Attachment Exhibit C

This document pretains to SES-MOD-20150819-00532 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2015081900532_1100514

Exhibit'C')'Radiation'Hazard'Analysis! ' ' Temporary)Fixed'Earth'Station'Terminal! Sat)Lite'1156'Ka'band'Antenna! ! Introduction! ! This!analysis!calculates!the!non/ionizing!radiation!levels!for!a!ViaSat,!Inc.!(“ViaSat”)! temporary/fixed!earth!station!terminal!(“TF!terminal”).!The!calculations!performed!in!this! analysis!comply!with!the!methods!described!in!FCC!Office!of!Engineering!and!Technology! Bulletin,!Number!65!(Edition!97/01)!(“Bulletin!65”).!This!analysis!demonstrates!that!ViaSat! TF!terminals!are!compliant!and!will!not!result!in!exposure!levels!exceeding!the!applicable! radiation!hazard!limits.! ! Bulletin!65!and!section!1.1310!of!the!Commission's!rules!specify!two!separate!tiers!of! exposure!limits:!one!for!Occupational/Controlled!Exposures!and!one!for!General! Population/Uncontrolled!Exposures.!Limits!for!Occupational/Controlled!Exposures!apply!in! situations!when!persons!are!exposed!as!a!consequence!of!their!employment!and!are!fully! aware!of!and!can!control!their!exposure.!These!limits!also!apply!in!situations!when!a! person!is!transient!through!a!location!where!such!limits!would!otherwise!apply!provided!the! person!is!made!aware!of!the!potential!for!exposure.!The!limits!for!General! Population/Uncontrolled!Exposure!apply!in!situations!in!which!the!general!public!may!be! exposed,!or!in!which!persons!that!are!exposed!as!a!consequence!of!their!employment!may! not!be!fully!aware!of!the!potential!for!exposure!or!cannot!exercise!control!over!their! exposure.!ViaSat!will!typically!deploy!its!CP!terminals!in!General!Population/Uncontrolled! Environments.!Accordingly,!this!analysis!discusses!only!the!Maximum!Permissible! Exposure!(“MPE”)!limit!for!those!types!of!exposures,!which!is!a!power!density!equal!to!1! milliwatt!per!centimeter!squared!averaged!over!a!thirty!minute!period.! ! As!described!in!the!definitional!section!of!Appendix!A,!this!report!analyzes!the!maximum! power!density!levels!in!the!vicinity!of!a!TF!terminal!antenna!in!five!regions:!(1)!the!far!field,! (2)!the!near!field,!(3)!the!transition!region!between!near!field!and!far!field,!(4)!near!the!main! reflector!surface,!and!(5)!between!the!main!reflector!and!the!feed.!These!radiation!regions! were!analyzed!using!the!definitions!and!formulas!in!Bulletin!65!for!aperture!antennas.!The! results!of!this!analysis!are!summarized!in!Tables!1!and!2!in!Appendix!A,!which!identify!the! potential!exposure!under!nominal!operating!conditions!and!worst/case!conditions,! respectively.! ! TF'Terminal'Description! ! The!TF!terminal!transmits!bursts!of!information!at!designated!times!that!are!assigned!to!the! terminal!by!the!network.!The!length!and!carrier!frequency!of!each!transmission!burst! depend!on!the!TF!terminal's!mode!of!operation.!There!are!three!modes!of!operation!(a)!Idle! Mode,!during!which!the!TF!terminal!is!not!in!active!use^!(b)!Normal!Mode,!when!there! terminal!is!actively!used!under!typical!network!loading!conditions^!and!(c)!High!Capacity! Mode,!When!the!terminal!is!actively!used!under!maximum!uplink!data!transfer!conditions.! !

