Attachment RADIATION HAZARD STU

This document pretains to SES-LIC-20060412-00642 for License on a Satellite Earth Station filing.

IBFS_SESLIC2006041200642_481433

RADIATION HAZARD STUDY ANTENNA- PRODELIN CORPORATION 2.4 METER (Antenna Model No. 1251) Analysis of Non-Ionizing Radiation for Prodelin Corporation 2.4 Meter (Model No. 1251) Earth Station Systems This report analyzes the non-ionizing radiation levels for a 2.4 meter earth station system. The analysis and calculations performed in this report are in compliance with the methods described in the FCC Office of Engineering and Technology Bulletin, No. 65 first published in 1985 and revised in 1997 in Edition 97-01. The radiation safety limits used in the analysis are in conformance with the FCC R&O 96-326. Bulletin No. 65 and the FCC R&O specifies that there are two separate tiers of exposure limits that are dependant on the situation in which the exposure takes place and/or the status of the individuals who are subject to the exposure. The Maximum Permissible Exposure (MPE) limits for persons in a General Population/Uncontrolled environment are shown in Table 1. The General Population/Uncontrolled MPE is a function of transmit frequency and is for an exposure period of thirty minutes or less. The MPE limits for persons in an Occupational/Controlled environment are shown in Table 2. The Occupational MPE is a function of transmit frequency and is for an exposure period of six minutes or less. The purpose of the analysis described in this report is to determine the power flux density levels of the earth station in the far-field, near-field, transition region, between the subreflector or feed and main reflector surface, at the main reflector surface, and between the antenna edge and the ground and to compare these levels to the specified MPEs. Table 1. Limits for General Population/Uncontrolled Exposure(MPE) Frequency Range (MHz) Power Density (mW/cm2) 30-300 0.2 300-1500 Frequency(MHz)*(0.8/1200) 1500-100,000 1.0 Table 2. Limits for Occupational/Controlled Exposure (MPE) Frequency Range (MHz) Power Density (mW/cm2) 30-300 1.0 300-1500 Frequency(MHz)*(4.0/1200) 1500-100,000 5.0 Table 3 contains the parameters that are used to calculate the various power densities for the earth stations.

Table 3. Formulas and Parameters Used for Determining Power Flux Densities Parameter Abbreviation Value Units Antenna Diameter D 2.4 m Antenna Surface Area SAA π * D2/4 m2 Feed Flange Diameter DFF 14.0 cm Feed Flange Surface Area SFA π * DFL 2/4 cm2 Frequency (Ku-band) F 14250 MHz Frequency (Ku-band) T 7.018E-11 s Wavelength λ c/(t) m Transmit Power PW 8.00 W Antenna Gain GES 49.2 dBi Antenna Efficiency η 0.65 n/a EIRP EIRP1 400949.799 W Speed of Light C 299792458 m/s Pi π 3.141592654 n/a 1. Far Field Distance Calculation The distance to the beginning of the far field can be determined from the following equation:(1) Distance to the Far Field Region (RFF) = 0.60 * D2 / λ (1) = 164.27 m where: RFF = distance to beginning of far-field D = antenna diameter λ = wavelength The maximum main beam power density in the Far Field can be determined from the following equation:(2) On-Axis Power Density in the Far Field (SFF) = GES * PW / 4 * π * RFF2 or EIRP / 4 * π * RF2 (2) = 1.962 W/m2 2 = 0.196 mW/cm where: SFF = power density (on axis) PW = power fed to the antenna GES = power gain of the antenna in the direction of interest relative to an isotropic radiator RF = distance to the point of interest 2. Near Field Calculation Power flux density is considered to be at a maximum value throughout the entire length of the defined Near Field region. The region is contained within a cylindrical volume having the same diameter as the antenna. Past the boundary of the Near Field region the power density from the antenna decreases linearly with respect to increasing distance. The distance to the end of the Near Field can be determined from the following equation:(3) Extent of the Near Field (RNF) = D2 / (4 * λ) (3) = 68.45 m 1 EIRP Calculator when PW = 8.0W and GES = 49.6 dBi

