Attachment Rad. Haz. Study

This document pretains to SES-LIC-20161208-00938 for License on a Satellite Earth Station filing.

IBFS_SESLIC2016120800938_1160868

Radiofrequency (RF) Radiation Hazard Study License No. Pending: Antenna ID ATT-2M4 (AT&T ) This report summarizes the non-ionizing radiofrequency (RF) exposure levels associated with the above antenna system. RF prediction models and associated exposure limits referenced in this study are outlined in the Federal Communications Commission (FCC) Office of Engineering and Technology (OET) Bulletin 65 Edition 97-01 (August 1997). The FCC-exposure limits define the level of RF energy that a person may be continuously exposed without experiencing adverse health effects. This "safe" level, herein referred to as Maximum Permissible Exposure (MPE) limit, is comprised of two-tiers: one for conditions which the public may be exposed (General Population/Uncontrolled) and the other for exposure situations usually involving workers (Occupational/Controlled). Therefore, the intent of this study is to define the maximum "worst-case" RF exposure levels and compare the results relative to the applicable MPE limits. Based upon the following system parameters, the applicable MPE limits are: 1.0 mW/cm^2 and 5.0 mW/cm^2 for General Population/Uncontrolled and Occupational/Controlled environments, respectively, as specified in 47 CFR Part 1.1310. System Parameters Antenna Diameter (D1): 2.40 meters Antenna Surface Area (D1a): 4.52 meters^2 Feed horn Diameter (D2): 0.20 meters Feed horn Surface Area (D2a): 0.03 meters^2 Operating Frequency: 6138 MHz Wavelength (l): 0.049 meters Antenna Gain (G), @ 6138 MHz: 41.8 dBi Numerical Gain: 15135.6125 Transmit Power @ Antenna Input*: 20.0 watts Calculated Aperture Efficiency (n ): 0.64 Center height above ground level: 2.9 meters * Based on maximum power amplifier rating, where the actual operating power level will normally be reduced by various reduction factors (e.g., minimum output backoff, transmission loss, etc). For purposes of this study, this equates to an aggregate output EIRP for all carriers of 54.81 dBW maximum. Hazard Assessment For parabolic aperture antennas, three (3) regions are defined for predicting maximum RF exposure levels within the main-beam (on-axis) path: near-field, transition, and far-field regions. RF prediction methods are based on where the point-of-interest falls within these regions: 1. The far field (Rff) region is determined by the following equation: 0.6 D^2/l . This equates to a linear distance of approximately 70.71 meters from the antenna. The maximum main beam RF exposure level (Sff), in terms of power density units, at this point can be calculated as follows: Sff = PG / 40p(Rff)^2 = 0.48 mW/cm^2 2. The near field (Rnf) region is determined by the following equation: D^2/ 4l . This equates to a linear distance of approximately 29.46 meters from the antenna. The maximum RF exposure level (Snf), in terms of power density units, within this region can be calculated as follows: Snf = 0.4n P/ D1a = 1.12 mW/cm^2 (Assume maximum value maintained throughout the near field region) ** The transition (Rt) region is between the near-field and far-field regions, defined as Rff - Rnf. This equates to a region extending 41.25 meters, beginning at 29.46 meters and ending 70.71 meters from the antenna. While the exposure intensity decreases inversely with the square of the distance in the November, 2016 Page 1 of 3 EHS-4501-FRM-1C

Radiofrequency (RF) Radiation Hazard Study - Continued License No. Pending: Antenna ID ATT-2M4 (AT&T ) Hazard Assessment - Continued far field region, the exposure intensity decreases inversely with distance in the transition region. Therefore, the maximum RF exposure level in the transition region will not exceed the above calculated near field value (Snf). If the point-of-interest falls within the transition region, the estimated RF exposure level (St), in terms of power density units, can be calculated using the following mid-point (Rt) example: St = Snf * Rnf / R = 0.66 mW/cm^2 - at mid-point of Rt note: where 'R' is the point-of-interest within the Rt This offset prime focus antenna design uses a focal-point feed horn to direct RF energy towards the main reflector dish. The following calculations are used to predict the RF exposure levels at the main reflector surface and feed horn aperture: 3. The maximum RF exposure level (Smain-surface) in front of the main reflector surface (at rim), in terms of power density units, can be calculated as follows: Smain-surface = 0.4*P / D1a = 1.77 mW/cm^2 4. The maximum RF exposure level at the feed horn surface (Sfeed), in terms of power density units, can be calculated as follows: Sfeed = 0.4*P / D2a = 254.65 mW/cm^2 For evaluating accessible areas outside the main beam path, a practical estimation is to consider the maximum allowable gain pattern envelope for fixed-satellite services. Specifically, the antenna gain shall lie below the envelope defined as -10 dBi for angles greater than 48 degrees and less than/equal to 180 degrees from the main lobe axis. In considering areas immediately below the main reflector rim, the maximum RF exposure levels directed towards this region (Spoi), in terms of power density units, can be calculated as follows: 5. Spoi = PG/40p(R)^2 = 0.011 mW/cm^2 Note : where 'R' is the point-of-interest is just below antenna rim, which equates (in this case) to a centerline distance: 1.2 meters November, 2016 Page 2 of 3 EHS-4501-FRM-1C

Radiofrequency (RF) Radiation Hazard Study - Continued License No. Pending: Antenna ID ATT-2M4 (AT&T ) Hazard Assessment - Summary Summary of Calculated RF Exposure Levels Region Level (mW/cm^2) Assessment A. Far Field (Rff), 70.71 meters, = 0.48 Satisfies FCC MPE Limits B. Near Field (Rnf), 29.46 meters, = 1.12 Potential to exceed FCC General Population MPE Limit C. Rim of Main Reflector = 1.77 Potential to exceed FCC General Population MPE Limit D. Feed Horn Surface = 254.65 Potential to exceed FCC Occupational MPE Limit E. Area below Antenna Rim = 0.011 Satisfies FCC MPE Limits A C Far Field Rim of Main Reflector B Near Field D Feed Horn E Area Below Antenna Rim Conclusion The results of this study indicate RF levels directly in front of the antenna may exceed the FCC RF exposure limits. Appropriate measures such as use of fencing, barriers or RF safety signs must be taken to restrict access to regions where RF levels may exceed the FCC General Population/Uncontrolled MPE limit. The highest RF exposure levels are isolated to regions located between the feed horn and main reflector surface. Transmitter(s) must be turned off during antenna maintenance or servicing activities wtihin these regions to ensure compliance with the FCC Occupational/Controlled MPE limit. Performed by: MinSeok Cho (mc277x) Organization: Network Architect, Int'l & Alliances Date: 12/16/16 Phone No. +1 (425) 615-8067 November, 2016 Page 3 of 3 EHS-4501-FRM-1C


Document Created: 2016-12-08 13:31:59
Document Modified: 2016-12-08 13:31:59
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