Attachment Exhibit-C

This document pretains to SES-LIC-INTR2019-01069 for License on a Satellite Earth Station filing.

IBFS_SESLICINTR201901069_1651299

Viasat, Inc. Exhibit C Analysis of Non-Ionizing Radiation for a 0.3 m Earth Station Antenna System Introduction This report analyzes the non-ionizing radiation levels for a 0.3 m earth station (ES) antenna system. The FCC’s Office of Engineering Technology’s Bulletin No. 65 specifies that there are two separate tiers of exposure limits that are dependent upon the situation in which the exposure takes place and/or the status of the individuals who are subject to the exposure. The two tiers are General Population / Uncontrolled environment, and an Occupational / Controlled environment. This ES antenna is mounted on the fuselage or vertical stabilizer on aircraft, well above head height of people working in the area and is covered by a radome which prevents access to the area between feed and reflector and reflector surface and which is clearly marked with RF warnings. Due to its location on top of the aircraft, the antenna is inaccessible to ground crew during normal gate operations when the antenna is active. The antenna will be turned off during maintenance windows where personnel may have access to areas near the antenna. Additionally, as discussed below, when maintenance occurs inside a hanger, the system will not transmit because receive communications (a precursor to transmit operations) with the satellite will be blocked. Because the environment is controlled and any potential exposure of a transitory nature, the limits for Occupational/Controlled Exposures are assumed to apply. Accordingly, this analysis discusses only the Maximum Permissible Exposure (MPE) limit for those types of exposures, which is a power density equal to five milliwatts per centimeter squared averaged over a six minute period. As described in the definitional section of this document, this report considers the maximum power density levels in the vicinity of an ES antenna in several regions: (1) the far field, (2) the near field, (3) the transition region between near field and far field, and (4) the surface of the radiating aperture. These radiation regions were analyzed using the definitions and formulas in Bulletin 65 for aperture antennas. The results of this analysis are summarized at the end of this document. Terminal Description The ES terminal transmits bursts of information at designated times that are assigned to the terminal by the network. The length and carrier frequency of each transmission burst depend on the ES terminal's traffic requirements. In normal operation, the ES terminal transmits burst traffic to the network with a nominal duty cycle of less than 5%. The ES terminal incorporates two “fail safe" features that limit the potential for human exposure. First, the transmitter is not enabled until the receive down link connection to the satellite has been established and an acceptable down link bit error rate has been achieved. The transmitter is disabled very quickly, in less than 40 milliseconds, if a loss of down connectivity occurs. This includes the case where human interference causes degradation

Viasat, Inc. in the link. Transmissions will not resume until approximately 10 seconds after downlink communications have been reestablished. Secondly, the terminal's transmitter is not capable of operating in a continuous transmit mode of operation. The ES terminal's power amplifier unit prevents the transmitter from remaining in a continuous transmit state for more than a few seconds. Under these conditions, the transmitter will be turned off briefly then resume normal operation after an internal reset has occurred. Analysis of Occupational/Controlled Environment The calculated values in the analysis show the exposure rates calculated using the formulae from the Office of Engineering and Technology Bulletin Number 65 (Edition 97-01) for the peak RF power output during transmission as reduced by the effect of duty cycle. This is because the Viasat network is based on a Time Division Multiple Access (TDMA) scheme using so-called “shared pipes". Viasat terminals transmit short bursts of data periodically as instructed by the network and are neither designed for nor capable of continuous transmission. Therefore, in order to compute the effective radiated energy of a Viasat ES terminal, the terminal’s transmitter duty cycle has been used to adjust the values calculated in accordance with Bulletin Number 65. To do this, the average power during the averaging period is calculated as the maximum transmitter peak transmit power output adjusted by the nominal duty cycle of 5%. An important aspect of the Viasat ES terminal is the “fail safe" feature. When the receive signal is lost due to signal blockage, the transmitter is shut down until the receive downlink is restored. The transmitter is shutdown in less than 40 milliseconds of the loss of the downlink. Since the areas of high field strength near the antenna aperture are very sensitive to blockage of the down link, this “fail safe" feature minimizes the potential for human exposure in the area between the feed and reflector. If the blockage due to human exposure occurs in these areas, the down link will be interrupted causing the transmitter to turn off almost immediately and it will remain off until the blockage is removed. After the blockage is removed, the ES terminal will have to reacquire the receive downlink and wait to be invited back into the network before the transmitter will be enabled. The complete downlink recovery time is 10 seconds. Accordingly, the average power value would be multiplied by 0.004 because the transmitter cannot transmit more than 0.4% of any rolling six minute period (the period over which the power density is averaged) with significant blockage near the aperture.

