Attachment Rad Haz complete set

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

IBFS_SESLIC2014100100781_1063460

Radiation Hazard Study - Orbit AL-7103-Ka, 1.20 m Antenna Radiation Hazard Study The study in this section analyzes the potential RF human exposure levels caused by the Electro Magnetic (EM) fields of an Orbit AL-7103-Ka, 1.20 m antenna, operating with a maximum power at the flange of 20 Watts. The mathematical analysis performed below complies with the methods described in the FCC Office of Engineering and Technology (OET) Bulletin No. 65 (1985 rev. 1997) R&O 96-3 26 in "Evaluating Compliance with FCC Guideliness for Human Exposure to RF EM Fields, OET Bulletin 65 (Edition 97-01), Supplement B, FCC Office of Engineering & Technology, November 1997". Maximum Permissible Exposure There are two separate levels of exposure limits. The first applies to persons in the general population who are in an uncontrolled environment. The second applies to trained personnel in a controlled environment. According to 47 C.F.R. § 1.1310, the Maximum Permissible Exposure (MPE) limits for frequencies above 1.5 GHz are as follows: * General Population / Uncontrolled Exposure: 1.0 mW/cm2 * Occupational / Controlled Exposure: 5.0 mW/cm2 The purpose of this study is to determine the power flux density levels for the earth station under study as compared with the MPE limits. This comparison is done in each of the following regions: 1. Far-field region 2. Near-field region 3. Transition region 4. The region between the feed and the antenna surface 5. The main reflector region 6. The region between the antenna edge and the ground Input Parameters The following input parameters were used in the calculations: Calculated Parameters The following values were calculated using the above input parameters and the corresponding formula: Page - 1 of 4

Radiation Hazard Study - Orbit AL-7103-Ka, 1.20 m Antenna Behavior of EM Fields as a Function of Distance The behavior of the characteristics of EM fields varies depending on the distance from the radiating antenna. These characteristics are analyzed in three primary regions: the near-field region, the far-field region and the transition region. Of interest also are the region between the antenna main reflector and the subreflector, the region of the main reflector area and the region between the main reflector and ground. Figure 1. Electro-Magnetic Fields as a Function of Distance For parabolic aperture antennas with circular cross sections, such as the antenna under study, the near-field, far-field and transition region distances are calculated as follows: Page - 2 of 4

Radiation Hazard Study - Orbit AL-7103-Ka, 1.20 m Antenna The distance in the transition region is between the near and far fields. Thus, Rnf ≤ Rt ≤ Rff . However, the power density in the transition region will not exceed the power density in the near-field. Therefore, for purposes of the present analysis, the distance of the transition region can equate the distance to the near-field. Power Flux Density Calculations The power flux density is considered to be at a maximum through the entire length of the near-field. This region is contained within a cylindrical volume with a diameter, D, equal to the diameter of the antenna. In the transition region and the far-field, the power density decreases inversely with the square of the distance. The following equations are used to calculate power density in these regions: The region between the main reflector and the subreflector is confined to within a conical shape defined by the feed assembly. The most common feed assemblies are waveguide flanges. This energy is determined as follows: The power density in the main reflector is determined similarly to the power density at the feed flange; except that the area of the reflector is used. The power density between the reflector and ground, assuming uniform illumination of the reflector surface, is calculated as follows: Page - 3 of 4

Radiation Hazard Study - Orbit AL-7103-Ka, 1.20 m Antenna Summary of Calculations Table 1 below summarizes the calculated power flux density values for each region. In a controlled environment, the only regions that exceed FCC limitations are the regions between the main reflector and the sub-reflector as well as the main reflector region. These regions are only accessible by trained technicians who, as a matter of procedure, turn off transmit power before performing any work in these areas. Table 1. Power Flux Density for Each Region: In conclusion, the results show that the antenna, in a controlled environment, and under the proper mitigation procedures, meets the guidelines specified in § 1.1310 of the Regulations. Page - 4 of 4

Radiation Hazard Study - Orbit AL-7107-Ka, 2.2 m Antenna Radiation Hazard Study The study in this section analyzes the potential RF human exposure levels caused by the Electro Magnetic (EM) fields of an Orbit AL-7107-Ka, 2.2 m antenna, "OceanTrx7" operating with a maximum power at the flange of 40 Watts. The mathematical analysis performed below complies with the methods described in the FCC Office of Engineering and Technology (OET) Bulletin No. 65 (1985 rev. 1997) R&O 96-3 26 in "Evaluating Compliance with FCC Guideliness for Human Exposure to RF EM Fields, OET Bulletin 65 (Edition 97-01), Supplement B, FCC Office of Engineering & Technology, November 1997". Maximum Permissible Exposure There are two separate levels of exposure limits. The first applies to persons in the general population who are in an uncontrolled environment. The second applies to trained personnel in a controlled environment. According to 47 C.F.R. § 1.1310, the Maximum Permissible Exposure (MPE) limits for frequencies above 1.5 GHz are as follows: * General Population / Uncontrolled Exposure: 1.0 mW/cm2 * Occupational / Controlled Exposure: 5.0 mW/cm2 The purpose of this study is to determine the power flux density levels for the earth station under study as compared with the MPE limits. This comparison is done in each of the following regions: 1. Far-field region 2. Near-field region 3. Transition region 4. The region between the feed and the antenna surface 5. The main reflector region 6. The region between the antenna edge and the ground Input Parameters The following input parameters were used in the calculations: Calculated Parameters The following values were calculated using the above input parameters and the corresponding formula: Page - 1 of 4

