Attachment Radiation Analysis

This document pretains to SES-AMD-20100409-00430 for Amended Filing on a Satellite Earth Station filing.

IBFS_SESAMD2010040900430_810029

EXHIBIT A Page 1 of 5 Analysis of Non-Ionizing Radiation for a 6.3 Meter Earth Station System This report analyzes the non-ionizing radiation levels for a 6.3 meter earth station system. The analysis and calculations performed in this report are in compliance with the methods described in the FCC Office of Engineering and Technology Bulletin, No. 65 first published in 1985 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 specifies that there are two separate tiers of exposure limits that are dependant 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 in Table 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, transition region, 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)*(0.8/1200) 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.

EXHIBIT A Page 2 of 5 Table 3. Formulas and Parameters Used for Determining Power Flux Densities Parameter Abbreviation Value Units Antenna Diameter D 6.3 meters Antenna Surface Area Sa II * D**2/4 meters**2 Subreflector Diameter Ds 81.3 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 57.4 dBi Pi II 3.1415927 n/a Antenna Efficiency n 0.63 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 (1) = 1113.3 meters 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 (2) = 10.512 Watts/meters**2 = 1.051 mWatts/cm**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: (3) Extent of the Near Field,(Rn) = D**2 / (4 * lambda) (3) = 463.9 meters

EXHIBIT A Page 3 of 5 The maximum power density in the Near Field can be determined from the following equation:(4) Near Field Power Density,(Wn) = 16.0 * n * P / II * D**2 (4) = 24.541 Watts/meters**2 = 2.454 mWatts/cm**2 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) = 2.454 mWatts/cm**2 (5) = Wn * Rn / Rt 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) Power Density at Feed Flange,(Ws) = = 4 * P / As (6) = 231.159 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 = 4 * P / Sa (7) Surface,(Wm) = 39.114 Watts/meters**2

EXHIBIT A Page 4 of 5 = 3.911 mWatts/cm**2 6. Region between Main Reflector and Ground Assuming uniform illumination of the reflector surface, the power density between the antenna and ground can be determined from the following equation:(8) Power Density between Reflector and = P / Sa (8) Ground,(Wg) = 9.778 Watts/meters**2 = 0.978 mWatts/cm**2 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) = 1113.3 meters 1.051 Potential Hazard 2. Near Field (Rn) = 463.9 meters 2.454 Potential Hazard 3. Transition Region 2.454 Potential Hazard Rn < Rt < Rf, (Rt) 4. Between Main Reflector and 231.159 Potential Hazard Subreflector 5. Main Reflector 3.911 Potential Hazard 6. Between Main Reflector and 0.978 Satisfies FCC MPE Ground

EXHIBIT A Page 5 of 5 Table 5. Summary of Expected Radiation levels for Controlled Environment It is the applicant's responsibility to ensure that the public and operational personnel are not exposed to harmful levels of radiation. Calculated Maximum Radiation Power Density Level Region (mWatts/cm**2) Hazard Assessment 1. Far Field (Rf) = 1113.3 meters 1.051 Satisfies FCC MPE 2. Near Field (Rn) = 463.9 meters 2.454 Satisfies FCC MPE 3. Transition Region 2.454 Satisfies FCC MPE Rn < Rt < Rf, (Rt) 4. Between Main Reflector and 231.159 Satisfies FCC MPE Subreflector 5. Main Reflector 3.911 Satisfies FCC MPE 6. Between Main Reflector and 0.978 Satisfies FCC MPE Ground 7. Conclusions Based upon the above analysis, it is concluded that harmful levels of radiation may exist in those regions noted for the Uncontrolled (Table 4) Environment. The antenna will be installed at Palmdale Production Facility near Palmdale, CA. The facility is surrounded by a fence and maintains 24 hour security which will restrict any public access. The earth station will be marked with the standard radiation hazard warning signs and lights, as well as the area in the vicinity of the earth station to inform those in the general population, who might be working or otherwise present in or near the direct path of the main beam. Northrop Grumman Systems Corporation will ensure that the main beam of the antenna will be pointed at least one diameter away from any building, walkway or other obstacles in those areas that exceed the MPE levels. Further, the earth station's operating personnel will not have access to areas that exceed the MPE levels while the earth station is in operation. The transmitter will be turned off except for periods of active use and 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 main reflector, which could be occupied by operating personnel.


Document Created: 2010-03-16 15:13:35
Document Modified: 2010-03-16 15:13:35
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