In!Idle!Mode,!the!TF!terminal!transmits!only!timing!and!system!information!to!the!network! for!0.4!milliseconds!every!640!ms!seconds.!The!average!duty!cycle!(ratio!of!transmitter!on! to!transmitter!off!time)!in!Idle!Mode!is!0.06%.!In!Normal!Mode,!the!TF!terminal!transmits! burst!traffic!to!the!network!with!a!nominal!duty!cycle!of!10%.!To!support!heavy!data!upload! requirements!such!as!file!transfer,!current!network!configuration!allows!TF!terminals!to! increase!their!transmit!duty!cycle!to!30%!in!High!Capacity!Mode.!! ! Table!1!provides!a!summary!of!the!radiation!exposure!analysis!for!each!of!the!three!ViaSat! operating!modes.! ! The!TF!terminal!uses!transmitter!power!control!system!to!reduce!uplink!interference!and! mitigate!the!effects!of!changing!atmospheric!conditions.!Under!clear!sky!and!cloudy! conditions,!all!74!cm!Ka!band!TF!terminals!will!transmit!at!a!nominal!power!level!of!2.8! watts!or!less.!This!includes!terminals!at!the!edge!of!beam!locations.!In!rainy!conditions,!a! TF!terminal!typically!adjusts!its!transmitted!symbol!rate,!modulation,!and!forward!error! correction!coding!to!maintain!a!robust!link,!but!transmit!power!is!not!increased!beyond!the! maximum!power!level!of!2.8!watts.!! ! The!TF!terminal!incorporates!two!“fail!safe”!features!that!limit!the!potential!for!human! exposure.!First,!the!transmitter!is!not!enabled!until!the!received!down!link!connection!to!the! satellite!has!been!established!and!an!acceptable!down!link!bit!error!rate!has!been! achieved.!The!transmitter!is!disabled!very!quickly,!in!less!than!40!milliseconds,!if!a!loss!of! down!connectivity!occurs.!Transmissions!will!not!resume!until!approximately!10!seconds! after!downlink!communications!have!been!reestablished.!!Secondly,!the!terminal's! transmitter!is!not!capable!of!operating!in!a!continuous!transmit!mode!of!operation.!The!TF! terminal's!outdoor!unit!incorporates!a!watchdog!timer!that!will!shut!down!the!transmitter!if!it! remains!in!a!continuous!transmit!state!for!more!than!10!seconds.!Under!these!conditions,! the!transmitter!will!be!turned!off!for!3!ms!then!resume!normal!operation!after!an!internal! reset!has!occurred.! ! Explanation'of'the'Analysis! ! The!“Calculated!Values”!!in!Table!1!are!the!exposure!rates!calculated!using!the!formula! from!the!Office!of!Engineering!and!Technology!Bulletin!Number!65!(Edition!97/01)!for!a! system!with!continuous!(100%!transmit!duty!cycle)!transmission.!The!ViaSat!network,! however,!is!based!on!so/called!“shared!pipes”.!ViaSat!terminals!transmit!short!bursts!of! data!periodically!as!instructed!by!the!network!and!are!neither!designed!for!nor!capable!of! continuous!transmission.!Therefore,!in!order!to!compute!the!effective!radiated!energy!of!a! ViaSat!TF!terminal,!the!terminals!transmitter!duty!cycle!has!been!used!to!adjust!the!values! calculated!from!Bulletin!Number!65.! ! The!columns!in!the!tables!labeled!“Idle!Mode,”!!“Normal!Mode,”!and!“High!Capacity!Mode”! reflect!the!total!potential!for!human!exposure!based!on!the!length!of!time!that!the!TF! terminal!transmits!energy!during!a!rolling!30!minute!period.!In!Idle!Mode,!the!maximum! transmitter!duty!cycle!is!0.06%!and!therefore!the!values!in!the!column!labeled!“Idle!Mode”! are!equal!to!the!calculated!values!multiplied!by!0.0006.!Similarly,!in!Normal!Mode!the! maximum!transmitter!duty!cycle!is!10%!and!the!values!in!the!column!labeled!“Normal! Mode”!are!equal!to!the!Calculated!Values!multiplied!by!0.1.!!And!finally,!in!High!Capacity!

