Attachment WSYR Rad-Haz 1 2m Ku

This document pretains to SES-LIC-20111109-01342 for License on a Satellite Earth Station filing.

IBFS_SESLIC2011110901342_925547

RADIATION HAZARD ANALYSIS FOR PRODELIN SERIES 1134 1.2m Ku-Band Antenna PERFORMED FOR WSYR-TV November 8, 2011 Prepared By: COLIN M ROBINSON General Dynamics SATCOM Technologies 1500 Prodelin Drive Newton NC 28658 USA 828-464-4141 www.gdsatcom.com CMR 11-2011

RADIATION HAZARD ANALYSIS FOR PRODELIN SERIES 1134 Ku-BAND 1.2m ANTENNA (PERFORMED FOR WSYR-TV) SUMMARY: This Rad-Haz analysis has been undertaken for WSYR-TV for a Prodelin 1134 Series Ku- band 1.2 m diameter antenna. The analysis follows the guidelines published in the FCC OET Bulletin 65 titled, "Evaluating Compliance with FCC Guidelines for Human Exposure to Radio Frequency Electromagnetic Fields", dated August 1997. (Refer to Appendix 1 & 2 attached hereto.) The referenced document identifies two exposure levels for non- ionizing microwave radiation to which (a) employees and operators and (b) the general public may be exposed. The former condition (a), is defined as a controlled environment wherein the maximum exposure power density is limited to 5 mW / cm2 averaged over any 6-minute period. The second condition (b), applies to the general public and is defined as an uncontrolled environment, wherein the exposure is limited to 1 mW / cm2 averaged over any 30-minute period. For this analysis we have assumed the condition (b) (1 mW / cm2), time-averaged for a 30 minute exposure and a transmitter input power of 25 watts. KEY PARAMETERS: The following information lists the key parameters and assumptions used in this analysis. Antenna Diameter (D) 1.2m (120 cm) Mid-band Tx Frequency (F) 14.25 GHz Nominal Antenna Efficiency (η) 64.8% Nominal input power to antenna (P) 25 watts Mid band antenna gain (dB) 43.2 dBi DERIVED PARAMETERS: This section presents the values derived from the antenna parameters, frequency etc. following the FCC guidelines. Regions: (a) Mid-band wavelength λ (cm) = 30 / Freq (GHz) = (30 / 14.25) = 2.11 cm (b) Near Field Limit (Rnf) = (D2 / 4λ ) = (1202) / (4 x 2.11) = 1706.2 cm (17.1 m) (c) Approx. Far Field Limit (Rff) = (0.6 D2 / λ = (0.6 x 1202) / (2.11) = 4094.0 cm (40.9 m) CMR 11-2011

The “Transition Region” is defined as region between Rnf and Rff. In this case it extends over a distance of 17.1 m to 40.9 m in front of the antenna. POWER DENSITY CALCULATIONS (ON AXIS): Power Density at Antenna Surface (PD ref): PDref = 4P/ reflector area = 4P / {π D2 / 4} = 4 x 25,000 / {π x 1202 / 4} = 8.84 mW / cm2 Maximum Power Density in the Nearfield Region (PDnf): PDnf = 16ηP/π D2 = 16 x 0.648 x 25000 / π x 1202 = 5.73 mW / cm2 Power Density at beginning of Farfield Region (PDff) PDff (approx) = (P x Gabs) / (4 x π x Rff2) = (25000 x 1043.2/10) / (4 x π x 40942) = 2.48 mW / cm2 To establish the distance at which a 1 mW/ cm2 power density is achieved when using a 25 watt transmitter, we would set the limit at 1 mW / cm2 and utilize the equation above to compute the corresponding R value. Thus the 1 mW / cm2 limit is achieved at a distance of approx. 64.5 meters (211.5’) in front of the antenna – measured along the radiation axis. At a typical elevation look angle of 40 deg above the horizon, the 1mW / cm2 for this case occurs at a height of 136’ above the local ground level. OFF-AXIS POWER DENSITY CONSIDERATIONS (Near Field & Transition Region) Off-axis power densities are typically 20 dB, or more, below the corresponding on-axis levels for locations displaced by one antenna diameter from the center of the main beam. As the maximum power density levels (on-axis) are approx. 5.73 mW / cm2 in the near- field, the off-axis exposure levels 1.2m of the central radiation axis will be reduced by a further factor 100 or 20 dB. This equates to a power density exposure of 0.06 mW / cm2. Per the FCC OET-65 Bulletin, it can be assumed that these off axis power density predictions apply through the near-field and transition field regions. In the case of the 1.2m antenna for the WSYR-TV application, the 0.06 mW/cm2 condition would extend out to a distance of 4094 cm (134’). At this distance the edge of the off-axis cylinder would be approximately 86 feet above ground level assuming a 40 degree elevation look angle to the satellite of interest. CMR 11-2011

