Attachment Second RadHad

This document pretains to SES-LIC-20071010-01408 for License on a Satellite Earth Station filing.

IBFS_SESLIC2007101001408_600807

Exhibit C Radiation Hazard Study 1.0 Introduction This study analyzes the radiation hazard environment produced by 1.2 meter Ku-band antenna with a maximum power of 1.7 Watts into the antenna feed. 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. 2.0 Earth Station Antenna Parameters Major Axis (M) = 1.2 meters Minor Axis (m) = 1.2 meters Wavelength (λ) = 0.021 meters at 14.25 GHz Maximum power to the antenna (P) = 1.7 Watts 1.2 meter antenna gain (G) = 43.3 dBi at 14.25 GHz 1.2 meter antenna efficiency (η) = 0.65 Area of Reflector (A) = 1.13 m2 Area of the Feed (a) = 0.0167 m2 3.0 Region Definition The limit of the near field (Rnf) and the beginning of the far field (Rff) are calculated as follows: Near Field Extent Rnf = M2 4λ Rnf = 1.22 /(4 * 0.021) = 17.2 m Far Field Extent Rff = 0.6 M2 λ

Rff = (0.6)(1.22)/(0.021) = 41.2 m The region between 17.2 m and 41.2 m is designated as the transition region. 4.0 Power Density Calculations 4.1 Near Field Region The on-axis near field power density is calculated as follows: Snf = 4ηP A Snf = (4)(0.65)(1.7) 1.13 Snf = 3.9 W/m2 = 0.39 mW/cm2 The maximum on-axis power density in the near field region is is Snf = 0.39 mW/cm2. This meets the Uncontrolled Exposure limit of 1.0mW/cm2 found in Appendix A or OET Bulletin 65. The off-axis power density in the near field will always be less than the on-axis power density and therefore all volumes within the near field will meet the Uncontrolled Exposure limit of 1.0mW/cm2. 4.2 Transition Region The on-axis power density in the transition region is calculated as follows: St = SnfRnf R The maximum on-axis power density in the transition region is when R = Rnf at which point the power density is St = Snf = 0.39 mW/cm2. This meets the Uncontrolled Exposure limit of 1.0mW/cm2 found in Appendix A or OET Bulletin 65. The off-axis power density in the transition region will always be less than the on-axis power density and therefore all volumes within the transition region will meet the Uncontrolled Exposure limit of 1.0mW/cm2 found in Appendix A of OET Bulletin 65.

4.3 Far Field Region The on-axis power density in the far field region is calculated as follows: Sff = PG 4πRff2 Sff = (1.7)(10(43.3/10)) (4)(3.14)(41.2)2 Sff = 1.70 W/m2 = 0.170 mW/cm2 The maximum on-axis power density in the far field region is is Sff = 0.170 mW/cm2. This meets the Uncontrolled Exposure limit of 1.0mW/cm2 found in Appendix A of OET Bulletin 65. The off-axis power density in the far field will always be less than the on-axis power density and therefore all volumes within the far field will meet the Uncontrolled Exposure limit of 1.0mW/cm2. 4.4 Region between the Feed Flange and Main Reflector Transmissions from the feed horn are directed toward the reflector surface. The maximum power density between the feed and reflector surface can be calculated as: Sfl = 4P/A Sfl = (4)(1.7)/0.0167 Sfl = 407.1 W/m2 = 40.7 mW/cm2 This value exceeds the Uncontrolled and Controlled Exposure limits of 1.0mW/cm2 and 5.0mW/cm2, respectively, found in Appendix A of OET Bulletin 65 and represents a potential hazard. Therefore, a warning label will be affixed to the surface of the reflector to warn people to avoid the region between the antenna feed and the surface of the reflector. 4.5 Reflector Surface Region The power density at the surface of the reflector is approximated by: Sr = 4P/A Sr = (4)(1.7)/(1.13)

Sr = 6.01 W/m2 = .601 mW/cm2 This value meets the Uncontrolled Exposure limit of 1.0 mW/cm2 found in Appendix A of OET Bulletin 65. 4.5 Region Between Antenna and Ground Assuming uniform illumination of the reflector surface, the power density between the antenna and the ground can be calculated as follows: Sg = P/A Sg = 1.7/1.13 = 1.5 W/m2 = 0.15 mW/cm2 This value meets the Uncontrolled Exposure limit found in Appendix A of OET Bulletin 65. 5.0 Summary Table 1. Summary of Expected Radiation Levels General Occupational/Controlled Population/Uncontrolled Exposure Exposure Maximum Radiation Level Maximum Radiation Level (5.0 mW/cm²) (1.0 mW/cm²) Radiation Region Level Hazard Assessment Hazard Assessment (mW/cm2) Near Field 0.39 Satisfies FCC MPE Satisfies FCC MPE Rnf = 17.2 m Far Field 0.17 Satisfies FCC MPE Satisfies FCC MPE Rff = 41.2 m Transition Region 0.39 Satisfies FCC MPE Satisfies FCC MPE Rnf < Rt < Rff Region between Feed and 40.7 Potential Hazard Potential Hazard Reflector Reflector Surface 0.601 Satisfies FCC MPE Satisfies FCC MPE Region between Antenna and 0.15 Satisfies FCC MPE Satisfies FCC MPE Ground

6.0 Conclusion Using the methods outlined in OET Bulletin 65, the 1.2 m antennas meet the Uncontrolled and Controlled Exposure limits in all regions except in the region between the antenna feed and the reflector. A warning label will be affixed to the surface of the reflectors to warn people to avoid the region between the antenna's flange and the surface of the reflector.


Document Created: 2007-10-29 17:06:02
Document Modified: 2007-10-29 17:06:02
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