Radiation Hazard Study - Orbit AL-7107-Ka, 2.2 m Antenna Behavior of EM Fields as a Function of Distance The behavior of the characteristics of EM fields varies depending on the distance from the radiating antenna. These characteristics are analyzed in three primary regions: the near-field region, the far-field region and the transition region. Of interest also are the region between the antenna main reflector and the subreflector, the region of the main reflector area and the region between the main reflector and ground. Figure 1. Electro-Magnetic Fields as a Function of Distance For parabolic aperture antennas with circular cross sections, such as the antenna under study, the near-field, far-field and transition region distances are calculated as follows: Page - 2 of 4

Radiation Hazard Study - Orbit AL-7107-Ka, 2.2 m Antenna The distance in the transition region is between the near and far fields. Thus, Rnf ≤ Rt ≤ Rff . However, the power density in the transition region will not exceed the power density in the near-field. Therefore, for purposes of the present analysis, the distance of the transition region can equate the distance to the near-field. Power Flux Density Calculations The power flux density is considered to be at a maximum through the entire length of the near-field. This region is contained within a cylindrical volume with a diameter, D, equal to the diameter of the antenna. In the transition region and the far-field, the power density decreases inversely with the square of the distance. The following equations are used to calculate power density in these regions: The region between the main reflector and the subreflector is confined to within a conical shape defined by the feed assembly. The most common feed assemblies are waveguide flanges. This energy is determined as follows: The power density in the main reflector is determined similarly to the power density at the feed flange; except that the area of the reflector is used. The power density between the reflector and ground, assuming uniform illumination of the reflector surface, is calculated as follows: Page - 3 of 4

Radiation Hazard Study - Orbit AL-7107-Ka, 2.2 m Antenna Summary of Calculations Table 1 below summarizes the calculated power flux density values for each region. In a controlled environment, the only regions that exceed FCC limitations are the regions between the main reflector and the sub-reflector as well as the main reflector region. These regions are only accessible by trained technicians who, as a matter of procedure, turn off transmit power before performing any work in these areas. Table 1. Power Flux Density for Each Region: In conclusion, the results show that the antenna, in a controlled environment, and under the proper mitigation procedures, meets the guidelines specified in § 1.1310 of the Regulations. Page - 4 of 4

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 O3b Limited ("O3b") provides analysis of 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 / (4λ) where: Rnear = extent of the near-field (in meters) Dant = diameter of the antenna main reflector (in meters) λ = wavelength of the RF transmit frequency (in meters) The maximum on-axis power density within near-field is defined by the following equation: Snear = {(16ηPfeed) / [π(Dant)2]} / 10 where: Snear = maximum on-axis power density within the near-field (in milliwatts per square centimeter) η = antenna aperature efficiency Pfeed = maximum power into antenna feed flange (in watts) Dant = diameter of the antenna main reflector (in meters) Page 1

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] / λ where: Rfar = distance to beginning of far-field (in meters) Dant = diameter of the antenna main reflector (in meters) λ = 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) / 4π(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 ≤ 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)] / {[π(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 2

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)] / {[π(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 / {[π(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 O3b 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 O3b 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 above) 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 3

DISTRIBUTION

1. Fo ormulas and Parameters Used U Th he following data d is used throughout t th he analysis: 2. Density D at Fee ed Flange he maximum power flux density Th d at the surface of thhe feed flangee is as followss: 3. Density D at Main Reflector he maximum power flux density Th d at the surface of thhe main reflecctor is as follo ows: 4. Density D betwe een Main Refflector and Grround Thhe maximum power flux density d in the area betweeen the edge off the main reflector and th he grround is as fo ollows

5. Density D within n the Near Fie eld Th d environment for a parabo he Near Field olic reflector antenna is co ontained withhin a cylinder with th he same diam meter as the main m reflectorr which extennds to a distan nce called thee Near Field EExtent Po ower within the t Near Field d is constant with the folloowing maximum flux density: 6. Density D at Transition Regio on Th he Transition Region is the en the Near FField and Far Field regions where poweer e area betwee decreases linearly with distance. Thhe maximum power flux density d n the Transitioon Region is located at thee Near Field eextent within raange and is caalculated as fo ollows: 7. Density D at Begginning of the e Far Field Th he Far Field region is the range r at which power decrreases inverseely with the ssquare of the distance. The maximum m power flux denssity within thee Far Field region occurs aat the Far Field Boundary and is calculated as follows:

8. Range to Far Field F General Population Exposure E Lim mit In n addition to the t power fluux density calculations at kkey locations,, it’s valuable to locate thee sp pecific range at which MPEE limits are re eached to aid in managingg exposure control. Th he following calculation c sh General Population MPE lim hows the rangge at which thhe Far Field G mit occurs: 9. Non‐Ionizing N Radiation R Sum mmary Fllux Densities & Exposure Limits L Gen mW/cm2 neral Populattion Exposure Limit = 1.0 m Occupational O mit = 5.0 mW//cm2 l Exposure Lim

Range to Key Points an nd General Po opulation Exp posure Limit A Avoidance Meethods 10. Co onclusion Th he above anaalysis confirms the presencce of potentiaally hazardous power flux densities at tthe O3b O Tier 2 MEO terminals which w will req quire physicall and operatio on protection ns to manage General Population and Occcupational Exxposure. As appropriatee, O3b will use fencing, signage, and othher measuress to limit acceess to the releevant arrea. Procedurres will be in place requirin ng that transmmit power bee turned off b before work o on the 2.4m antenna is performed d. Where an enclosed e areaa is necessary,, the size of the enclosed aarea will w consider th he RF hazardss and the surrrounding terrrain. The signage will clearrly state the sttandard Radiaation Hazard warning. ersonnel with Pe h access to th nas are off before he antenna wiill be trained to ensure thaat the antenn working w in the e vicinity or on n the antennaa systems direectly.


Document Created: 2014-10-01 03:42:59
Document Modified: 2014-10-01 03:42:59
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