Mode!the!transmitter!duty!cycle!is!30%!and!the!values!in!the!column!labeled!“High! Capacity!Mode”!are!equal!to!the!Calculated!Values!multiplied!by!0.3.! ! The!MPE!level!calculations!for!each!of!the!three!operating!modes!for!conditions!labeled! “Between!feed!and!reflector”!are!calculated!based!on!the!“fail!safe”!features!of!the!ViaSat! TF!Terminal.!When!the!receive!signal!is!lost!due!to!signal!blockage,!the!transmitter!is!shut! down!until!the!received!down!link!is!restored.!The!transmitter!is!shutdown!in!less!than!40! milliseconds!of!the!loss!of!the!downlink.!Since!the!areas!of!high!field!strength!near!the! reflector!and!the!feed!are!very!sensitive!to!blockage!of!the!down!link,!this!“fail!safe”!feature! minimizes!the!potential!for!human!exposure.!If!the!blockage!due!to!human!exposure!occurs! in!these!areas,!the!down!link!will!be!interrupted!causing!the!transmitter!to!turn!off!almost! immediately!and!it!will!remain!off!until!the!blockage!is!removed.!After!the!blockage!is! removed,!the!TF!terminal!will!have!to!reacquire!the!receive!downlink!and!wait!to!be!invited! back!into!the!network!before!the!transmitter!will!be!enabled.!The!complete!downlink! recovery!time!is!10!seconds.!The!values!in!the!column!labeled!“Idle”,!“Normal”,!and!“Worst! Case”!are!multiplied!by!0.004!because!the!transmitter!can!not!transmit!more!than!0.4%!of! any!rolling!30!minute!period!with!significant!blockage!near!the!sub!reflector!and!between! the!sub/reflector!and!the!feed.! ! Results'of'Analysis! ! This!analysis!demonstrates!that!this!terminal!is!not!a!radiation!hazard!because!the!terminal! does!not!exceed!the!MPE!limit!of!1!milliwatt!per!centimeter!squared!averaged!over!a!thirty/ minute!period.!As!demonstrated!in!Tables!1!and!2,!the!areas!with!the!greatest!field! concentrations!is!between!the!feed!and!the!reflector!surface.!The!areas!in!which!these!high! field!concentrations!exist!are!very!small!in!size,!which!limits!the!risk!of!human!exposure!to! a!person's!hands!or!arms.!If!the!down!link!(receive!signal)!is!interrupted!by!an!object!in!an! area!of!high!field!concentration,!the!uplink!(transmit!signal)!is!shut!down!in!less!than!40! milliseconds!and!the!receiver!down!link!recovery!time!is!10!seconds.!The!uplink!will!remain! off!until!the!blockage!is!removed!and!the!downlink!recovery!is!complete.!This!feature,! coupled!with!the!terminal's!use!of!uplink!power!control!and!non/continuous!operation,! ensures!that!the!general!population!will!not!be!exposed!to!harmful!levels!of!radiation.! ! Conclusion! ! This!radiation!hazard!analysis!demonstrates!that!these!TF!terminals!will!not!result!in! exposure!levels!exceeding!the!applicable!radiation!hazard!limits.

Definitions! ! 1) Far Field Region ! The far field region extends outward from the mail reflector, beginning at a distance of 2 0.6 ⋅ Dmaj meters where the larger diameter of the elliptical antenna is Dmaj. The maximum power λ density is calculated using the equation recommended in Bulletin 65.! ! 2) Near Field Region! ! The near field region is an elliptical volume co-incident with the boresight of the main beam 2 D maj extending outward from the main reflector the length of the near field meters. The larger 4⋅ λ dimension (Dmaj) of the elliptical antenna is used in place of the diameter of a circular antenna to calculate the worst case length of the near field.! ! 3) Transition Region! ! The transition region is located between the near field region and the far field region. This region has a power density that decreases inversely with increasing distance. Therefore the power density in the transition region will be less than the power density in the near field for the purpose of evaluating potential exposure.! ! 4) Region Near the Main Reflector Surface! ! The power density near the main reflector surface can be estimated as equal to four times the the power divided by the area of the main reflector surface, assuming that the illumination is uniform and that it would be possible to intercept equal amounts of energy radiating towards and reflected from the antenna surface.! ! 5) Region between the Main Reflector and the Feed! ! The power radiated from the feed toward the reflector is conical in shape with the vertex at the feed. The maximum power is at the feed mouth and can be estimated as four times the transmit power divided by the area of the feed mouth. ! ! ! !

Table 1: Radiation from Sat—Lite 1156 Ka 1 m Temporary—Fixed Terminal Input Parometers Antenns Aperture MajorAxis: Day = 1207—cm Antenns Aperture MinorAxis: Das > 117.0.cm Diamate of Feed Mouth Dag > §46t<em Frequency otOperation: Max Pover into Anterna: p=2e w Apertre Eficiency: 4 = 042 Calculated Warelergth: a~s A=00tm F Area of Refector Area of Feed Mouth: Antenns Gain 10—log(G) = 4758 dBi Length of Near Fiekd Ry — $446m Beginning of FarFilt Ry — €7471m

Power Densiy Calculations Far Fild 1tle Mode Normal Mode High Capacity Mode 5p= 505e w r » 00125 o mw gyann oosh 2 gyt ts = 001725 pellly mw ap ooR Near Filt: ttle Mode Normal Mode Sy e 12 54050 » 0006—255.. sy. ons on 22 rDn2 ont ont Transtion Region: Power densit is less than the maximum near feld region power densty and greate than the minimum frReld region power density 1de Mode Normal Mode Figh Capacity Mode mw 5.10e » 00120 sans oons mw 1dle Mode Normal High Capacty Mode Mode mw 5,,,.0046 0 19— M 5,,2.0 0043 = 0 017 mw 5,,,.0 1286 — 0577 mw


Document Created: 1170-04-19 00:00:00
Document Modified: 1170-04-19 00:00:00
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