Attachment Ex A - Hazard Study

This document pretains to SES-LIC-20130219-00188 for License on a Satellite Earth Station filing.

IBFS_SESLIC2013021900188_986237

Exhibit A – Radiation Hazard Study

Design Analysis Author: Alan Jones Date: 17 August, 2012 Revision: - Subject: Radiation Hazard Analysis of the MNLA VA-91-KA 9.1M Antenna 1. Introduction This analysis has been prepared to determine the radiation hazard levels for the VA-91-KA 9.1M antenna. This analysis is not intended to certify that a safety hazard does or does not exist. It is the responsibility of the organization operating the antenna to evaluate the results of this analysis, along with other sources of data, and determine if a safety hazard exists. 2. Applicable Safety Standards The safety standards for electromagnetic field exposure vary between different countries and organizations, and there is not a single worldwide standard currently in effect. Some of the standards that ViaSat is familiar with are listed in Table 1. TABLE 1 - ELECTROMAGNETIC FIELD EXPOSURE STANDARDS Power Density Limit Standard Issuing Controlled Uncontrolled Number Standard Title Organization Environments Environments ANSI/IEEE IEEE Standard for Safety Institute of C95.1-1991 Levels with Respect to Electrical and 10.0 mW/cm2 10.0 mW/cm2 Human Exposure to Radio Electronics 15-300 GHz 15-300 GHz Frequency Electromagnetic Engineers Fields, 3 kHz to 300 GHz OET Evaluating Compliance with Federal Bulletin 65 FCC Guidelines for Human Communications 5.0 mW/cm2 1.0 mW/cm2 Edition 97- Exposure to Radiofrequency Commission 1.5-100 GHz 1.5-100 GHz 01 Electromagnetic Fields The standards listed above set exposure limits in terms of the mean squared electric (E2) and magnetic (M2) field strengths (V2/m2) and/or in terms of the equivalent plane-wave free-space power density (mW/cm2), as a function of frequency. The power density values given are those that apply to the transmit frequency band of the VA-91-KA antenna, 28.1 – 30.0 GHz. VA-91-KA Radiation Hazard Analysis Last Changed: 8/17/12 Exhibit A, Page 1 of 7

Radiation Hazard Analysis of the VA-91-KA 9.1M Antenna 17-Aug-12 3. Antenna Description The antenna being considered in this analysis utilizes a high efficiency 9.14-meter diameter axi-symmetric dual-reflector design. Some of the antenna dimensions are shown in Figure 1. The antenna is capable of transmitting over the 28.1 to 30.0 GHz frequency band. This analysis will be performed at the mid-band frequency of 29 GHz. feed aperture The antenna is equipped with three high power 5.40" dia amplifiers (HPA); each capable of producing a maximum output power of 250 watts. The HPAs are arranged in a 3 for 2 configuration 13.1° with only 2 operational at any time for a total transmit power of 500 watts. 360.0 in 52.0 in The power delivered to the antenna is determined by subtracting the transmission line losses from the HPA output power. The subreflector losses between the HPA output and the antenna feed horn are approximately 1.73 dB. This results in 335.7 watts maximum being radiated by the antenna feed. main reflector FIGURE 1 - ANTENNA GEOMETRY 4. Analysis 4.1 General The power flux densities in the spatial areas surrounding the antenna can be estimated from the geometry of the antenna system and by the use of computer programs capable of computing the near- and far-field radiation patterns of the antenna. The spatial areas around the antenna will be divided into specific regions and an appropriate analysis method will be used for each region. The following regions will be considered: • Region between the subreflector and main reflector • Region directly in front of the reflector aperture (parallel beam region) • Nearfield region • Far-field region These regions are illustrated in Figure 2. For a large antenna of aperture diameter D, most of the energy in the far-field region, beginning at a distance R=2D2/λ, occurs within a conical volume having a half-angle of λ/D radians. Close to the antenna, the energy is mostly confined to a cylindrical volume of diameter D. This energy is substantially parallel over the first part of the Nearfield region, diverging into a cone of half-angle λ/D at a transition range Exhibit A, Page 2 of 7

Radiation Hazard Analysis of the VA-91-KA 9.1M Antenna 17-Aug-12 R 0 =D2/2λ. The transition from one region to the next is gradual, and the dimensions shown indicate the traditional boundaries. Within the region between the subreflector and main reflector, the energy radiated by the feed is enclosed in a conical shaped volume extending from the feed aperture to the subreflector, and from the subreflector to the main reflector. λ/D (0.06°) D "parallel" beam region R0=D2/2λ (13,268 ft) near-field region R=2D2/λ (53,072 ft) far-field region FIGURE 2 - FIELD REGIONS 4.2 Main Reflector – Subreflector Region The energy radiated from the feed horn is confined to a conically shaped region that extends from the feed aperture to the surface of the subreflector. The energy reflects from the surface of the subreflector and is directed back towards the main reflector surface. The feed horn is designed such that the energy level at the edge of the subreflector is less than the level at the center of the subreflector. As a first approximation, the energy distribution can be assumed to be uniform over the conical region’s cross-section and the power density can be expressed as: P W = A where A = cross sectional area of the conical region in square centimeters P = radiated power in milliwatts. At the feed aperture we have a power density of: A f = π (R f ) = π (6.86 cm ) = 147.76 cm 2 2 2 P = 335.7 W = 3.357 × 105 mW W f = 2271.9 mW/cm 2 At the subreflector we have a power density of: Exhibit A, Page 3 of 7

