Attachment RadHaz Study

This document pretains to SES-MOD-20120508-00423 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2012050800423_951104

RadHaz Exhibit Page 1 of 5 Analysis of Non-Ionizing Radiation for a 8.1 Meter Earth Station System This report analyzes the non-ionizing radiation levels for a 8.1 meter earth station system. The analysis and calculations performed in this report are in compliance with the methodsdescribed in the FCC Office of Engineering and Technology Bulletin, No. 65 first published in1985 and revised in 1997 in Edition 97-01. The radiation safety limits used in the analysis are in conformance with the FCC R&O 96-326. Bulletin No. 65 and the FCC R&O specify that there are two separate tiers of exposure limits that are dependent on the situation in which the exposure takes place and/or the status of the individuals who are subject to the exposure. The Maximum Permissible Exposure (MPE) limits for persons in a General Population/ Uncontrolled environment are shown inTable 1. The General Population/ Uncontrolled MPE is a function of transmit frequency and is for an exposure period of thirty minutes or less. The MPE limits for persons in an occupational/controlled environment are shown in Table 2. The Occupational MPE is a function of transmit frequency and is for an exposure period of six minutes or less. The purpose of the analysis described in this report is to determine the power flux density levels of the earth station in the far-field, near-field, transitionregion, between the subreflector or feed and main reflector surface, at the main reflector surface, and between the antenna edge and the ground and to compare these levels to the specified MPEs. Table 1. Limits for General Population/Uncontrolled Exposure (MPE) Frequency Range (MHz) Power Density (mWatts/cm**2) 30-300 0.2 300-1500 Frequency (MHz)*(O.B/1200) 1500-100,000 1.0 Table 2. Limits for Occupational/Controlled Exposure (MPE) Frequency Range (MHz) Power Density (mWatts/cm**2) 30-300 1.0 300-1500 Frequency (MHz)*(4.0/1200) 1500-100,000 5.0 Table 3 contains the parameters that are used to calculate the various power densities for the earth stations.

RadHaz Exhibit Page 2 of 5 Table 3. Formulas and Parameters Used for Determining Power Flux Densities Parameter Abbreviation Value Units Antenna Diameter D 8.1 meters Antenna Surface Area Sa II * D**2/4 meters**2 Subreflector Diameter Ds 105.0 cm Area of Subreflector As II * Ds**2/4 cm**2 Frequency Frequency 14250 MHz Wavelength lambda 300/frequency(MHz) meters Transmit Power P 300.00 Watts Antenna Gain Ges 59.8 dBi Pi II 3.1415927 N/A Antenna Efficiency n 0.65 N/A 1. Far Field Distance Calculation The distance to the beginning of the far field can be determined from the following equation:(1) Distance to the Far Field Region,(Rf) = 0.60 * D**2 / lambda = 1869.9 meters (1) The maximum main beam power density in the Far Field can be determined from the following equation: (2) On-Axis Power Density in the Far Field,(Wf) = Ges * P / 4 * II * Rf**2 = 6.521 Watts/meters**2 = 0.652 mWatts/cm**2 (2) 2. Near Field ·calculation Power flux density is considered to be at a maximum value throughout the entire length of the defined Near Field region. The region is contained within a cylindrical volume having the same diameter as the antenna. Past the boundary of the Near Field region the power density from the antenna decreases linearly with respect to increasing distance. The distance to the end of the Near Field can be determined from the following equation: Extent of the Near Field, (Rn) = D**2 / (4 * lambda) = 779.1 meters (3) The maximum power density in the Near Field can be determined from the following equation: Near Field Power Density, (Wn) = 16.0 * n * P / II * D**2 = 15.222 Watts/meters**2 = 1.522 mWatts/cm**2 (4)

