Attachment RF Analysis

This document pretains to SES-MOD-20120601-00479 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2012060100479_951909

Radiation Hazard Analysis Exhibit A Page 1 of 12 RF RADIATION HAZARD ANALYSIS FOR PROPOSED 3.7- METER KU-BAND TRANSMIT/RECEIVE SATELLITE EARTH STATION Prepared for: California State University, Chico, CA Prepared by: 1835 Algoa Friendswood Road Alvin, TX 77511 May 3, 2012

Radiation Hazard Analysis Exhibit A Page 2 of 12 I. INTRODUCTION Because of the highly directional nature of parabolic antenna systems, the possibility of significant human exposure to RF radiation is unlikely if precautions are taken to prevent incidental human access to those few areas where the existing power densities are in excess 1 of those recommended for human exposure. The predicted RF power density levels that can be generated by the proposed Ku-band satellite earth station are calculated below. The calculations show that there will be regions in the vicinity of the antenna that can experience substantial power density levels, such as the area between the feed and the reflector and the area directly in front and along the axis of the antenna. However, operational procedures will be rigidly enforced to ensure that personnel are never exposed to radiation levels above the FCC-adopted MPE limits of 5.00 mW/cm2 for occupational/controlled exposure, and 1.00 mW/cm2 for general population/uncontrolled exposure, even during periods of peak power output. Specific parameters used in the following RF radiation analyses for the proposed Ku-band satellite earth station are as follows: D = antenna diameter = 3.7 meters (12.1 feet) d = sub-reflector diameter = 0.478 meters (18.8 inches) f = frequency = 14,500 MHz λ = wavelength = 0.0207 meters π = Pi = 3.1416 2 A = physical aperture area (πD /4) = 10.75 square meters 2 a = surface area of sub-reflector (πd /4) = 0.179 square meters G = antenna transmit gain = 53.0 dBi = 199,526 P = maximum power into antenna feed = 79.4 Watts η = antenna efficiency = 0.63 EIRP = maximum EIRP from antenna = 72.0 dBW II. POWER DENSITY CALCULATIONS A. NEAR-FIELD REGION Within the near-field region of a parabolic reflector antenna, the maximum value of RF power 2 density occurs on-axis, at a distance of ( 0.2 D ) / λ. For the proposed Ku-band satellite 1 “Evaluating Compliance with FCC-Specified Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields,” OST Bulletin No. 65, August 1997, Federal Communications Commission, Office of Science and Technology, Washington, DC 20554.

Radiation Hazard Analysis Exhibit A Page 3 of 12 earth station, this distance will be 132 meters (434 feet) from the antenna. For conservatism in this analysis, however, it will be assumed that the maximum value of power density will exist throughout the entire length of the near-field region Rn, where Rn is determined as follows: Rn = D2/(4λ) = 165 m (543 ft) The maximum value of on-axis power density that will be possible within the near-field region of the proposed Ku-band satellite earth station antenna can be calculated as follows: PD (near-field) = (16 η P)/( π D2 ) = (4 η P) / A = 4 [(0.63) (79.4 W)] / (10.75 m2 ) 2 2 = 18.68 W/m = 1.87 mW/cm The on-axis power density (energy) in the near-field region of a parabolic reflector antenna can be assumed to be contained within a cylinder having a diameter equal to the antenna's diameter and extending upward into space at an angle equal to the antenna's elevation angle. For the proposed Ku-band satellite earth station, the elevated geometry of the reflector (the bottom edge will be approximately 15 meters or higher from the ground) and the rising edges of the cylindrical near-field and transition regions of the antenna will be such that these regions will generally not be accessible by the public or by earth station personnel. Conservative estimates of off-axis power density calculations in the near-field region can be made assuming a point of interest at least one antenna diameter from the center of the main beam. The resulting off-axis power density at any given distance from the antenna will be at least a factor of 100 (20 dB) less than the on-axis power density value at the same distance from the antenna. Therefore, for the proposed Ku-band satellite earth station, it may be assumed that the off-axis power density will be at least 20 dB below the maximum level at a radial distance of 3.7 meters (12.1 feet) from the center line axis of the antenna. At distances within the near field the maximum off-axis power density will, therefore, be no greater than: 2 2 ( 1.87 mW/cm ) / 100 = 0.0187 mW/cm B. TRANSITION REGION The power density in the transition region between the near field and the far field of a parabolic reflector antenna decreases inversely with distance from the antenna. For purposes of evaluating RF radiation levels, it is assumed that the transition region will extend from the end of the near field (165 meters or 543 feet) to the to the beginning of the far-field, which is determined as follows: Rf = (0.6 D2 ) / λ = 397 m (1,303 ft) The maximum power density levels in the transition region are again on-axis, and can be conservatively estimated (upper-bounded) in the following manner: PD (transition) = PD (near-field) x ( Rn / Rt )