Radiation Hazard Analysis of the VA-91-KA 9.1M Antenna 17-Aug-12 As = π (Rs ) = π (66.0 cm ) = 13,701.4 cm 2 2 2 P = 335.7 W = 3.357 × 10 5 mW Ws = 24.5 mW/cm 2 Assuming that total reflection occurs at the subreflector, the power density over the reflector aperture is: Am = π (Rm ) = π (457.2 cm ) = 656,692.9 cm 2 2 2 P = 335.7 W = 3.357 × 10 5 mW Wm = 0.511 mW/cm 2 Throughout most of the region between the subreflector and the main reflector, the actual power density that exists at a particular point is the combination of direct radiation and reflected radiation. For example, over most of the reflector aperture a person would be exposed to direct energy from the subreflector scattered field and to energy reflected from the main reflector. As a result, the electric field in some regions could be twice as strong, resulting in a power density four times as strong (power is proportional to voltage squared). As a conservative estimate, the power densities computed above are multiplied by four, resulting in the following power density values: C Feed Aperture W f x 4 = 9088.0 mW/cm2 Subreflector Surface Ws x 4 = 98.0 mW/cm2 Main Reflector Surface W m x 4 = 2.04 mW/cm2 4.3 On-Axis Power Density The radiated power in the region directly in front of the antenna reflector is primarily confined to a cylindrical volume having the same diameter as the reflector and extending out to a distance of approximately R 0 =D2/2λ. In this region, the power density varies as both a function of distance along the antenna axis and of distance away from the antenna axis. Figure 3 shows the on-axis power density vs. distance for a circular aperture with a 6 dB edge taper, computed using the expression derived by Mumford [3]. Also shown in Figure 3 are approximate formulas by Mumford that can be used to estimate the maximum power density. Exhibit A, Page 4 of 7

Radiation Hazard Analysis of the VA-91-KA 9.1M Antenna 17-Aug-12 10 1 Power Density (mW/cm^2) 0.1 0.01 3 4 5 100 1×10 1×10 1×10 Distance (feet) Exact Expression Approximate Expression FIGURE 3 - ON-AXIS POWER DENSITY VS. DISTANCE FOR A CIRCULAR APERTURE WITH A 6 DB PARABOLIC ON PEDESTAL APERTURE TAPER The simple expression for the maximum on-axis power density in the near-field region is: 4P Wnf = mW/cm 2 Am where P is the transmit power and A m is the reflector aperture area. For the VA-91-KA antenna, this is: Am = π (Rm ) = π (457.2 cm ) = 656,692.9 cm 2 2 2 P = 335.7 W = 3.357 × 10 5 mW Wnf = 2.045 mW/cm 2 The simple expression for the maximum on-axis power density in the far-field region is: Am P W ff = mW/cm 2 λ2 r 2 Exhibit A, Page 5 of 7

Radiation Hazard Analysis of the VA-91-KA 9.1M Antenna 17-Aug-12 where λ is the wavelength and r is the distance from the aperture. Table 4-1 shows the on-axis distance required to reach various power density levels. These distances are measured along the boresite axis of the antenna in the direction of the satellite. TABLE 4-1: ON-AXIS DISTANCE VS POWER DENSITY Power Density (W ff ) mW/cm2 Distance (meters) Distance (feet) 2.045 ≤ 3,176 ≤ 10,420 1.0 4,542 14,901 0.5 6,423 21,073 0.1 14,363 47,122 4.4 Off-Axis Power Density In order to determine the variation of power density off of the antenna axis, more sophisticated antenna analysis methods must be used. One such tool is the GRASP8 computer code, which permits the near- and far-field patterns of dual-shaped reflector antennas, such as the VA-91-KA antenna, to be analyzed. Previous analyses of similar antennas shows that the power density is relatively constant over the angular region corresponding to the cylindrical projection of the main reflector aperture, and that the power drops off rapidly outside the main reflector boundaries. The magnitude of the power density corresponds to the on-axis power density levels predicted by the approximate expression in the previous sections. Because the on-axis power density for the VA-91-KA antenna is well below the 10.0 mW/cm2 power density limit of the IEEE C95.1 standard, it is not necessary to compute the off-axis power density levels. 5. Summary of Results The results of the analyses are summarized in Table 2. TABLE 2 - SUMMARY OF RESULTS Comparison to Safety Standard Power FCC OET Bulletin 65 Density IEEE C95.1 (uncontrolled areas) Region mW/cm2 10 mW/cm2 1 mW/cm2 Feed Aperture 9,087.6 Exceeded Exceeded Subreflector Surface 98.0 Exceeded Exceeded Main Reflector Surface 2.04 Acceptable Exceeded Aperture Plane 2.04 Acceptable Exceeded Near-field at a Radius of 2.04 Acceptable Exceeded 10,000 feet Far-field (beam peak) See Figure 3 Acceptable Acceptable Exhibit A,Page 6 of 7

Radiation Hazard Analysis of the VA-91-KA 9.1M Antenna 17-Aug-12 These results indicate that the only region where the referenced safety standards are exceeded is the following: • The conical shaped region between the feed and subreflector and directly on boresight with the aperture out to approximately 15,000 ft (4572m). Personnel hazards in this area may be avoided by disabling the transmitter whenever anyone attempts to access the area between the feed and subreflector and whenever the antenna is pointed toward an inhabited location. 6. References 1. IEEE Std. C95. 1-1991, IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz 2. Federal Communications Commission, Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, OET Bulletin 65, Revision 97-01, Appendix A, August 1997. 3. Mumford, W.W., “Some Technical Aspects of Microwave Radiation Hazards”, Proc. IRE, vol. 49, pp. 427-447, February 1961. Exhibit A, Page 7 of 7


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