Attachment RF Analysis Exhibit

This document pretains to SES-LIC-20050412-00429 for License on a Satellite Earth Station filing.

IBFS_SESLIC2005041200429_424272

Analysis of Non—lonizimg Radiation associated with a 2.4 Meter Ku— band Earth Station Uplink System — Enginecring statement concerning the application of the Aircraft Owners and Pilots Asscciation (AOPA) for a transmit—receive Earth station. Uplink Antenna designation: RADIA;ITION HAZARD STUDY Introduction This study has; been performed by United Media on behalf of the AOPA to estimate the potential radiation hazz rd that could exist is the vicinity of it‘s fixed satellite service Earth station in the 14 CGHz band which emaploys a Prodedin model 1251 2.4 meter antenna. The power values employed in this study ire the maximum that the station can generate. Typical operating values would be lower. This study has been prepared in arcord with the Commission‘s "OST Bulletin #655 Edition 97—01", this bulletin gives methods for prelicting (and measuring) the expected power—dengity levels in the vicinity of an antenna, and has ber:n used throughout this study. The safety limits employed in this study are in conformance with FCX R&O 96—326. Bulletin #65 and the R&O define two classes of Maximum Permissible Exposure (MPE). The first and most restrictive applies to persons in an uncontrolled , public environment This MPE is an average of 1 mW/cem? in any 30 minute period. The second and less restrictive ME applies to persons in a controlled / Occupational environment where the MEE is an average of 5 mW/cm2 over any 6 minute period. This study will report the maximtim power flux densities in the far field, near field, and transition region of the Earthstation‘s beara. The study will also report the maximum power flux densities between the fzed and the main retlector, at the main reflector surface, and between the edge of the antenna and tie ground.

Mar 18 0S O0#:4€p § UU J Antenna Characteristic:s The antenna employed by the Earh station in this study has the following Characteristics: Anteniia Diameter C) 2.4 meters Antem a surface area (Sa) 1 (D/2)2 4.52 m2 U Feed ciameter (Df 6.63 cm Feed srea (Fa) x (Df/2)2 34.5 cm2 Waveength at 14.25 GHz. (1) 0.021 m Transinit power at feed (P) 15.38 Watts Antenna Gain (As P ratio) (G) 83176 at 14.25 GHz (49.2 dBi) Antenna aperture efficienc." (e) 0.65 (65 %) 3.1416

0 10. 158 US UY:i%¢%@p 11004 \Calculations and Resutts The field in front of an antenna in this portion of the spectrum can be characterized by referring to two separate regions, the near—fiel l or Fresnel region and the far—field or Fraunhofer region. 1. The Far Field region The boginniang of the far—fir:ld (RF) can be calculated by: Rf=0.6 D: /1 Where: D = antenns. diameter J = wavelength In this case the antenna is a Prodelin mode] 1251 2.4 meter antenna operating at a wavelsngth of 0.021 mete:s so the beginning of the far—field (Rf) is: = 0.6(2.421/1 or 3.456 / .021 or 164.6 m The maximum power der.:sity (Sf) on the main beam axis in the far—field region may be deterrvined by calculating the power density at the beginning of the far field: Sf = PG, 4R Wher: P = Power fed to the antenna in Watts G = anterpa gain as a ratio relative to isotropic (83176 or 49.2 dB) R = distarice to the point of interest Since this stndy concentr:tes on maximum potential exposure to humans (R) will be set to the b:ginning of the far—field (RFf) or 164.6 meters from above. So in this case the maxiinum intensity in the far field (Sf) will be: = 15.88 (;3176) / 4 (3.1416) 164.62 or 1.32 x.106 / 3.4 x 105 or 3.87Watts / m2 Convertin:; units, Sf = 0.387 mW / cem2 2. The near field region The extent of the near—fie:d region (Rn) can be found by: (1) Rn=D2/ 1(1) Where: D = antenia diameter 1 = waveength

vus 197 auuy v.a9 piaa Mar 18 OS 08:47%p Ig] 005 In this case the antenna is a 2.4 Meter operating at a wavelength of .021 Meters so the cxtent of the near field (Rn: is: = 242/4(021) or 5.76 / .084 or 68.57 c The vi Jue of the maximumnear field power density (Sn) is given by: S 16eP ; D2 II Where: P = Powerfed to the antenna in Watts = Apertite efficiency (In this case 0.65) D Anterna dameter In thr case the naximum. power reaching the antenna is 15.88 Watts, so the maximum near—f:eld intensity (Sn) will be: = 16(,65)15.88 / 3.1416(2.42) or 165.15 / 18.09 or 4.56 W/im2 Converting.units, S = 0456 mW/om2 3. The transition region The mgion between the rear field and the far field is the transition region. It is in the transiion region where whe power density starts to decrease with distance, thus the maximum power density:in the transition region will be equal to the maximum power densit ; calculated above f¢‘rthe near field or S = 0.456 +aW/cm2. 4. The region between the feed an the reflector AnottFer region to be investigated is between the feed and the main teflector. This is an area vith the shape of a cone extending from the feed horn to the main reflector. The power density will be highest at thie feed end of this cone and can be calculated by: Sp, = 2P / 5a Where: P = Powefed to the antenna in Watts Fa = Ars::of the feed aperture in cm In thi: case the maximumi.power reaching the feed is 15.88 Watts, so the maximum power density at the feed aperturi: (Sp,) will be: = 2P}ffia = 2(15.88)W /34.5 cm2 or 0.92 W/iem2 5. The main ieflector region

