Attachment Radiation Hazard Exh

This document pretains to SES-MOD-20101222-01633 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2010122201633_857406

Koch - Application for a Earth Station Authorization Exhibit A - Radiation Hazard Study When applying for a license to construct and operate, modify, or renew an earth station, it is understood that the applicant 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. § 1.1307. In this report Koch 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. 1. Antenna Near-Field Power Density Calculation The extent of the near-field is defined by the following equation1: Rnear = (Dantenna)² / ( 4˨ ) where: Rnear = extent of the near-field (in meters) Dantenna = diameter of the antenna main reflector (in meters) ˨ = wavelength of the RF transmit frequency (in meters) The maximum on-axis power density within near-field is defined by the following equation2: Snear = {(16η Pfeed) / [˭ (Dantenna)²]} / 10 where: Snear = maximum on-axis power density within the near-field (in milliwatts per square centimeter) η = antenna aperture efficiency Pfeed = maximum power into antenna feed flange (in watts) Dantenna = diameter of the antenna main reflector (in meters) 1 See OET 65 page 27 formula (12). 2 See OET 65 page 28 formula (13). The right side of the equation is divided by 10 so that the power 2 spectral density units on the left side will be mW/cm . Page 1 of 6

Koch - Application for a Earth Station Authorization Exhibit A - Radiation Hazard Study 2. Antenna Far-Field Power Density Calculation The distance to the beginning of the far-field region is defined by the following equation3: Rfar = [0.6(Dantenna)²] /˨ where: Rfar = distance to beginning of far-field (in meters) Dantenna = diameter of the antenna main reflector (in meters) ˨ = wavelength of the transmit frequency in (meters) The maximum on-axis power density within the far-field is defined by the following equation4: Sfar = [(Pfeed Gantenna) / 4˭ (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) Gantenna = antenna main beam gain at AF transmit frequency (in numeric value) Rfar = distance to beginning of far-field (in meters) The on-axis power densities calculated from the above formulas represent the maximum exposure levels that the system can produce. Off-axis power densities will be considerably less. 3. Antenna Transition Region Power Density Calculation The on-axis power spectral density for the transition region is defined by the following formula5: Str = Snear Rnear / R 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) Rnear = is the distance that defines the end of the near field region. R = is the distance within in the transition region between the near field and far field regions. 3 See OET 65 page 29 formula (16). 4 See OET 65 Section 2, page 19, formula (3) and page 29, formula (18). The right side of the equation is 2 divided by 10 so that the power spectral density units on the left side will be mW/cm . 5 See OET 65 page 34, formula (17). Page 2 of 6

Koch - Application for a Earth Station Authorization Exhibit A - Radiation Hazard Study Since the distance within the transition region “R” will always be greater than the distance to the end of the near field region “Rnear” then Str ” Snear. 4. Antenna Feed-Flange Power Density Calculation The maximum power density at the antenna feed-flange is defined by the following equation6: Sfeed = 1000{[4(Pfeed)] / {[˭ (Dfeed)²] / 4}} where: Sfeed = maximum power density at the antenna feed-flange (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dfeed = diameter of the antenna feed-flange (in centimeters ) 5. Antenna Main Reflector Power Density Calculation The maximum power density in the main reflector region of the antenna is defined by the following equation7: Santenna = {[4(Pfeed)] / {[˭ {(Dantenna)²] / 4}} / 10 where: Santenna = maximum power density in the antenna main reflector region (in milliwatts per square centimeter) Pfeed = maximum power into antenna feed flange (in watts) Dantenna = diameter of the antenna main reflector (in meters) 6 The formula is multiplied by 1,000 on the right side of the equation to change the units from watts on the right side of the equation to milliwatts on the left side. 7 See OET 65 equation (11) which is “S = 4 P / A”, where “A” is the area of the reflector and for a circular 2 reflector A = (Dantenna ) / 4. The formula is divided by 10 on the right side to change the units from meters and watts on the right side of the formula to cm and mW on the left side. Page 3 of 6