Radiation Hazard Analysis Exhibit A Page 4 of 12 = ( 1.87 mW/cm2 ) x (165 m / Rt ) 2 < 1.87 mW/cm where Rt is point of interest in meters, with 165 meters (543 feet) < Rt < 397 meters (1,303 feet). The on-axis power density (energy) in the transition region of the antenna can again be assumed to be contained within a cylinder having a diameter equal to the antenna's diameter and extending upward into space at an angle equal to the antenna's elevation angle. For the proposed Ku-band satellite earth station, this geometry will make the transition region well out of reach by either the general public or by earth station technical/operations personnel. Conservative estimates of off-axis calculations in the transition region can be made in the same fashion as for the near-field region, by again assuming a point of interest at least one antenna diameter from the center of the main beam. The resulting off-axis power density at any given distance from the antenna will be at least a factor of 100 (20 dB) less than the on- axis power density value at the same distance from the antenna. Therefore, for the proposed Ku-band satellite earth station, it may be assumed that the off-axis power density will be at least 20 dB below the maximum level at a radial distance of 3.7 meters (12.1 feet) from the center line axis of the antenna. Within the transition region, the maximum off-axis 2 power density will be less than the maximum value of 0.0187 mW/cm that was determined above for the near-field region. C. FAR-FIELD REGION In the far-field region of a parabolic reflector antenna, the power is distributed in a pattern of maxima and minima (sidelobes) as a function of the off-axis angle between the antenna center line and the point of interest. For the proposed Ku-band satellite earth station, the maximum possible value of on-axis power density in the far-field region can be determined as follows: PD (far-field) = [(P) (G)] / (4 π Rf2 ) 2 = [(79.4 W) (199,526)] / [4 π (397 m) ] 2 = 0.80 mW/cm Off-axis power densities in the far-field region are reduced by at least 30 dB at angles of one degree or more from beam center). Therefore, for the proposed Ku-band satellite earth station, the far-field off-axis power density will be less than: 2 PD = (0.80 mW/cm ) / 1,000 2 = 0.00080 mW/cm

Radiation Hazard Analysis Exhibit A Page 5 of 12 D. IMMEDIATE VICINITY OF THE ANTENNA 1. BESIDE AND BEHIND ANTENNA For areas beside and behind the antenna structure, the radiation level will be less than the tapered illumination level of the reflector. For the proposed Ku-band satellite earth station, this level will be as follows: PD < the transmit power, P, divided by the area of the antenna reflector, A, less 6 dB taper. 2 PD < (79.4 W) / (10.75 m ) - 6 dB 2 = 0.185 mW/cm This value will be applicable at the edge of the main reflector, so the power density levels beside and behind the reflector will be even smaller. 2. REFLECTOR SURFACE For the proposed Ku-band satellite earth station, the maximum power density on the reflector surface can be determined as follows: PD = (4) (P) / (A) 2 = (4) (79.4 W) / (10.75 m ) 2 = 29.6 W/m 2 = 2.96 mW/cm 2 where "A" is the surface area of the reflector (10.75 m ) and the factor of 4 again results from the 6 dB tapered illumination level.

Radiation Hazard Analysis Exhibit A Page 6 of 12 3. BETWEEN MAIN REFLECTOR AND SUB-REFLECTOR For the proposed Ku-band satellite earth station, the maximum power density in this region will be on the feed flange surface, and is determined as follows: PD = (4) (P) / (a) 2 = (4) (79.4 W) / (0.179 m ) 2 = 1,774.1 W/m 2 = 177.4 mW/cm where “a” is the surface area of the feed output flange ( 0.179 m2) and the factor of 4 results from the 6 dB tapered illumination level. 4. BETWEEN ANTENNA AND GROUND For this area, the radiation level will be less than the tapered illumination level of the main reflector, and can be calculated in a fashion identical to that used for areas beside and behind the main reflector. As shown previously, this level will be bounded by: 2 PD = (79.4 W) / (10.75 m ) - 6 dB 2 = 0.185 mW/cm

Radiation Hazard Analysis Exhibit A Page 7 of 12 III. SUMMARY OF CALCULATION RESULTS Maximum Radiation Level 2 Region (mW/cm ) Hazard Assessment Between main reflector 177.4 Potential hazard. & sub-reflector Reflector surface 2.96 Potential hazard. Between antenna and ground 0.185 Complies with guidelines. Beside and behind antenna 0.185 Complies with guidelines. Near field, Rn < 165 m 1.87 (on-axis) Potential hazard. < 0.0187 (off-axis) Complies with guidelines. Transition region, Rt < 1.87 (on-axis) Potential hazard. (165 m < Rt < 397 m) < 0.0187 (off-axis) Complies with guidelines. Far field, Rf > 397 m 0.80 (on-axis) Complies with guidelines. < 0.00080 (off-axis) Complies with guidelines.