where: RNF = extent of near-field D = maximum dimension of antenna (diameter if circular) λ = wavelength The maximum power density in the Near Field can be determined from the following equation:(4) Near Field Power Density (SNF) = 16.0 * η * PW / π * D2 (4) = 4.598 W/m2 = 0.460 mW/cm2 where: SNF = maximum near-field power density η = aperture efficiency, typically 0.5-0.75 PW = power fed to the antenna D = antenna diameter 3. Transition Region Calculations The Transition region is located between the Near and Far Field regions. The power density begins to decrease linearly with increasing distance in the Transition region. While the power density decreases inversely with 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. The power density calculated in Section 1 is the highest power density the antenna can produce in any of the regions away from the antenna. The power density at a distance Rt can be determined from the following equation:(5) Transition region Power Density (ST) = SNF * RNF / RT (5) = 0.460 mW/cm2 where: ST = power density in the transition region SNF = maximum power density for near-field calculated above RNF = extent of near-field calculated above RT = distance to point of interest 4. Region between Main Reflector and Subreflector Transmissions from the feed assembly are directed toward the subreflector surface, and are reflected back toward the main reflector. The most common feed assemblies are waveguide flanges, horns or subreflectors. The energy between the subreflector and the reflector surfaces can be calculated by determining the power density at the subreflector surface. This can be determined from the following equation:(6) Power Density at Feed Flange (SFL) = 4 * PW / AS (6) = 207.876 mW/cm2 5. Main Reflector Region The power density in the main reflector is determined in the same manner as the power density at the subreflector. The area is now the area of the main reflector aperture and can be determined from the following equation:(7) Power Density at the Main Reflector Surface (SRS) = 4 * PW / S2A (7) = 7.074 W/m = 0.707 mW/cm2

where: SRS = maximum power density at the antenna surface PW = power fed to the antenna AS = physical area of the aperture antenna 6. Region between Main Reflector and Ground Assuming uniform illumination of the reflector surface, the power density between the antenna and ground can be determined from the following equation:(8) Power Density between Reflector and Ground (SG) = PW / SA (8) = 1.768 W/m2 2 = 0.177 mW/cm Table 4. Summary of Expected Radiation levels for Uncontrolled Environment Region Calculated Maximum Radiation Hazard Assessment Power Density Level (mW/cm2) 1. Far Field (RFF) = 164.27 m 0.196 Satisfies FCC MPE 2. Near Field (RNF) = 68.45 m 0.460 Satisfies FCC MPE 3. Transition Region 0.460 Satisfies FCC MPE SNF < ST < SFF, (ST) 4. Between Main Reflector and 207.876 Potential Hazard Subreflector 5. Main Reflector 0.707 Satisfies FCC MPE 6. Between Main Reflector and 0.177 Satisfies FCC MPE Ground Table 5. Summary of Expected Radiation levels for Controlled Environment Region Calculated Maximum Radiation Hazard Assessment Power Density Level (mW/cm2) 1. Far Field (RFF) = 164.27 m 0.196 Satisfies FCC MPE 2. Near Field (RNF) = 68.45 m 0.460 Satisfies FCC MPE 3. Transition Region 0.460 Satisfies FCC MPE SNF < ST < SFF, (ST) 4. Between Main Reflector and 207.876 Potential Hazard Subreflector 5. Main Reflector 0.707 Satisfies FCC MPE 6. Between Main Reflector and 0.177 Satisfies FCC MPE Ground It is the applicant's responsibility to ensure that the public and operational personnel are not exposed to harmful levels of radiation. 7. Conclusions Based on the above analysis it is concluded that harmful levels of radiation will not exist in regions normally occupied by the public or the earth station's operating personnel. The transmitter will be turned off during antenna maintenance so that the FCC MPE of 5.0 mW/cm2 will be complied with for those regions with close proximity to the reflector that exceed acceptable levels.


Document Created: 2006-02-03 17:09:51
Document Modified: 2006-02-03 17:09:51
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