OFF-AXIS POWER DENSITY CONSIDERATIONS (Far Field Region) The radiation pattern for the Prodelin 1134 antenna in far field region will be such that the antenna gain (dBi) from 1 to 48 degrees will below 32 – (25 log10 (θ)), where θ is the angle in degrees from the axis of the main lobe. The off-axis gain for an angle of 40 degrees off beam peak will be – 8.05 dBi. Since the on-axis power density on at the beginning of the far field (4094 cm from the antenna) is 2.48 mW/cm2, the power density at 40 degrees (essentially ground level at this distance is 0.39 mW / cm2. This falls below the 1.0 mW / cm2 limit recommended by the FCC. POWER DENSITY – FEED CONSIDERATIONS: A condition not directly addressed by OET-65, covers the region immediately in front of, and close to the antenna feed. Here the radiated field is confined to a cylindrical beam with a diameter matching that of the feed horn aperture. The power density in this region is determined from the input power to the feed divided by the feed aperture area. The feed for the Prodelin model 1134 Ku-band antenna has a nominal aperture diameter of 14.6 cm. With this diameter, and an input power of 25 watts, power density levels of approx. 149 mW / cm2 can be anticipated. Clearly this is a region of concern if work is performed on the antenna when the transmitter is supplying an input power of 25 watts to the feed. Warning decals are strongly recommended, alerting personnel to potential radiation hazards in the immediate antenna vicinity. CONCLUSIONS: The operational conditions for this application have been investigated following the FCC OET-65 guidelines. Safe operations require that precautions be limit the public exposure to a maximum of 1 mW / cm2 when the antenna is supplied with an input power of 25 watts. This can be accomplished by the operator, (WSYR-TV) ensuring that no un-trained personnel are allowed access to the front of the antenna of the feed region the transmitter is activated. Further the operator, (WSYR-TV) shall ensure that the transmitter is only turned on when the antenna is set to an elevated look angle following satellite acquisition. We recommend that prominent warning signs be displayed indicating the potential hazards from microwave radiation when the antenna is operating at its maximum power level. It is the responsibility of WSYR-TV and its operators to ensure that no person is accidentally permitted to enter the region in front of the antenna where power densities exceed the allowable 1 mW limit established by the FCC for the general population and in an uncontrolled exposure environment. Colin M. Robinson. CMR 11-2011

APPENDIX 1: FCC LIMITS FOR MAXIMUM PERMISSIBLE EXPOSURE [MPE] (From supplement C to FCC OET-65) CMR 11-2011

APPENDIX 2: EXTRACT FROM FCC OET 65, EVALUATING COMPLIANCE WITH FCC GUIDELINES FOR HUMAN EXPOSURE TO RADIOFREQUENCY ELECTROMAGNETIC FIELDS. CMR 11-2011

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Document Created: 2011-11-09 13:29:09
Document Modified: 2011-11-09 13:29:09
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