Mar 18 0S 03:47p 1090 Anothcr region to be investigated is at the main reflector. The power density (Sr) can be deterpuned in the same ‘nanner as at the feed except that the area is now that area represi:nted by the main reflector. This value can be found by: Sr = 2P / S:. Where: P = Powerfed to thc antenna in Watts Sa = Arez of the main reflector in meters? In this case the maximum sower reaching the feed is 15.88 Watts, so the maximum power densit= at the main reflecto: (Sr) will be: Sr =, 2P/S., = 2(15.88)W /5.76 m2 = 31.76/8.76 or 5.51 W /m2 Converting:units = 0.551 mW /cm 6. The region between the reflecto> edgeand the ground Another region to be inveg‘igated is between the edge of the main reflector and the ground. If the sowey were evenly cistributed over the surface of the reflector, that is if the aperture illumi iation was uniform, he power density at the cdge of the reflector (Sg) would be: Sg = P/Sz = 15.88W /5.76m or 0.275 mW/icm2,

Us: 4tp guu‘r Summary Table 1 For 5 mW / cm2 MP3 for Controlied / Occupational environments Regio:i Power Density Hazard Assessment 1. Far field, Rf = 164.6m 0.387 mW / cm2 No Hazard 2. Near—field, Rn = 68.57in 0.456 mW / cm2 No Hazard 3. Transition region, Rt 0.456—0.387 mW / cm2 No Hazard Rn <Rt<Rf 4. IBet ween main reflector aml Feed 0.92 W / cm?2 Potential Hazard 5. Reflector surface 0.551 mW / em2 No Hazard 6. Beiween antenna and g.:ound 0.275 mW / cm2 No Hazard Note to #G —above: Ass the case with all earth station antennas, the i!fumination is actua ly tapered to achiev s lower sidelobe leve)s. Specifically, those required by the FCC Rule: to achieve two—degree spacing. Tapers on the order of 10 dB or more are typical. With such an illuminaticn taper, the power density at the edge of the antenna will be consijerably below this vilue. United Media has consicerable experience in building, testing and maintaining satellite communication facilities of this type, and our experience testing high efficiency antennas of this tpe suggest an edge aper of at least 10dB will exist on this antenna.

s : 4Ep . igiuus Summary Table 2 For 1 mW / cm2 NPE for Uncontrolled / Public environmeunts Region Deasity Hazard Assessment l; Far field, Rf = 164.6m 0.387 mW / cm2 | No Hazard 2. Ne:r—field, Rn = 68.5711 0456 mW / cm2 No Hazard 3. Traasition region, Rt 0.456—0.387 mW / cm2 No Hazard Rn <Rt<Rf 4. Between main reflector: ani| Feed. 0.92 W / cm2 Potential Hazard 5. Reflector surface 0.551 mW / cm2 No Hazard 6. Between antenna and ground 0.275 mW / cm2 No Hazard

b : 4kp — wyuuzy Conclusion: This re latively low power cigital uplink does not represent a radiation hazard since the only potent al hazard is inside the antenna structure near the feedhorn. This is an easy area to control access to, and the "ransmitter will not be operational during any required antenna maintenance This station will be locatzd on the secured roof of the AOPA building located at the Frederick, MD airport. The: antenna will be mounted to an existing steel structure above the roof that would preclude 15cess to radiation with out the use of a ladder or lift of some type. Based on the above analysis and operating practices it is concluded that hnmans cannot come slose enough to the. Earth station antenna itself to be a hazard to members of the public or station personnel The Earth station antenns will be marked with standard radiation hazard warning signs including one placed on the surface of the antenna, thus warning individuals to avoid the area in front of the antenne. Unite1 Media MupmrdQ Covoven Raymiond A. Conover Presi—ent, Director of Engineetring


Document Created: 2005-03-21 10:34:17
Document Modified: 2005-03-21 10:34:17
© 2024 FCC.report
This site is not affiliated with or endorsed by the FCC