Koch - Application for a Earth Station Authorization Exhibit A - Radiation Hazard Study 6. 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 / {[˭ {(Dantenna)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) Dantenna = diameter of the antenna main reflector (in meters) 7. Calculation of Radiation Levels and FCC Standards Koch understands that a licensee must ensure that people are not exposed to harmful levels of radiation. Koch plans to utilize the 1.2 meter Prodelin fixed and temporary-fixed antennas with 0.5 and 2-watt transmitters. The transmitters will be operated at full output power. The preceding formulas were used to calculate the power densities shown on the following page. The Commission’s maximum permissible exposure (MPE) limits at the transmit frequency band for the earth stations included in this application are provided in the table set forth below. Maximum Permissible Exposure (MPE) Limits at 14,000-14,500 MHz Power Averaging Density Time Exposure Criteria (mW/cm2) (minutes) Reference OET 65 page 67 general population/uncontrolled 1 6 Appendix A exposure Table 1 (A) OET 65 page 67 occupational/controlled exposure 5 30 Appendix A Table 1 (B) Page 4 of 6

Koch - Application for a Earth Station Authorization Exhibit A - Radiation Hazard Study Radiation Hazard Calculations – 1.2 meter Prodelin Antenna Antenna main reflector diameter 1.2 m 1.2 m Feed flange diameter 7.49 cm 7.49 cm RF transmit frequency 14.250 GHz 14.250 GHz Maximum power into antenna feed-flange 0.5 W 2.0 W Main-beam gain of antenna 43.2 dBi 43.2 dBi Antenna aperture efficiency 0.65 0.65 Antenna main reflector surface area 1.131 m² 1.131 m² Feed flange surface area 44.1 cm² 44.1 cm² Wavelength at RF transmit frequency 0.021 m 0.021 m Distance to beginning of far-field region 41.0 m 41.0 m Distance to extent of near-field region 17.1 m 17.1 m 2 2 Max. on-axis power density in far-field 0.05 mW/cm 0.20 mW/cm Satisfies MPE Limits Satisfies MPE Limits 2 2 Max. on-axis power density in near-field 0.12 mW/cm 0.46 mW/cm Satisfies MPE Limits Satisfies MPE Limits 2 2 Max. on-axis power density in transition region 0.12 mW/cm 0.46 mW/cm Satisfies MPE Limits Satisfies MPE Limits 2 2 Max. power density at feed-flange (see note) 45.4 mW/cm 181.4 mW/cm Potential Hazard Potential Hazard 2 2 Max. power density at main reflector 0.18 mW/cm 0.71 mW/cm Satisfies All MPE Limits Satisfies All MPE Limits 2 2 Max. power density between main reflector and 0.05 mW/cm 0.18 mW/cm ground Satisfies All MPE Limits Satisfies All MPE Limits 2 2 Note: Feed flange power density exceeds both uncontrolled MPE limit of 1 mW/cm and controlled MPE limit of 5 mW/cm Page 5 of 6

Koch - Application for a Earth Station Authorization Exhibit A - Radiation Hazard Study 8. Conclusion The calculations provided in this exhibit indicate that MPE limits are exceeded in certain areas of the 1.2 meter General Dynamics SATCOM Technologies Prodelin Series 1123-350 earth stations with 0.5 and 2-watt transmitters which are the subject of this application. The 1.2 meter antenna exceeds the MPE limits for occupational/controlled and general population/uncontrolled exposure at the feed horn and in the area between the feed horn and reflector for the 0.5 and 2-watt transmitters. All 1.2 meter antennas will be installed such that the area where the MPE is exceeded will not be readily accessible to humans. Additionally, all transmissions will be terminated whenever the technical staff is required, for maintenance or other activities, to occupy the regions where potentially hazardous power density levels can exist. The earth station electronics to be used with the 1.2 meter antenna have an automatic shut-off mechanism that will terminate transmissions if the receive signal is lost, which will occur if there is blockage of the area between the feed horn and reflector. Page 6 of 6


Document Created: 2010-12-20 15:18:52
Document Modified: 2010-12-20 15:18:52
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