Radiation Hazard Study

0196-EX-ST-2012 Text Documents

Intelsat License LLC

2012-03-06ELS_123742

Attachment A Radiation Hazard Analysis TECOM KuStream 1500 Antenna This exhibit presents the radiation hazard analysis for the TECOM KuStream 1500 antenna to be used in demonstration/validation testing. The analysis uses the procedure outlined in OET Bulletin No. 65, Evaluating Compliance with FCC Guidelines for Human Exposure to Radio Frequency Electromagnetic Fields, Edition 97-01, pp. 26-30. The maximum level of non-ionizing radiation to which employees may be exposed is limited to a power density level of 5 milliwatts per square centimeter (5 mW/cm2) averaged over any 6 minute period in a controlled environment. The maximum level of non-ionizing radiation to which the general public may exposed is limited to a power density level of 1 milliwatt per square centimeter (1 mW/cm2) averaged over any 30 minute period in an uncontrolled environment. Note that the worst-case radiation hazards exist along the beam axis. Under normal circumstances, it is highly unlikely that the antenna beam axis will be aligned with an occupied area since that would represent a blockage to the desired signals, thus rendering the link unusable. This analysis is done for exposure to radiation in the near field, the far field, and the transition region. Safe limits are computed for the controlled and uncontrolled exposure for both the antenna main beam and sidelobes. The near field region for the main beam is defined in terms of the radius Rnf according to the relation Rnf = D2/4λ where D is the antenna panel width and λ is the transmit wavelength. Rnf, D and λ all have units of cm, centimeters. The maximum near field power density, Snf (units mW/cm2), is present at the face of the antenna and is determined from Snf = PPA/A where PPA is the transmit power, in mW, (after cable losses are accounted for) and A is the surface area of the antenna panel, in cm2. For a rectangular antenna such as the KuStream 1500, the surface area is A = D*h, where h is antenna height. The far field region for the main beam is at any distance (R) away from the antenna greater than Rff given by Rff = 0.60 D2/λ The far field power density Sff at distance R from the antenna is Sff = PEIRP/4π R2 where R is ≥ Rff and PEIRP is the Effective Isotropic Radiated Power of the antenna. The maximum far field power density is at R = Rff.

Near Field Exposure from Main Antenna Beam The KuStream 1500 antenna has dimensions D = 62.5 cm and h = 15.7 cm resulting in a surface area A = 981.25 cm2. At a transmit frequency of 14.5 GHz, the wavelength is 2.053 cm. The near field radius is then Rnf = 475 cm (4.75 m). The maximum permitted antenna radiation is 44.0 dBW. The antenna has a transmit gain of 28.8 dB. Consequently, the maximum transmit power is PPA = 15.2 dBW = 33.1 W = 33,113 mW. This results in a maximum near field power density of Snf = 33.7 mW/cm2 at the surface of the antenna. Far Field Exposure from Main Antenna Beam The minimum far field radius is Rff = 11.4 m. The maximum far field power density is at the minimum far field radius, Rff. At the terminal’s maximum transmit EIRP of 44.0 dBW, the far field power density at Rff is Sff = 1.53 mW/cm2. Meeting Radiation Exposure Limits The 5 mW/cm2 power density for controlled exposure occurs in the near field. Assuming that the field density decreases linearly from Snf of 33.7 mW/cm2 at R = 0 m to Sff of 1.53 mW/cm2 at R = 11.4m, the controlled exposure limit of 5 mW/cm2 occurs at 10.2 m. The 1 mW/cm2 power density for uncontrolled exposure occurs in the far field. At distance R = 14.1m, the far field power density is Sff = 1.00 mW/cm2. Both of these distances are at beam peak and assume the terminal is transmitting at maximum EIRP of 44.0 dBW. Based on antenna sidelobes with 12 dB reduction from the main beam and using the far field expressions,  to meet the limit of 5 mW/cm2 power density for less than 6 minutes for controlled exposure, no individual shall be within 1.6 m of the antenna while it is transmitting  to meet the limit of 1 mW/cm2 power density for less than 30 minutes for uncontrolled exposure, no individual shall be within 3.6 m of the antenna while it is transmitting. Summary This document presents the radiation hazard analysis for the TECOM KuStream 1500 antenna with a maximum EIRP of 44.0 dBW. If individuals are in the main beam of the antenna  For a controlled exposure, they shall be at least 10.2 meters away and for no more than 6 minutes  For an uncontrolled exposure, they shall be at least 14.1 meters away for no more than 30 minutes.

Intelsat shall ensure that no individuals shall be within the above-referenced distances of the antenna while it is transmitting. In particular, the antenna will be mounted to the top of an aircraft and Intelsat will control the area around the aircraft during on-ground operations to ensure that no individuals are within the main beam or sidelobes at the specified distances. During in-flight operation, there is no possibility of human RF exposure since no individuals will be within the specified distances of the aircraft. Backlobe roll-off and attenuation from the antenna tracking system, mounting assembly and aircraft fuselage ensure that individuals inside the aircraft will not be exposed to RF radiation in excess of permissible levels.


Document Created: 2012-03-06 20:26:49
Document Modified: 2012-03-06 20:26:49
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