10 where: Sfar = maximum on-axis power density in the far-field (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Gant = antenna main beam gain at RF transmit frequency (in watts) Rfar = distance to beginning of far-field (in meters) III. Antenna Transition Region Power Density Calculation By definition, the maximum on-axis power densitiy in the transition region will never be greater than the maximum on-axis power densities in the near-field: Str d Snear where: Str = maximum on-axis power density in the transition region (in milliwatts per square centimeter) Snear = maximum on-axis power density in the near-field (in milliwatts per square centimeter) IV. Antenna Feed-Flange (or Subreflector) Power Density Calculation The maximum power density at the antenna feed-flange (or subreflector surface) is defined by the following equation: Sfeed(sub) = 1000 {[4(Pfeed)] / {[S(Dfeed(sub))2 ] / 4}} where: Sfeed(sub) = maximum power density at the antenna feed-flange or subreflector surface (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dfeed(sub) = diameter of the antenna feed-flange or subreflector (in centimeters) Page 3

V. Antenna Main Reflector Power Density Calculation The maximum power density in the main reflector region of the antenna is defined by the following equation: Sant = {[2(Pfeed)] / {[S(Dant)2 ] / 4}} / 10 where: Sant = maximum power density in the antenna main reflector region (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dant = diameter of the antenna main reflector (in meters) VI. Power Density Calculation between the Antenna Main Reflector and the Ground The maximum power density between the antenna main reflector and the ground is defined by the following equation: Sground = {Pfeed / {[S(Dant)2 ] / 4}} / 10 where: Sground = maximum power density between the antenna main reflector and the ground (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dant = diameter of the antenna main reflector (in meters) VII. Summary of Calculated Radiation Levels SES-GS understands the licensee must ensure people are not exposed to harmful levels of radiation. Maximum permissible exposure (MPE) limits for general population/uncontrolled exposure were not considered in this analysis for several reasons. The main-beam orientation and height above ground of this highly directional antenna significantly limit exposure to the general population. Furthermore, access to SES-GS stations is limited to authorized personnel who have been appropriately briefed and advised. MPE limits for occupational/controlled exposure, however, were considered in this analysis. It is standard practice for our technical staff to cease transmissions whenever maintenance is performed in close proximity to antenna reflector regions with potentially hazardous power density levels. Based on the results (see next page entitled “Radiation Hazard Calculations”) and our standard practices within our controlled antenna environment, the earth station operators / technicians should not be exposed to radiation levels exceeding 5 mW/cm2 power density over a six minute averaging time. Page 4

Antenna main reflector diameter 1.8 m Feed flange (or subreflector) diameter 4.4500 cm RF transmit frequency 28.388 GHz Maximum power into antenna feed-flange 40.00 W Main-beam gain of antenna (at RF transmit frequency) 52.8 dBi 190546.1 W Antenna aperature efficiency 0.65 Antenna main reflector surface area 2.54 m^2 Feed flange (or subreflector) surface area 15.553 cm^2 Wavelength of the RF transmit frequency 0.011 m Distance to beginning of far-field region 184.08 m Distance to extent of near-field region 76.70 m Max. on-axis power density [far-field] 1.790 mW/cm^2 SATISFIES MPE LIMITS Max. on-axis power density [near-field] 4.087 mW/cm^2 SATISFIES MPE LIMITS Max. on-axis power density [transition region] 4.087 mW/cm^2 SATISFIES MPE LIMITS Max. power density [feed-flange or subreflector] 10287.505 mW/cm^2 POTENTIAL HAZARD Max. power density [main reflector region] 6.288 mW/cm^2 POTENTIAL HAZARD Max. power density [between main reflector and ground] 1.572 mW/cm^2 SATISFIES MPE LIMITS Page 5


Document Created: 2014-12-11 12:43:53
Document Modified: 2014-12-11 12:43:53
© 2024 FCC.report
This site is not affiliated with or endorsed by the FCC