Attachment Rad. Hazard Study

This document pretains to SES-LIC-20120106-00023 for License on a Satellite Earth Station filing.

IBFS_SESLIC2012010600023_933501

Radiation Hazard Page 1 of 3 Analysis of Non-Ionizing Radiation for an 0.98 meter Earth Station at Maximum EIRP. This report analyzes the Non-Ionizing radiation levels for an 1.0 meter Earth Station. The offices of Science and Technology Bulletin, Number 65, October 1985, specifies that the maximum level of Non-Ionizing radiation that a person may be exposed to over a six minute period is an average power density equal to 5 mW / cm^2. It is the purpose of this report to determine the power flux densities radiated by the Earth Station in the Far Field, the Near Field, Transition Region, Between the Feed Flange and the Reflector Surface, at the Reflector Surface, between the antenna edge and the ground, and on the other side of a steel reinforced concrete structure. The Chinese maximum exposure limit is much more conservative at 0.038 mW / cm^2. This standard does not have an exposure time limitation, and is therefore much lower to account for the possibility of continuous exposure. Calculation Parameters : The following parameters were used to calculate the various power flux densities radiated by this Earth Station. Antenna Manufacturer Prodelin Antenna Model 1984 value units Antenna Diameter D= 0.980 meters Antenna Surface Area A= 0.75 meters ^2 Feed Flange Diameter Df = 0.100 meters Area of Feed Flange Af = 0.0079 meters^2 Wavelength at 14.25 GHz Lambda = 0.021 meters Transmit Power at HPA Flange HPA = 16.000 Watts Losses to Antenna Flange L= 0.580 dB (+) Transmit Power at Antenna Input Flange P= 14.00 Watts Antenna Gain at 14.25 GHz G= 41.300 dBi Antenna Gain (ratio using 10^(41.3/10)) G= 13,489.6 PI PI = 3.141593 Antenna Aperture efficiency n= 0.63 Summary of Expected Radiation Levels : Far Field Calculations Calculated Value units Hazard? Distance to Far Field Region Rf = 27.37 meters Power Density in Far Field Region Wf = 2.01 mW / cm^2 Satisfies ANSI Near Field Calculations Extent of Near Field Region Rn = 11.40 meters Power Density in Near Field Region Wn = 4.68 mW / cm^2 Satisfies ANSI Transition Region Calculations Power Density in Transition Region Wn = 4.68 mW / cm^2 Satisfies ANSI Region between Feed Flange and Reflector Power Density at Feed Flange Wfl = 356.50 mW / cm^2 Potential Hazard Reflector Region Power Density at Reflector Surface Wr = 3.71 mW / cm^2 Satisfies ANSI Region between Reflector and Ground Power Density at Edge of Reflector Surface Wg = 0.037 mW / cm^2 Satisfies ANSI Region on other side of Reinforced Concrete Transmitted Power Density Wt = 0.00037 mW / cm^2 Satisfies ANSI Note: Calculations are at the maximum allowable power level for an antenna this size.

Radiation Hazard Page 2 of 3 Analysis of Non-Ionizing Radiation for an 0.98 meter Earth Station at Maximum EIRP. (Continued) Calculation Details : Far Field Calculations This region is contained within a roughly conical volume having the same diameter as the antenna at the beginning of the far field. The value calculated below is the maximum power in the volume. The power density in this region decreases inversely with the square of the distance. Distance to the beginning of the Far Field Reg Rf = 0.60 * D^2 / Lambda (meters) Rf = 27.37 meters Maximum Power Density in Far Field Region Wf = G * P / 4 * PI *Rf^2 (mW / cm^2) Wf = 2.01 mW / cm^2 Near Field Calculations Power flux density is considered to be at a maximum value throughout the entire length of the defined region. The region is contained within a cylindrical volume having the same diameter as the antenna. Past the extent of the near field region the power density decreases with distance from the transmitting antenna. Distance to the end of the Near Field Region Rn = D^2 / 4 * Lambda (meters) (extent of the near field) Rn = 11.40 meters Power Density in Near Field Region Wn = 16 * n * P / PI * D^2 (mW / cm^2) Wn = 4.68 mW / cm^2 Transition Region Calculations The transition region is located between the near field and far field regions. As stated above, the power density begins to decrease with distance in the transition region. While the power density decreases inversely with the distance in the transition region. The power density decreases inversely with the square of the distance in the far field region. The maximum power density in the transition region will not exceed that calculated for the near field region (4.68 mW/cm^2), as shown above. Region between Feed Flange and Reflector Transmissions from the feed horn are directed toward the reflector surface, and are confined within a conical shape defined by the feed. The maximum energy density between the feed and reflector surface is at the apex of the cone (at the feed horn flange) This power density can be calculated as follows: Power Density at Feed Flange Wfl = 2 * P / Af (mW / cm^2) Wfl = 356.50 mW / cm^2 Reflector Region The power density in the reflector region is determined in the same manner as the power density at the feed flange, above, but the area is now the area of the reflector aperture. Power Density at Reflector Surface Wr = 2 * P / A (mW / cm^2) Wr = 3.71 mW / cm^2

Radiation Hazard Page 3 of 3 Analysis of Non-Ionizing Radiation for an 0.98 meter Earth Station at Maximum EIRP. (Continued) Calculation Details (continued) : Region between Reflector and Ground Assuming uniform illumination of the reflector surface, the power density between the antenna and ground can be approximated using a formula from the Offices of Science and Technology Bulletin, Number 65, October 1985, Page 18, as follows: Power Density between Reflector and ground Wg = Wr * 10 ^(-20/10) (mW / cm^2) Wg = 0.037 mW / cm^2 Transmission through steel reinforced concrete Assuming steel reinforced concrete of a thickness greater than 1/2 of the wavelength of the incident illumination, (1.05 cm.) the transmission attenuation is greater than 20 dB. This results in a transmitted power as follows: Transmitted Power Density Wt = Wg * (10 ^(-20/10)) (mW / cm^2) Wt = 0.00037 mW / cm^2 Conclusions : Based on the analysis, it is concluded that harmful levels of radiation will not occur in the regions accessible by people. Fencing, padlocks, and/or signs will be used to restrict access of the public and operating personnel to areas where the radiation level exceeds the ANSI standard . The transmitter will be turned off during maintenance activities so that the ANSI standard of 5 mW / cm^2 will be complied with for those regions that exceed acceptable levels.


Document Created: 2012-01-03 11:31:11
Document Modified: 2012-01-03 11:31:11
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