MT2220 Exhibit B - R

LETTER submitted by ViaSat, Inc.

New RADHAZ

2016-01-19

This document pretains to SES-MOD-20151203-00909 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2015120300909_1123209

FCC Form 312 Exhibit B RF Hazard Analysis of the Terminal Analysis of Non-Ionizing Radiation for MT2220 Earth Station Antenna System This report analyzes the non-ionizing radiation levels for the MT2220 earth station 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. 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/cm2 average power density over a 30 minute period. The applicable exposure limit for the Occupational / Controlled environment, i.e., areas that only authorized / trained personnel have access to, at this frequency of operation is 5 mW/cm2 average power density over a 6 minute period. Summary of expected radiation levels for an Uncontrolled environment Region Maximum Power Density Hazard Assessment Safe region range (R) ≥ 0.475 m 1.0 mW/cm2 Satisfies FCC MPE Far field (Rff) = 0.091 m (3.6 inches) 27.2 mW/cm2 Potential Hazard Conclusions The proposed earth station system will be mounted on the top of a vehicle. During operation, the user will be greater than 0.475 m (18.7 inches) away from the unit. The maximum gain (used in this analysis) occurs at a 90 degree elevation angle and is reduced significantly at an elevation angle of 15 degrees or less. At the edge of far field region, a PFD of 27.2 mW/cm2 is obtained, decaying rapidly to 1 mW/cm2 at a distance of 0.475m (18.7 inches) from the antenna axis. Power decays dramatically from that point towards personnel near or inside the vehicle, remaining below hazardous PSD levels. Based on the above analysis it is concluded that no hazard exists for the public.

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: S = power density at the specified distance Rff = distance to the beginning of the far-field R = 0.475 m (18.7 in) distance to point of interest P = 6.3W power fed to the antenna in Watts D = 0.166 m effective diameter of antenna array G = 4.5 (6.5 dB) power gain relative to an isotropic radiator F = 1660.5 frequency in MHz  = 0.181 m wavelength in meters (300/MHz) Figure 1 illustrates a typical configuration in which the antenna is installed on top on a vehicle. The exact mounting location will vary depending on the vehicle. It will be shown in this report for this analytical case that the RF exposure hazard environment is benign for personnel on the ground or in the vehicle. .. Figure 1: MT2220/Explore 122 Mobile SATCOM Terminal

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) / . = (0.6 * (0.166 m)2) / 0.181 m = 0.091 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 * π * Rff2) = (6.3 W * 4.5) / (4 * π * (0.091 m)2) = 27.2 mW/cm2 The power density at the point of interest in the far-field region of the radiation pattern can be estimated by the equation: Sff = (P * G) / (4 * π* R2) = (6.3 W * 4.5) / (4 * π * (0.475 m)2 ) = 0.999 mW/cm2


Document Created: 2016-01-19 15:56:51
Document Modified: 2016-01-19 15:56:51
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