Attachment A Radiation Analysis

This document pretains to SES-LIC-20100217-00203 for License on a Satellite Earth Station filing.

IBFS_SESLIC2010021700203_802081

Analysis of Non-Ionizing Radiation for a 0.6m Earth station system This report analyzes the non-ionizing radiation levels for a 0.6m earth station system. The analysis and calculations performed in this report comply with the methods described in the FCC Office of Engineering and Technology Bulletin, No. 65 first published in 1985 and revised in 1987 in Edition 97-01. The radiation safety limits used in the analysis are in conformance 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 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 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 earth station in the far-field, near-field, transmission region, between the 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. Frequency Range (MHz) Power Density (mW/cm2) 30-300 0.2 300-1500 Frequency (MHz)*(0.8/1200) 1500-100,00 1.0 Table 1. Limits for General Population/Uncontrolled Exposure (MPE) Frequency Range (MHz) Power Density (mW/cm2) 30-300 0.2 300-1500 Frequency (MHz)*(0.8/1200) 1500-100,00 1.0 Table 2. Limits for Occupationa;/Controlled Exposure (MPE) Parameter Symbol Formula Value Units Antenna D Input 0.6 m Diameter Antenna Asurface D2/4 0.2826 m2 Surface Area Frequency F Input 6250 MHz Wavelength 300/F 0.048 M Transmit Power P Input 4 W Antenna Gain Ges Input 28 dBi (dBi) Antenna Gain G 10Ges/10 630 n/a (factor) Pi Constant 3.1415927 n/a Antenna G 2/( 2D2) 65 % Efficiency Table 3. Formulas & Parameters Used for determining Power Flux Densities

1. Far Field distance Calculation The distance to the beginning of the far field can be determined from the following equation: Distance to the Far Field Region Rff = 0.60 D2 / =4.5 m The maximum main beam power density in the far field can be determined from the following equation: On-Axis Power Density in the Far-Field Sff = G P / (4 Rff2) =10 W/m2 = 1mW/cm2 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 using the following equation: Extent of the Near Field Rnf = D2 / (4 ) = 1.875 m The maximum power Flux Density in the Near Field can be determined from the following equation: Near Field Power Flux Density Snf = 16 P / ( D2) = 3.6 mW/cm2 3. Transition Region Power Density 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 calculation 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: Transition Region Power Density St = Snf Rnf / Rt = 1.5 mW/cm2

4. Main Reflector Region The power density in the main reflector is determined using the following equation: Power Density at Main Reflector Ssurface = 4 P / Asurface = 5.6 mW/cm2 5. Region Between the Main Reflector and the Ground Assuming uniform illumination of the reflector surface, the power density between the antenna and the ground can be determined from the following equation: Power density between Reflector and Ground Sg = P / Asurface = 1.4 mW/cm2 6. Summary of Calculations Region Calculated Maximum Radiation Hazard assessment power Density Level (mW/cm2) 1. Far Field Sff 9.8 Satisfies FCC MPE 2. Near Field Snf 3.6 Satisfies FCC MPE 3. Transition Region St 0.99 Satisfies FCC MPE (Rnf<Rt<Rff) 4. Main Reflector Ssurface 5.6 Satisfies FCC MPE 5. Between Main Reflector Sg 1.4 Satisfies FCC MPE and Ground Table 4. Summary of Expected Radiation Levels for Uncontrolled Environments 1. Far Field Sff 1.875 Satisfies FCC MPE 2. Near Field Snf 3.6 Satisfies FCC MPE 3. Transition Region St 1.5 Satisfies FCC MPE (Rnf<Rt<Rff) 4. Main Reflector Ssurface 5.6 Satisfies FCC MPE 5. Between Main Reflector Sg 1.4 Satisfies FCC MPE and Ground Table 4. Summary of Expected Radiation Levels for Controlled Environments It is the applicant’s responsibility to ensure that the public and operational personnel are not exposed to harmful levels of radiation. 7. Conclusion Based on the above analysis it is concluded that harmful levels of radiation will not exist in regions normally occupied by the public or the earth station’s operating personne. The transmitter will be turned off during antenna maintenance so that FCC MPE of 5 mW/cm2 will be complied with for those regions with close proximity to the reflector that exceed acceptable levels.


Document Created: 2010-02-19 09:17:43
Document Modified: 2010-02-19 09:17:43
© 2025 FCC.report
This site is not affiliated with or endorsed by the FCC