Radiation Hazard Analysis Exhibit A Page 8 of 12 IV. CONCLUSIONS The above analyses show that, if the proposed Ku-band satellite earth station were to operate at its highest possible value of peak power, power density levels in excess of the FCC-adopted MPE limit of 5.0 mW/cm2 for occupational/controlled exposure could occur in the following regions: • Between the main reflector and sub-reflector (maximum power density of 177.4 mW/cm2). • On the main reflector surface (maximum power density of 2.96 mW/cm2). The preceding analyses also show that power density levels in excess of the FCC-adopted MPE limit of 1.0 mW/cm2 for general population/uncontrolled exposure could occur in the following region: • Near field (maximum power density of 1.87 mW/cm2). • Transition region (maximum on-axis power density of less than 1.87 mW/cm2). The proposed Ku-band satellite earth station consists of a 3.7-meter antenna approximately 15 meters (or higher) from the ground (the antenna is mounted on the roof of a tall building). This will minimize the possibility of personnel in the general vicinity of the antenna being accidentally exposed to harmful levels of RF radiation. In addition, potentially high RF power density levels along the antenna pointing axis will not pose a hazard to either the general public or the earth station personnel. Due to the antenna elevation angle range (to cover the full domestic arc), the rising edges of the cylindrical near-field, transition regions, and far field of the antenna will be such that these regions will not be accessible to the general population located on the ground. However, the following measures will also be exercised to further guarantee that neither the general public nor technical/operations personnel will ever be subjected to harmful levels of RF radiation, should they temporarily be in the immediate vicinity of the antenna: • The antenna will be marked with standard radiation hazard warnings, advising personnel to stay away from the area in front of the reflector when the transmitter is operating. • The HPA will be turned off whenever maintenance or repair personnel are required to work on or in front of the antenna.

Radiation Hazard Analysis Exhibit A - Page 9 of 12 RADIATION HAZARD ANALYSIS for PROPOSED 3.7-METER KU-BAND TRANSMIT/RECEIVE SATELLITE EARTH STATION EQUIPMENT SPECIFICATIONS and PERFORMANCE PARAMETERS (Antenna Feed Type: Gregorian ) Antenna diameter: D = 3.7 meters D = 12.1 feet D = 146 inches Sub-reflector diameter: d = 18.8 inches d = 0.478 meters Frequency (maximum): f = 14,500 MHz Wavelength: λ = 0.0207 meters Antenna transmit gain: G = 53.0 dBi G = 199,526 numeric Antenna physical aperture area: A = 10.75 sq. meters Sub-reflector physical area: a = 0.179 sq. meters Antenna efficiency: η = 0.63 numeric HPA maximum power output: Pmax = 100.0 Watts Pmax = 20.0 dBW

Radiation Hazard Analysis Exhibit A - Page 10 of 12 RADIATION HAZARD ANALYSIS for PROPOSED 3.7-METER KU-BAND TRANSMIT/RECEIVE SATELLITE EARTH STATION EQUIPMENT SPECIFICATIONS and PERFORMANCE PARAMETERS, cont'd (Antenna Feed Type: Gregorian) Transmit system losses: Lt = -1.0 dB Lt = 0.79 numeric Maximum RF power into P = 79.4 Watts antenna feed: P = 19.0 dBW Maximum EIRP from antenna: EIRP = 72.0 dBW EIRP = 15,848,932 Watts

Radiation Hazard Analysis Exhibit A - Page 11 of 12 RADIATION HAZARD ANALYSIS for PROPOSED 3.7-METER KU-BAND TRANSMIT/RECEIVE SATELLITE EARTH STATION COMPUTATIONAL RESULTS (Antenna Feed Type: Gregorian) Distance to beginning Rf = 397 meters of the far field: Rf = 1,303 feet Maximum on-axis power S = 8.00 Watts/sq. meter density in the far field: S = 0.80 mW/sq. cm Off-axis power density S < 0.0080 Watts/sq. meter in the far field: S < 0.00080 mW/sq. cm Extent of the near field: Rn = 165 meters Rn = 543 feet Maximum on-axis power S = 18.68 Watts/sq. meter density in the near field: S = 1.87 mW/sq. cm Distance to maximum 0.2(D^2)/λ = 132 meters on-axis power density in the near field: 0.2(D^2)/λ = 434 feet Off-axis power density S < 0.187 Watts/sq. meter in the near field: S < 0.0187 mW/sq. cm

Radiation Hazard Analysis Exhibit A - Page 12 of 12 RADIATION HAZARD ANALYSIS for PROPOSED 3.7-METER KU-BAND TRANSMIT/RECEIVE SATELLITE EARTH STATION COMPUTATIONAL RESULTS, cont'd (Antenna Feed Type: Gregorian) Maximum on-axis power S < 18.7 Watts/sq. meter density in the transition region between the near S < 1.87 mW/sq. cm field and the far field: Off-axis power density S < 0.187 Watts/sq. meter in the transition region between the near field S < 0.0187 mW/sq. cm and the far field: Between main reflector S = 1,774.1 Watts/sq. meter and sub-reflector: S = 177.4 mW/sq. cm On reflector surface: S = 29.6 Watts/sq. meter S = 2.96 mW/sq. cm Between antenna and ground: S < 1.85 Watts/sq. meter S < 0.185 mW/sq. cm Beside and behind antenna: S < 1.85 Watts/sq. meter S < 0.185 mW/sq. cm


Document Created: 2012-05-04 14:04:13
Document Modified: 2012-05-04 14:04:13
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