Viasat, Inc. Summary of expected radiation levels for a Controlled environment Region Maximum Power Density1 Hazard Assessment Safe region range ≥ 2.3 m 2.7 mW/cm2 Satisfies FCC MPE Far field (Rff) = 5.6 m 1.2 mW/cm2 Satisfies FCC MPE Near field (Rnf) = 2.3 m 2.7 mW/cm2 Satisfies FCC MPE Transition region (Rt) (Rt) = Rnf < Rt < Rff 2.8 mW/cm2 Satisfies FCC MPE Main Reflector Surface (Ssurface) 5.5 mW/cm2 Exceeds FCC MPE* * Note, that the power density level in the area between the feed and the reflector surface is greater than the reflector surface and is assumed to be a potential hazard. However, as discussed above, this region and the main reflector surface are covered by a radome, which prevents access to these areas. Analysis of General Population/Uncontrolled Environment The applicable exposure limit for the General Population / Uncontrolled environment, i.e., areas that people may enter freely, at this frequency of operation is 1 mW/cm^2 average power density over a 30 minute period. In the case of passengers and other members of the general public, no access is available near the antenna, and given the minimum operating elevation any area of uncontrolled access where general population may travel are well removed from the cylinder of RF projected by the antenna. Per OET-65, it can be assumed that if the point of interest is at least one antenna diameter removed from the center of the main beam, the power density at that point would be at least a factor of 100 (20 dB) less than the value calculated for the equivalent distance in the main beam. The expected power density then in any uncontrolled access area would be at least a factor of 100 below the values in the controlled environment and well below the 1 mW/cm2 general population limit. 1 Includes duty cycle factor of 5% typical in calculation of average power density over the reference period.

Viasat, Inc. Analysis The analysis and calculations that follow in this report are performed in compliance with the methods described in the OET Bulletin No. 65. Definition of terms The terms are used in the formulas here are defined as follows: Ssurface = maximum power density at the antenna surface Snf = maximum near-field power density St = power density in the transition region Sff = power density (on axis) Rnf = extent of near-field Rff = distance to the beginning of the far-field R = distance to point of interest Pa = 20 W maximum power amplifier output Lfs = 0 dB loss between power amplifier and antenna feed P = 20 W power fed to the antenna in Watts A = 0.73 m2 physical area of the aperture antenna G = 45910 power gain relative to an isotropic radiator D = 0.3 m diameter of antenna in meters F = 30.0 frequency in GHz l = 0.01 m wavelength in meters (300/FMHz) h = 0.50 aperture efficiency Antenna Surface. The maximum power density directly in front of an antenna (e.g., at the antenna surface) can be approximated by the following equation: Ssurface = (4 * P) / A (1.1) = (4 * 20 W * 0.05) / 0.073 m2 = 5.5 mW/cm2 Near Field Region. In the near-field or Fresnel region, of the main beam, the power density can reach a maximum before it begins to decrease with distance. The extent of the near field can be described by the following equation (D and l in same units): Rnf = D2 / (4 * l) (1.2) = (0.3 m)2 / (4 * 0.01 m) = 2.285 m

Viasat, Inc. The magnitude of the on-axis (main beam) power density varies according to location in the near field. However, the maximum value of the near-field, on-axis, power density can be expressed by the following equation: Snf = (16 * h * P) / (p * D2) (1.3) = (16 * 0.57 * 20 W * 0.05) / (p * (0.3 m)2) = 2.7 mW/cm2 Transition Region. Power density in the transition region decreases inversely with distance from the antenna, while power density in the far field (Fraunhofer region) of the antenna decreases inversely with the square of the distance. The transition region will then be the region extending from Rnf to Rff. If the location of interest falls within this transition region, the on-axis power density can be determined from the following equation: St = (Snf * Rnf) / R (1.4) = (2.7 mW/cm2 * 2.285 m) / R = (6.4 m * mW/cm2) / R where R is the location of interest in meters Far-Field Region. The power density in the far-field or Fraunhofer region of the antenna pattern decreases inversely as the square of the distance. The distance to the start of the far field can be calculated by the following equation: Rff = (0.6 * D2) / l (1.5) = (0.6 * (0.7 m)2) / 0.01 m = 5.485 m The power density at the start of the far-field region of the radiation pattern can be estimated by the equation: Sff = (P * G) / (4 * p * Rff2) (1.6) = (20 W * 45910) / (4 * p * (5.485 m)2) = 1.7 mW/cm2 Safe Region for Uncontrolled Access. As given above, the power density in the far field region of the antenna pattern decreases inversely as the square of the distance. The

Viasat, Inc. distance to the point where the power density equals the 5 mW/cm2 level can be determined by the equation: R5 mW = ( (P * G) / (4 * π * 5 mW/cm2 * 10) )0.5 (1.7) = ( ( 20 W * 45910 * 0.05) / (62.8 mW/cm^2) )0.5 = 2.7 m


Document Created: 0730-04-26 00:00:00
Document Modified: 0730-04-26 00:00:00
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