RadHaz Exhibit Page 3 of 5 3. Transition Region Calculations The Transition region is located between the Near and Far Field regions. The power density begins to decrease linearly with increasing distance in the Transition region. While the power density decreases inversely with distance in the Transition region, the power density decreases inversely with the square of the distance in the Far Field region. The maximum power density in the Transition region will not exceed that calculated for the Near Field region. The power density calculated in Section 1 is the highest power density the antenna can produce in any of the regions away from the antenna. The power density at a distance Rt can be determined from the following equation: (5) Transition region Power Density, (Tt) = Wn * Rn / Rt (5) = 1.522 mWatts/cm**2 4. Region between Main Reflector and Subreflector Transmissions from the feed assembly are directed toward the subreflector surface, and are reflected back toward the main reflector. The most common feed assemblies are waveguide flanges, horns or subreflectors. The energy between the subreflector and the reflector surfaces can be calculated by determining the power density at the subreflector surface. This can be determined from the following equation: (6) (6) Power Density at Feed Flange,(Ws) = 4 * P / As = 138.584 mWatts/cm**2 5. Main Reflector Region The power density in the main reflector is determined in the same manner as the power density at the subreflector. The area is now the area of the main reflector aperture and can be determined from the following equation: (7) Power Density at the Main Reflector Surface, (Wm) = 4 * P / Sa (7) = 23.287 Watts/meters**2 = 2.329 mWatts/cm**2 6. Region Between the Main Reflector and the Ground Assuming uniform illumination of the reflector surface, the power density between the antenna and ground can be Determined from the following equation: (8) (8) Power Density between the Reflector and the Ground, (wg) = P / Sa = 5.822 Watts/meters**2 = 0.582 mWatts/cm**2

RadHaz Exhibit Page 4 of 5 Table 4. Summary of Expected Radiation levels for Uncontrolled Environment Calculated Maximum Radiation Power Density Level Region (mWatts/cm**2) Hazard Assessment 1. Far Field (Rf) = 1869.9 meters 0.652 Satisfies FCC MPE 2. Near Field (Rn) = 779.1 meters 1.522 Potential Hazard 3. Transition Region Rn < Rt < Rf, (Rt) 1.522 Potential Hazard 4. Between Main Reflector and Subreflector 138.584 Potential Hazard 5. Main Reflector 2.329 Potential Hazard 6. Between Main Reflector and Ground 0.582 Satisfies FCC MPE Table 5. Summary of Expected Radiation levels for Controlled Environment Calculated Maximum Radiation Power Density Level Region (mWatts/cm**2) Hazard Assessment 1. Far Field (Rf) = 1869.9 meters 0.652 Satisfies FCC MPE 2. Near Field (Rn) = 779.1 meters 1.522 Satisfies FCC MPE 3. 4. Transition Region Rn < Rt < Rf, (Rt) 1.522 Satisfies FCC MPE 5. Between Main Reflector and Subreflector 138.584 Potential Hazard 6. Main Reflector 2.329 Satisfies FCC MPE 7. Between Main Reflector and Ground 0.582 Satisfies FCC MPE It is the applicant's responsibility to ensure that the public and operational personnel are not exposed to harmful levels of radiation.

RadHaz Exhibit Page 5 of 5 7. Conclusions Based upon the above analysis, it is concluded that harmful levels of radiation may exist in those regions noted for the Uncontrolled Environment (Table 4). The licensed earth station is installed at Encompass Digital Media’s Stamford facility. This facility is surrounded by a fence, which restricts public access to the site. The earth station is marked with the standard radiation hazard warnings, as well as the area in the vicinity of the e a r t h station to inform those in the general population, who may be working or otherwise present in or near the direct path of the main beam. Encompass Digital Media will ensure that the main beam of the antenna will be pointed at least one diameter away from any buildings, or other obstacles in those areas that exceed the MPE levels. Finally the earth station's operating personnel will not have excess to areas that exceed the MPE levels, while the earth station is in operation. The transmitter will be turned off during periods of maintenance, so that the MPE standard of 5.0 mw/cm**2 will be complied with for those regions in close proximity to the reflector, and normally occupied by operating personnel.


Document Created: 2012-05-04 18:03:52
Document Modified: 2012-05-04 18:03:52
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